{Core,examples}: set window title via component

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

examples/core-custom-entrypoint/Game.zig

@@ -51,7 +51,7 @@ fn init(game: *Mod, core: *mach.Core.Mod) !void {
         .title_timer = try mach.Timer.start(),
         .pipeline = pipeline,
     });
-    try updateWindowTitle();
+    try updateWindowTitle(core);
 }
 
 pub fn deinit(game: *Mod) void {
@@ -109,13 +109,19 @@ fn tick(core: *mach.Core.Mod, game: *Mod) !void {
     // update the window title every second
     if (game.state().title_timer.read() >= 1.0) {
         game.state().title_timer.reset();
-        try updateWindowTitle();
+        try updateWindowTitle(core);
     }
 }
 
-fn updateWindowTitle() !void {
+fn updateWindowTitle(core: *mach.Core.Mod) !void {
-    try mach.core.printTitle("mach.Core - custom entrypoint [ {d}fps ] [ Input {d}hz ]", .{
+    try mach.Core.printTitle(
-        mach.core.frameRate(),
+        core,
-        mach.core.inputRate(),
+        core.state().main_window,
-    });
+        "core-custom-entrypoint [ {d}fps ] [ Input {d}hz ]",
+        .{
+            mach.core.frameRate(),
+            mach.core.inputRate(),
+        },
+    );
+    core.send(.update, .{});
 }

examples/glyphs/Game.zig

@@ -57,9 +57,6 @@ fn afterInit(
     glyphs: *Glyphs.Mod,
     game: *Mod,
 ) !void {
-    // The Mach .core is where we set window options, etc.
-    mach.core.setTitle("gfx.Sprite example");
-
     // Create a sprite rendering pipeline
     const texture = glyphs.state().texture;
     const pipeline = try sprite_pipeline.newEntity();
@@ -231,7 +228,7 @@ fn tick(
     game.state().time += delta_time;
 }
 
-fn endFrame(game: *Mod) !void {
+fn endFrame(game: *Mod, core: *mach.Core.Mod) !void {
     // Finish render pass
     game.state().frame_render_pass.end();
     const label = @tagName(name) ++ ".endFrame";
@@ -245,7 +242,13 @@ fn endFrame(game: *Mod) !void {
 
     // Every second, update the window title with the FPS
     if (game.state().fps_timer.read() >= 1.0) {
-        try mach.core.printTitle("gfx.Sprite example [ FPS: {d} ] [ Sprites: {d} ]", .{ game.state().frame_count, game.state().sprites });
+        try mach.Core.printTitle(
+            core,
+            core.state().main_window,
+            "glyphs [ FPS: {d} ] [ Sprites: {d} ]",
+            .{ game.state().frame_count, game.state().sprites },
+        );
+        core.send(.update, .{});
         game.state().fps_timer.reset();
         game.state().frame_count = 0;
     }

examples/sprite/Game.zig

@@ -51,9 +51,6 @@ fn init(
     sprite_pipeline: *gfx.SpritePipeline.Mod,
     game: *Mod,
 ) !void {
-    // The Mach .core is where we set window options, etc.
-    mach.core.setTitle("gfx.Sprite example");
-
     // We can create entities, and set components on them. Note that components live in a module
     // namespace, e.g. the `.mach_gfx_sprite` module could have a 3D `.location` component with a different
     // type than the `.physics2d` module's `.location` component if you desire.
@@ -215,7 +212,7 @@ fn tick(
     game.state().time += delta_time;
 }
 
-fn endFrame(game: *Mod) !void {
+fn endFrame(game: *Mod, core: *mach.Core.Mod) !void {
     // Finish render pass
     game.state().frame_render_pass.end();
     const label = @tagName(name) ++ ".endFrame";
@@ -229,7 +226,13 @@ fn endFrame(game: *Mod) !void {
 
     // Every second, update the window title with the FPS
     if (game.state().fps_timer.read() >= 1.0) {
-        try mach.core.printTitle("gfx.Sprite example [ FPS: {d} ] [ Sprites: {d} ]", .{ game.state().frame_count, game.state().sprites });
+        try mach.Core.printTitle(
+            core,
+            core.state().main_window,
+            "sprite [ FPS: {d} ] [ Sprites: {d} ]",
+            .{ game.state().frame_count, game.state().sprites },
+        );
+        core.send(.update, .{});
         game.state().fps_timer.reset();
         game.state().frame_count = 0;
     }

examples/text/Game.zig

@@ -258,7 +258,7 @@ fn tick(
     game.state().time += delta_time;
 }
 
-fn endFrame(game: *Mod, text: *gfx.Text.Mod) !void {
+fn endFrame(game: *Mod, text: *gfx.Text.Mod, core: *mach.Core.Mod) !void {
     // Finish render pass
     game.state().frame_render_pass.end();
     const label = @tagName(name) ++ ".tick";
@@ -288,7 +288,13 @@ fn endFrame(game: *Mod, text: *gfx.Text.Mod) !void {
             }
         }
 
-        try mach.core.printTitle("gfx.Text example [ FPS: {d} ] [ Texts: {d} ] [ Glyphs: {d} ]", .{ game.state().frame_count, num_texts, num_glyphs });
+        try mach.Core.printTitle(
+            core,
+            core.state().main_window,
+            "text [ FPS: {d} ] [ Texts: {d} ] [ Glyphs: {d} ]",
+            .{ game.state().frame_count, num_texts, num_glyphs },
+        );
+        core.send(.update, .{});
         game.state().fps_timer.reset();
         game.state().frame_count = 0;
     }

src/Core.zig

@@ -15,6 +15,10 @@ pub const global_events = .{
 };
 
 pub const local_events = .{
+    .update = .{ .handler = update, .description = 
+    \\ Send this when window entities have been updated and you want the new values respected.
+    },
+
     .init = .{ .handler = init },
     .init_done = .{ .handler = fn () void },
 
@@ -26,10 +30,40 @@ pub const local_events = .{
     .exit = .{ .handler = exit },
 };
 
+pub const components = .{
+    .title = .{ .type = [:0]u8, .description = 
+    \\ Window title slice. Can be set with a format string and arguments via:
+    \\
+    \\ ```
+    \\ try mach.Core.printTitle(core_mod, core_mod.state().main_window, "Hello, {s}!", .{"Mach"});
+    \\ ```
+    \\
+    \\ If setting this component yourself, ensure the buffer is allocated using core.state().allocator
+    \\ as it will be freed for you as part of the .deinit event.
+    },
+};
+
+/// Prints into the window title buffer using a format string and arguments. e.g.
+///
+/// ```
+/// try mach.Core.printTitle(core_mod, core_mod.state().main_window, "Hello, {s}!", .{"Mach"});
+/// ```
+pub fn printTitle(
+    core: *mach.Core.Mod,
+    window_id: mach.EntityID,
+    comptime fmt: []const u8,
+    args: anytype,
+) !void {
+    const slice = try std.fmt.allocPrintZ(core.state().allocator, fmt, args);
+    try core.set(window_id, .title, slice);
+}
+
 var gpa = std.heap.GeneralPurposeAllocator(.{}){};
 
+allocator: std.mem.Allocator,
 device: *mach.gpu.Device,
 queue: *mach.gpu.Queue,
+main_window: mach.EntityID,
 should_exit: bool = false,
 
 fn init(core: *Mod) !void {
@@ -41,19 +75,52 @@ fn init(core: *Mod) !void {
     try mach.core.init(.{});
 
     core.init(.{
+        .allocator = mach.core.allocator,
         .device = mach.core.device,
         .queue = mach.core.device.getQueue(),
+        .main_window = try core.newEntity(),
     });
 
     core.sendGlobal(.init, .{});
     core.send(.init_done, .{});
 }
 
+fn update(core: *Mod) !void {
+    var archetypes_iter = core.entities.query(.{ .all = &.{
+        .{ .mach_core = &.{
+            .title,
+        } },
+    } });
+
+    var num_windows: usize = 0;
+    while (archetypes_iter.next()) |archetype| {
+        for (
+            archetype.slice(.entity, .id),
+            archetype.slice(.mach_core, .title),
+        ) |window_id, title| {
+            num_windows += 1;
+            _ = window_id;
+            try mach.core.printTitle("{s}", .{title});
+        }
+    }
+    if (num_windows > 1) @panic("mach: Core currently only supports a single window");
+}
+
 fn deinit(core: *Mod) void {
     core.state().queue.release();
     // TODO: this triggers a device loss error, which we should handle correctly
     // core.state().device.release();
     mach.core.deinit();
+
+    var archetypes_iter = core.entities.query(.{ .all = &.{
+        .{ .mach_core = &.{
+            .title,
+        } },
+    } });
+    while (archetypes_iter.next()) |archetype| {
+        for (archetype.slice(.mach_core, .title)) |title| core.state().allocator.free(title);
+    }
+
     _ = gpa.deinit();
 }