Direct2D (18) : 圖層之 TD2D1LayerParameters.contentBounds (圖層的有效範圍)

{相關方法}TDirect2DCanvas.RenderTarget.CreateLayer(); //建立層TDirect2DCanvas.RenderTarget.PushLayer();   //開始層；層的功能及效果取決於它的 TD2D1LayerParameters 結構參數TDirect2DCanvas.RenderTarget.PopLayer();    //結束層{相關結構}TD2D1LayerParameters = record  contentBounds: TD2D1RectF;             //層的有效範圍  geometricMask: ID2D1Geometry;          //用於剪裁的幾何圖形  maskAntialiasMode: TD2D1AntiAliasMode; //消除鋸齒模式  maskTransform: TD2D1Matrix3x2F;        //2D 變換  opacity: Single;                       //層的透明度  opacityBrush: ID2D1Brush;              //蒙版畫刷  layerOptions: TD2D1LayerOptions;       //文本消除鋸齒模式end;

測試圖層範圍(用不同的透明度繪製了兩次圖片，第二次通過層指定了有效範圍)：

uses Direct2D, D2D1;procedure TForm1.FormPaint(Sender: TObject);var  cvs: TDirect2DCanvas;  iLayer: ID2D1Layer;  rLayerParameters: TD2D1LayerParameters;  wic: TWICImage;  R: TRect;begin  wic := TWICImage.Create;  wic.LoadFromFile('C:\Temp\Test.png');  R := Rect(0, 0, wic.Width, wic.Height);  cvs := TDirect2DCanvas.Create(Canvas, ClientRect);  cvs.RenderTarget.SetTransform(TD2DMatrix3x2F.Translation((ClientWidth-wic.width)/2, (ClientHeight-wic.height)/2));  cvs.BeginDraw;  cvs.StretchDraw(R, wic, 128);  {建立層}  cvs.RenderTarget.CreateLayer(nil, iLayer); //參數1是初始大小，一般無需指定  {為 PushLayer() 方法準備參數}  InflateRect(R, -50, -40);  rLayerParameters.contentBounds := R; //指定層的有效範圍//  rLayerParameters.geometricMask := nil;  rLayerParameters.maskAntialiasMode := D2D1_ANTIALIAS_MODE_PER_PRIMITIVE;//  rLayerParameters.maskTransform := TD2DMatrix3x2F.Identity;  rLayerParameters.opacity := 1.0;//  rLayerParameters.opacityBrush := nil;  rLayerParameters.layerOptions := D2D1_LAYER_OPTIONS_NONE;  {開始層}  cvs.RenderTarget.PushLayer(rLayerParameters, iLayer);  cvs.Draw(0, 0, wic);  {結束層}  cvs.RenderTarget.PopLayer;  cvs.EndDraw;  cvs.Free;  wic.Free;end;procedure TForm1.FormResize(Sender: TObject);begin  Repaint;end;

：