Package: ShaderAnimatedControl

ShaderAnimatedControl builds on CompositionAnimatedControl and turns a Skia runtime effect into an Avalonia control.

Install

dotnet add package ShaderAnimatedControl

Public surface

ShaderUri
ShaderWidth
ShaderHeight
IsShaderFillCanvas
Draw event with DrawEventArgs

Basic usage

<ShaderAnimatedControl ShaderUri="avares://EffectsDemo/Assets/shader.txt"
                       ShaderWidth="500"
                       ShaderHeight="500"
                       IsShaderFillCanvas="True"
                       Draw="ShaderAnimatedControl_OnDraw" />

Binding uniforms in the draw callback

private SKRuntimeEffectUniforms? _uniforms;

private void ShaderAnimatedControl_OnDraw(object? sender, DrawEventArgs e)
{
    if (e.ErrorText is not null)
    {
        return;
    }

    var targetWidth = (float)(e.IsShaderFillCanvas ? e.DestRect.Width : e.ShaderWidth);
    var targetHeight = (float)(e.IsShaderFillCanvas ? e.DestRect.Height : e.ShaderHeight);

    _uniforms ??= new SKRuntimeEffectUniforms(e.Effect);
    _uniforms["iTime"] = (float)e.EffectiveElapsed.TotalSeconds;
    _uniforms["iResolution"] = new[] { targetWidth, targetHeight, 0f };

    using var paint = new SKPaint();
    using var shader = e.Effect.ToShader(_uniforms);
    paint.Shader = shader;

    var rect = new SKRect((float)e.DestRect.X, (float)e.DestRect.Y, (float)e.DestRect.Right, (float)e.DestRect.Bottom);
    e.Canvas.DrawRect(rect, paint);
}

Notes

The control automatically starts on Loaded and stops on Unloaded.
DrawEventArgs.ErrorText lets you detect SKSL compilation errors.
IsShaderFillCanvas switches between a fixed logical shader size and the current control bounds.

For more detail, see Shader Uniform Binding.