c–如何使用ID2D1PathGeometry绘制圆

ID2D1PathGeometry :: Open返回一个支持添加直线,圆弧和曲线的ID2D1GeometrySink.但有没有办法添加一个圆(椭圆),或至少以某种方式模拟一个？

解决方法:

使用AddArc函数,您可以简单地绘制两个具有相同x和y半径的圆弧来构建圆.这是图片和代码,希望这可以帮到你.

// create circle with two arcs
hr = g_pD2DFactory->CreatePathGeometry(&g_pCircleGeometry) ;
if (SUCCEEDED(hr))
{
ID2D1GeometrySink *pSink = NULL;
hr = g_pCircleGeometry->Open(&pSink);
if (SUCCEEDED(hr))
{
pSink->SetFillMode(D2D1_FILL_MODE_WINDING);
pSink->BeginFigure(
D2D1::Point2F(100, 300), // Start point of the top half circle
D2D1_FIGURE_BEGIN_FILLED
);
// Add the top half circle
pSink->AddArc(
D2D1::ArcSegment(
D2D1::Point2F(400, 300), // end point of the top half circle, also the start point of the bottom half circle
D2D1::SizeF(150, 150), // radius
0.0f, // rotation angle
D2D1_SWEEP_DIRECTION_CLOCKWISE,
D2D1_ARC_SIZE_SMALL
));
// Add the bottom half circle
pSink->AddArc(
D2D1::ArcSegment(
D2D1::Point2F(100, 300), // end point of the bottom half circle
D2D1::SizeF(150, 150), // radius of the bottom half circle, same as previous one.
0.0f, // rotation angle
D2D1_SWEEP_DIRECTION_CLOCKWISE,
D2D1_ARC_SIZE_SMALL
));
pSink->EndFigure(D2D1_FIGURE_END_CLOSED);
}
hr = pSink->Close();
SAFE_RELEASE(pSink);
}