使位图透明

(GDI)----------------------------------------------------  

CPaintDC dc(this);
  CBitmap FootballBMP;
  FootballBMP.LoadBitmap(IDB_FOOTBALLBMP);
  CDC ImageDC;
  ImageDC.CreateCompatibleDC(&dc);
  CBitmap *pOldImageBMP = ImageDC.SelectObject(&FootballBMP);
  TransparentBlt(dc.m_hDC, 0, 0, 218, 199, ImageDC.m_hDC, 0, 0, 218, 199, RGB(0xff,0xff,0xff));
  ImageDC.SelectObject(pOldImageBMP);

 

(GDI+ )----------------------------------------------------  

void CTestGdiDlg::DrawPNG()
{
 CDC *pDC = GetDC();
 Graphics graph(pDC->m_hDC);
 ImageAttributes imAtt;
 int n1 = 20;
 int n2 = 255;//最重要的就是调整这两数
 imAtt.SetColorKey(Color(n1,n1,n1),Color(n2,n2,n2),ColorAdjustTypeDefault);
 graph.SetSmoothingMode(SmoothingModeAntiAlias);
 Image imageBlue(L"a.png");
 graph.DrawImage(&imageBlue,Rect(0,0,300,300),0,0,200,200,UnitPixel,&imAtt);
}

（GetEncoderClsid）--------------------------------------------------------

INT CTestGdiDlg::GetEncoderClsid(const   WCHAR*   format,   CLSID*   pClsid)
{
 UINT     num   =   0;                     //   number   of   image   encoders
 UINT     size   =   0;                   //   size   of   the   image   encoder   array   in   bytes
 ImageCodecInfo*   pImageCodecInfo   =   NULL;
 GetImageEncodersSize(&num,   &size);
 if(size   ==   0)
  return   -1;     //   Failure
 pImageCodecInfo   =   (ImageCodecInfo*)(malloc(size));
 if(pImageCodecInfo   ==   NULL)
  return   -1;     //   Failure
 GetImageEncoders(num,   size,   pImageCodecInfo);
 for(UINT   j   =   0;   j   <   num;   ++j)
 {
  if(   wcscmp(pImageCodecInfo[j].MimeType,   format)   ==   0   )
  {
   *pClsid   =   pImageCodecInfo[j].Clsid;
   free(pImageCodecInfo);
   return   j;     //   Success
  }        
 }
 free(pImageCodecInfo);
 return   -1;     //   Failure
}