1 在CPictureEx::OnPaint() 函数中2 将下面代码：3 ::BitBlt(dc.m_hDC, 0, 0, nPaintWidth, nPaintHeight,  m_hMemDC, m_PaintRect.left, m_PaintRect.top, SRCCOPY);4 5 替换为：6 7 SIZE size = GetSize();8 9 ::StretchBlt(dc.m_hDC,0,0,(int)(size.cx*0.5),(int)(size.cy*0.5),m_hMemDC,0,0,size.cx,size.cy,SRCCOPY);