画透明背景

来源：互联网发布：淘宝分销不好做编辑：程序博客网时间：2024/05/21 07:14

void CToumingbmpView::OnIamgeCircle()
{
// TODO: Add your command handler code here
CDC *pDC=GetDC();

//以下为叠加图层代码
CDC *dcImage,*dcMask;
dcImage=new CDC;
dcMask=new CDC;
CRect rect;
GetClientRect(&rect);
int nWidth=rect.Width(),nHeight=rect.Height();
//COLORREF srcbkcolor=pDC->GetBkColor();
CBitmap *lineimage=new CBitmap;
dcImage->CreateCompatibleDC(pDC);

lineimage->CreateCompatibleBitmap(pDC,nWidth,nHeight);
OnPrepareDC(dcImage,NULL);
CBrush brushBkColor;
brushBkColor.CreateSolidBrush(RGB(255,255,255));
CBitmap* pOldBitmapImage=dcImage->SelectObject(lineimage);
dcImage->FillRect(rect,&brushBkColor);//填充位图数据,默认为白色
//dcImage->SetBkColor(RGB(255,255,255));
dcImage->Ellipse(CRect(120,120,200,200));

//pDC->BitBlt(0, 0, nWidth, nHeight, dcImage, 0, 0, SRCCOPY);

dcImage->SetBkColor(RGB(255,255,255));//设置透明色

dcMask->CreateCompatibleDC(pDC);
OnPrepareDC(dcMask,NULL);
CBitmap bitmapMask; //掩码位图
bitmapMask.CreateBitmap(nWidth, nHeight, 1, 1, NULL);
CBitmap* pOldBitmapMask = dcMask->SelectObject(&bitmapMask);

dcMask->BitBlt(0, 0, nWidth, nHeight, dcImage, 0, 0, SRCCOPY);//分3步进行实际的绘
    pDC->BitBlt(0, 0, nWidth, nHeight, dcImage, 0, 0, SRCINVERT); //原图像数据和目标数据异或
    pDC->BitBlt(0, 0, nWidth, nHeight, dcMask, 0, 0, SRCAND);   //原图像数据和目标数据相与
    pDC->BitBlt(0, 0, nWidth, nHeight, dcImage, 0, 0, SRCINVERT); //恢复原先设置
    dcImage->SelectObject(pOldBitmapImage);
    dcMask->SelectObject(pOldBitmapMask);
ReleaseDC(dcImage);
ReleaseDC(dcMask);
}