PaletteBuilder Class

[Fact]
public void PaletteBuilder_SharedPalette()
{
    // An animation of two frames with different colors
    using var animation = new Image<Rgba32>(32, 32);
    animation.AppendFrame();
    for (var i = 0; i < animation.Frames.Count; i++)
    {
        var shift = i * 100;
        animation.Frames[i].ProcessPixelRows(pixels =>
        {
            for (var y = 0; y < pixels.Height; y++)
            {
                var row = pixels.GetRowSpan(y);
                for (var x = 0; x < row.Length; x++)
                {
                    row[x] = new Rgba32((byte)(x * 8), (byte)((y * 4) + shift), (byte)shift);
                }
            }
        });
    }

    // One palette for every frame, then every frame maps to it
    ImagePalette palette;
    using (var builder = new PaletteBuilder())
    {
        builder.Add(animation);
        palette = builder.Build(maxColors: 64);
    }

    animation.Quantize(new QuantizeOptions { Palette = palette, Dithering = DitheringMode.Sierra });

    foreach (var frame in animation.Frames)
    {
        var colors = new HashSet<Rgba32>();
        frame.ProcessPixelRows(pixels =>
        {
            for (var y = 0; y < pixels.Height; y++)
            {
                colors.UnionWith(pixels.GetRowSpan(y).ToArray());
            }
        });

        Assert.True(colors.IsSubsetOf(palette.Colors.ToArray()));
    }
}