Direct2D (19) : 图层之 TD2D1LayerParameters.geometricMask (使用几何图形剪裁图层)

uses Direct2D, D2D1;

procedure TForm1.FormPaint(Sender: TObject);
var
  cvs: TDirect2DCanvas;
  iLayer: ID2D1Layer;
  rLayerParameters: TD2D1LayerParameters;
  wic: TWICImage;
  R: TRect;
  iEllipse: ID2D1EllipseGeometry;
begin
  wic := TWICImage.Create;
  wic.LoadFromFile('C:\Temp\Test.png');
  R := Rect(0, 0, wic.Width, wic.Height);

  {几何图形}
  D2DFactory.CreateEllipseGeometry(D2D1Ellipse(D2D1PointF(wic.Width/2, wic.Height/2), wic.Width/2, wic.Height/2), iEllipse);

  cvs := TDirect2DCanvas.Create(Canvas, ClientRect);
  cvs.RenderTarget.SetTransform(TD2DMatrix3x2F.Translation((ClientWidth-wic.width)/2, (ClientHeight-wic.height)/2));

  cvs.BeginDraw;
  cvs.RenderTarget.CreateLayer(nil, iLayer);
  rLayerParameters.contentBounds := R;
  rLayerParameters.geometricMask := iEllipse; //!
  rLayerParameters.maskAntialiasMode := D2D1_ANTIALIAS_MODE_PER_PRIMITIVE;
  rLayerParameters.maskTransform := TD2DMatrix3x2F.Identity;
  rLayerParameters.opacity := 1.0;
//  rLayerParameters.opacityBrush := nil;
  rLayerParameters.layerOptions := D2D1_LAYER_OPTIONS_NONE;

  cvs.RenderTarget.PushLayer(rLayerParameters, iLayer);
  cvs.StretchDraw(R, wic);
  cvs.RenderTarget.PopLayer;

  cvs.EndDraw;
  cvs.Free;
  wic.Free;
end;

procedure TForm1.FormResize(Sender: TObject);
begin
  Repaint;
end;

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效果图：

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