Direct2D (23) : 复合几何对象之 ID2D1GeometryGroup

uses Direct2D, D2D1;

procedure TForm1.FormPaint(Sender: TObject);
var
cvs: TDirect2DCanvas;
iGeometryGroup: ID2D1GeometryGroup;
arrGeometry: array[0..3] of ID2D1EllipseGeometry;
ptCenter: TD2D1Point2F;
i: Integer;
rh,rv: Single;
iFactory: ID2D1Factory;
begin
ptCenter := D2D1PointF(ClientWidth/2, ClientHeight/2);

{建立几何对象数组}
iFactory := D2DFactory();
rh := ClientWidth / 12;
rv := ClientHeight / 12;
for i := 0 to Length(arrGeometry)-1 do
begin
iFactory.CreateEllipseGeometry(D2D1Ellipse(ptCenter, rh*(i+1), rv*(i+1)), arrGeometry[i]);
end;

{建立 ID2D1GeometryGroup 对象}
D2DFactory.CreateGeometryGroup(
D2D1_FILL_MODE_ALTERNATE, //另可选 D2D1_FILL_MODE_WINDING，测试效果图演示了两种填充模式的区别
@arrGeometry[0],
Length(arrGeometry),
iGeometryGroup
);

cvs := TDirect2DCanvas.Create(Canvas, ClientRect);
cvs.BeginDraw;
cvs.Brush.Color := clWebCornFlowerBlue;
cvs.FillGeometry(iGeometryGroup);
cvs.DrawGeometry(iGeometryGroup);
cvs.EndDraw;
cvs.Free;
end;

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