3.1 PaletteFactory

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/FrameProcessor/ImagePipeline/PaletteFactory.cs

@@ -0,0 +1,38 @@
+using FrameProcessor.Domain;
+using SixLabors.ImageSharp;
+
+namespace FrameProcessor.ImagePipeline;
+
+/// <summary>
+/// Builds ImageSharp <see cref="Color"/> palettes from a frame's <see cref="PaletteEntry"/> list.
+/// The display palette is what we dither *against* (what the eye sees on the panel); the device
+/// palette is the set of RGB values firmware expects in the input PNG. Order is preserved in both.
+/// </summary>
+public static class PaletteFactory
+{
+    public static ReadOnlyMemory<Color> BuildDisplay(IReadOnlyList<PaletteEntry> entries)
+    {
+        ArgumentNullException.ThrowIfNull(entries);
+
+        var colors = new Color[entries.Count];
+        for (var i = 0; i < entries.Count; i++)
+        {
+            colors[i] = entries[i].DisplayColor;
+        }
+
+        return colors;
+    }
+
+    public static ReadOnlyMemory<Color> BuildDevice(IReadOnlyList<PaletteEntry> entries)
+    {
+        ArgumentNullException.ThrowIfNull(entries);
+
+        var colors = new Color[entries.Count];
+        for (var i = 0; i < entries.Count; i++)
+        {
+            colors[i] = entries[i].DeviceColor;
+        }
+
+        return colors;
+    }
+}