refactor(gui): move RGBA to color module

build.zig

@@ -492,7 +492,12 @@ pub fn build_exe(
                 const win32_dep = b.lazyDependency("win32", .{}) orelse break :blk tui_renderer_mod;
                 const win32_mod = win32_dep.module("win32");
                 const gui_xy_mod = b.createModule(.{ .root_source_file = b.path("src/gui/xy.zig") });
-                const gui_cell_mod = b.createModule(.{ .root_source_file = b.path("src/gui/Cell.zig") });
+                const gui_cell_mod = b.createModule(.{
+                    .root_source_file = b.path("src/gui/cell.zig"),
+                    .imports = &.{
+                        .{ .name = "color", .module = color_mod },
+                    },
+                });
                 const gui_glyph_cache_mod = b.createModule(.{ .root_source_file = b.path("src/gui/GlyphIndexCache.zig") });
                 const gui_xterm_mod = b.createModule(.{ .root_source_file = b.path("src/gui/xterm.zig") });
                 const gui_mod = b.createModule(.{
@@ -509,7 +514,7 @@ pub fn build_exe(
                         .{ .name = "gui_config", .module = gui_config_mod },
                         .{ .name = "tracy", .module = tracy_mod },
                         .{ .name = "xy", .module = gui_xy_mod },
-                        .{ .name = "Cell", .module = gui_cell_mod },
+                        .{ .name = "cell", .module = gui_cell_mod },
                         .{ .name = "GlyphIndexCache", .module = gui_glyph_cache_mod },
                         .{ .name = "xterm", .module = gui_xterm_mod },
                     },
@@ -550,7 +555,12 @@ pub fn build_exe(
                 const sokol_mod = sokol_dep.module("sokol");
 
                 const gui_xy_mod = b.createModule(.{ .root_source_file = b.path("src/gui/xy.zig") });
-                const gui_cell_mod = b.createModule(.{ .root_source_file = b.path("src/gui/Cell.zig") });
+                const gui_cell_mod = b.createModule(.{
+                    .root_source_file = b.path("src/gui/cell.zig"),
+                    .imports = &.{
+                        .{ .name = "color", .module = color_mod },
+                    },
+                });
                 const gui_glyph_cache_mod = b.createModule(.{ .root_source_file = b.path("src/gui/GlyphIndexCache.zig") });
                 const gui_xterm_mod = b.createModule(.{ .root_source_file = b.path("src/gui/xterm.zig") });
 
@@ -609,10 +619,11 @@ pub fn build_exe(
                 const gpu_mod = b.createModule(.{
                     .root_source_file = b.path("src/gui/gpu/gpu.zig"),
                     .imports = &.{
+                        .{ .name = "color", .module = color_mod },
                         .{ .name = "sokol", .module = sokol_mod },
                         .{ .name = "rasterizer", .module = combined_rasterizer_mod },
                         .{ .name = "xy", .module = gui_xy_mod },
-                        .{ .name = "Cell", .module = gui_cell_mod },
+                        .{ .name = "cell", .module = gui_cell_mod },
                         .{ .name = "GlyphIndexCache", .module = gui_glyph_cache_mod },
                     },
                 });
@@ -620,6 +631,7 @@ pub fn build_exe(
                 const app_mod = b.createModule(.{
                     .root_source_file = b.path("src/gui/wio/app.zig"),
                     .imports = &.{
+                        .{ .name = "color", .module = color_mod },
                         .{ .name = "wio", .module = wio_mod },
                         .{ .name = "sokol", .module = sokol_mod },
                         .{ .name = "gpu", .module = gpu_mod },
@@ -635,6 +647,7 @@ pub fn build_exe(
                 const mod = b.createModule(.{
                     .root_source_file = b.path("src/renderer/gui/renderer.zig"),
                     .imports = &.{
+                        .{ .name = "color", .module = color_mod },
                         .{ .name = "theme", .module = themes_dep.module("theme") },
                         .{ .name = "cbor", .module = cbor_mod },
                         .{ .name = "thespian", .module = thespian_mod },

src/color.zig

@@ -106,6 +106,47 @@ pub const RGBf = struct {
     const GAMMA = 2.4;
 };
 
+// Packed RGBA color type used by GPUs
+pub const RGBA = packed struct(u32) {
+    a: u8,
+    b: u8,
+    g: u8,
+    r: u8,
+
+    pub fn init(r: u8, g: u8, b: u8, a: u8) RGBA {
+        return .{ .r = r, .g = g, .b = b, .a = a };
+    }
+
+    pub fn from_RGB(v: RGB) RGBA {
+        return .{ .r = v.r, .g = v.g, .b = v.b, .a = 255 };
+    }
+
+    pub inline fn from_u32(v: u32) RGBA {
+        return @bitCast(v);
+    }
+
+    pub inline fn from_u24(v: u24) RGBA {
+        return from_RGB(RGB.from_u24(v));
+    }
+
+    pub inline fn from_u8s(v: [3]u8) RGBA {
+        return .{ .r = v[0], .g = v[1], .b = v[2], .a = 255 };
+    }
+
+    pub inline fn to_u32(v: RGBA) u32 {
+        return @bitCast(v);
+    }
+
+    pub fn to_vec4(c: RGBA) [4]f32 {
+        return .{
+            @as(f32, @floatFromInt(c.r)) / 255.0,
+            @as(f32, @floatFromInt(c.g)) / 255.0,
+            @as(f32, @floatFromInt(c.b)) / 255.0,
+            @as(f32, @floatFromInt(c.a)) / 255.0,
+        };
+    }
+};
+
 pub fn u24_to_u8s(v: u24) [3]u8 {
     return .{ @truncate(v >> 16), @truncate(v >> 8), @truncate(v) };
 }

src/gui/Cell.zig

@@ -1,20 +0,0 @@
-// Shared GPU cell types used by all GPU renderer backends.
-
-pub const Rgba8 = packed struct(u32) {
-    a: u8,
-    b: u8,
-    g: u8,
-    r: u8,
-    pub fn initRgb(r: u8, g: u8, b: u8) Rgba8 {
-        return .{ .r = r, .g = g, .b = b, .a = 255 };
-    }
-    pub fn initRgba(r: u8, g: u8, b: u8, a: u8) Rgba8 {
-        return .{ .r = r, .g = g, .b = b, .a = a };
-    }
-};
-
-pub const Cell = extern struct {
-    glyph_index: u32,
-    background: Rgba8,
-    foreground: Rgba8,
-};

src/gui/cell.zig

@@ -0,0 +1,9 @@
+// Shared GPU cell types used by all GPU renderer backends.
+
+const RGBA = @import("color").RGBA;
+
+pub const Cell = extern struct {
+    glyph_index: u32,
+    background: RGBA,
+    foreground: RGBA,
+};

src/gui/gpu/gpu.zig

@@ -7,16 +7,14 @@ const std = @import("std");
 const sg = @import("sokol").gfx;
 const Rasterizer = @import("rasterizer");
 const GlyphIndexCache = @import("GlyphIndexCache");
-const gui_cell = @import("Cell");
 const XY = @import("xy").XY;
 const builtin_shader = @import("builtin.glsl.zig");
 
 pub const Font = Rasterizer.Font;
 pub const GlyphKind = Rasterizer.GlyphKind;
 pub const RasterizerBackend = Rasterizer.Backend;
-pub const Cell = gui_cell.Cell;
+pub const Cell = @import("cell").Cell;
-pub const Color = gui_cell.Rgba8;
+pub const RGBA = @import("color").RGBA;
-const Rgba8 = gui_cell.Rgba8;
 
 pub const CursorShape = enum(i32) { block = 0, beam = 1, underline = 2 };
 
@@ -25,7 +23,7 @@ pub const CursorInfo = struct {
     row: u16 = 0,
     col: u16 = 0,
     shape: CursorShape = .block,
-    color: Color = Color.initRgb(255, 255, 255),
+    color: RGBA = .init(255, 255, 255, 255),
 };
 
 const log = std.log.scoped(.gpu);
@@ -44,7 +42,7 @@ fn getAtlasCellCount(cell_size: XY(u16)) XY(u16) {
 // Shader cell layout for the RGBA32UI cell texture.
 // Each texel encodes one terminal cell:
 //   .r = glyph_index  (u32)
-//   .g = bg packed    (Rgba8 bit-cast to u32: r<<24|g<<16|b<<8|a)
+//   .g = bg packed    (RGBA bit-cast to u32: r<<24|g<<16|b<<8|a)
 //   .b = fg packed    (same)
 //   .a = 0 (reserved)
 const ShaderCell = extern struct {
@@ -61,7 +59,7 @@ const global = struct {
     var glyph_sampler: sg.Sampler = .{};
     var cell_sampler: sg.Sampler = .{};
     var glyph_cache_arena: std.heap.ArenaAllocator = undefined;
-    var background: Rgba8 = .{ .r = 19, .g = 19, .b = 19, .a = 255 };
+    var background: RGBA = .init(0, 255, 255, 255); // default is warning yellow
 };
 
 pub fn init(allocator: std.mem.Allocator) !void {
@@ -118,7 +116,7 @@ pub fn setFontWeight(font: *Font, w: u8) void {
     Rasterizer.setFontWeight(font, w);
 }
 
-pub fn setBackground(color: Rgba8) void {
+pub fn setBackground(color: RGBA) void {
     global.background = color;
 }
 
@@ -387,15 +385,15 @@ pub fn paint(
             const src = cells[src_row_offset + ci];
             shader_cells[dst_row_offset + ci] = .{
                 .glyph_index = src.glyph_index,
-                .bg = @bitCast(src.background),
+                .bg = src.background.to_u32(),
-                .fg = @bitCast(src.foreground),
+                .fg = src.foreground.to_u32(),
             };
         }
         for (copy_len..shader_col_count) |ci| {
             shader_cells[dst_row_offset + ci] = .{
                 .glyph_index = blank_glyph_index,
-                .bg = @bitCast(global.background),
+                .bg = global.background.to_u32(),
-                .fg = @bitCast(global.background),
+                .fg = global.background.to_u32(),
             };
         }
     }
@@ -448,10 +446,10 @@ pub fn paint(
     bindings.samplers[1] = global.cell_sampler;
     sg.applyBindings(bindings);
 
-    const sec_color: Color = if (secondary_cursors.len > 0)
+    const sec_color: RGBA = if (secondary_cursors.len > 0)
         secondary_cursors[0].color
     else
-        Color.initRgb(255, 255, 255);
+        .init(255, 255, 255, 255);
 
     const fs_params = builtin_shader.FsParams{
         .cell_size_x = font.cell_size.x,
@@ -463,8 +461,8 @@ pub fn paint(
         .cursor_row = cursor.row,
         .cursor_shape = @intFromEnum(cursor.shape),
         .cursor_vis = if (cursor.vis) 1 else 0,
-        .cursor_color = colorToVec4(cursor.color),
+        .cursor_color = cursor.color.to_vec4(),
-        .sec_cursor_color = colorToVec4(sec_color),
+        .sec_cursor_color = sec_color.to_vec4(),
     };
     sg.applyUniforms(0, .{
         .ptr = &fs_params,
@@ -476,15 +474,6 @@ pub fn paint(
     // Note: caller (app.zig) calls sg.commit() and window.swapBuffers()
 }
 
-fn colorToVec4(c: Color) [4]f32 {
-    return .{
-        @as(f32, @floatFromInt(c.r)) / 255.0,
-        @as(f32, @floatFromInt(c.g)) / 255.0,
-        @as(f32, @floatFromInt(c.b)) / 255.0,
-        @as(f32, @floatFromInt(c.a)) / 255.0,
-    };
-}
-
 fn oom(e: error{OutOfMemory}) noreturn {
     @panic(@errorName(e));
 }

src/gui/wio/app.zig

@@ -15,6 +15,7 @@ const gpu = @import("gpu");
 const thespian = @import("thespian");
 const cbor = @import("cbor");
 const vaxis = @import("vaxis");
+const RGBA = @import("color").RGBA;
 
 const input_translate = @import("input.zig");
 const root = @import("soft_root").root;
@@ -26,7 +27,6 @@ const log = std.log.scoped(.wio_app);
 // can use them without a direct dependency on the gpu module.
 pub const CursorInfo = gpu.CursorInfo;
 pub const CursorShape = gpu.CursorShape;
-pub const GpuColor = gpu.Color;
 
 // ── Shared state (protected by screen_mutex) ──────────────────────────────
 
@@ -57,7 +57,7 @@ var stop_requested: std.atomic.Value(bool) = .init(false);
 
 // Background color (written from TUI thread, applied by wio thread on each paint).
 // Stored as packed RGBA u32 to allow atomic reads/writes.
-var background_color: std.atomic.Value(u32) = .init(0x131313ff); // matches gpu.zig default
+var background_color: std.atomic.Value(u32) = .init(RGBA.init(0, 255, 255, 255).to_u32()); // warning yellow, we should never see the default
 var background_dirty: std.atomic.Value(bool) = .init(false);
 
 var config_arena_instance: std.heap.ArenaAllocator = std.heap.ArenaAllocator.init(std.heap.page_allocator);
@@ -316,7 +316,7 @@ fn saveConfig() void {
         log.err("failed to write gui config file", .{});
 }
 
-pub fn setBackground(color: gpu.Color) void {
+pub fn setBackground(color: RGBA) void {
     const color_u32: u32 = (@as(u32, color.r) << 24) | (@as(u32, color.g) << 16) | (@as(u32, color.b) << 8) | color.a;
     background_color.store(color_u32, .release);
     background_dirty.store(true, .release);
@@ -371,19 +371,11 @@ fn maybeReloadFont(win_size: wio.Size, state: *gpu.WindowState, cell_width: *u16
     }
 }
 
-fn colorFromVaxis(color: vaxis.Cell.Color) gpu.Color {
+fn colorFromVaxis(color: vaxis.Cell.Color) RGBA {
     return switch (color) {
-        .default => gpu.Color.initRgb(0, 0, 0),
+        .default => .init(0, 0, 0, 255),
-        .index => |idx| blk: {
+        .index => |idx| .from_u24(@import("xterm").colors[idx]),
-            const xterm = @import("xterm");
+        .rgb => |rgb| .from_u8s(rgb),
-            const rgb24 = xterm.colors[idx];
-            break :blk gpu.Color.initRgb(
-                @truncate(rgb24 >> 16),
-                @truncate(rgb24 >> 8),
-                @truncate(rgb24),
-            );
-        },
-        .rgb => |rgb| gpu.Color.initRgb(rgb[0], rgb[1], rgb[2]),
     };
 }
 

src/renderer/gui/renderer.zig

@@ -3,6 +3,7 @@ pub const log_name = "renderer";
 
 const std = @import("std");
 const cbor = @import("cbor");
+const RGBA = @import("color").RGBA;
 pub const vaxis = @import("vaxis");
 const Style = @import("theme").Style;
 const Color = @import("theme").Color;
@@ -57,9 +58,9 @@ thread: ?std.Thread = null,
 window_ready: bool = false,
 
 cursor_info: app.CursorInfo = .{},
-cursor_color: app.GpuColor = app.GpuColor.initRgb(255, 255, 255),
+cursor_color: RGBA = .init(255, 255, 255, 255),
 secondary_cursors: std.ArrayListUnmanaged(app.CursorInfo) = .{},
-secondary_color: app.GpuColor = app.GpuColor.initRgb(255, 255, 255),
+secondary_color: RGBA = .init(255, 255, 255, 255),
 
 cursor_blink: bool = false,
 blink_on: bool = true,
@@ -545,7 +546,7 @@ pub fn show_multi_cursor_yx(self: *Self, y: i32, x: i32) !void {
     });
 }
 
-fn themeColorToGpu(color: Color) app.GpuColor {
+fn themeColorToGpu(color: Color) RGBA {
     return .{
         .r = @truncate(color.color >> 16),
         .g = @truncate(color.color >> 8),

test/tests_color.zig

@@ -2,6 +2,7 @@ const std = @import("std");
 const color = @import("color");
 
 const RGB = color.RGB;
+const RGBA = color.RGBA;
 const rgb = RGB.from_u24;
 
 test "contrast white/yellow" {
@@ -41,3 +42,19 @@ test "best contrast black/white to blue" {
     const best = color.max_contrast(0x0000FF, 0xFFFFFF, 0x000000);
     try std.testing.expectEqual(best, 0xFFFFFF);
 }
+
+test "verify RGBA byte order" {
+    const v1: RGBA = .init(0xA, 0xB, 0xC, 0xD);
+    const v1_u32: u32 = @bitCast(v1);
+    const v2: RGBA = .{
+        .r = @truncate(v1_u32 >> 24),
+        .g = @truncate(v1_u32 >> 16),
+        .b = @truncate(v1_u32 >> 8),
+        .a = @truncate(v1_u32),
+    };
+    const v3: RGBA = @bitCast(v1_u32);
+
+    const testing = @import("std").testing;
+    try testing.expectEqual(v1, v2);
+    try testing.expectEqual(v1, v3);
+}