feat(inline): rendering without alternate screen

Fix issue with growth resize for containers with corresponding
borders, padding and gaps.

.gitea/workflows/release.yaml

@@ -15,9 +15,15 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v4
       - name: Setup zig installation
-        uses: mlugg/setup-zig@v2
+        uses: https://codeberg.org/mlugg/setup-zig@v2
         with:
-          version: master
+          version: latest
+      - name: Lint check
+        run: zig fmt --check .
+      - name: Spell checking
+        uses: crate-ci/typos@v1.39.0
+        with:
+          config: ./.typos-config
       - name: Run tests
         run: zig build --release=fast
       - name: Release build artifacts

.gitea/workflows/test.yaml

@@ -14,13 +14,13 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v4
       - name: Setup zig installation
-        uses: mlugg/setup-zig@v2
+        uses: https://codeberg.org/mlugg/setup-zig@v2
         with:
-          version: master
+          version: latest
       - name: Lint check
         run: zig fmt --check --exclude src/test .
       - name: Spell checking
-        uses: crate-ci/typos@v1.25.0
+        uses: crate-ci/typos@v1.39.0
         with:
           config: ./.typos-config
       - name: Run tests

README.md

@@ -2,9 +2,6 @@
 
 `zterm` is a terminal user interface library (*tui*) to implement terminal (fullscreen or inline) applications.
 
-> [!CAUTION]
-> Only builds using the zig master version are tested to work.
-
 ## Demo
 
 Clone this repository and run `zig build --help` to see the available examples. Run a given example as follows:
@@ -13,7 +10,7 @@ Clone this repository and run `zig build --help` to see the available examples.
 zig build --release=safe -Dexample=demo run
 ```
 
-> [!TIP]
+> [!tip]
 > Every example application can be quit using `ctrl+c`.
 
 See the [wiki](https://gitea.yves-biener.de/yves-biener/zterm/wiki) for a showcase of the examples and the further details.
@@ -33,8 +30,6 @@ const zterm: *Dependency = b.dependency("zterm", .{
     .target = target,
     .optimize = optimize,
 });
-// ...
-exe.root_module.addImport("zterm", zterm.module("zterm"));
 ```
 
 ### Documentation

build.zig

@@ -11,7 +11,9 @@ pub fn build(b: *std.Build) void {
         button,
         input,
         progress,
+        radio_button,
         scrollable,
+        selection,
         // layouts:
         vertical,
         horizontal,
@@ -22,6 +24,8 @@ pub fn build(b: *std.Build) void {
         palette,
         // error handling
         errors,
+        // non alternate screen applications
+        direct,
     };
 
     const example = b.option(Examples, "example", "Example to build and/or run. (default: all)") orelse .all;
@@ -33,20 +37,15 @@ pub fn build(b: *std.Build) void {
     options.addOption(bool, "debug", debug_rendering);
     const options_module = options.createModule();
 
-    // dependencies
-    const zg = b.dependency("zg", .{
-        .target = target,
-        .optimize = optimize,
-    });
-
     // library
     const lib = b.addModule("zterm", .{
         .root_source_file = b.path("src/root.zig"),
         .target = target,
         .optimize = optimize,
+        .imports = &.{
+            .{ .name = "build_options", .module = options_module },
+        },
     });
-    lib.addImport("code_point", zg.module("code_point"));
-    lib.addImport("build_options", options_module);
 
     //--- Examples ---
     const examples = std.meta.fields(Examples);
@@ -54,45 +53,54 @@ pub fn build(b: *std.Build) void {
         if (@as(Examples, @enumFromInt(e.value)) == .all) continue; // skip `.all` entry
         const demo = b.addExecutable(.{
             .name = e.name,
-            .root_source_file = b.path(switch (@as(Examples, @enumFromInt(e.value))) {
-                .demo => "examples/demo.zig",
-                .continuous => "examples/continuous.zig",
-                // elements:
-                .alignment => "examples/elements/alignment.zig",
-                .button => "examples/elements/button.zig",
-                .input => "examples/elements/input.zig",
-                .progress => "examples/elements/progress.zig",
-                .scrollable => "examples/elements/scrollable.zig",
-                // layouts:
-                .vertical => "examples/layouts/vertical.zig",
-                .horizontal => "examples/layouts/horizontal.zig",
-                .grid => "examples/layouts/grid.zig",
-                .mixed => "examples/layouts/mixed.zig",
-                // styles:
-                .text => "examples/styles/text.zig",
-                .palette => "examples/styles/palette.zig",
-                // error handling
-                .errors => "examples/errors.zig",
-                .all => unreachable, // should never happen
+            .root_module = b.createModule(.{
+                .root_source_file = b.path(switch (@as(Examples, @enumFromInt(e.value))) {
+                    .demo => "examples/demo.zig",
+                    .continuous => "examples/continuous.zig",
+                    // elements:
+                    .alignment => "examples/elements/alignment.zig",
+                    .button => "examples/elements/button.zig",
+                    .input => "examples/elements/input.zig",
+                    .progress => "examples/elements/progress.zig",
+                    .radio_button => "examples/elements/radio-button.zig",
+                    .scrollable => "examples/elements/scrollable.zig",
+                    .selection => "examples/elements/selection.zig",
+                    // layouts:
+                    .vertical => "examples/layouts/vertical.zig",
+                    .horizontal => "examples/layouts/horizontal.zig",
+                    .grid => "examples/layouts/grid.zig",
+                    .mixed => "examples/layouts/mixed.zig",
+                    // styles:
+                    .text => "examples/styles/text.zig",
+                    .palette => "examples/styles/palette.zig",
+                    // error handling
+                    .errors => "examples/errors.zig",
+                    // non-alternate screen
+                    .direct => "examples/direct.zig",
+                    .all => unreachable, // should never happen
+                }),
+                .target = target,
+                .optimize = optimize,
+                .imports = &.{
+                    .{ .name = "zterm", .module = lib },
+                },
             }),
-            .target = target,
-            .optimize = optimize,
         });
-        // import dependencies
-        demo.root_module.addImport("zterm", lib);
         // mapping of user selected example to compile step
         if (@intFromEnum(example) == e.value or example == .all) b.installArtifact(demo);
     }
 
     // zig build test
     const lib_unit_tests = b.addTest(.{
-        .root_source_file = b.path("src/root.zig"),
-        .target = target,
-        .optimize = optimize,
+        .root_module = b.createModule(.{
+            .root_source_file = b.path("src/root.zig"),
+            .target = target,
+            .optimize = optimize,
+            .imports = &.{
+                .{ .name = "build_options", .module = options_module },
+            },
+        }),
     });
-    lib_unit_tests.root_module.addImport("code_point", zg.module("code_point"));
-    lib_unit_tests.root_module.addImport("DisplayWidth", zg.module("DisplayWidth"));
-    lib_unit_tests.root_module.addImport("build_options", options_module);
 
     const run_lib_unit_tests = b.addRunArtifact(lib_unit_tests);
 

build.zig.zon

@@ -35,12 +35,7 @@
     // `zig build --fetch` can be used to fetch all dependencies of a package, recursively.
     // Once all dependencies are fetched, `zig build` no longer requires
     // internet connectivity.
-    .dependencies = .{
-        .zg = .{
-            .url = "git+https://codeberg.org/atman/zg#9427a9e53aaa29ee071f4dcb35b809a699d75aa9",
-            .hash = "zg-0.14.1-oGqU3IQ_tALZIiBN026_NTaPJqU-Upm8P_C7QED2Rzm8",
-        },
-    },
+    .dependencies = .{},
     .paths = .{
         "LICENSE",
         "build.zig",

examples/continuous.zig

@@ -5,7 +5,7 @@ const QuitText = struct {
         return .{ .ptr = this, .vtable = &.{ .content = content } };
     }
 
-    fn content(ctx: *anyopaque, cells: []zterm.Cell, size: zterm.Point) !void {
+    fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
         _ = ctx;
         assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
 
@@ -41,7 +41,7 @@ const Spinner = struct {
         };
     }
 
-    fn content(ctx: *anyopaque, cells: []zterm.Cell, size: zterm.Point) !void {
+    fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
         const this: *@This() = @ptrCast(@alignCast(ctx));
         assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
 
@@ -57,18 +57,20 @@ const Spinner = struct {
 };
 
 const InputField = struct {
+    allocator: std.mem.Allocator,
     input: std.ArrayList(u21),
     queue: *App.Queue,
 
     pub fn init(allocator: std.mem.Allocator, queue: *App.Queue) @This() {
         return .{
-            .input = .init(allocator),
+            .allocator = allocator,
+            .input = std.ArrayList(u21).initCapacity(allocator, 8) catch unreachable,
             .queue = queue,
         };
     }
 
-    pub fn deinit(this: @This()) void {
-        this.input.deinit();
+    pub fn deinit(this: *@This()) void {
+        this.input.deinit(this.allocator);
     }
 
     pub fn element(this: *@This()) App.Element {
@@ -81,14 +83,14 @@ const InputField = struct {
         };
     }
 
-    fn handle(ctx: *anyopaque, event: App.Event) !void {
+    fn handle(ctx: *anyopaque, _: *App.Model, event: App.Event) !void {
         const this: *@This() = @ptrCast(@alignCast(ctx));
         switch (event) {
             .key => |key| {
-                if (key.isAscii()) try this.input.append(key.cp);
+                if (key.isUnicode()) try this.input.append(this.allocator, key.cp);
 
                 if (key.eql(.{ .cp = zterm.input.Enter }) or key.eql(.{ .cp = zterm.input.KpEnter }))
-                    this.queue.push(.{ .accept = try this.input.toOwnedSlice() });
+                    this.queue.push(.{ .accept = try this.input.toOwnedSlice(this.allocator) });
 
                 if (key.eql(.{ .cp = zterm.input.Backspace }))
                     _ = this.input.pop();
@@ -100,7 +102,7 @@ const InputField = struct {
         }
     }
 
-    fn content(ctx: *anyopaque, cells: []zterm.Cell, size: zterm.Point) !void {
+    fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
         const this: *@This() = @ptrCast(@alignCast(ctx));
         assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
 
@@ -131,7 +133,7 @@ pub fn main() !void {
 
     const allocator = gpa.allocator();
 
-    var app: App = .init;
+    var app: App = .init(.{}, .{});
     var renderer = zterm.Renderer.Buffered.init(allocator);
     defer renderer.deinit();
 
@@ -151,7 +153,7 @@ pub fn main() !void {
     defer container.deinit();
 
     try container.append(try App.Container.init(allocator, .{
-        .rectangle = .{ .fill = .light_grey },
+        .rectangle = .{ .fill = .lightgrey },
         .size = .{
             .grow = .horizontal,
             .dim = .{ .y = 10 },
@@ -159,11 +161,11 @@ pub fn main() !void {
     }, input_field.element()));
 
     const nested_container: App.Container = try .init(allocator, .{
-        .rectangle = .{ .fill = .light_grey },
+        .rectangle = .{ .fill = .lightgrey },
     }, spinner.element());
     try container.append(nested_container);
 
-    try app.start();
+    try app.start(.full);
     defer app.stop() catch |err| log.err("Failed to stop application: {any}", .{err});
 
     var framerate: u64 = 60;
@@ -176,7 +178,7 @@ pub fn main() !void {
         if (now_ms >= next_frame_ms) {
             next_frame_ms = now_ms + tick_ms;
         } else {
-            time.sleep((next_frame_ms - now_ms) * time.ns_per_ms);
+            std.Thread.sleep((next_frame_ms - now_ms) * time.ns_per_ms);
             next_frame_ms += tick_ms;
         }
 
@@ -212,7 +214,7 @@ pub fn main() !void {
                 else => {},
             }
 
-            container.handle(event) catch |err| app.postEvent(.{
+            container.handle(&app.model, event) catch |err| app.postEvent(.{
                 .err = .{
                     .err = err,
                     .msg = "Container Event handling failed",
@@ -226,9 +228,9 @@ pub fn main() !void {
             }
         }
 
-        container.resize(try renderer.resize());
-        container.reposition(.{});
-        try renderer.render(@TypeOf(container), &container);
+        container.resize(&app.model, try renderer.resize());
+        container.reposition(&app.model, .{});
+        try renderer.render(@TypeOf(container), &container, App.Model, &app.model);
         try renderer.flush();
     }
 }
@@ -240,6 +242,6 @@ const std = @import("std");
 const time = std.time;
 const assert = std.debug.assert;
 const zterm = @import("zterm");
-const App = zterm.App(union(enum) {
+const App = zterm.App(struct {}, union(enum) {
     accept: []u21,
 });

examples/demo.zig

@@ -1,11 +1,11 @@
 const QuitText = struct {
-    const text = "Press ctrl+c to quit. Press ctrl+n to launch helix.";
+    const text = "Press ctrl+c to quit. Press ctrl+n to launch `vim`.";
 
     pub fn element(this: *@This()) App.Element {
         return .{ .ptr = this, .vtable = &.{ .content = content } };
     }
 
-    pub fn content(ctx: *anyopaque, cells: []zterm.Cell, size: zterm.Point) !void {
+    pub fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
         _ = ctx;
         assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
 
@@ -27,13 +27,12 @@ const QuitText = struct {
 pub fn main() !void {
     errdefer |err| log.err("Application Error: {any}", .{err});
 
-    // TODO maybe create own allocator as some sort of arena allocator to have consistent memory usage
     var gpa: std.heap.DebugAllocator(.{}) = .init;
     defer if (gpa.deinit() == .leak) log.err("memory leak", .{});
 
     const allocator = gpa.allocator();
 
-    var app: App = .init;
+    var app: App = .init(.{}, .{});
     var renderer = zterm.Renderer.Buffered.init(allocator);
     defer renderer.deinit();
 
@@ -57,15 +56,14 @@ pub fn main() !void {
         },
     }, .{});
     try box.append(try App.Container.init(allocator, .{
-        .rectangle = .{ .fill = .light_green },
+        .rectangle = .{ .fill = .lightgreen },
     }, .{}));
     try box.append(try App.Container.init(allocator, .{
-        .rectangle = .{ .fill = .light_green },
+        .rectangle = .{ .fill = .lightgreen },
     }, .{}));
     try box.append(try App.Container.init(allocator, .{
-        .rectangle = .{ .fill = .light_green },
+        .rectangle = .{ .fill = .lightgreen },
     }, .{}));
-    defer box.deinit();
 
     var scrollable: App.Scrollable = .init(box, .disabled);
 
@@ -92,7 +90,7 @@ pub fn main() !void {
             .direction = .vertical,
         },
         .border = .{
-            .color = .light_blue,
+            .color = .lightblue,
             .sides = .all,
         },
     }, .{});
@@ -135,7 +133,7 @@ pub fn main() !void {
     }, .{}));
     defer container.deinit(); // also de-initializes the children
 
-    try app.start();
+    try app.start(.full);
     defer app.stop() catch |err| log.err("Failed to stop application: {any}", .{err});
 
     // event loop
@@ -151,8 +149,8 @@ pub fn main() !void {
                 if (key.eql(.{ .cp = 'n', .mod = .{ .ctrl = true } })) {
                     try app.interrupt();
                     renderer.size = .{}; // reset size, such that next resize will cause a full re-draw!
-                    defer app.start() catch @panic("could not start app event loop");
-                    var child = std.process.Child.init(&.{"hx"}, allocator);
+                    defer app.start(.full) catch @panic("could not start app event loop");
+                    var child = std.process.Child.init(&.{"vim"}, allocator);
                     _ = child.spawnAndWait() catch |err| app.postEvent(.{
                         .err = .{
                             .err = err,
@@ -168,7 +166,7 @@ pub fn main() !void {
         }
 
         // NOTE returned errors should be propagated back to the application
-        container.handle(event) catch |err| app.postEvent(.{
+        container.handle(&app.model, event) catch |err| app.postEvent(.{
             .err = .{
                 .err = err,
                 .msg = "Container Event handling failed",
@@ -181,9 +179,9 @@ pub fn main() !void {
             else => {},
         }
 
-        container.resize(try renderer.resize());
-        container.reposition(.{});
-        try renderer.render(@TypeOf(container), &container);
+        container.resize(&app.model, try renderer.resize());
+        container.reposition(&app.model, .{});
+        try renderer.render(@TypeOf(container), &container, App.Model, &app.model);
         try renderer.flush();
     }
 }
@@ -195,4 +193,4 @@ const std = @import("std");
 const assert = std.debug.assert;
 const zterm = @import("zterm");
 const input = zterm.input;
-const App = zterm.App(union(enum) {});
+const App = zterm.App(struct {}, union(enum) {});

examples/direct.zig

@@ -0,0 +1,191 @@
+const QuitText = struct {
+    const text = "Press ctrl+c to quit.";
+
+    pub fn element(this: *@This()) App.Element {
+        return .{
+            .ptr = this,
+            .vtable = &.{
+                .minSize = minSize,
+                .content = content,
+            },
+        };
+    }
+
+    fn minSize(_: *anyopaque, _: *const App.Model, size: zterm.Point) zterm.Point {
+        return .{ .x = size.x, .y = 10 }; // this includes the border
+    }
+
+    pub fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
+        _ = ctx;
+        assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
+
+        const y = 0;
+        const x = 2;
+        const anchor = (y * size.x) + x;
+
+        for (text, 0..) |cp, idx| {
+            cells[anchor + idx].style.fg = .white;
+            cells[anchor + idx].style.emphasis = &.{ .bold, .underline };
+            cells[anchor + idx].cp = cp;
+
+            // NOTE do not write over the contents of this `Container`'s `Size`
+            if (anchor + idx == cells.len - 1) break;
+        }
+    }
+};
+
+const Prompt = struct {
+    len: u16 = 3,
+    pub fn element(this: *@This()) App.Element {
+        return .{
+            .ptr = this,
+            .vtable = &.{
+                // .minSize = minSize,
+                .content = content,
+            },
+        };
+    }
+
+    // NOTE size hint is not required as the `.size = .{ .dim = .{..} }` property is set accordingly which denotes the minimal size
+    // fn minSize(ctx: *anyopaque, _: *const App.Model, _: zterm.Point) zterm.Point {
+    //     const this: *@This() = @ptrCast(@alignCast(ctx));
+    //     return .{ .x = this.len, .y = 1 };
+    // }
+
+    pub fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
+        const this: *@This() = @ptrCast(@alignCast(ctx));
+        assert(cells.len > 2); // expect at least two cells
+        assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
+
+        for (0..this.len) |idx| {
+            cells[idx].style.bg = .blue;
+            cells[idx].style.fg = .black;
+            cells[idx].style.emphasis = &.{.bold};
+        }
+        cells[1].cp = '>';
+        // leave one clear whitespace after the prompt
+        cells[this.len].style.bg = .default;
+        cells[this.len].style.cursor = true; // marks the actual end of the rendering!
+    }
+};
+
+pub fn main() !void {
+    errdefer |err| log.err("Application Error: {any}", .{err});
+
+    var allocator: std.heap.DebugAllocator(.{}) = .init;
+    defer if (allocator.deinit() == .leak) log.err("memory leak", .{});
+
+    const gpa = allocator.allocator();
+
+    var app: App = .init(.{}, .{});
+    var renderer = zterm.Renderer.Direct.init(gpa);
+    defer renderer.deinit();
+
+    var container: App.Container = try .init(gpa, .{
+        .layout = .{
+            .direction = .vertical,
+            .gap = 1, // show empty line between elements to allow navigation through paragraph jumping
+        },
+        .size = .{
+            .grow = .horizontal_only,
+        },
+    }, .{});
+    defer container.deinit();
+
+    var quit_text: QuitText = .{};
+    var intermediate: App.Container = try .init(gpa, .{
+        .border = .{
+            .sides = .{ .left = true },
+            .color = .grey,
+        },
+        .layout = .{
+            .direction = .horizontal,
+            .padding = .{ .left = 1, .top = 1 },
+        },
+    }, quit_text.element());
+    try intermediate.append(try .init(gpa, .{
+        .rectangle = .{ .fill = .blue },
+    }, .{}));
+
+    try intermediate.append(try .init(gpa, .{
+        .rectangle = .{ .fill = .green },
+    }, .{}));
+
+    var padding_container: App.Container = try .init(gpa, .{
+        .layout = .{
+            .padding = .horizontal(1),
+        },
+    }, .{});
+    try padding_container.append(intermediate);
+    try container.append(padding_container);
+
+    var prompt: Prompt = .{};
+    try container.append(try .init(gpa, .{
+        .rectangle = .{ .fill = .grey },
+        .size = .{
+            .dim = .{ .y = 1 },
+        },
+    }, prompt.element()));
+
+    try app.start(.direct); // needs to become configurable, as what should be enabled / disabled (i.e. show cursor, hide cursor, use alternate screen, etc.)
+    defer app.stop() catch |err| log.err("Failed to stop application: {any}", .{err});
+
+    // event loop
+    event: while (true) {
+        // batch events since last iteration
+        const len = blk: {
+            app.queue.poll();
+            app.queue.lock();
+            defer app.queue.unlock();
+            break :blk app.queue.len();
+        };
+
+        // handle events
+        for (0..len) |_| {
+            const event = app.queue.pop();
+            log.debug("received event: {s}", .{@tagName(event)});
+
+            // pre event handling
+            switch (event) {
+                // NOTE maybe I want to decouple the `key`s from the user input too? i.e. this only makes sense if the output is not echoed!
+                // otherwise just use gnu's `readline`?
+                .line => |line| {
+                    log.debug("{s}", .{line});
+                },
+                // NOTE errors could be displayed in another container in case one was received, etc. to provide the user with feedback
+                .err => |err| log.err("Received {s} with message: {s}", .{ @errorName(err.err), err.msg }),
+                else => {},
+            }
+
+            // NOTE returned errors should be propagated back to the application
+            container.handle(&app.model, event) catch |err| app.postEvent(.{
+                .err = .{
+                    .err = err,
+                    .msg = "Container Event handling failed",
+                },
+            });
+
+            // post event handling
+            switch (event) {
+                .quit => break :event,
+                else => {},
+            }
+        }
+        // if there are more events to process continue handling them otherwise I can render the next frame
+        if (app.queue.len() > 0) continue :event;
+
+        container.resize(&app.model, try renderer.resize());
+        container.reposition(&app.model, .{});
+        try renderer.render(@TypeOf(container), &container, App.Model, &app.model);
+        try renderer.flush();
+    }
+}
+
+pub const panic = App.panic_handler;
+const log = std.log.scoped(.default);
+
+const std = @import("std");
+const assert = std.debug.assert;
+const zterm = @import("zterm");
+const input = zterm.input;
+const App = zterm.App(struct {}, union(enum) {});

examples/elements/alignment.zig

@@ -5,7 +5,7 @@ const QuitText = struct {
         return .{ .ptr = this, .vtable = &.{ .content = content } };
     }
 
-    fn content(ctx: *anyopaque, cells: []zterm.Cell, size: zterm.Point) !void {
+    fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
         _ = ctx;
         assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
 
@@ -32,7 +32,7 @@ pub fn main() !void {
 
     const allocator = gpa.allocator();
 
-    var app: App = .init;
+    var app: App = .init(.{}, .{});
     var renderer = zterm.Renderer.Buffered.init(allocator);
     defer renderer.deinit();
 
@@ -55,7 +55,7 @@ pub fn main() !void {
     var alignment: App.Alignment = .init(quit_container, .center);
     try container.append(try .init(allocator, .{}, alignment.element()));
 
-    try app.start();
+    try app.start(.full);
     defer app.stop() catch |err| log.err("Failed to stop application: {any}", .{err});
 
     // event loop
@@ -70,7 +70,7 @@ pub fn main() !void {
             else => {},
         }
 
-        container.handle(event) catch |err| app.postEvent(.{
+        container.handle(&app.model, event) catch |err| app.postEvent(.{
             .err = .{
                 .err = err,
                 .msg = "Container Event handling failed",
@@ -83,9 +83,9 @@ pub fn main() !void {
             else => {},
         }
 
-        container.resize(try renderer.resize());
-        container.reposition(.{});
-        try renderer.render(@TypeOf(container), &container);
+        container.resize(&app.model, try renderer.resize());
+        container.reposition(&app.model, .{});
+        try renderer.render(@TypeOf(container), &container, App.Model, &app.model);
         try renderer.flush();
     }
 }
@@ -96,4 +96,4 @@ const log = std.log.scoped(.default);
 const std = @import("std");
 const assert = std.debug.assert;
 const zterm = @import("zterm");
-const App = zterm.App(union(enum) {});
+const App = zterm.App(struct {}, union(enum) {});

examples/elements/button.zig

@@ -5,7 +5,7 @@ const QuitText = struct {
         return .{ .ptr = this, .vtable = &.{ .content = content } };
     }
 
-    fn content(ctx: *anyopaque, cells: []zterm.Cell, size: zterm.Point) !void {
+    fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
         _ = ctx;
         assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
 
@@ -40,7 +40,7 @@ const Clickable = struct {
         };
     }
 
-    fn handle(ctx: *anyopaque, event: App.Event) !void {
+    fn handle(ctx: *anyopaque, _: *App.Model, event: App.Event) !void {
         const this: *@This() = @ptrCast(@alignCast(ctx));
         switch (event) {
             .mouse => |mouse| if (mouse.button == .left and mouse.kind == .release) {
@@ -55,7 +55,7 @@ const Clickable = struct {
         }
     }
 
-    fn content(ctx: *anyopaque, cells: []zterm.Cell, size: zterm.Point) !void {
+    fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
         const this: *@This() = @ptrCast(@alignCast(ctx));
         assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
 
@@ -82,7 +82,7 @@ pub fn main() !void {
 
     const allocator = gpa.allocator();
 
-    var app: App = .init;
+    var app: App = .init(.{}, .{});
     var renderer = zterm.Renderer.Buffered.init(allocator);
     defer renderer.deinit();
 
@@ -99,10 +99,10 @@ pub fn main() !void {
     }, quit_text.element());
     defer container.deinit();
 
-    try container.append(try App.Container.init(allocator, .{ .rectangle = .{ .fill = .light_grey } }, element));
+    try container.append(try App.Container.init(allocator, .{ .rectangle = .{ .fill = .lightgrey } }, element));
     try container.append(try App.Container.init(allocator, .{ .rectangle = .{ .fill = .black } }, button.element()));
 
-    try app.start();
+    try app.start(.full);
     defer app.stop() catch |err| log.err("Failed to stop application: {any}", .{err});
 
     // event loop
@@ -119,7 +119,7 @@ pub fn main() !void {
             else => {},
         }
 
-        container.handle(event) catch |err| app.postEvent(.{
+        container.handle(&app.model, event) catch |err| app.postEvent(.{
             .err = .{
                 .err = err,
                 .msg = "Container Event handling failed",
@@ -132,9 +132,9 @@ pub fn main() !void {
             else => {},
         }
 
-        container.resize(try renderer.resize());
-        container.reposition(.{});
-        try renderer.render(@TypeOf(container), &container);
+        container.resize(&app.model, try renderer.resize());
+        container.reposition(&app.model, .{});
+        try renderer.render(@TypeOf(container), &container, App.Model, &app.model);
         try renderer.flush();
     }
 }
@@ -145,7 +145,10 @@ const log = std.log.scoped(.default);
 const std = @import("std");
 const assert = std.debug.assert;
 const zterm = @import("zterm");
-const App = zterm.App(union(enum) {
-    click: [:0]const u8,
-    accept,
-});
+const App = zterm.App(
+    struct {},
+    union(enum) {
+        click: [:0]const u8,
+        accept,
+    },
+);

examples/elements/input.zig

@@ -5,7 +5,7 @@ const QuitText = struct {
         return .{ .ptr = this, .vtable = &.{ .content = content } };
     }
 
-    fn content(ctx: *anyopaque, cells: []zterm.Cell, size: zterm.Point) !void {
+    fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
         _ = ctx;
         assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
 
@@ -37,7 +37,7 @@ const MouseDraw = struct {
         };
     }
 
-    fn handle(ctx: *anyopaque, event: App.Event) !void {
+    fn handle(ctx: *anyopaque, _: *App.Model, event: App.Event) !void {
         const this: *@This() = @ptrCast(@alignCast(ctx));
         switch (event) {
             .mouse => |mouse| this.position = .{ .x = mouse.x, .y = mouse.y },
@@ -45,7 +45,7 @@ const MouseDraw = struct {
         }
     }
 
-    fn content(ctx: *anyopaque, cells: []zterm.Cell, size: zterm.Point) !void {
+    fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
         assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
         const this: *@This() = @ptrCast(@alignCast(ctx));
 
@@ -65,13 +65,11 @@ pub fn main() !void {
 
     const allocator = gpa.allocator();
 
-    var app: App = .init;
+    var app: App = .init(.{}, .{});
     var renderer = zterm.Renderer.Buffered.init(allocator);
     defer renderer.deinit();
 
-    var input_field: App.Input(.accept) = .init(allocator, &app.queue, .init(.black));
-    defer input_field.deinit();
-
+    var input_field: App.Input(.accept) = .init(allocator, &app.queue, .init(.black, .blue));
     var mouse_draw: MouseDraw = .{};
     var second_mouse_draw: MouseDraw = .{};
     var quit_text: QuitText = .{};
@@ -86,7 +84,7 @@ pub fn main() !void {
     defer container.deinit();
 
     try container.append(try App.Container.init(allocator, .{
-        .rectangle = .{ .fill = .light_grey },
+        .rectangle = .{ .fill = .lightgrey },
         .size = .{
             .grow = .horizontal,
             .dim = .{ .y = 1 },
@@ -98,7 +96,7 @@ pub fn main() !void {
             .sides = .all,
             .color = .black,
         },
-        .rectangle = .{ .fill = .light_grey },
+        .rectangle = .{ .fill = .lightgrey },
         .layout = .{
             .separator = .{
                 .enabled = true,
@@ -107,14 +105,14 @@ pub fn main() !void {
         },
     }, .{});
     try nested_container.append(try .init(allocator, .{
-        .rectangle = .{ .fill = .light_grey },
+        .rectangle = .{ .fill = .lightgrey },
     }, mouse_draw.element()));
     try nested_container.append(try .init(allocator, .{
-        .rectangle = .{ .fill = .light_grey },
+        .rectangle = .{ .fill = .lightgrey },
     }, second_mouse_draw.element()));
     try container.append(nested_container);
 
-    try app.start();
+    try app.start(.full);
     defer app.stop() catch |err| log.err("Failed to stop application: {any}", .{err});
 
     // event loop
@@ -133,7 +131,7 @@ pub fn main() !void {
             else => {},
         }
 
-        container.handle(event) catch |err| app.postEvent(.{
+        container.handle(&app.model, event) catch |err| app.postEvent(.{
             .err = .{
                 .err = err,
                 .msg = "Container Event handling failed",
@@ -146,9 +144,9 @@ pub fn main() !void {
             else => {},
         }
 
-        container.resize(try renderer.resize());
-        container.reposition(.{});
-        try renderer.render(@TypeOf(container), &container);
+        container.resize(&app.model, try renderer.resize());
+        container.reposition(&app.model, .{});
+        try renderer.render(@TypeOf(container), &container, App.Model, &app.model);
         try renderer.flush();
     }
 }
@@ -161,6 +159,9 @@ const assert = std.debug.assert;
 const zterm = @import("zterm");
 const Color = zterm.Color;
 
-const App = zterm.App(union(enum) {
-    accept: []u8,
-});
+const App = zterm.App(
+    struct {},
+    union(enum) {
+        accept: []u8,
+    },
+);

examples/elements/progress.zig

@@ -5,7 +5,7 @@ const QuitText = struct {
         return .{ .ptr = this, .vtable = &.{ .content = content } };
     }
 
-    fn content(ctx: *anyopaque, cells: []zterm.Cell, size: zterm.Point) !void {
+    fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
         _ = ctx;
         assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
 
@@ -32,26 +32,60 @@ pub fn main() !void {
 
     const allocator = gpa.allocator();
 
-    var app: App = .init;
+    var app: App = .init(.{}, .{});
     var renderer = zterm.Renderer.Buffered.init(allocator);
     defer renderer.deinit();
 
     var progress_percent: u8 = 0;
-    var progress: App.Progress(.progress) = .init(&app.queue, .{
-        .percent = .{ .enabled = true },
-        .fg = .green,
-        .bg = .grey,
-    });
     var quit_text: QuitText = .{};
 
     var container = try App.Container.init(allocator, .{
-        .layout = .{ .padding = .all(5) },
+        .layout = .{ .padding = .all(5), .direction = .vertical },
     }, quit_text.element());
     defer container.deinit();
 
-    try container.append(try App.Container.init(allocator, .{}, progress.element()));
-
-    try app.start();
+    {
+        var progress: App.Progress(.progress) = .init(&app.queue, .{
+            .percent = .{
+                .enabled = true,
+                .alignment = .left,
+            },
+            .fg = .blue,
+            .bg = .grey,
+        });
+        try container.append(try App.Container.init(allocator, .{}, progress.element()));
+    }
+    {
+        var progress: App.Progress(.progress) = .init(&app.queue, .{
+            .percent = .{
+                .enabled = true,
+                .alignment = .middle, // default
+            },
+            .fg = .red,
+            .bg = .grey,
+        });
+        try container.append(try App.Container.init(allocator, .{}, progress.element()));
+    }
+    {
+        var progress: App.Progress(.progress) = .init(&app.queue, .{
+            .percent = .{
+                .enabled = true,
+                .alignment = .right,
+            },
+            .fg = .green,
+            .bg = .grey,
+        });
+        try container.append(try App.Container.init(allocator, .{}, progress.element()));
+    }
+    {
+        var progress: App.Progress(.progress) = .init(&app.queue, .{
+            .percent = .{ .enabled = false },
+            .fg = .default,
+            .bg = .grey,
+        });
+        try container.append(try App.Container.init(allocator, .{}, progress.element()));
+    }
+    try app.start(.full);
     defer app.stop() catch |err| log.err("Failed to stop application: {any}", .{err});
 
     var framerate: u64 = 60;
@@ -67,7 +101,7 @@ pub fn main() !void {
         if (now_ms >= next_frame_ms) {
             next_frame_ms = now_ms + tick_ms;
         } else {
-            time.sleep((next_frame_ms - now_ms) * time.ns_per_ms);
+            std.Thread.sleep((next_frame_ms - now_ms) * time.ns_per_ms);
             next_frame_ms += tick_ms;
         }
 
@@ -104,7 +138,7 @@ pub fn main() !void {
                 else => {},
             }
 
-            container.handle(event) catch |err| app.postEvent(.{
+            container.handle(&app.model, event) catch |err| app.postEvent(.{
                 .err = .{
                     .err = err,
                     .msg = "Container Event handling failed",
@@ -118,9 +152,9 @@ pub fn main() !void {
             }
         }
 
-        container.resize(try renderer.resize());
-        container.reposition(.{});
-        try renderer.render(@TypeOf(container), &container);
+        container.resize(&app.model, try renderer.resize());
+        container.reposition(&app.model, .{});
+        try renderer.render(@TypeOf(container), &container, App.Model, &app.model);
         try renderer.flush();
     }
 }
@@ -132,6 +166,9 @@ const std = @import("std");
 const time = std.time;
 const assert = std.debug.assert;
 const zterm = @import("zterm");
-const App = zterm.App(union(enum) {
-    progress: u8,
-});
+const App = zterm.App(
+    struct {},
+    union(enum) {
+        progress: u8,
+    },
+);

examples/elements/radio-button.zig

@@ -0,0 +1,98 @@
+const QuitText = struct {
+    const text = "Press ctrl+c to quit.";
+
+    pub fn element(this: *@This()) App.Element {
+        return .{ .ptr = this, .vtable = &.{ .content = content } };
+    }
+
+    fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
+        _ = ctx;
+        assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
+
+        const row = 2;
+        const col = size.x / 2 -| (text.len / 2);
+        const anchor = (row * size.x) + col;
+
+        for (text, 0..) |cp, idx| {
+            cells[anchor + idx].style.fg = .white;
+            cells[anchor + idx].style.bg = .black;
+            cells[anchor + idx].cp = cp;
+
+            // NOTE do not write over the contents of this `Container`'s `Size`
+            if (anchor + idx == cells.len - 1) break;
+        }
+    }
+};
+
+pub fn main() !void {
+    errdefer |err| log.err("Application Error: {any}", .{err});
+
+    var gpa: std.heap.DebugAllocator(.{}) = .init;
+    defer if (gpa.deinit() == .leak) log.err("memory leak", .{});
+
+    const allocator = gpa.allocator();
+
+    var app: App = .init(.{}, .{});
+    var renderer = zterm.Renderer.Buffered.init(allocator);
+    defer renderer.deinit();
+
+    var radiobutton: App.RadioButton = .init(false, .{
+        .label = "Test Radio Button",
+        .style = .squared,
+    });
+    var button: App.Button(.accept) = .init(&app.queue, .init(.default, "Button"));
+    var quit_text: QuitText = .{};
+
+    var container = try App.Container.init(allocator, .{
+        .rectangle = .{ .fill = .grey },
+        .layout = .{ .padding = .all(5) },
+    }, quit_text.element());
+    defer container.deinit();
+    try container.append(try .init(allocator, .{}, radiobutton.element()));
+    try container.append(try App.Container.init(allocator, .{ .rectangle = .{ .fill = .black } }, button.element()));
+
+    try app.start(.full);
+    defer app.stop() catch |err| log.err("Failed to stop application: {any}", .{err});
+
+    // event loop
+    while (true) {
+        const event = app.nextEvent();
+        log.debug("received event: {s}", .{@tagName(event)});
+
+        // pre event handling
+        switch (event) {
+            .key => |key| if (key.eql(.{ .cp = 'c', .mod = .{ .ctrl = true } })) app.quit(),
+            .accept => log.info("Clicked built-in button using the mouse", .{}),
+            .err => |err| log.err("Received {s} with message: {s}", .{ @errorName(err.err), err.msg }),
+            else => {},
+        }
+
+        container.handle(&app.model, event) catch |err| app.postEvent(.{
+            .err = .{
+                .err = err,
+                .msg = "Container Event handling failed",
+            },
+        });
+
+        // post event handling
+        switch (event) {
+            .quit => break,
+            else => {},
+        }
+
+        container.resize(&app.model, try renderer.resize());
+        container.reposition(&app.model, .{});
+        try renderer.render(@TypeOf(container), &container, App.Model, &app.model);
+        try renderer.flush();
+    }
+}
+
+pub const panic = App.panic_handler;
+const log = std.log.scoped(.default);
+
+const std = @import("std");
+const assert = std.debug.assert;
+const zterm = @import("zterm");
+const App = zterm.App(struct {}, union(enum) {
+    accept,
+});

examples/elements/scrollable.zig

@@ -5,7 +5,7 @@ const QuitText = struct {
         return .{ .ptr = this, .vtable = &.{ .content = content } };
     }
 
-    fn content(ctx: *anyopaque, cells: []zterm.Cell, size: zterm.Point) !void {
+    fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
         _ = ctx;
         assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
 
@@ -34,7 +34,7 @@ const HelloWorldText = packed struct {
         };
     }
 
-    fn content(ctx: *anyopaque, cells: []zterm.Cell, size: zterm.Point) !void {
+    fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
         _ = ctx;
         assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
 
@@ -56,7 +56,6 @@ const HelloWorldText = packed struct {
 pub fn main() !void {
     errdefer |err| log.err("Application Error: {any}", .{err});
 
-    // TODO maybe create own allocator as some sort of arena allocator to have consistent memory usage
     var gpa: std.heap.DebugAllocator(.{}) = .init;
     defer {
         const deinit_status = gpa.deinit();
@@ -66,7 +65,7 @@ pub fn main() !void {
     }
     const allocator = gpa.allocator();
 
-    var app: App = .init;
+    var app: App = .init(.{}, .{});
     var renderer = zterm.Renderer.Buffered.init(allocator);
     defer renderer.deinit();
 
@@ -87,24 +86,23 @@ pub fn main() !void {
         },
     }, .{});
     try top_box.append(try App.Container.init(allocator, .{
-        .rectangle = .{ .fill = .light_green },
+        .rectangle = .{ .fill = .lightgreen },
         .size = .{
             .dim = .{ .y = 30 },
         },
     }, .{}));
     try top_box.append(try App.Container.init(allocator, .{
-        .rectangle = .{ .fill = .light_green },
+        .rectangle = .{ .fill = .lightgreen },
         .size = .{
             .dim = .{ .y = 5 },
         },
     }, element));
     try top_box.append(try App.Container.init(allocator, .{
-        .rectangle = .{ .fill = .light_green },
+        .rectangle = .{ .fill = .lightgreen },
         .size = .{
             .dim = .{ .y = 2 },
         },
     }, .{}));
-    defer top_box.deinit();
 
     var bottom_box = try App.Container.init(allocator, .{
         .border = .{
@@ -132,7 +130,6 @@ pub fn main() !void {
     try bottom_box.append(try App.Container.init(allocator, .{
         .rectangle = .{ .fill = .grey },
     }, .{}));
-    defer bottom_box.deinit();
 
     var container = try App.Container.init(allocator, .{
         .layout = .{
@@ -148,13 +145,13 @@ pub fn main() !void {
     defer container.deinit();
 
     // place empty container containing the element of the scrollable Container.
-    var scrollable_top: App.Scrollable = .init(top_box, .enabled(.grey));
+    var scrollable_top: App.Scrollable = .init(top_box, .enabled(.default, false));
     try container.append(try App.Container.init(allocator, .{}, scrollable_top.element()));
 
-    var scrollable_bottom: App.Scrollable = .init(bottom_box, .enabled(.white));
+    var scrollable_bottom: App.Scrollable = .init(bottom_box, .enabled(.white, true));
     try container.append(try App.Container.init(allocator, .{}, scrollable_bottom.element()));
 
-    try app.start();
+    try app.start(.full);
     defer app.stop() catch |err| log.err("Failed to stop application: {any}", .{err});
 
     // event loop
@@ -169,7 +166,7 @@ pub fn main() !void {
             else => {},
         }
 
-        container.handle(event) catch |err| app.postEvent(.{
+        container.handle(&app.model, event) catch |err| app.postEvent(.{
             .err = .{
                 .err = err,
                 .msg = "Container Event handling failed",
@@ -182,9 +179,9 @@ pub fn main() !void {
             else => {},
         }
 
-        container.resize(try renderer.resize());
-        container.reposition(.{});
-        try renderer.render(@TypeOf(container), &container);
+        container.resize(&app.model, try renderer.resize());
+        container.reposition(&app.model, .{});
+        try renderer.render(@TypeOf(container), &container, App.Model, &app.model);
         try renderer.flush();
     }
 }
@@ -196,4 +193,4 @@ const std = @import("std");
 const assert = std.debug.assert;
 const zterm = @import("zterm");
 const input = zterm.input;
-const App = zterm.App(union(enum) {});
+const App = zterm.App(struct {}, union(enum) {});

examples/elements/selection.zig

@@ -0,0 +1,97 @@
+const QuitText = struct {
+    const text = "Press ctrl+c to quit.";
+
+    pub fn element(this: *@This()) App.Element {
+        return .{ .ptr = this, .vtable = &.{ .content = content } };
+    }
+
+    fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
+        _ = ctx;
+        assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
+
+        const row = 2;
+        const col = size.x / 2 -| (text.len / 2);
+        const anchor = (row * size.x) + col;
+
+        for (text, 0..) |cp, idx| {
+            cells[anchor + idx].style.fg = .white;
+            cells[anchor + idx].style.bg = .black;
+            cells[anchor + idx].cp = cp;
+
+            // NOTE do not write over the contents of this `Container`'s `Size`
+            if (anchor + idx == cells.len - 1) break;
+        }
+    }
+};
+
+pub fn main() !void {
+    errdefer |err| log.err("Application Error: {any}", .{err});
+
+    var gpa: std.heap.DebugAllocator(.{}) = .init;
+    defer if (gpa.deinit() == .leak) log.err("memory leak", .{});
+
+    const allocator = gpa.allocator();
+
+    var app: App = .init(.{}, .{});
+    var renderer = zterm.Renderer.Buffered.init(allocator);
+    defer renderer.deinit();
+
+    var selection: App.Selection(enum {
+        one,
+        two,
+        three,
+    }) = .init(.{
+        .label = "Selection",
+    });
+    var quit_text: QuitText = .{};
+
+    var container = try App.Container.init(allocator, .{
+        .rectangle = .{ .fill = .grey },
+        .layout = .{ .padding = .all(5) },
+    }, quit_text.element());
+    defer container.deinit();
+    try container.append(try .init(allocator, .{}, selection.element()));
+
+    try app.start(.full);
+    defer app.stop() catch |err| log.err("Failed to stop application: {any}", .{err});
+
+    // event loop
+    while (true) {
+        const event = app.nextEvent();
+        log.debug("received event: {s}", .{@tagName(event)});
+
+        // pre event handling
+        switch (event) {
+            .key => |key| if (key.eql(.{ .cp = 'c', .mod = .{ .ctrl = true } })) app.quit(),
+            .err => |err| log.err("Received {s} with message: {s}", .{ @errorName(err.err), err.msg }),
+            else => {},
+        }
+
+        container.handle(&app.model, event) catch |err| app.postEvent(.{
+            .err = .{
+                .err = err,
+                .msg = "Container Event handling failed",
+            },
+        });
+
+        // post event handling
+        switch (event) {
+            .quit => break,
+            else => {},
+        }
+
+        container.resize(&app.model, try renderer.resize());
+        container.reposition(&app.model, .{});
+        try renderer.render(@TypeOf(container), &container, App.Model, &app.model);
+        try renderer.flush();
+    }
+}
+
+pub const panic = App.panic_handler;
+const log = std.log.scoped(.default);
+
+const std = @import("std");
+const assert = std.debug.assert;
+const zterm = @import("zterm");
+const Error = zterm.Error;
+const App = zterm.App(struct {}, union(enum) {});

examples/errors.zig

@@ -5,7 +5,7 @@ const QuitText = struct {
         return .{ .ptr = this, .vtable = &.{ .content = content } };
     }
 
-    fn content(ctx: *anyopaque, cells: []zterm.Cell, size: zterm.Point) !void {
+    fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
         _ = ctx;
         assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
 
@@ -31,7 +31,7 @@ const InfoText = struct {
         return .{ .ptr = this, .vtable = &.{ .content = content } };
     }
 
-    fn content(ctx: *anyopaque, cells: []zterm.Cell, size: zterm.Point) !void {
+    fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
         _ = ctx;
         assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
 
@@ -57,7 +57,7 @@ const ErrorNotification = struct {
         return .{ .ptr = this, .vtable = &.{ .handle = handle, .content = content } };
     }
 
-    fn handle(ctx: *anyopaque, event: App.Event) !void {
+    fn handle(ctx: *anyopaque, _: *App.Model, event: App.Event) !void {
         const this: *@This() = @ptrCast(@alignCast(ctx));
         switch (event) {
             .key => |key| if (!key.isAscii()) return zterm.Error.TooSmall,
@@ -66,7 +66,7 @@ const ErrorNotification = struct {
         }
     }
 
-    fn content(ctx: *anyopaque, cells: []zterm.Cell, size: zterm.Point) !void {
+    fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
         const this: *@This() = @ptrCast(@alignCast(ctx));
         assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
 
@@ -97,7 +97,7 @@ pub fn main() !void {
 
     const allocator = gpa.allocator();
 
-    var app: App = .init;
+    var app: App = .init(.{}, .{});
     var renderer = zterm.Renderer.Buffered.init(allocator);
     defer renderer.deinit();
 
@@ -116,7 +116,7 @@ pub fn main() !void {
     try container.append(try App.Container.init(allocator, .{}, info_text.element()));
     try container.append(try App.Container.init(allocator, .{}, error_notification.element()));
 
-    try app.start();
+    try app.start(.full);
     defer app.stop() catch |err| log.err("Failed to stop application: {any}", .{err});
 
     while (true) {
@@ -130,7 +130,7 @@ pub fn main() !void {
             else => {},
         }
 
-        container.handle(event) catch |err| app.postEvent(.{
+        container.handle(&app.model, event) catch |err| app.postEvent(.{
             .err = .{
                 .err = err,
                 .msg = "Container Event handling failed",
@@ -143,9 +143,9 @@ pub fn main() !void {
             else => {},
         }
 
-        container.resize(try renderer.resize());
-        container.reposition(.{});
-        try renderer.render(@TypeOf(container), &container);
+        container.resize(&app.model, try renderer.resize());
+        container.reposition(&app.model, .{});
+        try renderer.render(@TypeOf(container), &container, App.Model, &app.model);
         try renderer.flush();
     }
 }
@@ -156,4 +156,4 @@ const log = std.log.scoped(.default);
 const std = @import("std");
 const assert = std.debug.assert;
 const zterm = @import("zterm");
-const App = zterm.App(union(enum) {});
+const App = zterm.App(struct {}, union(enum) {});

examples/layouts/grid.zig

@@ -8,7 +8,7 @@ const QuitText = struct {
         };
     }
 
-    fn content(ctx: *anyopaque, cells: []zterm.Cell, size: zterm.Point) !void {
+    fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
         _ = ctx;
         assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
 
@@ -35,7 +35,7 @@ pub fn main() !void {
 
     const allocator = gpa.allocator();
 
-    var app: App = .init;
+    var app: App = .init(.{}, .{});
     var renderer = zterm.Renderer.Buffered.init(allocator);
     defer renderer.deinit();
 
@@ -69,7 +69,7 @@ pub fn main() !void {
     }
     defer container.deinit(); // also de-initializes the children
 
-    try app.start();
+    try app.start(.full);
     defer app.stop() catch |err| log.err("Failed to stop application: {any}", .{err});
 
     // event loop
@@ -86,7 +86,7 @@ pub fn main() !void {
         }
 
         // NOTE returned errors should be propagated back to the application
-        container.handle(event) catch |err| app.postEvent(.{
+        container.handle(&app.model, event) catch |err| app.postEvent(.{
             .err = .{
                 .err = err,
                 .msg = "Container Event handling failed",
@@ -99,9 +99,9 @@ pub fn main() !void {
             else => {},
         }
 
-        container.resize(try renderer.resize());
-        container.reposition(.{});
-        try renderer.render(@TypeOf(container), &container);
+        container.resize(&app.model, try renderer.resize());
+        container.reposition(&app.model, .{});
+        try renderer.render(@TypeOf(container), &container, App.Model, &app.model);
         try renderer.flush();
     }
 }
@@ -112,4 +112,4 @@ const log = std.log.scoped(.default);
 const std = @import("std");
 const assert = std.debug.assert;
 const zterm = @import("zterm");
-const App = zterm.App(union(enum) {});
+const App = zterm.App(struct {}, union(enum) {});

examples/layouts/horizontal.zig

@@ -8,7 +8,7 @@ const QuitText = struct {
         };
     }
 
-    fn content(ctx: *anyopaque, cells: []zterm.Cell, size: zterm.Point) !void {
+    fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
         _ = ctx;
         assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
 
@@ -35,7 +35,7 @@ pub fn main() !void {
 
     const allocator = gpa.allocator();
 
-    var app: App = .init;
+    var app: App = .init(.{}, .{});
     var renderer = zterm.Renderer.Buffered.init(allocator);
     defer renderer.deinit();
 
@@ -61,7 +61,7 @@ pub fn main() !void {
     }, .{}));
     defer container.deinit(); // also de-initializes the children
 
-    try app.start();
+    try app.start(.full);
     defer app.stop() catch |err| log.err("Failed to stop application: {any}", .{err});
 
     // event loop
@@ -78,7 +78,7 @@ pub fn main() !void {
         }
 
         // NOTE returned errors should be propagated back to the application
-        container.handle(event) catch |err| app.postEvent(.{
+        container.handle(&app.model, event) catch |err| app.postEvent(.{
             .err = .{
                 .err = err,
                 .msg = "Container Event handling failed",
@@ -91,9 +91,9 @@ pub fn main() !void {
             else => {},
         }
 
-        container.resize(try renderer.resize());
-        container.reposition(.{});
-        try renderer.render(@TypeOf(container), &container);
+        container.resize(&app.model, try renderer.resize());
+        container.reposition(&app.model, .{});
+        try renderer.render(@TypeOf(container), &container, App.Model, &app.model);
         try renderer.flush();
     }
 }
@@ -104,4 +104,4 @@ const log = std.log.scoped(.default);
 const std = @import("std");
 const assert = std.debug.assert;
 const zterm = @import("zterm");
-const App = zterm.App(union(enum) {});
+const App = zterm.App(struct {}, union(enum) {});

examples/layouts/mixed.zig

@@ -8,7 +8,7 @@ const QuitText = struct {
         };
     }
 
-    fn content(ctx: *anyopaque, cells: []zterm.Cell, size: zterm.Point) !void {
+    fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
         _ = ctx;
         assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
 
@@ -35,7 +35,7 @@ pub fn main() !void {
 
     const allocator = gpa.allocator();
 
-    var app: App = .init;
+    var app: App = .init(.{}, .{});
     var renderer = zterm.Renderer.Buffered.init(allocator);
     defer renderer.deinit();
 
@@ -77,7 +77,7 @@ pub fn main() !void {
     }
     defer container.deinit(); // also de-initializes the children
 
-    try app.start();
+    try app.start(.full);
     defer app.stop() catch |err| log.err("Failed to stop application: {any}", .{err});
 
     // event loop
@@ -94,7 +94,7 @@ pub fn main() !void {
         }
 
         // NOTE returned errors should be propagated back to the application
-        container.handle(event) catch |err| app.postEvent(.{
+        container.handle(&app.model, event) catch |err| app.postEvent(.{
             .err = .{
                 .err = err,
                 .msg = "Container Event handling failed",
@@ -107,9 +107,9 @@ pub fn main() !void {
             else => {},
         }
 
-        container.resize(try renderer.resize());
-        container.reposition(.{});
-        try renderer.render(@TypeOf(container), &container);
+        container.resize(&app.model, try renderer.resize());
+        container.reposition(&app.model, .{});
+        try renderer.render(@TypeOf(container), &container, App.Model, &app.model);
         try renderer.flush();
     }
 }
@@ -120,4 +120,4 @@ const log = std.log.scoped(.default);
 const std = @import("std");
 const assert = std.debug.assert;
 const zterm = @import("zterm");
-const App = zterm.App(union(enum) {});
+const App = zterm.App(struct {}, union(enum) {});

examples/layouts/vertical.zig

@@ -8,7 +8,7 @@ const QuitText = struct {
         };
     }
 
-    fn content(ctx: *anyopaque, cells: []zterm.Cell, size: zterm.Point) !void {
+    fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
         _ = ctx;
         assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
 
@@ -35,7 +35,7 @@ pub fn main() !void {
 
     const allocator = gpa.allocator();
 
-    var app: App = .init;
+    var app: App = .init(.{}, .{});
     var renderer = zterm.Renderer.Buffered.init(allocator);
     defer renderer.deinit();
 
@@ -60,7 +60,7 @@ pub fn main() !void {
     }, .{}));
     defer container.deinit(); // also de-initializes the children
 
-    try app.start();
+    try app.start(.full);
     defer app.stop() catch |err| log.err("Failed to stop application: {any}", .{err});
 
     // event loop
@@ -77,7 +77,7 @@ pub fn main() !void {
         }
 
         // NOTE returned errors should be propagated back to the application
-        container.handle(event) catch |err| app.postEvent(.{
+        container.handle(&app.model, event) catch |err| app.postEvent(.{
             .err = .{
                 .err = err,
                 .msg = "Container Event handling failed",
@@ -90,9 +90,9 @@ pub fn main() !void {
             else => {},
         }
 
-        container.resize(try renderer.resize());
-        container.reposition(.{});
-        try renderer.render(@TypeOf(container), &container);
+        container.resize(&app.model, try renderer.resize());
+        container.reposition(&app.model, .{});
+        try renderer.render(@TypeOf(container), &container, App.Model, &app.model);
         try renderer.flush();
     }
 }
@@ -103,4 +103,4 @@ const log = std.log.scoped(.default);
 const std = @import("std");
 const assert = std.debug.assert;
 const zterm = @import("zterm");
-const App = zterm.App(union(enum) {});
+const App = zterm.App(struct {}, union(enum) {});

examples/styles/palette.zig

@@ -5,7 +5,7 @@ const QuitText = struct {
         return .{ .ptr = this, .vtable = &.{ .content = content } };
     }
 
-    fn content(ctx: *anyopaque, cells: []zterm.Cell, size: zterm.Point) !void {
+    fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
         _ = ctx;
         assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
 
@@ -32,7 +32,7 @@ pub fn main() !void {
 
     const allocator = gpa.allocator();
 
-    var app: App = .init;
+    var app: App = .init(.{}, .{});
     var renderer = zterm.Renderer.Buffered.init(allocator);
     defer renderer.deinit();
 
@@ -50,7 +50,6 @@ pub fn main() !void {
     var box = try App.Container.init(allocator, .{
         .layout = .{ .direction = .horizontal },
     }, .{});
-    defer box.deinit();
 
     inline for (std.meta.fields(zterm.Color)) |field| {
         if (field.value == 0) continue; // zterm.Color.default == 0 -> skip
@@ -59,7 +58,7 @@ pub fn main() !void {
     var scrollable: App.Scrollable = .init(box, .disabled);
     try container.append(try App.Container.init(allocator, .{}, scrollable.element()));
 
-    try app.start();
+    try app.start(.full);
     defer app.stop() catch |err| log.err("Failed to stop application: {any}", .{err});
 
     while (true) {
@@ -73,7 +72,7 @@ pub fn main() !void {
             else => {},
         }
 
-        container.handle(event) catch |err| app.postEvent(.{
+        container.handle(&app.model, event) catch |err| app.postEvent(.{
             .err = .{
                 .err = err,
                 .msg = "Container Event handling failed",
@@ -86,9 +85,9 @@ pub fn main() !void {
             else => {},
         }
 
-        container.resize(try renderer.resize());
-        container.reposition(.{});
-        try renderer.render(@TypeOf(container), &container);
+        container.resize(&app.model, try renderer.resize());
+        container.reposition(&app.model, .{});
+        try renderer.render(@TypeOf(container), &container, App.Model, &app.model);
         try renderer.flush();
     }
 }
@@ -99,4 +98,4 @@ const log = std.log.scoped(.default);
 const std = @import("std");
 const assert = std.debug.assert;
 const zterm = @import("zterm");
-const App = zterm.App(union(enum) {});
+const App = zterm.App(struct {}, union(enum) {});

examples/styles/text.zig

@@ -5,7 +5,7 @@ const QuitText = struct {
         return .{ .ptr = this, .vtable = &.{ .content = content } };
     }
 
-    fn content(ctx: *anyopaque, cells: []zterm.Cell, size: zterm.Point) !void {
+    fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
         _ = ctx;
         assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
 
@@ -24,14 +24,109 @@ const QuitText = struct {
     }
 };
 
+const TableText = struct {
+    pub fn element(this: *@This()) App.Element {
+        return .{
+            .ptr = this,
+            .vtable = &.{
+                .content = content,
+            },
+        };
+    }
+
+    fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
+        _ = ctx;
+        _ = size;
+        var idx: usize = 0;
+        {
+            const text = "Normal ";
+            for (text) |cp| {
+                cells[idx].cp = cp;
+                idx += 1;
+            }
+        }
+        {
+            const text = "Bold   ";
+            for (text) |cp| {
+                cells[idx].cp = cp;
+                idx += 1;
+            }
+        }
+        {
+            const text = "Dim    ";
+            for (text) |cp| {
+                cells[idx].cp = cp;
+                idx += 1;
+            }
+        }
+        {
+            const text = "Italic ";
+            for (text) |cp| {
+                cells[idx].cp = cp;
+                idx += 1;
+            }
+        }
+        {
+            const text = "Underl ";
+            for (text) |cp| {
+                cells[idx].cp = cp;
+                idx += 1;
+            }
+        }
+        {
+            const text = "Blink  ";
+            for (text) |cp| {
+                cells[idx].cp = cp;
+                idx += 1;
+            }
+        }
+        {
+            const text = "Invert ";
+            for (text) |cp| {
+                cells[idx].cp = cp;
+                idx += 1;
+            }
+        }
+        {
+            const text = "Hidden ";
+            for (text) |cp| {
+                cells[idx].cp = cp;
+                idx += 1;
+            }
+        }
+        {
+            const text = "Strikethrough";
+            for (text) |cp| {
+                cells[idx].cp = cp;
+                idx += 1;
+            }
+        }
+    }
+};
+
 const TextStyles = struct {
     const text = "Example";
 
     pub fn element(this: *@This()) App.Element {
-        return .{ .ptr = this, .vtable = &.{ .content = content } };
+        return .{
+            .ptr = this,
+            .vtable = &.{
+                .minSize = minSize,
+                .content = content,
+            },
+        };
     }
 
-    fn content(ctx: *anyopaque, cells: []zterm.Cell, size: zterm.Point) !void {
+    fn minSize(ctx: *anyopaque, _: *const App.Model, size: zterm.Point) zterm.Point {
+        _ = ctx;
+        _ = size;
+        return .{
+            .x = std.meta.fields(zterm.Style.Emphasis).len * TextStyles.text.len,
+            .y = (std.meta.fields(zterm.Color).len - 1) * (std.meta.fields(zterm.Color).len - 2),
+        };
+    }
+
+    fn content(ctx: *anyopaque, _: *const App.Model, cells: []zterm.Cell, size: zterm.Point) !void {
         @setEvalBranchQuota(10000);
         _ = ctx;
         assert(cells.len == @as(usize, size.x) * @as(usize, size.y));
@@ -83,7 +178,7 @@ pub fn main() !void {
 
     const allocator = gpa.allocator();
 
-    var app: App = .init;
+    var app: App = .init(.{}, .{});
     var renderer = zterm.Renderer.Buffered.init(allocator);
     defer renderer.deinit();
 
@@ -94,56 +189,67 @@ pub fn main() !void {
 
     var container = try App.Container.init(allocator, .{
         .layout = .{
-            .gap = 2,
+            // .gap = 2,
             .padding = .{ .top = 5, .bottom = 3, .left = 3, .right = 3 },
+            .direction = .vertical,
         },
     }, element);
     defer container.deinit();
 
-    var box = try App.Container.init(allocator, .{
-        .layout = .{ .direction = .vertical },
+    var table_head: TableText = .{};
+    try container.append(try .init(allocator, .{
         .size = .{
-            .dim = .{
-                .x = std.meta.fields(zterm.Style.Emphasis).len * TextStyles.text.len,
-                .y = (std.meta.fields(zterm.Color).len - 1) * (std.meta.fields(zterm.Color).len - 2),
-            },
+            .dim = .{ .y = 1 },
+            .grow = .horizontal,
         },
-    }, text_styles.element());
-    defer box.deinit();
+    }, table_head.element()));
 
-    var scrollable: App.Scrollable = .init(box, .disabled);
+    var scrollable: App.Scrollable = .init(try .init(allocator, .{
+        .layout = .{ .direction = .vertical },
+    }, text_styles.element()), .enabled(.white, true));
     try container.append(try App.Container.init(allocator, .{}, scrollable.element()));
 
-    try app.start();
+    try app.start(.full);
     defer app.stop() catch |err| log.err("Failed to stop application: {any}", .{err});
 
-    while (true) {
-        const event = app.nextEvent();
-        log.debug("received event: {s}", .{@tagName(event)});
+    // event loop
+    loop: while (true) {
+        // batch events since last iteration
+        const len = blk: {
+            app.queue.poll();
+            app.queue.lock();
+            defer app.queue.unlock();
+            break :blk app.queue.len();
+        };
 
-        // pre event handling
-        switch (event) {
-            .key => |key| if (key.eql(.{ .cp = 'c', .mod = .{ .ctrl = true } })) app.quit(),
-            .err => |err| log.err("Received {s} with message: {s}", .{ @errorName(err.err), err.msg }),
-            else => {},
+        // handle events
+        for (0..len) |_| {
+            const event = app.queue.pop();
+            log.debug("handling event: {s}", .{@tagName(event)});
+            // pre event handling
+            switch (event) {
+                .key => |key| if (key.eql(.{ .cp = 'c', .mod = .{ .ctrl = true } })) app.quit(),
+                .err => |err| log.err("Received {s} with message: {s}", .{ @errorName(err.err), err.msg }),
+                else => {},
+            }
+
+            container.handle(&app.model, event) catch |err| app.postEvent(.{
+                .err = .{
+                    .err = err,
+                    .msg = "Container Event handling failed",
+                },
+            });
+
+            // post event handling
+            switch (event) {
+                .quit => break :loop,
+                else => {},
+            }
         }
 
-        container.handle(event) catch |err| app.postEvent(.{
-            .err = .{
-                .err = err,
-                .msg = "Container Event handling failed",
-            },
-        });
-
-        // post event handling
-        switch (event) {
-            .quit => break,
-            else => {},
-        }
-
-        container.resize(try renderer.resize());
-        container.reposition(.{});
-        try renderer.render(@TypeOf(container), &container);
+        container.resize(&app.model, try renderer.resize());
+        container.reposition(&app.model, .{});
+        try renderer.render(@TypeOf(container), &container, App.Model, &app.model);
         try renderer.flush();
     }
 }
@@ -154,4 +260,5 @@ const log = std.log.scoped(.default);
 const std = @import("std");
 const assert = std.debug.assert;
 const zterm = @import("zterm");
-const App = zterm.App(union(enum) {});
+
+const App = zterm.App(struct {}, union(enum) {});

src/app.zig

@@ -12,75 +12,116 @@
 /// ```zig
 ///   const zterm = @import("zterm");
 ///   const App = zterm.App(
-///       union(enum) {},
+///       struct {}, // empty model
+///       union(enum) {}, // no additional user event's
 ///   );
 ///   // later on create an `App` instance and start the event loop
-///   var app: App = .init;
-///   try app.start();
-///   defer app.stop() catch unreachable;
+///   var app: App = .init(io, .{}); // provide instance of the `std.Io` and `App` model that shall be used
+///   try app.start(.full);
+///   defer app.stop() catch unreachable; // does not clean-up the resources used in the model
 /// ```
-pub fn App(comptime E: type) type {
-    if (!isTaggedUnion(E)) {
-        @compileError("Provided user event `E` for `App(comptime E: type)` is not of type `union(enum)`.");
-    }
+pub fn App(comptime M: type, comptime E: type) type {
+    if (!isStruct(M)) @compileError("Provided model `M` for `App(comptime M: type, comptime E: type)` is not of type `struct`");
+    if (!isTaggedUnion(E)) @compileError("Provided user event `E` for `App(comptime M: type, comptime E: type)` is not of type `union(enum)`.");
     return struct {
+        io: std.Io,
+        model: Model,
         queue: Queue,
         thread: ?Thread = null,
         quit_event: Thread.ResetEvent,
         termios: ?posix.termios = null,
-        winch_registered: bool = false,
+        handler_registered: bool = false,
+        config: TerminalConfiguration,
+
+        pub const TerminalConfiguration = struct {
+            altScreen: bool,
+            saveScreen: bool,
+            rawMode: bool,
+            hideCursor: bool,
+
+            pub const full: @This() = .{
+                .altScreen = true,
+                .saveScreen = true,
+                .rawMode = true,
+                .hideCursor = true,
+            };
+
+            pub const direct: @This() = .{
+                .altScreen = false,
+                .saveScreen = false,
+                .rawMode = false,
+                .hideCursor = false,
+            };
+        };
 
         // global variable for the registered handler for WINCH
         var handler_ctx: *anyopaque = undefined;
         /// registered WINCH handler to report resize events
-        fn handleWinch(_: c_int) callconv(.C) void {
+        fn handleWinch(_: i32) callconv(.c) void {
+            const this: *@This() = @ptrCast(@alignCast(handler_ctx));
+            // NOTE this does not have to be done if in-band resize events are supported
+            // -> the signal might not work correctly when hosting the application over ssh!
+            this.postEvent(.resize);
+        }
+        /// registered CONT handler to force a complete redraw
+        fn handleCont(_: i32) callconv(.c) void {
             const this: *@This() = @ptrCast(@alignCast(handler_ctx));
             // NOTE this does not have to be done if in-band resize events are supported
             // -> the signal might not work correctly when hosting the application over ssh!
             this.postEvent(.resize);
         }
 
-        pub const init: @This() = .{
-            .queue = .{},
-            .quit_event = .{},
-        };
+        pub fn init(io: std.Io, model: Model) @This() {
+            return .{
+                .io = io,
+                .model = model,
+                .queue = .{},
+                .quit_event = .{},
+                .config = undefined,
+            };
+        }
 
-        pub fn start(this: *@This()) !void {
+        pub fn start(this: *@This(), config: TerminalConfiguration) !void {
+            this.config = config;
             if (this.thread) |_| return;
 
             // post init event (as the very first element to be in the queue - event loop)
             this.postEvent(.init);
 
-            if (!this.winch_registered) {
+            if (!this.handler_registered) {
                 handler_ctx = this;
-                var act = posix.Sigaction{
+                posix.sigaction(posix.SIG.WINCH, &.{
                     .handler = .{ .handler = handleWinch },
                     .mask = posix.sigemptyset(),
                     .flags = 0,
-                };
-                posix.sigaction(posix.SIG.WINCH, &act, null);
-                this.winch_registered = true;
+                }, null);
+                posix.sigaction(posix.SIG.CONT, &.{
+                    .handler = .{ .handler = handleCont },
+                    .mask = posix.sigemptyset(),
+                    .flags = 0,
+                }, null);
+                this.handler_registered = true;
             }
 
             this.quit_event.reset();
             this.thread = try Thread.spawn(.{}, @This().run, .{this});
 
             var termios: posix.termios = undefined;
-            try terminal.enableRawMode(&termios);
+            if (this.config.rawMode) try terminal.enableRawMode(&termios);
             if (this.termios) |_| {} else this.termios = termios;
 
-            try terminal.saveScreen();
-            try terminal.enterAltScreen();
-            try terminal.hideCursor();
-            try terminal.enableMouseSupport();
+            if (this.config.altScreen) try terminal.enterAltScreen();
+            if (this.config.saveScreen) try terminal.saveScreen();
+            if (this.config.hideCursor) try terminal.hideCursor();
+            if (this.config.altScreen and this.config.rawMode) try terminal.enableMouseSupport();
         }
 
         pub fn interrupt(this: *@This()) !void {
             this.quit_event.set();
-            try terminal.disableMouseSupport();
-            try terminal.exitAltScreen();
-            try terminal.restoreScreen();
-            if (this.thread) |thread| {
+            if (this.config.altScreen and this.config.rawMode) try terminal.disableMouseSupport();
+            if (this.config.saveScreen) try terminal.restoreScreen();
+            if (this.config.altScreen) try terminal.exitAltScreen();
+            if (this.thread) |*thread| {
                 thread.join();
                 this.thread = null;
             }
@@ -88,18 +129,16 @@ pub fn App(comptime E: type) type {
 
         pub fn stop(this: *@This()) !void {
             try this.interrupt();
-            if (this.termios) |*termios| {
-                try terminal.disableMouseSupport();
-                try terminal.showCursor();
-                try terminal.exitAltScreen();
-                try terminal.disableRawMode(termios);
-                try terminal.restoreScreen();
+            if (this.config.hideCursor) try terminal.showCursor();
+            if (this.config.saveScreen) try terminal.resetCursor();
+            if (this.termios) |termios| {
+                if (this.config.rawMode) try terminal.disableRawMode(&termios);
+                this.termios = null;
             }
-            this.termios = null;
         }
 
         /// Quit the application loop.
-        /// This will stop the internal input thread and post a **.quit** `Event`.
+        /// This will cancel the internal input thread and post a **.quit** `Event`.
         pub fn quit(this: *@This()) void {
             this.quit_event.set();
             this.postEvent(.quit);
@@ -117,13 +156,42 @@ pub fn App(comptime E: type) type {
 
         fn run(this: *@This()) !void {
             // thread to read user inputs
-            var buf: [256]u8 = undefined;
+            var buf: [512]u8 = undefined;
+            // NOTE set the `NONBLOCK` option for the stdin file, such that reading is not blocking!
+            {
+                // TODO is there a better way to do this through the `std.Io` interface?
+                var fl_flags = posix.fcntl(posix.STDIN_FILENO, posix.F.GETFL, 0) catch |err| switch (err) {
+                    error.FileBusy => unreachable,
+                    error.Locked => unreachable,
+                    error.PermissionDenied => unreachable,
+                    error.DeadLock => unreachable,
+                    error.LockedRegionLimitExceeded => unreachable,
+                    else => |e| return e,
+                };
+                fl_flags |= 1 << @bitOffsetOf(posix.system.O, "NONBLOCK");
+                _ = posix.fcntl(posix.STDIN_FILENO, posix.F.SETFL, fl_flags) catch |err| switch (err) {
+                    error.FileBusy => unreachable,
+                    error.Locked => unreachable,
+                    error.PermissionDenied => unreachable,
+                    error.DeadLock => unreachable,
+                    error.LockedRegionLimitExceeded => unreachable,
+                    else => |e| return e,
+                };
+            }
             while (true) {
-                // FIX I still think that there is a race condition (I'm just waiting 'long' enough)
                 this.quit_event.timedWait(20 * std.time.ns_per_ms) catch {
-                    // FIX in case the queue is full -> the next user input should panic and quit the application? because something seems to clock up the event queue
-                    const read_bytes = try terminal.read(buf[0..]);
-                    // TODO `break` should not terminate the reading of the user inputs, but instead only the received faulty input!
+                    var remaining_bytes: usize = 0;
+
+                    // non-blocking read
+                    const read_bytes = terminal.read(buf[remaining_bytes..]) catch |err| switch (err) {
+                        error.WouldBlock => {
+                            // wait a bit
+                            std.Thread.sleep(20);
+                            continue;
+                        },
+                        else => return err,
+                    } + remaining_bytes;
+
                     // escape key presses
                     if (buf[0] == 0x1b and read_bytes > 1) {
                         switch (buf[1]) {
@@ -150,9 +218,9 @@ pub fn App(comptime E: type) type {
                                 if (read_bytes < 3) continue;
 
                                 // We start iterating at index 2 to get past the '['
-                                const sequence = for (buf[2..], 2..) |b, i| {
+                                const sequence: []u8 = blk: for (buf[2..], 2..) |b, i| {
                                     switch (b) {
-                                        0x40...0xFF => break buf[0 .. i + 1],
+                                        0x40...0xFF => break :blk buf[0 .. i + 1],
                                         else => continue,
                                     }
                                 } else continue;
@@ -283,18 +351,19 @@ pub fn App(comptime E: type) type {
                                         // const alt = button_mask & mouse_bits.alt > 0;
                                         // const ctrl = button_mask & mouse_bits.ctrl > 0;
 
-                                        const mouse: Mouse = .{
-                                            .button = button,
-                                            .x = px -| 1,
-                                            .y = py -| 1,
-                                            .kind = blk: {
-                                                if (motion and button != Mouse.Button.none) break :blk .drag;
-                                                if (motion and button == Mouse.Button.none) break :blk .motion;
-                                                if (sequence[sequence.len - 1] == 'm') break :blk .release;
-                                                break :blk .press;
+                                        this.postEvent(.{
+                                            .mouse = .{
+                                                .button = button,
+                                                .x = px -| 1,
+                                                .y = py -| 1,
+                                                .kind = blk: {
+                                                    if (motion and button != Mouse.Button.none) break :blk .drag;
+                                                    if (motion and button == Mouse.Button.none) break :blk .motion;
+                                                    if (sequence[sequence.len - 1] == 'm') break :blk .release;
+                                                    break :blk .press;
+                                                },
                                             },
-                                        };
-                                        this.postEvent(.{ .mouse = mouse });
+                                        });
                                     },
                                     'c' => {
                                         // Primary DA (CSI ? Pm c)
@@ -376,9 +445,17 @@ pub fn App(comptime E: type) type {
                             },
                             0x7f => .{ .cp = input.Backspace },
                             else => {
-                                var iter = code_point.Iterator{ .bytes = buf[0..read_bytes] };
-                                while (iter.next()) |cp| this.postEvent(.{ .key = .{ .cp = cp.code } });
-                                continue;
+                                var len = read_bytes;
+                                while (!std.unicode.utf8ValidateSlice(buf[0..len])) len -= 1;
+                                remaining_bytes = read_bytes - len;
+                                if (this.config.rawMode) {
+                                    var iter: std.unicode.Utf8Iterator = .{ .bytes = buf[0..len], .i = 0 };
+                                    while (iter.nextCodepoint()) |cp| this.postEvent(.{ .key = .{ .cp = cp } });
+                                    continue;
+                                } else {
+                                    this.postEvent(.{ .line = buf[0..len] });
+                                    continue;
+                                }
                             },
                         };
                         this.postEvent(.{ .key = key });
@@ -391,9 +468,10 @@ pub fn App(comptime E: type) type {
 
         pub fn panic_handler(msg: []const u8, _: ?*std.builtin.StackTrace, ret_addr: ?usize) noreturn {
             terminal.disableMouseSupport() catch {};
-            terminal.exitAltScreen() catch {};
             terminal.showCursor() catch {};
-            var termios: posix.termios = .{
+            terminal.resetCursor() catch {};
+            terminal.restoreScreen() catch {};
+            terminal.disableRawMode(&.{
                 .iflag = .{},
                 .lflag = .{},
                 .cflag = .{},
@@ -402,22 +480,25 @@ pub fn App(comptime E: type) type {
                 .line = 0,
                 .ispeed = undefined,
                 .ospeed = undefined,
-            };
-            terminal.disableRawMode(&termios) catch {};
-            terminal.restoreScreen() catch {};
+            }) catch {};
+            terminal.exitAltScreen() catch {};
             std.debug.defaultPanic(msg, ret_addr);
         }
 
         const element = @import("element.zig");
+        pub const Model = M;
         pub const Event = mergeTaggedUnions(event.SystemEvent, E);
-        pub const Container = @import("container.zig").Container(Event);
-        pub const Element = element.Element(Event);
-        pub const Alignment = element.Alignment(Event);
-        pub const Button = element.Button(Event, Queue);
-        pub const Input = element.Input(Event, Queue);
-        pub const Progress = element.Progress(Event, Queue);
-        pub const Scrollable = element.Scrollable(Event);
-        pub const Queue = queue.Queue(Event, 256);
+        pub const Container = @import("container.zig").Container(Model, Event);
+        pub const Element = element.Element(Model, Event);
+        pub const Alignment = element.Alignment(Model, Event);
+        pub const Button = element.Button(Model, Event, Queue);
+        pub const TextField = element.TextField(Model, Event);
+        pub const Input = element.Input(Model, Event, Queue);
+        pub const Progress = element.Progress(Model, Event, Queue);
+        pub const RadioButton = element.RadioButton(Model, Event);
+        pub const Scrollable = element.Scrollable(Model, Event);
+        pub const Selection = element.Selection(Model, Event);
+        pub const Queue = queue.Queue(Event, 512);
     };
 }
 
@@ -429,13 +510,13 @@ const fmt = std.fmt;
 const posix = std.posix;
 const Thread = std.Thread;
 const assert = std.debug.assert;
-const code_point = @import("code_point");
 const event = @import("event.zig");
 const input = @import("input.zig");
 const terminal = @import("terminal.zig");
 const queue = @import("queue.zig");
 const mergeTaggedUnions = event.mergeTaggedUnions;
 const isTaggedUnion = event.isTaggedUnion;
+const isStruct = event.isStruct;
 const Mouse = input.Mouse;
 const Key = input.Key;
 const Point = @import("point.zig").Point;

src/cell.zig

@@ -1,6 +1,5 @@
 //! Cell type containing content and formatting for each character in the terminal screen.
 
-// TODO embrace `zg` dependency more due to utf-8 encoding
 cp: u21 = ' ',
 style: Style = .{ .emphasis = &.{} },
 
@@ -13,7 +12,7 @@ pub fn reset(this: *Cell) void {
     this.cp = ' ';
 }
 
-pub fn value(this: Cell, writer: anytype) !void {
+pub fn value(this: Cell, writer: *std.Io.Writer) !void {
     try this.style.value(writer, this.cp);
 }
 
@@ -26,20 +25,18 @@ test "ascii styled text" {
         .{ .cp = 'Y', .style = .{ .fg = .green, .bg = .grey, .emphasis = &.{} } },
         .{ .cp = 'v', .style = .{ .emphasis = &.{ .bold, .underline } } },
         .{ .cp = 'e', .style = .{ .emphasis = &.{.italic} } },
-        .{ .cp = 's', .style = .{ .fg = .light_green, .bg = .black, .emphasis = &.{.underline} } },
+        .{ .cp = 's', .style = .{ .fg = .lightgreen, .bg = .black, .emphasis = &.{.underline} } },
     };
 
-    var string = std.ArrayList(u8).init(std.testing.allocator);
-    defer string.deinit();
-
-    const writer = string.writer();
+    var writer = std.Io.Writer.Allocating.init(std.testing.allocator);
+    defer writer.deinit();
     for (cells) |cell| {
-        try cell.value(writer);
+        try cell.value(&writer.writer);
     }
     try std.testing.expectEqualSlices(
         u8,
         "\x1b[38;5;10;48;5;8;59mY\x1b[0m\x1b[39;49;59;1;4mv\x1b[0m\x1b[39;49;59;3me\x1b[0m\x1b[38;5;2;48;5;16;59;4ms\x1b[0m",
-        string.items,
+        writer.writer.buffer[0..writer.writer.end],
     );
 }
 
@@ -48,19 +45,17 @@ test "utf-8 styled text" {
         .{ .cp = '╭', .style = .{ .fg = .green, .bg = .grey, .emphasis = &.{} } },
         .{ .cp = '─', .style = .{ .emphasis = &.{} } },
         .{ .cp = '┄', .style = .{ .emphasis = &.{} } },
-        .{ .cp = '┘', .style = .{ .fg = .light_green, .bg = .black, .emphasis = &.{.underline} } },
+        .{ .cp = '┘', .style = .{ .fg = .lightgreen, .bg = .black, .emphasis = &.{.underline} } },
     };
 
-    var string = std.ArrayList(u8).init(std.testing.allocator);
-    defer string.deinit();
-
-    const writer = string.writer();
+    var writer = std.Io.Writer.Allocating.init(std.testing.allocator);
+    defer writer.deinit();
     for (cells) |cell| {
-        try cell.value(writer);
+        try cell.value(&writer.writer);
     }
     try std.testing.expectEqualSlices(
         u8,
         "\x1b[38;5;10;48;5;8;59m╭\x1b[0m\x1b[39;49;59m─\x1b[0m\x1b[39;49;59m┄\x1b[0m\x1b[38;5;2;48;5;16;59;4m┘\x1b[0m",
-        string.items,
+        writer.writer.buffer[0..writer.writer.end],
     );
 }

src/color.zig

@@ -1,13 +1,13 @@
 pub const Color = enum(u8) {
     default = 0,
     black = 16,
-    light_red = 1,
-    light_green,
-    light_yellow,
-    light_blue,
-    light_magenta,
-    light_cyan,
-    light_grey,
+    lightred = 1,
+    lightgreen,
+    lightyellow,
+    lightblue,
+    lightmagenta,
+    lightcyan,
+    lightgrey,
     grey,
     red,
     green,
@@ -18,24 +18,21 @@ pub const Color = enum(u8) {
     white,
     // TODO add further colors as described in https://gist.github.com/ConnerWill/d4b6c776b509add763e17f9f113fd25b # Color / Graphics Mode - 256 Colors
 
-    // TODO might be useful to use the std.ascii stuff!
-
-    pub inline fn write(this: Color, writer: anytype, comptime coloring: enum { fg, bg, ul }) !void {
+    pub inline fn write(this: Color, writer: *std.Io.Writer, comptime coloring: enum { fg, bg, ul }) !void {
         if (this == .default) {
             switch (coloring) {
-                .fg => try format(writer, "39", .{}),
-                .bg => try format(writer, "49", .{}),
-                .ul => try format(writer, "59", .{}),
+                .fg => try writer.printAscii("39", .{}),
+                .bg => try writer.printAscii("49", .{}),
+                .ul => try writer.printAscii("59", .{}),
             }
         } else {
             switch (coloring) {
-                .fg => try format(writer, "38;5;{d}", .{@intFromEnum(this)}),
-                .bg => try format(writer, "48;5;{d}", .{@intFromEnum(this)}),
-                .ul => try format(writer, "58;5;{d}", .{@intFromEnum(this)}),
+                .fg => try writer.print("38;5;{d}", .{@intFromEnum(this)}),
+                .bg => try writer.print("48;5;{d}", .{@intFromEnum(this)}),
+                .ul => try writer.print("58;5;{d}", .{@intFromEnum(this)}),
             }
         }
     }
 };
 
 const std = @import("std");
-const format = std.fmt.format;

src/container.zig

@@ -1,3 +1,6 @@
+// FIX known issues:
+// - hold fewer instances of the `Allocator`
+
 /// Border configuration struct
 pub const Border = packed struct {
     /// Color to use for the border
@@ -77,8 +80,9 @@ pub const Border = packed struct {
     test "all sides" {
         const event = @import("event.zig");
         const testing = @import("testing.zig");
+        const Model = struct {};
 
-        var container: Container(event.SystemEvent) = try .init(std.testing.allocator, .{
+        var container: Container(Model, event.SystemEvent) = try .init(std.testing.allocator, .{
             .border = .{
                 .color = .green,
                 .sides = .all,
@@ -89,14 +93,15 @@ pub const Border = packed struct {
         try testing.expectContainerScreen(.{
             .y = 20,
             .x = 30,
-        }, &container, @import("test/container/border.all.zon"));
+        }, @TypeOf(container), &container, Model, @import("test/container/border.all.zon"));
     }
 
     test "vertical sides" {
         const event = @import("event.zig");
         const testing = @import("testing.zig");
+        const Model = struct {};
 
-        var container: Container(event.SystemEvent) = try .init(std.testing.allocator, .{
+        var container: Container(Model, event.SystemEvent) = try .init(std.testing.allocator, .{
             .border = .{
                 .color = .green,
                 .sides = .vertical,
@@ -107,14 +112,15 @@ pub const Border = packed struct {
         try testing.expectContainerScreen(.{
             .y = 20,
             .x = 30,
-        }, &container, @import("test/container/border.vertical.zon"));
+        }, @TypeOf(container), &container, Model, @import("test/container/border.vertical.zon"));
     }
 
     test "horizontal sides" {
         const event = @import("event.zig");
         const testing = @import("testing.zig");
+        const Model = struct {};
 
-        var container: Container(event.SystemEvent) = try .init(std.testing.allocator, .{
+        var container: Container(Model, event.SystemEvent) = try .init(std.testing.allocator, .{
             .border = .{
                 .color = .green,
                 .sides = .horizontal,
@@ -125,7 +131,7 @@ pub const Border = packed struct {
         try testing.expectContainerScreen(.{
             .y = 20,
             .x = 30,
-        }, &container, @import("test/container/border.horizontal.zon"));
+        }, @TypeOf(container), &container, Model, @import("test/container/border.horizontal.zon"));
     }
 };
 
@@ -157,8 +163,9 @@ pub const Rectangle = packed struct {
     test "fill color overwrite parent fill" {
         const event = @import("event.zig");
         const testing = @import("testing.zig");
+        const Model = struct {};
 
-        var container: Container(event.SystemEvent) = try .init(std.testing.allocator, .{
+        var container: Container(Model, event.SystemEvent) = try .init(std.testing.allocator, .{
             .rectangle = .{ .fill = .green },
         }, .{});
         try container.append(try .init(std.testing.allocator, .{
@@ -170,14 +177,15 @@ pub const Rectangle = packed struct {
         try testing.expectContainerScreen(.{
             .y = 20,
             .x = 30,
-        }, &container, @import("test/container/rectangle_with_parent_fill_without_padding.zon"));
+        }, @TypeOf(container), &container, Model, @import("test/container/rectangle_with_parent_fill_without_padding.zon"));
     }
 
     test "fill color padding to show parent fill" {
         const event = @import("event.zig");
         const testing = @import("testing.zig");
+        const Model = struct {};
 
-        var container: Container(event.SystemEvent) = try .init(std.testing.allocator, .{
+        var container: Container(Model, event.SystemEvent) = try .init(std.testing.allocator, .{
             .layout = .{
                 .padding = .all(2),
             },
@@ -192,14 +200,15 @@ pub const Rectangle = packed struct {
         try testing.expectContainerScreen(.{
             .y = 20,
             .x = 30,
-        }, &container, @import("test/container/rectangle_with_parent_padding.zon"));
+        }, @TypeOf(container), &container, Model, @import("test/container/rectangle_with_parent_padding.zon"));
     }
 
     test "fill color padding to show parent fill (negative padding)" {
         const event = @import("event.zig");
         const testing = @import("testing.zig");
+        const Model = struct {};
 
-        var container: Container(event.SystemEvent) = try .init(std.testing.allocator, .{
+        var container: Container(Model, event.SystemEvent) = try .init(std.testing.allocator, .{
             .layout = .{
                 .padding = .{
                     .top = -18,
@@ -219,14 +228,15 @@ pub const Rectangle = packed struct {
         try testing.expectContainerScreen(.{
             .y = 20,
             .x = 30,
-        }, &container, @import("test/container/rectangle_with_parent_padding.zon"));
+        }, @TypeOf(container), &container, Model, @import("test/container/rectangle_with_parent_padding.zon"));
     }
 
     test "fill color spacer with padding" {
         const event = @import("event.zig");
         const testing = @import("testing.zig");
+        const Model = struct {};
 
-        var container: Container(event.SystemEvent) = try .init(std.testing.allocator, .{
+        var container: Container(Model, event.SystemEvent) = try .init(std.testing.allocator, .{
             .rectangle = .{
                 .fill = .black,
             },
@@ -247,14 +257,15 @@ pub const Rectangle = packed struct {
         try testing.expectContainerScreen(.{
             .y = 20,
             .x = 30,
-        }, &container, @import("test/container/rectangle_with_padding.zon"));
+        }, @TypeOf(container), &container, Model, @import("test/container/rectangle_with_padding.zon"));
     }
 
     test "fill color with gap" {
         const event = @import("event.zig");
         const testing = @import("testing.zig");
+        const Model = struct {};
 
-        var container: Container(event.SystemEvent) = try .init(std.testing.allocator, .{
+        var container: Container(Model, event.SystemEvent) = try .init(std.testing.allocator, .{
             .rectangle = .{
                 .fill = .black,
             },
@@ -278,14 +289,15 @@ pub const Rectangle = packed struct {
         try testing.expectContainerScreen(.{
             .y = 20,
             .x = 30,
-        }, &container, @import("test/container/rectangle_with_gap.zon"));
+        }, @TypeOf(container), &container, Model, @import("test/container/rectangle_with_gap.zon"));
     }
 
     test "fill color with separator" {
         const event = @import("event.zig");
         const testing = @import("testing.zig");
+        const Model = struct {};
 
-        var container: Container(event.SystemEvent) = try .init(std.testing.allocator, .{
+        var container: Container(Model, event.SystemEvent) = try .init(std.testing.allocator, .{
             .rectangle = .{
                 .fill = .black,
             },
@@ -310,7 +322,7 @@ pub const Rectangle = packed struct {
         try testing.expectContainerScreen(.{
             .y = 20,
             .x = 30,
-        }, &container, @import("test/container/rectangle_with_separator.zon"));
+        }, @TypeOf(container), &container, Model, @import("test/container/rectangle_with_separator.zon"));
     }
 };
 
@@ -400,8 +412,9 @@ pub const Layout = packed struct {
     test "separator without gaps" {
         const event = @import("event.zig");
         const testing = @import("testing.zig");
+        const Model = struct {};
 
-        var container: Container(event.SystemEvent) = try .init(std.testing.allocator, .{
+        var container: Container(Model, event.SystemEvent) = try .init(std.testing.allocator, .{
             .layout = .{
                 .separator = .{
                     .enabled = true,
@@ -415,14 +428,15 @@ pub const Layout = packed struct {
         try testing.expectContainerScreen(.{
             .y = 20,
             .x = 30,
-        }, &container, @import("test/container/separator_no_gaps.zon"));
+        }, @TypeOf(container), &container, Model, @import("test/container/separator_no_gaps.zon"));
     }
 
     test "separator without gaps with padding" {
         const event = @import("event.zig");
         const testing = @import("testing.zig");
+        const Model = struct {};
 
-        var container: Container(event.SystemEvent) = try .init(std.testing.allocator, .{
+        var container: Container(Model, event.SystemEvent) = try .init(std.testing.allocator, .{
             .layout = .{
                 .padding = .all(1),
                 .separator = .{
@@ -437,14 +451,15 @@ pub const Layout = packed struct {
         try testing.expectContainerScreen(.{
             .y = 20,
             .x = 30,
-        }, &container, @import("test/container/separator_no_gaps_with_padding.zon"));
+        }, @TypeOf(container), &container, Model, @import("test/container/separator_no_gaps_with_padding.zon"));
     }
 
     test "separator(2x) without gaps" {
         const event = @import("event.zig");
         const testing = @import("testing.zig");
+        const Model = struct {};
 
-        var container: Container(event.SystemEvent) = try .init(std.testing.allocator, .{
+        var container: Container(Model, event.SystemEvent) = try .init(std.testing.allocator, .{
             .layout = .{
                 .direction = .vertical,
                 .separator = .{
@@ -461,14 +476,15 @@ pub const Layout = packed struct {
         try testing.expectContainerScreen(.{
             .y = 20,
             .x = 30,
-        }, &container, @import("test/container/separator_2x_no_gaps.zon"));
+        }, @TypeOf(container), &container, Model, @import("test/container/separator_2x_no_gaps.zon"));
     }
 
     test "separator(2x) with border(all)" {
         const event = @import("event.zig");
         const testing = @import("testing.zig");
+        const Model = struct {};
 
-        var container: Container(event.SystemEvent) = try .init(std.testing.allocator, .{
+        var container: Container(Model, event.SystemEvent) = try .init(std.testing.allocator, .{
             .border = .{
                 .color = .red,
                 .sides = .all,
@@ -488,14 +504,15 @@ pub const Layout = packed struct {
         try testing.expectContainerScreen(.{
             .y = 20,
             .x = 30,
-        }, &container, @import("test/container/separator_2x_no_gaps_with_border.zon"));
+        }, @TypeOf(container), &container, Model, @import("test/container/separator_2x_no_gaps_with_border.zon"));
     }
 
     test "separator(2x) with border(all) and padding(all(1))" {
         const event = @import("event.zig");
         const testing = @import("testing.zig");
+        const Model = struct {};
 
-        var container: Container(event.SystemEvent) = try .init(std.testing.allocator, .{
+        var container: Container(Model, event.SystemEvent) = try .init(std.testing.allocator, .{
             .border = .{
                 .color = .red,
                 .sides = .all,
@@ -516,14 +533,15 @@ pub const Layout = packed struct {
         try testing.expectContainerScreen(.{
             .y = 20,
             .x = 30,
-        }, &container, @import("test/container/separator_2x_no_gaps_with_padding.zon"));
+        }, @TypeOf(container), &container, Model, @import("test/container/separator_2x_no_gaps_with_padding.zon"));
     }
 
     test "separator(2x) with border(all) and gap" {
         const event = @import("event.zig");
         const testing = @import("testing.zig");
+        const Model = struct {};
 
-        var container: Container(event.SystemEvent) = try .init(std.testing.allocator, .{
+        var container: Container(Model, event.SystemEvent) = try .init(std.testing.allocator, .{
             .border = .{
                 .color = .red,
                 .sides = .all,
@@ -544,14 +562,15 @@ pub const Layout = packed struct {
         try testing.expectContainerScreen(.{
             .y = 20,
             .x = 30,
-        }, &container, @import("test/container/separator_2x_with_gaps_with_border.zon"));
+        }, @TypeOf(container), &container, Model, @import("test/container/separator_2x_with_gaps_with_border.zon"));
     }
 
     test "separator(2x) with border(all) and gap and padding" {
         const event = @import("event.zig");
         const testing = @import("testing.zig");
+        const Model = struct {};
 
-        var container: Container(event.SystemEvent) = try .init(std.testing.allocator, .{
+        var container: Container(Model, event.SystemEvent) = try .init(std.testing.allocator, .{
             .border = .{
                 .color = .red,
                 .sides = .all,
@@ -573,25 +592,27 @@ pub const Layout = packed struct {
         try testing.expectContainerScreen(.{
             .y = 20,
             .x = 30,
-        }, &container, @import("test/container/separator_2x_with_gaps_with_border_with_padding.zon"));
+        }, @TypeOf(container), &container, Model, @import("test/container/separator_2x_with_gaps_with_border_with_padding.zon"));
     }
 };
 
 /// Sizing options which should be used by the `Container`
 pub const Size = packed struct {
     dim: Point = .{},
-    grow: enum(u2) {
+    grow: enum(u3) {
         both,
         fixed,
+        vertical_only,
+        horizontal_only,
         vertical,
         horizontal,
     } = .both,
 };
 
-pub fn Container(comptime Event: type) type {
+pub fn Container(Model: type, Event: type) type {
     if (!isTaggedUnion(Event)) @compileError("Provided user event `Event` for `Container(comptime Event: type)`");
 
-    const Element = @import("element.zig").Element(Event);
+    const Element = @import("element.zig").Element(Model, Event);
     return struct {
         allocator: Allocator,
         origin: Point,
@@ -622,23 +643,24 @@ pub fn Container(comptime Event: type) type {
                 .size = .{},
                 .properties = properties,
                 .element = element,
-                .elements = std.ArrayList(@This()).init(allocator),
+                .elements = try std.ArrayList(@This()).initCapacity(allocator, 2),
             };
         }
 
-        pub fn deinit(this: *const @This()) void {
+        pub fn deinit(this: *@This()) void {
             for (this.elements.items) |*element| element.deinit();
-            this.elements.deinit();
+            this.elements.deinit(this.allocator);
+            this.element.deinit();
         }
 
         pub fn append(this: *@This(), element: @This()) !void {
-            try this.elements.append(element);
+            try this.elements.append(this.allocator, element);
         }
 
-        pub fn reposition(this: *@This(), origin: Point) void {
+        pub fn reposition(this: *@This(), model: *const Model, origin: Point) void {
             const layout = this.properties.layout;
             this.origin = origin;
-            this.element.reposition(origin);
+            this.element.reposition(model, origin);
 
             var offset = origin.add(.{
                 .x = Layout.getAbsolutePadding(layout.padding.left, this.size.x),
@@ -650,7 +672,7 @@ pub fn Container(comptime Event: type) type {
             if (sides.top) offset.y += 1;
 
             for (this.elements.items) |*child| {
-                child.reposition(offset);
+                child.reposition(model, offset);
 
                 switch (layout.direction) {
                     .horizontal => offset.x += child.size.x + layout.gap,
@@ -665,7 +687,7 @@ pub fn Container(comptime Event: type) type {
         }
 
         /// Resize all fit sized `Containers` to the necessary size required by its child elements.
-        fn fit_resize(this: *@This()) Point {
+        fn fit_resize(this: *@This(), model: *const Model) Point {
             // NOTE this is supposed to be a simple and easy to understand algorithm, there are currently no optimizations done
             const layout = this.properties.layout;
             var size: Point = switch (layout.direction) {
@@ -690,7 +712,7 @@ pub fn Container(comptime Event: type) type {
             };
 
             for (this.elements.items) |*child| {
-                const child_size = child.fit_resize();
+                const child_size = child.fit_resize(model);
                 switch (layout.direction) {
                     .horizontal => {
                         size.x += child_size.x;
@@ -703,24 +725,29 @@ pub fn Container(comptime Event: type) type {
                 }
             }
 
+            size = this.minSize(model, size);
             // assign currently calculated size
             this.size = switch (this.properties.size.grow) {
-                .both => Point.max(size, this.properties.size.dim),
-                .fixed => this.properties.size.dim,
-                .horizontal => .{
-                    .x = @max(size.x, this.properties.size.dim.x),
-                    .y = this.properties.size.dim.y,
+                .both => .max(size, this.properties.size.dim),
+                .fixed => blk: {
+                    assert(this.properties.size.dim.x > 0 or size.x > 0);
+                    assert(this.properties.size.dim.y > 0 or size.y > 0);
+                    break :blk .max(size, this.properties.size.dim);
                 },
-                .vertical => .{
-                    .x = this.properties.size.dim.x,
-                    .y = @max(size.y, this.properties.size.dim.y),
+                .horizontal, .horizontal_only => blk: {
+                    assert(this.properties.size.dim.y > 0 or size.y > 0);
+                    break :blk .max(size, this.properties.size.dim);
+                },
+                .vertical, .vertical_only => blk: {
+                    assert(this.properties.size.dim.x > 0 or size.x > 0);
+                    break :blk .max(size, this.properties.size.dim);
                 },
             };
             return this.size;
         }
 
         /// growable implicitly requires the root `Container` to have a set a size property to the size of the available terminal screen
-        fn grow_resize(this: *@This(), max_size: Point) void {
+        fn grow_resize(this: *@This(), model: *const Model, max_size: Point) void {
             const layout = this.properties.layout;
             var remainder = switch (layout.direction) {
                 .horizontal => max_size.x -| (Layout.getAbsolutePadding(layout.padding.left, this.size.x) + Layout.getAbsolutePadding(layout.padding.right, this.size.x)),
@@ -737,23 +764,31 @@ pub fn Container(comptime Event: type) type {
 
             const sides = this.properties.border.sides;
             switch (layout.direction) {
-                .horizontal => {
+                .vertical => {
                     if (sides.top) {
-                        available -|= 1;
                         remainder -|= 1;
                     }
                     if (sides.bottom) {
-                        available -|= 1;
                         remainder -|= 1;
                     }
-                },
-                .vertical => {
                     if (sides.left) {
                         available -|= 1;
-                        remainder -|= 1;
                     }
                     if (sides.right) {
                         available -|= 1;
+                    }
+                },
+                .horizontal => {
+                    if (sides.top) {
+                        available -|= 1;
+                    }
+                    if (sides.bottom) {
+                        available -|= 1;
+                    }
+                    if (sides.left) {
+                        remainder -|= 1;
+                    }
+                    if (sides.right) {
                         remainder -|= 1;
                     }
                 },
@@ -774,21 +809,21 @@ pub fn Container(comptime Event: type) type {
                         if (growable_children == 0) first_growable_child = child;
                         growable_children += 1;
                     },
-                    .horizontal => if (layout.direction == .horizontal) {
+                    .horizontal, .horizontal_only => if (layout.direction == .horizontal) {
                         if (growable_children == 0) first_growable_child = child;
                         growable_children += 1;
                     },
-                    .vertical => if (layout.direction == .vertical) {
+                    .vertical, .vertical_only => if (layout.direction == .vertical) {
                         if (growable_children == 0) first_growable_child = child;
                         growable_children += 1;
                     },
                 }
                 // non layout direction side growth
                 switch (layout.direction) {
-                    .horizontal => if (child.properties.size.grow == .vertical or child.properties.size.grow == .both) {
+                    .horizontal => if (child.properties.size.grow == .vertical or child.properties.size.grow == .vertical_only or child.properties.size.grow == .both) {
                         child.size.y = available;
                     },
-                    .vertical => if (child.properties.size.grow == .horizontal or child.properties.size.grow == .both) {
+                    .vertical => if (child.properties.size.grow == .horizontal or child.properties.size.grow == .horizontal_only or child.properties.size.grow == .both) {
                         child.size.x = available;
                     },
                 }
@@ -806,8 +841,8 @@ pub fn Container(comptime Event: type) type {
                     if (child.properties.size.grow == .fixed) continue;
 
                     switch (layout.direction) {
-                        .horizontal => if (child.properties.size.grow == .vertical) continue,
-                        .vertical => if (child.properties.size.grow == .horizontal) continue,
+                        .horizontal => if (child.properties.size.grow == .vertical or child.properties.size.grow == .vertical_only) continue,
+                        .vertical => if (child.properties.size.grow == .horizontal or child.properties.size.grow == .horizontal_only) continue,
                     }
 
                     const size = switch (layout.direction) {
@@ -835,23 +870,23 @@ pub fn Container(comptime Event: type) type {
                     };
                     if (child.properties.size.grow != .fixed and child_size == smallest_size) {
                         switch (layout.direction) {
-                            .horizontal => if (child.properties.size.grow != .vertical) {
+                            .horizontal => if (child.properties.size.grow != .vertical and child.properties.size.grow != .vertical_only) {
                                 child.size.x += size_to_correct;
                                 remainder -|= size_to_correct;
                             },
-                            .vertical => if (child.properties.size.grow != .horizontal) {
+                            .vertical => if (child.properties.size.grow != .horizontal and child.properties.size.grow != .horizontal_only) {
                                 child.size.y += size_to_correct;
                                 remainder -|= size_to_correct;
                             },
                         }
                         if (overflow > 0) {
                             switch (layout.direction) {
-                                .horizontal => if (child.properties.size.grow != .vertical) {
+                                .horizontal => if (child.properties.size.grow != .vertical and child.properties.size.grow != .vertical_only) {
                                     child.size.x += 1;
                                     overflow -|= 1;
                                     remainder -|= 1;
                                 },
-                                .vertical => if (child.properties.size.grow != .horizontal) {
+                                .vertical => if (child.properties.size.grow != .horizontal and child.properties.size.grow != .horizontal_only) {
                                     child.size.y += 1;
                                     overflow -|= 1;
                                     remainder -|= 1;
@@ -862,31 +897,57 @@ pub fn Container(comptime Event: type) type {
                 }
             }
 
-            this.element.resize(this.size);
-            for (this.elements.items) |*child| child.grow_resize(child.size);
+            this.element.resize(model, this.size);
+            for (this.elements.items) |*child| child.grow_resize(model, child.size);
         }
 
-        pub fn resize(this: *@This(), size: Point) void {
+        pub fn resize(this: *@This(), model: *const Model, size: Point) void {
             // NOTE assume that this function is only called for the root `Container`
             this.size = size;
-            const fit_size = this.fit_resize();
-            // if (fit_size.y > size.y or fit_size.x > size.x) @panic("error: cannot render in available space");
-            switch (this.properties.size.grow) {
-                .both => this.size = Point.max(size, fit_size),
-                .fixed => {},
-                .horizontal => this.size = .{
+            const fit_size = this.fit_resize(model);
+            this.size = switch (this.properties.size.grow) {
+                .both => .max(size, fit_size),
+                .fixed => fit_size,
+                .horizontal_only => .{
+                    .x = size.x,
+                    .y = fit_size.y,
+                },
+                .vertical_only => .{
+                    .x = fit_size.x,
+                    .y = size.y,
+                },
+                .horizontal => .{
                     .x = @max(size.x, fit_size.x),
                     .y = size.y,
                 },
-                .vertical => this.size = .{
+                .vertical => .{
                     .x = size.x,
                     .y = @max(size.y, fit_size.y),
                 },
-            }
-            this.grow_resize(this.size);
+            };
+            this.grow_resize(model, this.size);
         }
 
-        pub fn handle(this: *const @This(), event: Event) !void {
+        pub fn minSize(this: *const @This(), model: *const Model, size: Point) Point {
+            var min_size: Point = .{};
+            for (this.elements.items) |*child| {
+                const child_size = child.minSize(model, child.properties.size.dim);
+                min_size = switch (this.properties.layout.direction) {
+                    .horizontal => .{
+                        .x = child_size.x + min_size.x,
+                        .y = @max(child_size.y, min_size.y),
+                    },
+                    .vertical => .{
+                        .x = @max(child_size.x, min_size.x),
+                        .y = child_size.y + min_size.y,
+                    },
+                };
+            }
+            const element_size = this.element.minSize(model, size);
+            return .max(element_size, min_size);
+        }
+
+        pub fn handle(this: *const @This(), model: *Model, event: Event) !void {
             switch (event) {
                 .mouse => |mouse| if (mouse.in(this.origin, this.size)) {
                     // the element receives the mouse event with relative position
@@ -894,17 +955,19 @@ pub fn Container(comptime Event: type) type {
                     var relative_mouse: input.Mouse = mouse;
                     relative_mouse.x -= this.origin.x;
                     relative_mouse.y -= this.origin.y;
-                    try this.element.handle(.{ .mouse = relative_mouse });
-                    for (this.elements.items) |*element| try element.handle(event);
+                    try this.element.handle(model, .{ .mouse = relative_mouse });
                 },
-                else => {
-                    try this.element.handle(event);
-                    for (this.elements.items) |*element| try element.handle(event);
+                .bell => {
+                    // ring the terminal bell and do not propagate the event any further
+                    _ = try terminal.ringBell();
+                    return;
                 },
+                else => try this.element.handle(model, event),
             }
+            for (this.elements.items) |*element| try element.handle(model, event);
         }
 
-        pub fn content(this: *const @This()) ![]Cell {
+        pub fn content(this: *const @This(), model: *const Model) ![]Cell {
             if (this.size.x == 0 or this.size.y == 0) return Error.TooSmall;
 
             const cells = try this.allocator.alloc(Cell, @as(usize, this.size.x) * @as(usize, this.size.y));
@@ -915,7 +978,7 @@ pub fn Container(comptime Event: type) type {
             this.properties.border.content(cells, this.size);
             this.properties.rectangle.content(cells, this.size);
 
-            try this.element.content(cells, this.size);
+            try this.element.content(model, cells, this.size);
 
             // DEBUG render corresponding corners (except top left) of this `Container` *red*
             if (comptime build_options.debug) {
@@ -945,6 +1008,7 @@ const assert = std.debug.assert;
 const Allocator = std.mem.Allocator;
 const build_options = @import("build_options");
 const input = @import("input.zig");
+const terminal = @import("terminal.zig");
 const isTaggedUnion = @import("event.zig").isTaggedUnion;
 const Cell = @import("cell.zig");
 const Color = @import("color.zig").Color;
@@ -959,8 +1023,9 @@ test {
 test "Container Fixed and Grow Size Vertical" {
     const event = @import("event.zig");
     const testing = @import("testing.zig");
+    const Model = struct {};
 
-    var container: Container(event.SystemEvent) = try .init(std.testing.allocator, .{
+    var container: Container(Model, event.SystemEvent) = try .init(std.testing.allocator, .{
         .layout = .{ .direction = .vertical },
     }, .{});
     try container.append(try .init(std.testing.allocator, .{
@@ -978,14 +1043,15 @@ test "Container Fixed and Grow Size Vertical" {
     try testing.expectContainerScreen(.{
         .y = 20,
         .x = 30,
-    }, &container, @import("test/container/fixed_grow_vertical.zon"));
+    }, @TypeOf(container), &container, Model, @import("test/container/fixed_grow_vertical.zon"));
 }
 
 test "Container Fixed and Grow Size Horizontal" {
     const event = @import("event.zig");
     const testing = @import("testing.zig");
+    const Model = struct {};
 
-    var container: Container(event.SystemEvent) = try .init(std.testing.allocator, .{}, .{});
+    var container: Container(Model, event.SystemEvent) = try .init(std.testing.allocator, .{}, .{});
     try container.append(try .init(std.testing.allocator, .{
         .size = .{
             .dim = .{ .x = 5 },
@@ -1001,5 +1067,5 @@ test "Container Fixed and Grow Size Horizontal" {
     try testing.expectContainerScreen(.{
         .y = 20,
         .x = 30,
-    }, &container, @import("test/container/fixed_grow_horizontal.zon"));
+    }, @TypeOf(container), &container, Model, @import("test/container/fixed_grow_horizontal.zon"));
 }

src/ctlseqs.zig

@@ -50,6 +50,7 @@ pub const home = "\x1b[H";
 pub const cup = "\x1b[{d};{d}H";
 pub const hide_cursor = "\x1b[?25l";
 pub const show_cursor = "\x1b[?25h";
+pub const reset_cursor_shape = "\x1b[0 q";
 pub const cursor_shape = "\x1b[{d} q";
 pub const ri = "\x1bM";
 pub const ind = "\n";
@@ -139,5 +140,6 @@ pub const osc10_reset = "\x1b]110\x1b\\"; // reset fg to terminal default
 pub const osc11_query = "\x1b]11;?\x1b\\"; // bg
 pub const osc11_set = "\x1b]11;rgb:{x:0>2}{x:0>2}/{x:0>2}{x:0>2}/{x:0>2}{x:0>2}\x1b\\"; // set default terminal bg
 pub const osc11_reset = "\x1b]111\x1b\\"; // reset bg to terminal default
+pub const osc12_set = "\x1b]12;{s}\x1b\\"; // set the cursor color through the name of the 8 base colors!
 pub const osc12_query = "\x1b]12;?\x1b\\"; // cursor color
 pub const osc12_reset = "\x1b]112\x1b\\"; // reset cursor to terminal default

src/event.zig

@@ -9,7 +9,13 @@ pub const SystemEvent = union(enum) {
     /// Quit event to signify the end of the event loop (rendering should stop afterwards)
     quit,
     /// Resize event to signify that the application should re-draw to resize
+    ///
+    /// Usually no `Container` nor `Element` should act on that event, as it
+    /// only serves for event based loops to force a re-draw with a new `Event`.
     resize,
+    /// Ring the terminal bell to notify the user. This `Event` is handled by
+    /// every `Container` and will not be passed through the container tree.
+    bell,
     /// Error event to notify other containers about a recoverable error
     err: struct {
         /// actual error
@@ -17,19 +23,25 @@ pub const SystemEvent = union(enum) {
         /// associated error message
         msg: []const u8,
     },
+    /// Input line event received in non *raw mode* (instead of individual `key` events)
+    line: []const u8,
     /// Input key event received from the user
     key: Key,
     /// Mouse input event
     mouse: Mouse,
-    /// Focus event for mouse interaction
-    /// TODO this should instead be a union with a `Size` to derive which container / element the focus meant for
+    /// Focus event indicating that the application has gained the focus of the user
     focus: bool,
 };
 
+/// Merge the two provided `union(enum)` `A` and `B` to a tagged union containing all fields of both tagged unions in `comptime`.
+/// Declarations are not supported for `comptime` created types, see https://github.com/ziglang/zig/issues/6709 for details.
 pub fn mergeTaggedUnions(comptime A: type, comptime B: type) type {
-    if (!isTaggedUnion(A) or !isTaggedUnion(B)) {
-        @compileError("Both types for merging tagged unions need to be of type `union(enum)`.");
-    }
+    // TODO maybe it makes sense to have a nested tagged union type (i.e. system: union(enum) and event: union(enum))
+    // - allows re-definition of system / built-in events
+    // - clearly shows which events are system / built-in ones and which are user defined events
+    // - the memory footprint for the nesting is not really harmful
+    if (!isTaggedUnion(A) or !isTaggedUnion(B)) @compileError("Both types for merging tagged unions need to be of type `union(enum)`.");
+
     const a_fields = @typeInfo(A).@"union".fields;
     const a_fields_tag = @typeInfo(A).@"union".tag_type.?;
     const a_enum_fields = @typeInfo(a_fields_tag).@"enum".fields;
@@ -54,11 +66,27 @@ pub fn mergeTaggedUnions(comptime A: type, comptime B: type) type {
         i += 1;
     }
 
-    const log2_i = @bitSizeOf(@TypeOf(i)) - @clz(i);
+    // NOTE declarations are not supported for `comptime` types: https://github.com/ziglang/zig/issues/6709
+    // -> will lead to a compilation error when constructing the tagged union
+    //    at the end of this function in case at least one of the provided tagged
+    //    unions to merge contains declarations (which in this case can only be the
+    //    user provided one)
+    const a_enum_decls = @typeInfo(A).@"union".decls;
+    const b_enum_decls = @typeInfo(B).@"union".decls;
+    var decls: [a_enum_decls.len + b_enum_decls.len]std.builtin.Type.Declaration = undefined;
+    var j: usize = 0;
+    for (a_enum_decls) |decl| {
+        decls[j] = decl;
+        j += 1;
+    }
+    for (b_enum_decls) |decl| {
+        decls[j] = decl;
+        j += 1;
+    }
 
     const EventType = @Type(.{ .int = .{
         .signedness = .unsigned,
-        .bits = log2_i,
+        .bits = @bitSizeOf(@TypeOf(i)) - @clz(i),
     } });
 
     const Event = @Type(.{ .@"enum" = .{
@@ -76,19 +104,25 @@ pub fn mergeTaggedUnions(comptime A: type, comptime B: type) type {
     } });
 }
 
-// Determine at `comptime` whether the provided type `E` is an `union(enum)`.
-pub fn isTaggedUnion(comptime E: type) bool {
-    switch (@typeInfo(E)) {
-        .@"union" => |u| {
-            if (u.tag_type) |_| {} else {
-                return false;
-            }
+/// Determine whether the provided type `T` is a tagged union: `union(enum)`.
+pub fn isTaggedUnion(comptime T: type) bool {
+    switch (@typeInfo(T)) {
+        .@"union" => |u| if (u.tag_type) |_| {} else {
+            return false;
         },
         else => return false,
     }
     return true;
 }
 
+/// Determine whether the provided type `T` is a `struct`.
+pub fn isStruct(comptime T: type) bool {
+    return switch (@typeInfo(T)) {
+        .@"struct" => true,
+        else => false,
+    };
+}
+
 const std = @import("std");
 const input = @import("input.zig");
 const terminal = @import("terminal.zig");

src/input.zig

@@ -65,7 +65,30 @@ pub const Key = packed struct {
         return meta.eql(this, other);
     }
 
-    // TODO might be useful to use the std.ascii stuff!
+    /// Determine if the `Key` is an unicode character that can be printed to
+    /// the screen. This means that the code point of the `Key` is an ascii
+    /// character between 32 - 255 (with the exception of 127 = Delete) and no
+    /// modifiers (alt and/or ctrl) are used.
+    ///
+    /// # Example
+    ///
+    /// Get user input's from the .key event from the application event loop:
+    ///
+    /// ```zig
+    /// switch (event) {
+    ///   .key => |key| if (key.isUnicode()) try this.input.append(key.cp),
+    ///   else => {},
+    /// }
+    /// ```
+    pub fn isUnicode(this: @This()) bool {
+        return this.mod.alt == false and this.mod.ctrl == false and // no modifier keys
+            (this.cp >= 32 and this.cp <= 126 or // ascii printable characters (except for input.Delete)
+                this.cp >= 128 and this.cp <= 255) or // extended ascii codes
+            ((this.cp >= 0x0080 and this.cp <= 0x07FF) or
+                (this.cp >= 0x0800 and this.cp <= 0xFFFF) or
+                (this.cp >= 0x100000 and this.cp <= 0x10FFFF)) and // allowed unicode character ranges (2 - 4 byte characters)
+                (this.cp < 57348 or this.cp > 57454); // no other predefined meanings (i.e. arrow keys, etc.)
+    }
 
     /// Determine if the `Key` is an ascii character that can be printed to
     /// the screen. This means that the code point of the `Key` is an ascii

src/queue.zig

@@ -1,7 +1,7 @@
 // taken from https://github.com/rockorager/libvaxis/blob/main/src/queue.zig (MIT-License)
 // with slight modifications
 
-/// Queue implementation. Thread safe. Fixed size. Blocking push and pop. Polling through tryPop and tryPush.
+/// Queue implementation. Thread safe. Fixed size. _Blocking_ `push` and `pop`. _Polling_ through `tryPop` and `tryPush`.
 pub fn Queue(comptime T: type, comptime size: usize) type {
     return struct {
         buf: [size]T = undefined,
@@ -215,7 +215,7 @@ fn sleepyPop(q: *Queue(u8, 2)) !void {
     // still full and the push in the other thread is still blocked
     // waiting for space.
     try Thread.yield();
-    std.time.sleep(std.time.ns_per_s);
+    std.Thread.sleep(std.time.ns_per_s);
     // Finally, let that other thread go.
     try testing.expectEqual(1, q.pop());
 
@@ -225,7 +225,7 @@ fn sleepyPop(q: *Queue(u8, 2)) !void {
         try Thread.yield();
     // But we want to ensure that there's a second push waiting, so
     // here's another sleep.
-    std.time.sleep(std.time.ns_per_s / 2);
+    std.Thread.sleep(std.time.ns_per_s / 2);
 
     // Another spurious wake...
     q.not_full.signal();
@@ -233,7 +233,7 @@ fn sleepyPop(q: *Queue(u8, 2)) !void {
     // And another chance for the other thread to see that it's
     // spurious and go back to sleep.
     try Thread.yield();
-    std.time.sleep(std.time.ns_per_s / 2);
+    std.Thread.sleep(std.time.ns_per_s / 2);
 
     // Pop that thing and we're done.
     try testing.expectEqual(2, q.pop());
@@ -270,14 +270,14 @@ test "Fill, block, fill, block" {
 fn sleepyPush(q: *Queue(u8, 1)) !void {
     // Try to ensure the other thread has already started trying to pop.
     try Thread.yield();
-    std.time.sleep(std.time.ns_per_s / 2);
+    std.Thread.sleep(std.time.ns_per_s / 2);
 
     // Spurious wake
     q.not_full.signal();
     q.not_empty.signal();
 
     try Thread.yield();
-    std.time.sleep(std.time.ns_per_s / 2);
+    std.Thread.sleep(std.time.ns_per_s / 2);
 
     // Stick something in the queue so it can be popped.
     q.push(1);
@@ -286,7 +286,7 @@ fn sleepyPush(q: *Queue(u8, 1)) !void {
         try Thread.yield();
     // Give the other thread time to block again.
     try Thread.yield();
-    std.time.sleep(std.time.ns_per_s / 2);
+    std.Thread.sleep(std.time.ns_per_s / 2);
 
     // Spurious wake
     q.not_full.signal();
@@ -317,7 +317,7 @@ test "2 readers" {
     const t1 = try Thread.spawn(cfg, readerThread, .{&queue});
     const t2 = try Thread.spawn(cfg, readerThread, .{&queue});
     try Thread.yield();
-    std.time.sleep(std.time.ns_per_s / 2);
+    std.Thread.sleep(std.time.ns_per_s / 2);
     queue.push(1);
     queue.push(1);
     t1.join();

src/render.zig

@@ -58,10 +58,10 @@ pub const Buffered = struct {
     }
 
     /// Render provided cells at size (anchor and dimension) into the *virtual screen*.
-    pub fn render(this: *@This(), comptime T: type, container: *T) !void {
+    pub fn render(this: *@This(), comptime Container: type, container: *Container, comptime Model: type, model: *const Model) !void {
         const size: Point = container.size;
         const origin: Point = container.origin;
-        const cells: []const Cell = try container.content();
+        const cells: []const Cell = try container.content(model);
 
         if (cells.len == 0) return;
 
@@ -80,7 +80,7 @@ pub const Buffered = struct {
         // free immediately
         container.allocator.free(cells);
 
-        for (container.elements.items) |*element| try this.render(T, element);
+        for (container.elements.items) |*element| try this.render(Container, element, Model, model);
     }
 
     /// Write *virtual screen* to alternate screen (should be called once and last during each render loop iteration in the main loop).
@@ -88,9 +88,10 @@ pub const Buffered = struct {
         try terminal.hideCursor();
         // TODO measure timings of rendered frames?
         var cursor_position: ?Point = null;
-        const writer = terminal.writer();
+        var writer = terminal.writer();
         const s = this.screen;
         const vs = this.virtual_screen;
+
         for (0..this.size.y) |row| {
             for (0..this.size.x) |col| {
                 const idx = (row * this.size.x) + col;
@@ -104,13 +105,14 @@ pub const Buffered = struct {
                         .x = @truncate(col),
                         .y = @truncate(row),
                     };
+                    try cvs.style.set_cursor_style(&writer);
                 }
 
                 if (cs.eql(cvs)) continue;
 
                 // render differences found in virtual screen
                 try terminal.setCursorPosition(.{ .y = @truncate(row), .x = @truncate(col) });
-                try cvs.value(writer);
+                try cvs.value(&writer);
                 // update screen to be the virtual screen for the next frame
                 s[idx] = vs[idx];
             }
@@ -122,6 +124,85 @@ pub const Buffered = struct {
     }
 };
 
+pub const Direct = struct {
+    gpa: Allocator,
+    size: Point,
+    resized: bool,
+    screen: []Cell,
+
+    pub fn init(gpa: Allocator) @This() {
+        return .{
+            .gpa = gpa,
+            .size = .{},
+            .resized = true,
+            .screen = undefined,
+        };
+    }
+
+    pub fn deinit(this: *@This()) void {
+        this.gpa.free(this.screen);
+    }
+
+    pub fn resize(this: *@This()) !Point {
+        this.size = .{};
+        if (!this.resized) {
+            this.gpa.free(this.screen);
+            this.screen = undefined;
+        }
+        this.resized = true;
+        return terminal.getTerminalSize();
+    }
+
+    pub fn clear(this: *@This()) !void {
+        _ = this;
+        try terminal.clearScreen();
+    }
+
+    /// Render provided cells at size (anchor and dimension) into the *screen*.
+    pub fn render(this: *@This(), comptime Container: type, container: *Container, comptime Model: type, model: *const Model) !void {
+        const size: Point = container.size;
+        const origin: Point = container.origin;
+
+        if (this.resized) {
+            this.size = size;
+            const n = @as(usize, this.size.x) * @as(usize, this.size.y);
+            this.screen = try this.gpa.alloc(Cell, n);
+            @memset(this.screen, .{});
+            this.resized = false;
+        }
+
+        const cells: []const Cell = try container.content(model);
+
+        var idx: usize = 0;
+        var vs = this.screen;
+        const anchor: usize = (@as(usize, origin.y) * @as(usize, this.size.x)) + @as(usize, origin.x);
+
+        blk: for (0..size.y) |row| {
+            for (0..size.x) |col| {
+                vs[anchor + (row * this.size.x) + col] = cells[idx];
+                idx += 1;
+
+                if (cells.len == idx) break :blk;
+            }
+        }
+        // free immediately
+        container.allocator.free(cells);
+        for (container.elements.items) |*element| try this.render(Container, element, Model, model);
+    }
+
+    pub fn flush(this: *@This()) !void {
+        var writer = terminal.writer();
+        for (0..this.size.y) |row| {
+            for (0..this.size.x) |col| {
+                const idx = (row * this.size.x) + col;
+                const cvs = this.screen[idx];
+                try cvs.value(&writer);
+                if (cvs.style.cursor) return; // that's where the cursor should be left!
+            }
+        }
+    }
+};
+
 const std = @import("std");
 const meta = std.meta;
 const assert = std.debug.assert;

src/style.zig

@@ -12,6 +12,8 @@ fg: Color = .default,
 bg: Color = .default,
 ul: Color = .default,
 cursor: bool = false,
+cursor_color: Color = .default,
+cursor_shape: CursorShape = .default,
 ul_style: Underline = .off,
 emphasis: []const Emphasis,
 
@@ -36,33 +38,51 @@ pub const Emphasis = enum(u8) {
     strikethrough,
 };
 
+pub const CursorShape = enum(u4) {
+    default = 0,
+    block_blinking = 1,
+    block_steady,
+    underline_blinking,
+    underline_steady,
+    bar_blinking,
+    bar_steady,
+};
+
 pub fn eql(this: Style, other: Style) bool {
+    // TODO should there be a compare for every field?
     return meta.eql(this, other);
 }
 
-// TODO might be useful to use the std.ascii stuff!
+pub fn set_cursor_style(this: Style, writer: *std.Io.Writer) !void {
+    if (!this.cursor) return;
+    switch (this.cursor_color) {
+        .default => try writer.print(ctlseqs.osc12_reset, .{}),
+        else => try writer.print(ctlseqs.osc12_set, .{@tagName(this.cursor_color)}),
+    }
+    try writer.print(ctlseqs.cursor_shape, .{@intFromEnum(this.cursor_shape)});
+}
 
-pub fn value(this: Style, writer: anytype, cp: u21) !void {
+pub fn value(this: Style, writer: *std.Io.Writer, cp: u21) !void {
     var buffer: [4]u8 = undefined;
     const bytes = try unicode.utf8Encode(cp, &buffer);
     assert(bytes > 0);
     // build ansi sequence for 256 colors ...
     // foreground
-    try format(writer, "\x1b[", .{});
+    try writer.printAscii("\x1b[", .{});
     try this.fg.write(writer, .fg);
     // background
-    try format(writer, ";", .{});
+    try writer.printAsciiChar(';', .{});
     try this.bg.write(writer, .bg);
     // underline
     // FIX assert that if the underline property is set that the ul style and the attribute for underlining is available
-    try format(writer, ";", .{});
+    try writer.printAsciiChar(';', .{});
     try this.ul.write(writer, .ul);
     // append styles (aka attributes like bold, italic, strikethrough, etc.)
-    for (this.emphasis) |attribute| try format(writer, ";{d}", .{@intFromEnum(attribute)});
-    try format(writer, "m", .{});
+    for (this.emphasis) |attribute| try writer.print(";{d}", .{@intFromEnum(attribute)});
+    try writer.printAsciiChar('m', .{});
     // content
-    try format(writer, "{s}", .{buffer[0..bytes]});
-    try format(writer, "\x1b[0m", .{});
+    try writer.printAscii(buffer[0..bytes], .{});
+    try writer.printAscii("\x1b[0m", .{});
 }
 
 // TODO implement helper functions for terminal capabilities:
@@ -73,6 +93,6 @@ const std = @import("std");
 const unicode = std.unicode;
 const meta = std.meta;
 const assert = std.debug.assert;
-const format = std.fmt.format;
 const Color = @import("color.zig").Color;
+const ctlseqs = @import("ctlseqs.zig");
 const Style = @This();

src/terminal.zig

@@ -42,6 +42,11 @@ pub fn showCursor() !void {
     _ = try posix.write(posix.STDIN_FILENO, ctlseqs.show_cursor);
 }
 
+pub fn resetCursor() !void {
+    _ = try posix.write(posix.STDIN_FILENO, ctlseqs.reset_cursor_shape);
+    _ = try posix.write(posix.STDIN_FILENO, ctlseqs.osc12_reset);
+}
+
 pub fn setCursorPositionHome() !void {
     _ = try posix.write(posix.STDIN_FILENO, ctlseqs.home);
 }
@@ -54,6 +59,10 @@ pub fn disableMouseSupport() !void {
     _ = try posix.write(posix.STDIN_FILENO, ctlseqs.mouse_reset);
 }
 
+pub fn ringBell() !void {
+    _ = try posix.write(posix.STDIN_FILENO, &.{7});
+}
+
 pub fn read(buf: []u8) !usize {
     return try posix.read(posix.STDIN_FILENO, buf);
 }
@@ -62,19 +71,25 @@ pub fn write(buf: []const u8) !usize {
     return try posix.write(posix.STDIN_FILENO, buf);
 }
 
-fn contextWrite(context: @This(), data: []const u8) anyerror!usize {
-    _ = context;
-    return try posix.write(posix.STDOUT_FILENO, data);
+fn drainFn(w: *std.Io.Writer, data: []const []const u8, splat: usize) error{WriteFailed}!usize {
+    _ = w;
+    if (data.len == 0 or splat == 0) return 0;
+    var len: usize = 0;
+
+    for (data) |bytes| len += posix.write(posix.STDOUT_FILENO, bytes) catch return error.WriteFailed;
+
+    return len;
 }
 
-const Writer = std.io.Writer(
-    @This(),
-    anyerror,
-    contextWrite,
-);
-
-pub fn writer() Writer {
-    return .{ .context = .{} };
+// TODO I now need to add that much, for just the one function above?
+pub fn writer() std.Io.Writer {
+    return .{
+        .vtable = &.{
+            .drain = drainFn,
+            .flush = std.Io.Writer.noopFlush,
+        },
+        .buffer = &.{},
+    };
 }
 
 pub fn setCursorPosition(pos: Point) !void {
@@ -83,7 +98,7 @@ pub fn setCursorPosition(pos: Point) !void {
     _ = try posix.write(posix.STDIN_FILENO, value);
 }
 
-pub fn getCursorPosition() !Size.Position {
+pub fn getCursorPosition() !Size {
     // Needs Raw mode (no wait for \n) to work properly cause
     // control sequence will not be written without it.
     _ = try posix.write(posix.STDIN_FILENO, "\x1b[6n");
@@ -191,7 +206,7 @@ pub fn enableRawMode(bak: *posix.termios) !void {
 }
 
 /// Reverts `enableRawMode` to restore initial functionality.
-pub fn disableRawMode(bak: *posix.termios) !void {
+pub fn disableRawMode(bak: *const posix.termios) !void {
     try posix.tcsetattr(
         posix.STDIN_FILENO,
         .FLUSH,
@@ -232,7 +247,7 @@ const log = std.log.scoped(.terminal);
 const std = @import("std");
 const mem = std.mem;
 const posix = std.posix;
-const code_point = @import("code_point");
+const assert = std.debug.assert;
 const ctlseqs = @import("ctlseqs.zig");
 const input = @import("input.zig");
 const Key = input.Key;

src/testing.zig

@@ -34,10 +34,10 @@ pub const Renderer = struct {
         @memset(this.screen, .{});
     }
 
-    pub fn render(this: *@This(), comptime T: type, container: *const T) !void {
+    pub fn render(this: *@This(), comptime T: type, container: *const T, comptime Model: type, model: *const Model) !void {
         const size: Point = container.size;
         const origin: Point = container.origin;
-        const cells: []const Cell = try container.content();
+        const cells: []const Cell = try container.content(model);
 
         if (cells.len == 0) return;
 
@@ -58,7 +58,7 @@ pub const Renderer = struct {
         // free immediately
         container.allocator.free(cells);
 
-        for (container.elements.items) |*element| try this.render(T, element);
+        for (container.elements.items) |*element| try this.render(T, element, Model, model);
     }
 
     pub fn save(this: @This(), writer: anytype) !void {
@@ -74,6 +74,8 @@ pub const Renderer = struct {
 /// Create a .zon file containing the expected `Cell` slice using the `zterm.testing.Renderer.save` method:
 ///
 /// ```zig
+/// const Model = struct {};
+/// var model: Model = .{};
 /// const file = try std.fs.cwd().createFile("test/container/border/all.zon", .{ .truncate = true });
 /// defer file.close();
 ///
@@ -81,8 +83,8 @@ pub const Renderer = struct {
 /// var renderer: testing.Renderer = .init(allocator, size);
 /// defer renderer.deinit();
 ///
-/// try container.handle(.{ .size = size });
-/// try renderer.render(Container(event.SystemEvent), &container);
+/// try container.handle(&model, .{ .size = size });
+/// try renderer.render(@TypeOf(container), &container, Model, &.{});
 /// try renderer.save(file.writer());
 /// ```
 ///
@@ -91,7 +93,8 @@ pub const Renderer = struct {
 /// Then later load that .zon file at compile time and run your test against this `Cell` slice.
 ///
 /// ```zig
-/// var container: Container(event.SystemEvent) = try .init(std.testing.allocator, .{
+/// const Model = struct {};
+/// var container: Container(Model, event.SystemEvent) = try .init(std.testing.allocator, .{
 ///     .border = .{
 ///         .color = .green,
 ///         .sides = .all,
@@ -102,20 +105,57 @@ pub const Renderer = struct {
 /// try testing.expectContainerScreen(.{
 ///     .rows = 20,
 ///     .cols = 30,
-/// }, &container, @import("test/container/border.all.zon"));
+/// }, @TypeOf(container), &container, Model, @import("test/container/border.all.zon"));
 /// ```
-pub fn expectContainerScreen(size: Point, container: *Container(event.SystemEvent), expected: []const Cell) !void {
+pub fn expectContainerScreen(size: Point, comptime T: type, container: *T, comptime Model: type, expected: []const Cell) !void {
     const allocator = testing.allocator;
     var renderer: Renderer = .init(allocator, size);
     defer renderer.deinit();
 
-    container.resize(size);
-    container.reposition(.{});
-    try renderer.render(Container(event.SystemEvent), container);
+    const model: Model = .{};
+
+    container.resize(&model, size);
+    container.reposition(&model, .{});
+    try renderer.render(T, container, Model, &model);
 
     try expectEqualCells(.{}, renderer.size, expected, renderer.screen);
 }
 
+/// Taken from: https://codeberg.org/atman/zg/src/branch/master/src/DisplayWidth.zig
+/// Owned by https://codeberg.org/atman licensed under MIT all credits for this function go to him
+fn center(allocator: Allocator, str: []const u8, total_width: usize, pad: []const u8) ![]u8 {
+    if (str.len > total_width) return error.StrTooLong;
+    if (str.len == total_width) return try allocator.dupe(u8, str);
+
+    if (pad.len > total_width or str.len + pad.len > total_width) return error.PadTooLong;
+
+    const margin_width = @divFloor((total_width - str.len), 2);
+    if (pad.len > margin_width) return error.PadTooLong;
+
+    const extra_pad: usize = if (total_width % 2 != str.len % 2) 1 else 0;
+    const pads = @divFloor(margin_width, pad.len) * 2 + extra_pad;
+
+    var result = try allocator.alloc(u8, pads * pad.len + str.len);
+    var bytes_index: usize = 0;
+    var pads_index: usize = 0;
+
+    while (pads_index < pads / 2) : (pads_index += 1) {
+        @memcpy(result[bytes_index..][0..pad.len], pad);
+        bytes_index += pad.len;
+    }
+
+    @memcpy(result[bytes_index..][0..str.len], str);
+    bytes_index += str.len;
+
+    pads_index = 0;
+    while (pads_index < pads / 2 + extra_pad) : (pads_index += 1) {
+        @memcpy(result[bytes_index..][0..pad.len], pad);
+        bytes_index += pad.len;
+    }
+
+    return result;
+}
+
 /// This function is intended to be used only in tests. Test if the two
 /// provided cell arrays are identical. Usually the `Cell` slices are
 /// the contents of a given screen from the `zterm.testing.Renderer`. See
@@ -127,28 +167,21 @@ pub fn expectEqualCells(origin: Point, size: Point, expected: []const Cell, actu
     try testing.expectEqual(expected.len, @as(usize, size.y) * @as(usize, size.x));
 
     var expected_cps = try std.ArrayList(Cell).initCapacity(allocator, size.x);
-    defer expected_cps.deinit();
+    defer expected_cps.deinit(allocator);
 
     var actual_cps = try std.ArrayList(Cell).initCapacity(allocator, size.x);
-    defer actual_cps.deinit();
+    defer actual_cps.deinit(allocator);
 
-    var output = try std.ArrayList(u8).initCapacity(allocator, expected_cps.capacity * actual_cps.capacity + 5 * size.y);
-    defer output.deinit();
+    var allocating_writer = std.Io.Writer.Allocating.init(allocator);
+    defer allocating_writer.deinit();
 
-    var buffer = std.io.bufferedWriter(output.writer());
-    defer buffer.flush() catch {};
-
-    const writer = buffer.writer();
+    var writer = &allocating_writer.writer;
     var differ = false;
 
-    const dwd = try DisplayWidth.DisplayWidthData.init(allocator);
-    defer dwd.deinit();
-    const dw: DisplayWidth = .{ .data = &dwd };
-
-    const expected_centered = try dw.center(allocator, "Expected Screen", size.x, " ");
+    const expected_centered = try center(allocator, "Expected Screen", size.x, " ");
     defer allocator.free(expected_centered);
 
-    const actual_centered = try dw.center(allocator, "Actual Screen", size.x, " ");
+    const actual_centered = try center(allocator, "Actual Screen", size.x, " ");
     defer allocator.free(actual_centered);
 
     try writer.print("Screens are not equivalent.\n{s} ┆ {s}\n", .{ expected_centered, actual_centered });
@@ -164,8 +197,8 @@ pub fn expectEqualCells(origin: Point, size: Point, expected: []const Cell, actu
 
             if (!expected_cell.eql(actual_cell)) differ = true;
 
-            try expected_cps.append(expected_cell);
-            try actual_cps.append(actual_cell);
+            try expected_cps.append(allocator, expected_cell);
+            try actual_cps.append(allocator, actual_cell);
         }
 
         // write screens both formatted to buffer
@@ -178,13 +211,16 @@ pub fn expectEqualCells(origin: Point, size: Point, expected: []const Cell, actu
     if (!differ) return;
 
     // test failed
-    try buffer.flush();
+    var buf: [1024]u8 = undefined;
 
-    debug.lockStdErr();
-    defer debug.unlockStdErr();
+    std.debug.lockStdErr();
+    defer std.debug.unlockStdErr();
+
+    var buffer = std.fs.File.stderr().writer(&buf);
+    var error_writer = &buffer.interface;
+    try error_writer.writeAll(writer.buffer[0..writer.end]);
+    try error_writer.flush();
 
-    const std_writer = std.io.getStdErr().writer();
-    try std_writer.writeAll(output.items);
     return error.TestExpectEqualCells;
 }
 
@@ -195,5 +231,4 @@ const Allocator = std.mem.Allocator;
 const event = @import("event.zig");
 const Container = @import("container.zig").Container;
 const Cell = @import("cell.zig");
-const DisplayWidth = @import("DisplayWidth");
 const Point = @import("point.zig").Point;