标签:
总之,就是不断反复遮罩“过滤掉”透明色就行,先来整段代码,后面再详细介绍。
void CTransDlg::OnPaint() { CPaintDC dc(this); CMemDC m_dc; if(!m_dc) m_dc.LoadBitmap(IDB_BITMAP4); CMemDC dcImage(100,100,&dc); CBitmap bmpMask; bmpMask.CreateBitmap(100,100,1,1,NULL); CDC dcMask; dcMask.CreateCompatibleDC(&dc); dcMask.SelectObject(bmpMask); dcImage.BitBlt(0,0,100,100,&m_dc,0,0,SRCCOPY); dc.BitBlt(10,10,100,100,&m_dc,0,0,SRCCOPY); //显示图1 dc.BitBlt(120,10,100,100,&dcMask,0,0,SRCCOPY); //显示图2 dcImage.SetBkColor(RGB(255,0,0)); dcMask.BitBlt(0,0,100,100,&dcImage,0,0,SRCCOPY); dc.BitBlt(230,10,100,100,&dcMask,0,0,SRCCOPY); //显示图3 dc.BitBlt(340,10,100,100,&dcImage,0,0,SRCCOPY); //显示图4 dcImage.SetBkColor(RGB(0,0,0)); dcImage.SetTextColor(RGB(255,255,255)); dc.BitBlt(450,10,100,100,&dcImage,0,0,SRCCOPY); //显示图5 dcImage.BitBlt(0,0,100,100,&dcMask,0,0,SRCAND); dc.BitBlt(10,120,100,100,&dcImage,0,0,SRCCOPY); //显示图6 dc.BitBlt(120,120,100,100,&dcMask,0,0,SRCCOPY); //显示图7 dc.SetBkColor(RGB(255,255,255)); dc.BitBlt(230,120,100,100,&dcMask,0,0,SRCAND); //显示图8 dc.BitBlt(230,120,100,100,&dcImage,0,0,SRCPAINT); //显示图8 }
m_dc.LoadBitmap(IDB_BITMAP4); //加载原图,就是下面这张,由红,绿,黄组成的,白色的是背景,不算原图
CMemDC dcImage(100,100,&dc);//演示原理中一共用到了三个DC,DC就理解成一张画布,dcImage是一个临时DC,也可以理解成为一张100X100的临时画布,原图没有这么大,所以会露出背景;
CBitmap bmpMask;
CBitmap bmpMask; bmpMask.CreateBitmap(100,100,1,1,NULL); //创建一张单色位图,位图要想看到,必须画在画布上,也就是复制到(BitBlt)DC上 CDC dcMask; dcMask.CreateCompatibleDC(&dc); //创建一张掩码用的画布 dcMask.SelectObject(bmpMask); //把那张单色位图画在画布上 dcImage.BitBlt(0,0,100,100,&m_dc,0,0,SRCCOPY); //m_dc这张画布上的原图COPY到临时画布dcImage上<pre name="code" class="cpp">dc.BitBlt(10,10,100,100,&m_dc,0,0,SRCCOPY); //在最终画布dc上显示原图 dc.BitBlt(120,10,100,100,&dcMask,0,0,SRCCOPY); //在最终画布dc上显示单色掩码位图
dcImage.SetBkColor(RGB(255,0,0)); //把红色设置成dcImage这张画布的背景色,也就是透明色 dcMask.BitBlt(0,0,100,100,&dcImage,0,0,SRCCOPY); //dcImage把自己复制给dcMask时,告诉他红色是背景色,dcMask只能显示两种颜色,所以dcImage上红色的地方变白色,其他地方是黑色 dc.BitBlt(230,10,100,100,&dcMask,0,0,SRCCOPY); //显示dcMask这张画布 dc.BitBlt(340,10,100,100,&dcImage,0,0,SRCCOPY); //显示显示dcImage这张画布
dcImage.SetBkColor(RGB(0,0,0)); //dcImage将黑色设置成背景色 dcImage.SetTextColor(RGB(255,255,255)); dc.BitBlt(450,10,100,100,&dcImage,0,0,SRCCOPY); //显示dcImage
dcImage.BitBlt(0,0,100,100,&dcMask,0,0,SRCAND); //dcImage与dcMask相与,注意此时dcImage的透明色是黑色,所以dcMask中的黑色到了dcImage上就成了透明色 dc.BitBlt(10,120,100,100,&dcImage,0,0,SRCCOPY); //显示dcImage dc.BitBlt(120,120,100,100,&dcMask,0,0,SRCCOPY); //显示dcMask 第一张是原来的dcImage,第二张是dcMask,第三张是相与以后的dcImage
dc.SetBkColor(RGB(255,255,255));<span style="white-space:pre"> </span>//最终画布dc的透明色设置成白色 dc.BitBlt(230,120,100,100,&dcMask,0,0,SRCAND); //dcMask与最终画布相与 dc.BitBlt(230,120,100,100,&dcImage,0,0,SRCPAINT); //dcImage与最终画布相或 第一张是dcMask,第二张是dcImage,第三张是最终效果
标签:
原文地址:http://blog.csdn.net/xiangsimoyinjiu/article/details/51001784