下面是通过自定义函数绘制菱形的测试代码。
uses Direct2D, D2D1; {自定义的绘制菱形的函数} function GetDiamondPath(ptLeft, ptTop: TD2DPoint2f): ID2D1PathGeometry; //返回路径接口 var sink: ID2D1GeometrySink; //给路径添加图形的接口 ptRight,ptBottom: TD2DPoint2f; begin {算出另外两个点} ptRight := D2D1PointF((ptTop.x-ptLeft.x)*2+ptLeft.x, ptLeft.y); ptBottom := D2D1PointF(ptTop.x, (ptLeft.y-ptTop.y)*2+ptTop.y); {构建 ID2D1PathGeometry} D2DFactory.CreatePathGeometry(Result); {建立并启用 ID2D1GeometrySink} Result.Open(sink); {开始添加图形,} sink.BeginFigure(ptLeft, D2D1_FIGURE_BEGIN_FILLED); //选项 D2D1_FIGURE_BEGIN_FILLED 标识图形可以填充 sink.AddLine(ptTop); sink.AddLine(ptRight); sink.AddLine(ptBottom); {结束图形并关闭 ID2D1GeometrySink} sink.EndFigure(D2D1_FIGURE_END_CLOSED); //选项 D2D1_FIGURE_END_CLOSED 标识图形自动封闭 sink.Close; end; {绘制} procedure TForm1.FormPaint(Sender: TObject); var path: ID2D1PathGeometry; begin path := GetDiamondPath(D2D1PointF(ClientWidth/5, ClientHeight/2), D2D1PointF(ClientWidth/2, ClientHeight/5)); with TDirect2DCanvas.Create(Canvas, ClientRect) do begin Pen.Color := clRed; Brush.Color := clYellow; BeginDraw; FillGeometry(path); DrawGeometry(path); EndDraw; Free; end; end; procedure TForm1.FormResize(Sender: TObject); begin Repaint; end;
效果图: