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Optimize background drawing and fix transparent background clearing #2091

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Optimize background drawing and fix transparent background clearing #2091

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a7d0dad
Initial plan
Copilot Feb 9, 2026
f03486e
Optimize background drawing by avoiding SaveLayer for opaque backgrounds
Copilot Feb 9, 2026
5b13a2f
Fix transparent background clearing to prevent ghosting (fixes #2044)
Copilot Feb 9, 2026
2ae7081
use SKBlendMode.Src for clearing frames
beto-rodriguez Feb 9, 2026
b878544
try SKBlendMode.SrcATop
beto-rodriguez Feb 9, 2026
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24 changes: 20 additions & 4 deletions src/skiasharp/LiveChartsCore.SkiaSharp/Drawing/SkiaSharpDrawingContext.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -105,11 +105,27 @@ public override void LogOnCanvas(string log)

internal override void OnBeginDraw()
{
if (Background == SKColor.Empty) return;
// For fully opaque backgrounds, Clear is safe and efficient.
if (Background.Alpha == 255)
{
Canvas.Clear(Background);
return;
}

// For transparent or translucent backgrounds, draw a filled rect with SrcOver
// to avoid clearing through to the underlying OS surface while still clearing
// the motion canvas to prevent ghosting/trails from previous frames.
var clearColor = Background == SKColor.Empty ? SKColors.Transparent : Background;

using var backgroundPaint = new SKPaint
{
Color = clearColor,
Style = SKPaintStyle.Fill,
BlendMode = SKBlendMode.SrcATop
};

_ = Canvas.SaveLayer();
Canvas.Clear(Background);
Canvas.Restore();
var bounds = Canvas.DeviceClipBounds;
Canvas.DrawRect(bounds, backgroundPaint);
}

internal override void OnEndDraw()
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