GDI+并没有提供GDI中的Chord函数(其它的还有RoundRect函数,可参考BobPowell 的这篇文章),只好自己动手了:
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BOOL
GDIplusChord(
HDC
hDC,
INT
x1,
INT
y1,
INT
x2,
INT
y2,
INT
x3,
INT
y3,
INT
x4,
INT
y4 )
{
Graphics graphics(hDC);
CRect rectBound(x1, y1, x2, y2);
rectBound.NormalizeRect();
Rect ellipseRect(rectBound.left, rectBound.top, rectBound.Width(), rectBound.Height());
////////////////////////////////////////////////////////////////////////////////
// For testing only.
BYTE
byAlpha = 200;
SolidBrush fillBrush(Color(byAlpha, 0, 0, 255));
Pen redPen(Color(byAlpha, 255, 0, 0), 3);
////////////////////////////////////////////////////////////////////////////////
Status ret = InvalidParameter;
if
( x3 == x4 && y3 == y4 )
{
// If the starting point and ending point of the curve are the same, a complete ellipse should be drawn.
ret = graphics.FillEllipse(&fillBrush, ellipseRect);
ret = graphics.DrawEllipse(&redPen, ellipseRect);
return
Gdiplus::Ok == ret;
}
CPoint ptCenter(rectBound.CenterPoint());
#define PI 3.1415926
REAL startAngle =
atan2
(y3-ptCenter.y, x3-ptCenter.x ) * 180.0f / PI;
REAL sweepAngle = (
atan2
(y4-ptCenter.y, x4-ptCenter.x ) * 180.0f / PI) - startAngle - 360.0f;
if
( sweepAngle < -360.0f )
sweepAngle += 360.0f;
GraphicsPath path;
path.StartFigure();
path.AddArc(ellipseRect, startAngle, sweepAngle);
path.CloseFigure();
ret = graphics.FillPath(&fillBrush, &path);
ret = graphics.DrawPath(&redPen, &path);
return
Gdiplus::Ok == ret;
}
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转自:http://www.cnblogs.com/yonken/archive/2010/05/06/Implement_Chord_Function_Using_GDIplus.html