GDI+繪制圓角矩形

1. 生成圓角矩形路徑對象。

   1) 創建CGraphicsRoundRectPath對象objRoundPath。

   2) objRoundPath調用添加圓角矩形路徑的函數AddRoundRect。

2. 使用Graphic::DrawPath繪制圓角矩形。

CGraphicsRoundRectPath的頭文件:

class CGraphicsRoundRectPath: public Gdiplus::GraphicsPath
{
public:
    CGraphicsRoundRectPath();
    CGraphicsRoundRectPath(INT x, INT y, INT width, INT height, INT cornerX, INT cornerY);

public:
    void AddRoundRect(INT x, INT y, INT width, INT height, INT cornerX, INT cornerY);
};

CGraphicsRoundRectPath的源代碼:

CGraphicsRoundRectPath::CGraphicsRoundRectPath(INT x, INT y, INT width, INT height, INT cornerX, INT cornerY)
    :Gdiplus::GraphicsPath()
{
    AddRoundRect(x,y,width,height,cornerX,cornerY);
}
void CGraphicsRoundRectPath::AddRoundRect(INT x, INT y, INT width, INT height, INT cornerX, INT cornerY)
{
    INT elWid = 2*cornerX;
    INT elHei = 2*cornerY;

    AddArc(x,y,elWid,elHei,180,90); // 左上角圓弧
    AddLine(x+cornerX,y,x+width-cornerX,y); // 上邊

    AddArc(x+width-elWid,y, elWid,elHei,270,90); // 右上角圓弧
    AddLine(x+width,y+cornerY, x+width,y+height-cornerY);// 右邊

    AddArc(x+width-elWid,y+height-elHei, elWid,elHei,0,90); // 右下角圓弧
    AddLine(x+width-cornerX,y+height, x+cornerX,y+height); // 下邊

    AddArc(x,y+height-elHei, elWid,elHei,90,90); 
    AddLine(x,y+cornerY, x, y+height-cornerY);
}