add(widget): Text widget to display static Cell contents

build.zig

@@ -32,41 +32,46 @@ pub fn build(b: *std.Build) void {
     lib.addImport("interface", interface.module("interface"));
     lib.addImport("code_point", zg.module("code_point"));
 
-    const exe = b.addExecutable(.{
-        .name = "zterm",
-        .root_source_file = b.path("src/main.zig"),
+    // example executables
+    const stack_example = b.addExecutable(.{
+        .name = "stack",
+        .root_source_file = b.path("examples/stack.zig"),
         .target = target,
         .optimize = optimize,
     });
-    exe.root_module.addImport("zterm", lib);
+    stack_example.root_module.addImport("zterm", lib);
+
+    const container_example = b.addExecutable(.{
+        .name = "container",
+        .root_source_file = b.path("examples/container.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+    container_example.root_module.addImport("zterm", lib);
+
+    const padding_example = b.addExecutable(.{
+        .name = "padding",
+        .root_source_file = b.path("examples/padding.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+    padding_example.root_module.addImport("zterm", lib);
+
+    const exec_example = b.addExecutable(.{
+        .name = "exec",
+        .root_source_file = b.path("examples/exec.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+    exec_example.root_module.addImport("zterm", lib);
 
     // This declares intent for the executable to be installed into the
     // standard location when the user invokes the "install" step (the default
     // step when running `zig build`).
-    b.installArtifact(exe);
-
-    // This *creates* a Run step in the build graph, to be executed when another
-    // step is evaluated that depends on it. The next line below will establish
-    // such a dependency.
-    const run_cmd = b.addRunArtifact(exe);
-
-    // By making the run step depend on the install step, it will be run from the
-    // installation directory rather than directly from within the cache directory.
-    // This is not necessary, however, if the application depends on other installed
-    // files, this ensures they will be present and in the expected location.
-    run_cmd.step.dependOn(b.getInstallStep());
-
-    // This allows the user to pass arguments to the application in the build
-    // command itself, like this: `zig build run -- arg1 arg2 etc`
-    if (b.args) |args| {
-        run_cmd.addArgs(args);
-    }
-
-    // This creates a build step. It will be visible in the `zig build --help` menu,
-    // and can be selected like this: `zig build run`
-    // This will evaluate the `run` step rather than the default, which is "install".
-    const run_step = b.step("run", "Run the app");
-    run_step.dependOn(&run_cmd.step);
+    b.installArtifact(stack_example);
+    b.installArtifact(container_example);
+    b.installArtifact(padding_example);
+    b.installArtifact(exec_example);
 
     // Creates a step for unit testing. This only builds the test executable
     // but does not run it.
@@ -79,18 +84,9 @@ pub fn build(b: *std.Build) void {
 
     const run_lib_unit_tests = b.addRunArtifact(lib_unit_tests);
 
-    const exe_unit_tests = b.addTest(.{
-        .root_source_file = b.path("src/main.zig"),
-        .target = target,
-        .optimize = optimize,
-    });
-
-    const run_exe_unit_tests = b.addRunArtifact(exe_unit_tests);
-
     // Similar to creating the run step earlier, this exposes a `test` step to
     // the `zig build --help` menu, providing a way for the user to request
     // running the unit tests.
     const test_step = b.step("test", "Run unit tests");
     test_step.dependOn(&run_lib_unit_tests.step);
-    test_step.dependOn(&run_exe_unit_tests.step);
 }

src/terminal/Cell.zig

@@ -2,7 +2,7 @@ const std = @import("std");
 pub const Style = @import("Style.zig");
 
 style: Style = .{},
-content: []u8 = undefined,
+content: []const u8 = undefined,
 
 pub const Result = struct {
     idx: usize,

src/widget.zig

@@ -91,11 +91,13 @@ pub fn Widget(comptime Event: type, comptime Renderer: type) type {
         }
 
         // import and export of `Widget` implementations
+        pub const Text = @import("widget/Text.zig").Widget(Event, Renderer);
         pub const RawText = @import("widget/RawText.zig").Widget(Event, Renderer);
         pub const Spacer = @import("widget/Spacer.zig").Widget(Event, Renderer);
     };
     // test widget implementation satisfies the interface
     comptime Type.Interface.satisfiedBy(Type);
+    comptime Type.Interface.satisfiedBy(Type.Text);
     comptime Type.Interface.satisfiedBy(Type.RawText);
     comptime Type.Interface.satisfiedBy(Type.Spacer);
     return Type;

src/widget/Text.zig

@@ -0,0 +1,50 @@
+const std = @import("std");
+const terminal = @import("../terminal.zig");
+
+const isTaggedUnion = @import("../event.zig").isTaggedUnion;
+const Error = @import("../event.zig").Error;
+const Cell = terminal.Cell;
+
+const log = std.log.scoped(.widget_text);
+
+pub fn Widget(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)`.");
+    }
+    return struct {
+        contents: []const Cell = undefined,
+        size: terminal.Size = undefined,
+        require_render: bool = false,
+
+        pub fn init(contents: []const Cell) @This() {
+            return .{
+                .contents = contents,
+            };
+        }
+
+        pub fn deinit(this: *@This()) void {
+            this.* = undefined;
+        }
+
+        pub fn handle(this: *@This(), event: Event) ?Event {
+            switch (event) {
+                // store the received size
+                .resize => |size| {
+                    this.size = size;
+                    this.require_render = true;
+                },
+                else => {},
+            }
+            return null;
+        }
+
+        pub fn render(this: *@This(), renderer: *Renderer) !void {
+            if (!this.require_render) {
+                return;
+            }
+            try renderer.clear(this.size);
+            try renderer.render(this.size, this.contents);
+            this.require_render = false;
+        }
+    };
+}