Direct2D (5) : 绘制自定义图形

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;