terminal: color palette structure and generation

src/Grid.zig

@@ -7,7 +7,8 @@ const testing = std.testing;
 const Allocator = std.mem.Allocator;
 const Atlas = @import("Atlas.zig");
 const FontAtlas = @import("FontAtlas.zig");
-const Terminal = @import("terminal/Terminal.zig");
+const terminal = @import("terminal/main.zig");
+const Terminal = terminal.Terminal;
 const gl = @import("opengl.zig");
 const gb = @import("gb_math.zig");
 const trace = @import("tracy/tracy.zig").trace;
@@ -42,7 +43,7 @@ cursor_visible: bool,
 cursor_style: CursorStyle,
 
 /// Default foreground color
-foreground: Terminal.RGB,
+foreground: terminal.color.RGB,
 
 const CursorStyle = enum(u8) {
     box = 3,

src/terminal/Terminal.zig

@@ -14,6 +14,8 @@ const csi = @import("csi.zig");
 const sgr = @import("sgr.zig");
 const Tabstops = @import("Tabstops.zig");
 const trace = @import("../tracy/tracy.zig").trace;
+const color = @import("color.zig");
+const RGB = color.RGB;
 
 const log = std.log.scoped(.terminal);
 
@@ -74,12 +76,6 @@ const Cursor = struct {
     pen: Cell = .{ .char = 0 },
 };
 
-pub const RGB = struct {
-    r: u8,
-    g: u8,
-    b: u8,
-};
-
 /// Initialize a new terminal.
 pub fn init(alloc: Allocator, cols: usize, rows: usize) !Terminal {
     return Terminal{

src/terminal/color.zig

@@ -0,0 +1,111 @@
+const std = @import("std");
+const assert = std.debug.assert;
+
+/// The default palette.
+pub const default: Palette = default: {
+    var result: Palette = undefined;
+
+    // Named values
+    var i: u8 = 0;
+    while (i < 16) : (i += 1) {
+        result[i] = Name.default(@intToEnum(Name, i)) catch unreachable;
+    }
+
+    // Cube
+    assert(i == 16);
+    var r: u8 = 0;
+    while (r < 6) : (r += 1) {
+        var g: u8 = 0;
+        while (g < 6) : (g += 1) {
+            var b: u8 = 0;
+            while (b < 6) : (b += 1) {
+                result[i] = .{
+                    .r = if (r == 0) 0 else (r * 40 + 55),
+                    .g = if (g == 0) 0 else (g * 40 + 55),
+                    .b = if (b == 0) 0 else (b * 40 + 55),
+                };
+
+                i += 1;
+            }
+        }
+    }
+
+    // Grey ramp
+    assert(i == 232);
+    assert(@TypeOf(i) == u8);
+    while (i > 0) : (i +%= 1) {
+        const value = ((i - 232) * 10) + 8;
+        result[i] = .{ .r = value, .g = value, .b = value };
+    }
+
+    break :default result;
+};
+
+/// Palette is the 256 color palette.
+pub const Palette = [256]RGB;
+
+/// Color names in the standard 8 or 16 color palette.
+pub const Name = enum(u8) {
+    black = 0,
+    red = 1,
+    green = 2,
+    yellow = 3,
+    blue = 4,
+    magenta = 5,
+    cyan = 6,
+    white = 7,
+
+    bright_black = 8,
+    bright_red = 9,
+    bright_green = 10,
+    bright_yellow = 11,
+    bright_blue = 12,
+    bright_magenta = 13,
+    bright_cyan = 14,
+    bright_white = 15,
+
+    // Remainders are valid unnamed values in the 256 color palette.
+    _,
+
+    /// Default colors for tagged values.
+    pub fn default(self: Name) !RGB {
+        return switch (self) {
+            .black => RGB{ .r = 0x1D, .g = 0x1F, .b = 0x21 },
+            .red => RGB{ .r = 0xCC, .g = 0x66, .b = 0x66 },
+            .green => RGB{ .r = 0xB5, .g = 0xBD, .b = 0x68 },
+            .yellow => RGB{ .r = 0xF0, .g = 0xC6, .b = 0x74 },
+            .blue => RGB{ .r = 0x81, .g = 0xA2, .b = 0xBE },
+            .magenta => RGB{ .r = 0xB2, .g = 0x94, .b = 0xBB },
+            .cyan => RGB{ .r = 0x8A, .g = 0xBE, .b = 0xB7 },
+            .white => RGB{ .r = 0xC5, .g = 0xC8, .b = 0xC6 },
+
+            .bright_black => RGB{ .r = 0x66, .g = 0x66, .b = 0x66 },
+            .bright_red => RGB{ .r = 0xD5, .g = 0x4E, .b = 0x53 },
+            .bright_green => RGB{ .r = 0xB9, .g = 0xCA, .b = 0x4A },
+            .bright_yellow => RGB{ .r = 0xE7, .g = 0xC5, .b = 0x47 },
+            .bright_blue => RGB{ .r = 0x7A, .g = 0xA6, .b = 0xDA },
+            .bright_magenta => RGB{ .r = 0xC3, .g = 0x97, .b = 0xD8 },
+            .bright_cyan => RGB{ .r = 0x70, .g = 0xC0, .b = 0xB1 },
+            .bright_white => RGB{ .r = 0xEA, .g = 0xEA, .b = 0xEA },
+
+            else => error.NoDefaultValue,
+        };
+    }
+};
+
+/// RGB
+pub const RGB = struct {
+    r: u8,
+    g: u8,
+    b: u8,
+};
+
+test "palette: default" {
+    const testing = std.testing;
+
+    // Safety check
+    var i: u8 = 0;
+    while (i < 16) : (i += 1) {
+        try testing.expectEqual(Name.default(@intToEnum(Name, i)), default[i]);
+    }
+}

src/terminal/main.zig

@@ -2,6 +2,7 @@ const stream = @import("stream.zig");
 const ansi = @import("ansi.zig");
 const csi = @import("csi.zig");
 const sgr = @import("sgr.zig");
+pub const color = @import("color.zig");
 
 pub const Terminal = @import("Terminal.zig");
 pub const Parser = @import("Parser.zig");
@@ -17,6 +18,7 @@ pub const Attribute = sgr.Attribute;
 
 test {
     _ = ansi;
+    _ = color;
     _ = csi;
     _ = sgr;
     _ = stream;