画自定义尺寸的圆角背景

首先准备一个png的圆角背景图

1.分三部分画，可以是”上，中，下”，也可以是“左，中，右”

注意的是圆角的宽度和高度

2.绘制的时候不要忘记设置ImageAttributes的绘制模式,这样就可以画无限的高度和宽度

ImageAttributes imgAtt;
imgAtt.SetWrapMode(WrapModeTileFlipY);

绘制效果

源码Demo

void DrawMargin(Graphics& g, Image* pImage, Rect& rcDst, Rect& rcSrc, int nMarginLeft, int nMarginRight, 
    int nMarginTop, int nMarginBottom, BOOL bDrawCenter/* = TRUE*/)
{
    //ASSERT(pImage);
    int nImgWidth = pImage->GetWidth();
    int nImgHeight = pImage->GetHeight();
    Rect rcImage(0, 0, nImgWidth, nImgHeight);
    //ASSERT(rcImage.Contains(rcSrc));

    //ASSERT((rcSrc.Width > (nMarginLeft + nMarginRight)) && (rcSrc.Height > (nMarginTop + nMarginBottom)));
    if((rcDst.Width <= (nMarginLeft + nMarginRight)) || (rcDst.Height <= (nMarginTop + nMarginBottom)))
        g.DrawImage(pImage, rcDst, rcSrc.X, rcSrc.Y, rcSrc.Width, rcSrc.Height, UnitPixel);

    ImageAttributes imgAtt;

    //上
    if(nMarginTop)
    {
        if(nMarginLeft)
        {
            Rect rcTopLeft(rcDst.X, rcDst.Y, nMarginLeft, nMarginTop);
            g.DrawImage(pImage, rcTopLeft, rcSrc.X, rcSrc.Y, nMarginLeft, nMarginTop, UnitPixel);
        }
        Rect rcTop(rcDst.X + nMarginLeft, rcDst.Y, rcDst.Width - nMarginLeft - nMarginRight, nMarginTop);
        imgAtt.SetWrapMode(WrapModeTileFlipX);
        g.DrawImage(pImage, rcTop, rcSrc.X + nMarginLeft, rcSrc.Y, rcSrc.Width - nMarginLeft - nMarginRight, nMarginTop, UnitPixel, &imgAtt);
        if(nMarginRight)
        {
            Rect rcTopRight(rcDst.GetRight() - nMarginRight, rcDst.Y, nMarginRight, nMarginTop);
            g.DrawImage(pImage, rcTopRight, rcSrc.GetRight() - nMarginRight, rcSrc.Y, nMarginRight, nMarginTop, UnitPixel);
        }
    }
    
    //中
    if(nMarginLeft)
    {
        Rect rcLeft(rcDst.X, rcDst.Y + nMarginTop, nMarginLeft, rcDst.Height - nMarginTop - nMarginBottom);
        imgAtt.SetWrapMode(WrapModeTileFlipY);
        g.DrawImage(pImage, rcLeft, rcSrc.X, rcSrc.Y + nMarginTop, nMarginLeft, rcSrc.Height - nMarginTop - nMarginBottom, UnitPixel, &imgAtt);
    }
    if(bDrawCenter)
    {
        Rect rcCenter(rcDst.X + nMarginLeft, rcDst.Y + nMarginTop, rcDst.Width - nMarginLeft - nMarginRight, rcDst.Height - nMarginTop - nMarginBottom);
        imgAtt.SetWrapMode(WrapModeTileFlipXY);
        g.DrawImage(pImage, rcCenter, rcSrc.X + nMarginLeft, rcSrc.Y + nMarginTop, rcSrc.Width - nMarginLeft - nMarginRight, rcSrc.Height - nMarginTop - nMarginBottom, UnitPixel, &imgAtt);
    }
    if(nMarginRight)
    {
        Rect rcRight(rcDst.GetRight() - nMarginRight, rcDst.Y + nMarginTop, nMarginRight, rcDst.Height - nMarginTop - nMarginBottom);
        imgAtt.SetWrapMode(WrapModeTileFlipY);
        g.DrawImage(pImage, rcRight, rcSrc.GetRight() - nMarginRight, rcSrc.Y + nMarginTop, nMarginRight, rcSrc.Height - nMarginTop - nMarginBottom, UnitPixel, &imgAtt);
    }
    
    //下
    if(nMarginTop)
    {
        if(nMarginLeft)
        {
            Rect rcBottomLeft(rcDst.X, rcDst.GetBottom() - nMarginBottom, nMarginLeft, nMarginBottom);
            g.DrawImage(pImage, rcBottomLeft, rcSrc.X, rcSrc.GetBottom() - nMarginBottom, nMarginLeft, nMarginBottom, UnitPixel);
        }
        Rect rcBottom(rcDst.X + nMarginLeft, rcDst.GetBottom() - nMarginBottom, rcDst.Width - nMarginLeft - nMarginRight, nMarginBottom);
        imgAtt.SetWrapMode(WrapModeTileFlipX);
        g.DrawImage(pImage, rcBottom, rcSrc.X + nMarginLeft, rcSrc.GetBottom() - nMarginBottom, rcSrc.Width - nMarginLeft - nMarginRight, nMarginBottom, UnitPixel, &imgAtt);
        if(nMarginRight)
        {
            Rect rcBottomRight(rcDst.GetRight() - nMarginRight, rcDst.GetBottom() - nMarginBottom, nMarginRight, nMarginBottom);
            g.DrawImage(pImage, rcBottomRight, rcSrc.GetRight() - nMarginRight, rcSrc.GetBottom() - nMarginBottom, nMarginRight, nMarginBottom, UnitPixel);
        }
    }
}

void DrawMargin1(Graphics& g, Image* pImage, Rect& rcDst, int nMarginLeft, int nMarginRight, int nMarginTop, int nMarginBottom)
{

    int nImgWidth = pImage->GetWidth();
    int nImgHeight = pImage->GetHeight();
    Rect rcSrc(0, 0, nImgWidth, nImgHeight);

    DrawMargin(g, pImage, rcDst, rcSrc, nMarginLeft, nMarginRight, nMarginTop, nMarginBottom, TRUE);
}