mod: replace Layout.content with Layout.render

The App.Renderer is used for the new `Layout.render` method. Each layout
renders itself now with corresponding renderers which might only update
parts of the screen, etc.

.gitignore

@@ -1,3 +1,4 @@
 .zig-cache/
 zig-out/
 log
+TODO.md

src/app.zig

@@ -45,9 +45,9 @@ pub fn App(comptime E: type, comptime R: fn (comptime bool) type, comptime fulls
     }
     return struct {
         pub const Event = mergeTaggedUnions(event.SystemEvent, E);
-        pub const Layout = @import("layout.zig").Layout(Event);
-        pub const Widget = @import("widget.zig").Widget(Event);
         pub const Renderer = R(fullscreen);
+        pub const Layout = @import("layout.zig").Layout(Event, Renderer);
+        pub const Widget = @import("widget.zig").Widget(Event);
 
         queue: Queue(Event, 256) = .{},
         thread: ?std.Thread = null,

src/layout.zig

@@ -1,7 +1,7 @@
 //! Dynamic dispatch for layout implementations.
 //! Each layout should at last implement these functions:
 //! - handle(this: *@This(), event: Event) anyerror!*std.ArrayList(Event) {}
-//! - content(this: *@This()) anyerror!*std.ArrayList(u8) {}
+//! - render(this: *@This(), renderer: Renderer) anyerror!void {}
 //! - deinit(this: *@This()) void {}
 //!
 //! Create a `Layout` using `createFrom(object: anytype)` and use them through
@@ -11,10 +11,13 @@
 //! Each `Layout` is responsible for clearing the allocated memory of the used
 //! widgets when deallocated. This means that `deinit()` will also deallocate
 //! every used widget too.
+//!
+//! When `Layout.render` is called the provided `Renderer` type is expected
+//! which handles how contents are rendered for a given layout.
 const std = @import("std");
 const isTaggedUnion = @import("event.zig").isTaggedUnion;
 
-pub fn Layout(comptime Event: type) type {
+pub fn Layout(comptime Event: type, comptime Renderer: type) type {
     if (!isTaggedUnion(Event)) {
         @compileError("Provided user event `Event` for `Layout(comptime Event: type)` is not of type `union(enum)`.");
     }
@@ -25,7 +28,7 @@ pub fn Layout(comptime Event: type) type {
 
         const VTable = struct {
             handle: *const fn (this: *LayoutType, event: Event) anyerror!*Events,
-            content: *const fn (this: *LayoutType) anyerror!*std.ArrayList(u8),
+            render: *const fn (this: *LayoutType, renderer: Renderer) anyerror!void,
             deinit: *const fn (this: *LayoutType) void,
         };
 
@@ -37,9 +40,9 @@ pub fn Layout(comptime Event: type) type {
             return try this.vtable.handle(this, event);
         }
 
-        // Return the entire content of this `Layout`.
-        pub fn content(this: *LayoutType) !*std.ArrayList(u8) {
-            return try this.vtable.content(this);
+        // Render this `Layout` completely. This will render contained sub-elements too.
+        pub fn render(this: *LayoutType, renderer: Renderer) !void {
+            return try this.vtable.render(this, renderer);
         }
 
         pub fn deinit(this: *LayoutType) void {
@@ -58,13 +61,13 @@ pub fn Layout(comptime Event: type) type {
                             return try layout.handle(event);
                         }
                     }.handle,
-                    .content = struct {
-                        // Return the entire content of this `Layout`.
-                        fn content(this: *LayoutType) !*std.ArrayList(u8) {
+                    .render = struct {
+                        // Render the contents of this `Layout`.
+                        fn render(this: *LayoutType, renderer: Renderer) !void {
                             const layout: @TypeOf(object) = @ptrFromInt(this.object);
-                            return try layout.content();
+                            try layout.render(renderer);
                         }
-                    }.content,
+                    }.render,
                     .deinit = struct {
                         fn deinit(this: *LayoutType) void {
                             const layout: @TypeOf(object) = @ptrFromInt(this.object);
@@ -76,9 +79,9 @@ pub fn Layout(comptime Event: type) type {
         }
 
         // import and export of `Layout` implementations
-        pub const HStack = @import("layout/HStack.zig").Layout(Event);
-        pub const VStack = @import("layout/VStack.zig").Layout(Event);
-        pub const Padding = @import("layout/Padding.zig").Layout(Event);
-        pub const Framing = @import("layout/Framing.zig").Layout(Event);
+        pub const HStack = @import("layout/HStack.zig").Layout(Event, Renderer);
+        pub const VStack = @import("layout/VStack.zig").Layout(Event, Renderer);
+        pub const Padding = @import("layout/Padding.zig").Layout(Event, Renderer);
+        pub const Framing = @import("layout/Framing.zig").Layout(Event, Renderer);
     };
 }

src/layout/Framing.zig

@@ -11,32 +11,28 @@ const Key = terminal.Key;
 
 const log = std.log.scoped(.layout_framing);
 
-pub fn Layout(comptime Event: type) type {
+pub fn Layout(comptime Event: type, comptime Renderer: type) type {
     if (!isTaggedUnion(Event)) {
         @compileError("Provided user event `Event` for `Layout(comptime Event: type)` is not of type `union(enum)`.");
     }
     const Element = union(enum) {
-        layout: @import("../layout.zig").Layout(Event),
+        layout: @import("../layout.zig").Layout(Event, Renderer),
         widget: @import("../widget.zig").Widget(Event),
     };
     const Events = std.ArrayList(Event);
-    const Contents = std.ArrayList(u8);
     return struct {
         size: terminal.Size = undefined,
-        contents: Contents = undefined,
         element: Element = undefined,
         events: Events = undefined,
 
         pub fn init(allocator: std.mem.Allocator, element: Element) @This() {
             return .{
-                .contents = Contents.init(allocator),
                 .element = element,
                 .events = Events.init(allocator),
             };
         }
 
         pub fn deinit(this: *@This()) void {
-            this.contents.deinit();
             this.events.deinit();
             switch ((&this.element).*) {
                 .layout => |*layout| {
@@ -85,19 +81,18 @@ pub fn Layout(comptime Event: type) type {
             return &this.events;
         }
 
-        pub fn content(this: *@This()) !*Contents {
-            this.contents.clearRetainingCapacity();
+        pub fn render(this: *@This(), renderer: Renderer) !void {
             // TODO: padding contents accordingly
             switch ((&this.element).*) {
                 .layout => |*layout| {
-                    const layout_content = try layout.content();
-                    try this.contents.appendSlice(layout_content.items);
+                    try layout.render(renderer);
                 },
                 .widget => |*widget| {
-                    try this.contents.appendSlice(try widget.content());
+                    const content = try widget.content();
+                    // TODO: use renderer
+                    _ = try terminal.write(content);
                 },
             }
-            return &this.contents;
         }
     };
 }

src/layout/HStack.zig

@@ -11,23 +11,21 @@ const Key = terminal.Key;
 
 const log = std.log.scoped(.layout_hstack);
 
-pub fn Layout(comptime Event: type) type {
+pub fn Layout(comptime Event: type, comptime Renderer: type) type {
     if (!isTaggedUnion(Event)) {
         @compileError("Provided user event `Event` for `Layout(comptime Event: type)` is not of type `union(enum)`.");
     }
     const Widget = @import("../widget.zig").Widget(Event);
-    const Lay = @import("../layout.zig").Layout(Event);
+    const Lay = @import("../layout.zig").Layout(Event, Renderer);
     const Element = union(enum) {
         layout: Lay,
         widget: Widget,
     };
     const Elements = std.ArrayList(Element);
     const Events = std.ArrayList(Event);
-    const Contents = std.ArrayList(u8);
     return struct {
         // TODO: current focused `Element`?
         size: terminal.Size = undefined,
-        contents: Contents = undefined,
         elements: Elements = undefined,
         events: Events = undefined,
 
@@ -53,7 +51,6 @@ pub fn Layout(comptime Event: type) type {
                 @compileError("child: " ++ field.name ++ " is not of type " ++ @typeName(Lay) ++ " or " ++ @typeName(Widget) ++ " but " ++ @typeName(ChildType));
             }
             return .{
-                .contents = Contents.init(allocator),
                 .elements = elements,
                 .events = Events.init(allocator),
             };
@@ -61,7 +58,6 @@ pub fn Layout(comptime Event: type) type {
 
         pub fn deinit(this: *@This()) void {
             this.events.deinit();
-            this.contents.deinit();
             for (this.elements.items) |*element| {
                 switch (element.*) {
                     .layout => |*layout| {
@@ -116,21 +112,21 @@ pub fn Layout(comptime Event: type) type {
             return &this.events;
         }
 
-        pub fn content(this: *@This()) !*Contents {
-            this.contents.clearRetainingCapacity();
-            // TODO: concat contents accordingly to create a vertical stack
+        pub fn render(this: *@This(), renderer: Renderer) !void {
+            // TODO: concat contents accordingly to create a horizontal stack
             for (this.elements.items) |*element| {
                 switch (element.*) {
                     .layout => |*layout| {
-                        const layout_content = try layout.content();
-                        try this.contents.appendSlice(layout_content.items);
+                        try layout.render(renderer);
                     },
                     .widget => |*widget| {
-                        try this.contents.appendSlice(try widget.content());
+                        // TODO: clear per widget if necessary (i.e. can I query that?)
+                        // TODO: render using `renderer`
+                        const content = try widget.content();
+                        _ = try terminal.write(content);
                     },
                 }
             }
-            return &this.contents;
         }
     };
 }

src/layout/Padding.zig

@@ -11,32 +11,28 @@ const Key = terminal.Key;
 
 const log = std.log.scoped(.layout_padding);
 
-pub fn Layout(comptime Event: type) type {
+pub fn Layout(comptime Event: type, comptime Renderer: type) type {
     if (!isTaggedUnion(Event)) {
         @compileError("Provided user event `Event` for `Layout(comptime Event: type)` is not of type `union(enum)`.");
     }
     const Element = union(enum) {
-        layout: @import("../layout.zig").Layout(Event),
+        layout: @import("../layout.zig").Layout(Event, Renderer),
         widget: @import("../widget.zig").Widget(Event),
     };
     const Events = std.ArrayList(Event);
-    const Contents = std.ArrayList(u8);
     return struct {
         size: terminal.Size = undefined,
-        contents: Contents = undefined,
         element: Element = undefined,
         events: Events = undefined,
 
         pub fn init(allocator: std.mem.Allocator, element: Element) @This() {
             return .{
-                .contents = Contents.init(allocator),
                 .element = element,
                 .events = Events.init(allocator),
             };
         }
 
         pub fn deinit(this: *@This()) void {
-            this.contents.deinit();
             this.events.deinit();
             switch ((&this.element).*) {
                 .layout => |*layout| {
@@ -85,19 +81,18 @@ pub fn Layout(comptime Event: type) type {
             return &this.events;
         }
 
-        pub fn content(this: *@This()) !*Contents {
-            this.contents.clearRetainingCapacity();
+        pub fn render(this: *@This(), renderer: Renderer) !void {
             // TODO: padding contents accordingly
             switch ((&this.element).*) {
                 .layout => |*layout| {
-                    const layout_content = try layout.content();
-                    try this.contents.appendSlice(layout_content.items);
+                    try layout.render(renderer);
                 },
                 .widget => |*widget| {
-                    try this.contents.appendSlice(try widget.content());
+                    const content = try widget.content();
+                    // TODO: use renderer
+                    _ = try terminal.write(content);
                 },
             }
-            return &this.contents;
         }
     };
 }

src/layout/VStack.zig

@@ -11,23 +11,24 @@ const Key = terminal.Key;
 
 const log = std.log.scoped(.layout_vstack);
 
-pub fn Layout(comptime Event: type) type {
+pub fn Layout(comptime Event: type, comptime Renderer: type) type {
     if (!isTaggedUnion(Event)) {
         @compileError("Provided user event `Event` for `Layout(comptime Event: type)` is not of type `union(enum)`.");
     }
     const Widget = @import("../widget.zig").Widget(Event);
-    const Lay = @import("../layout.zig").Layout(Event);
+    const Lay = @import("../layout.zig").Layout(Event, Renderer);
     const Element = union(enum) {
         layout: Lay,
         widget: Widget,
     };
     const Elements = std.ArrayList(Element);
     const Events = std.ArrayList(Event);
-    const Contents = std.ArrayList(u8);
     return struct {
         // TODO: current focused `Element`?
+        // FIX: this should not be 'hardcoded' but dynamically be calculated and updated (i.e. through the event system)
+        anchor: terminal.Position = .{ .col = 1, .row = 1 },
         size: terminal.Size = undefined,
-        contents: Contents = undefined,
+        element_rows: u16 = undefined,
         elements: Elements = undefined,
         events: Events = undefined,
 
@@ -53,7 +54,6 @@ pub fn Layout(comptime Event: type) type {
                 @compileError("child: " ++ field.name ++ " is not of type " ++ @typeName(Lay) ++ " or " ++ @typeName(Widget) ++ " but " ++ @typeName(ChildType));
             }
             return .{
-                .contents = Contents.init(allocator),
                 .elements = elements,
                 .events = Events.init(allocator),
             };
@@ -61,7 +61,6 @@ pub fn Layout(comptime Event: type) type {
 
         pub fn deinit(this: *@This()) void {
             this.events.deinit();
-            this.contents.deinit();
             for (this.elements.items) |*element| {
                 switch (element.*) {
                     .layout => |*layout| {
@@ -83,9 +82,15 @@ pub fn Layout(comptime Event: type) type {
                     this.size = size;
                     log.debug("Using size: {{ .cols = {d}, .rows = {d} }}", .{ size.cols, size.rows });
                     const len: u16 = @truncate(this.elements.items.len);
-                    const rows = size.rows / len;
+                    this.element_rows = @divTrunc(size.rows, len);
+                    var overflow = this.size.rows % len;
                     // adjust size according to the containing elements
                     for (this.elements.items) |*element| {
+                        var rows = this.element_rows;
+                        if (overflow > 0) {
+                            overflow -|= 1;
+                            rows += 1;
+                        }
                         const sub_event: Event = .{
                             .resize = .{
                                 .cols = size.cols,
@@ -124,26 +129,32 @@ pub fn Layout(comptime Event: type) type {
             return &this.events;
         }
 
-        pub fn content(this: *@This()) !*Contents {
-            this.contents.clearRetainingCapacity();
-            // TODO: concat contents accordingly to create a horizontal stack
-            for (this.elements.items, 1..) |*element, i| {
+        pub fn render(this: *@This(), renderer: Renderer) !void {
+            // FIX: renderer should clear only what is going to change! (i.e. the 'active' widget / layout)
+            try renderer.clear(this.anchor, this.size);
+            var overflow = this.size.rows % this.elements.items.len;
+            for (this.elements.items, 0..) |*element, i| {
+                const row_mul: u16 = @truncate(i);
+                var row = row_mul * this.element_rows + 1;
+                if (i > 0 and overflow > 0) {
+                    overflow -|= 1;
+                    row += 1;
+                }
+                const pos: terminal.Position = .{ .col = 1, .row = row };
+                log.debug("using position: .{{ .cols = {d}, .rows = {d} }}", .{ pos.col, pos.row });
+                // TODO: do this using the renderer
+                try terminal.setCursorPosition(pos);
                 switch (element.*) {
                     .layout => |*layout| {
-                        const layout_content = try layout.content();
-                        try this.contents.appendSlice(layout_content.items);
+                        try layout.render(renderer);
                     },
                     .widget => |*widget| {
-                        const widget_content = try widget.content();
-                        try this.contents.appendSlice(widget_content);
+                        // TODO: clear per widget if necesary (i.e. can I query that?)
+                        const content = try widget.content();
+                        _ = try terminal.write(content);
                     },
                 }
-                // TODO: support clear positioning of content on the tui screen
-                if (i != this.elements.items.len) {
-                    try this.contents.appendSlice("\n"); // NOTE: this assumes that the previous content fills all the provided size.rows accordingly with content, such that a newline introduces the start of the next content
             }
         }
-            return &this.contents;
-        }
     };
 }

src/main.zig

@@ -24,7 +24,9 @@ pub fn main() !void {
     const allocator = gpa.allocator();
 
     var app: App = .{};
-    var renderer: App.Renderer = .{};
+    const renderer: App.Renderer = .{};
+    // FIX: when not running fullscreen, the application needs to screen down accordingly to display the contents
+    // -> size hint how much should it use?
 
     const mainFile = try std.fs.cwd().openFile("./src/main.zig", .{});
     var mainFileText = App.Widget.RawText.init(allocator, mainFile);
@@ -35,17 +37,11 @@ pub fn main() !void {
     appFile.close();
 
     var spacer = App.Widget.Spacer.init();
-    var framing = App.Layout.Framing.init(allocator, .{
-        .widget = App.Widget.createFrom(&mainFileText),
-    });
-    var hstack = App.Layout.HStack.init(allocator, .{
-        App.Layout.createFrom(&framing),
-    });
     // TODO: corresponding contents need to be filled out by the layout accordingly!
     var vstack = App.Layout.VStack.init(allocator, .{
         App.Widget.createFrom(&appFileText),
-        App.Layout.createFrom(&hstack),
         App.Widget.createFrom(&spacer),
+        App.Widget.createFrom(&mainFileText),
     });
     var layout = App.Layout.createFrom(&vstack);
     defer layout.deinit();
@@ -88,6 +84,6 @@ pub fn main() !void {
         for (events.items) |e| {
             app.postEvent(e);
         }
-        try renderer.render(try layout.content());
+        try layout.render(renderer);
     }
 }

src/render.zig

@@ -3,6 +3,7 @@ const std = @import("std");
 const terminal = @import("terminal.zig");
 
 const Contents = std.ArrayList(u8);
+const Position = terminal.Position;
 const Size = terminal.Size;
 
 pub fn Buffered(comptime fullscreen: bool) type {
@@ -40,16 +41,23 @@ pub fn Buffered(comptime fullscreen: bool) type {
     };
 }
 
-pub fn Plain(comptime fullscreen: bool) type {
+pub fn Plain(comptime _: bool) type {
     return struct {
-        pub fn render(this: *@This(), content: *Contents) !void {
+        pub fn clear(this: @This(), anchor: Position, size: Size) !void {
             _ = this;
-            if (fullscreen) {
+            _ = size;
+            // NOTE: clear entire screen for the first content (derived from the anchor being at the very left-top)
+            if (anchor.col == 1 and anchor.row == 1) {
                 try terminal.clearScreen();
-                try terminal.setCursorPositionHome();
             }
-            // TODO: how would I clear the screen in case of a non fullscreen application (i.e. to clear to the start of the command)
-            _ = try terminal.write(content.items);
+        }
+
+        pub fn render(this: @This(), anchor: Position, size: Size, contents: *Contents) !void {
+            _ = this;
+            _ = size;
+            // FIXME: this should respect the given `size`
+            try terminal.setCursorPosition(anchor);
+            _ = try terminal.write(contents.items);
         }
     };
 }

src/terminal.zig

@@ -62,6 +62,12 @@ pub fn write(buf: []const u8) !usize {
     return try std.posix.write(std.posix.STDIN_FILENO, buf);
 }
 
+pub fn setCursorPosition(pos: Position) !void {
+    var buf: [64]u8 = undefined;
+    const value = try std.fmt.bufPrint(&buf, "\x1b[{d};{d}H", .{ pos.row, pos.col });
+    _ = try std.posix.write(std.posix.STDIN_FILENO, value);
+}
+
 pub fn getCursorPosition() !Position {
     // Needs Raw mode (no wait for \n) to work properly cause
     // control sequence will not be written without it.

src/widget.zig

@@ -10,8 +10,11 @@
 //!
 //! Each `Widget` may cache its content and should if the contents will not
 //! change for a long time.
+const std = @import("std");
 const isTaggedUnion = @import("event.zig").isTaggedUnion;
 
+const log = std.log.scoped(.widget);
+
 pub fn Widget(comptime Event: type) type {
     if (!isTaggedUnion(Event)) {
         @compileError("Provided user event `Event` for `Layout(comptime Event: type)` is not of type `union(enum)`.");
@@ -31,6 +34,12 @@ pub fn Widget(comptime Event: type) type {
 
         // Handle the provided `Event` for this `Widget`.
         pub fn handle(this: *WidgetType, event: Event) ?Event {
+            switch (event) {
+                .resize => |size| {
+                    log.debug("received size: .{{ .cols = {d}, .rows = {d} }}", .{ size.cols, size.rows });
+                },
+                else => {},
+            }
             return this.vtable.handle(this, event);
         }
 

src/widget/RawText.zig

@@ -46,7 +46,6 @@ pub fn Widget(comptime Event: type) type {
                 // store the received size
                 .resize => |size| {
                     this.size = size;
-                    log.debug("Using size: {{ .cols = {d}, .rows = {d} }}", .{ size.cols, size.rows });
                     if (this.line > this.line_index.items.len -| 1 -| size.rows) {
                         this.line = this.line_index.items.len -| 1 -| size.rows;
                     }
@@ -82,11 +81,12 @@ pub fn Widget(comptime Event: type) type {
             } else {
                 // more rows than we can display
                 const i = this.line_index.items[this.line];
-                log.debug("i := {d} this.line := {d}", .{ i, this.line });
-                const e = this.size.rows + this.line;
+                const e = this.size.rows + this.line + 1;
                 if (e >= this.line_index.items.len) {
                     return this.contents.items[i..];
                 }
+                // last line should not end with the last character (likely a newline character)
+                // FIX: what about files which do not end with a newline?
                 const x = this.line_index.items[e] - 1;
                 return this.contents.items[i..x];
             }