From 1af3b0a4f587b3ae4c25fad867decc2fbcfdc4af Mon Sep 17 00:00:00 2001
From: Meghan Denny <hello@nektro.net>
Date: Wed, 11 Oct 2023 22:40:57 -0700
Subject: [PATCH] add YCbCr -> sRGB conversion

---
 YCbCr.zig | 15 +++++++++++++++
 _x.zig    | 28 ++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+)
 create mode 100644 _x.zig

diff --git a/YCbCr.zig b/YCbCr.zig
index e62464eac452553eefd8deda3de2dda1df7381ac..8e87e6e848b5de016f60d8b6d767cb7f38f136fa 100644
--- a/YCbCr.zig
+++ b/YCbCr.zig
@@ -3,6 +3,7 @@
 const std = @import("std");
 const Self = @This();
 const color = @import("./mod.zig");
+const _x = @import("./_x.zig");
 
 y: u8,
 cb: u8,
@@ -25,3 +26,17 @@ pub fn initYCbCr(y: u8, cb: u8, cr: u8) Self {
 pub fn eql(x: Self, y: Self) bool {
     return x.y == y.y and x.cb == y.cb and x.cr == y.cr and x.a == y.a;
 }
+
+pub usingnamespace _x.mixin(@This(), .y, .cb, .cr);
+
+pub fn to_srgb(x: Self) color.sRGB {
+    // zig fmt: off
+    const f = x.to_vec();
+    return color.sRGB.from_vec(.{
+        @max(0, @min(255, f[0]                        + 1.402   * (f[2]-128))),
+        @max(0, @min(255, f[0] - 0.34414 * (f[1]-128) - 0.71414 * (f[2]-128))),
+        @max(0, @min(255, f[0] + 1.772   * (f[1]-128))),
+        @max(0, @min(255, f[3])),
+    });
+    // zig fmt: on
+}
diff --git a/_x.zig b/_x.zig
new file mode 100644
index 0000000000000000000000000000000000000000..28c4f726cecc159a01f9a9fb7d76ee6f6c6a3424
--- /dev/null
+++ b/_x.zig
@@ -0,0 +1,28 @@
+const std = @import("std");
+
+pub fn mixin(
+    comptime T: type,
+    comptime f1: std.meta.FieldEnum(T),
+    comptime f2: std.meta.FieldEnum(T),
+    comptime f3: std.meta.FieldEnum(T),
+) type {
+    return struct {
+        pub fn to_vec(x: T) @Vector(4, f32) {
+            return .{
+                @floatFromInt(@field(x, @tagName(f1))),
+                @floatFromInt(@field(x, @tagName(f2))),
+                @floatFromInt(@field(x, @tagName(f3))),
+                @floatFromInt(x.a),
+            };
+        }
+
+        pub fn from_vec(in: @Vector(4, f32)) T {
+            var x: T = undefined;
+            @field(x, @tagName(f1)) = @intFromFloat(in[0]);
+            @field(x, @tagName(f2)) = @intFromFloat(in[1]);
+            @field(x, @tagName(f3)) = @intFromFloat(in[2]);
+            x.a = @intFromFloat(in[3]);
+            return x;
+        }
+    };
+}
-- 
2.54.0