MFC Picture Ctrl 无失真自适应显示图片

int height, width;  
    CRect rect;//定义矩形类  
    CRect rect1;  
    CImage image; //创建图片类  
    image.Load("test.bmp");  
    height = image.GetHeight();  
    width = image.GetWidth();  

    m_src.GetClientRect(&rect); //获得pictrue控件所在的矩形区域  
    CDC *pDc = m_src.GetDC();//获得pictrue控件的Dc  
    SetStretchBltMode(pDc->m_hDC,STRETCH_HALFTONE);   

    if(width<=rect.Width() && height<=rect.Width()) //小图片，不缩放  
    {  
        rect1 = CRect(rect.TopLeft(), CSize(width,height));  
        image.StretchBlt(pDc->m_hDC,rect1,SRCCOPY); //将图片画到Picture控件表示的矩形区域  
        return TRUE;  
    }  
    else  
    {  
        float xScale=(float)rect.Width()/(float)width;  
        float yScale=(float)rect.Height()/(float)height;  
        float ScaleIndex=(xScale>=yScale?xScale:yScale);
        rect1 = CRect(rect.TopLeft(), CSize((int)width*ScaleIndex,(int)height*ScaleIndex));  
        image.StretchBlt(pDc->m_hDC,rect1,SRCCOPY); //将图片画到Picture控件表示的矩形区域  
    }  
    ReleaseDC(pDc);//释放picture控件的Dc 

http://blog.sina.com.cn/s/blog_69b5d2a50101a7qf.html