conversion of HICON to ARGB Image - Icon2Image()

[Thomas Arlt]

Here is a function for converting any windows icon to an ARGB Image.
Enjoy.

Thomas Arlt
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Maker of the free google translate client "Transmiti"
http://www.transmiti.org
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Code: Select all

Image* Icon2Image(HICON hIcon)
{
   BITMAP bm;
   ICONINFO iconInfo;
   GetIconInfo(hIcon, &iconInfo);
   GetObject(iconInfo.hbmColor, sizeof(BITMAP),&bm);
   int width = bm.bmWidth;
   int height = bm.bmHeight;
   int bytesPerScanLine = (width * 3 + 3) & 0xFFFFFFFC;
   int size = bytesPerScanLine * height;
   BITMAPINFO infoheader;
   infoheader.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
   infoheader.bmiHeader.biWidth = width;
   infoheader.bmiHeader.biHeight = height;
   infoheader.bmiHeader.biPlanes = 1;
   infoheader.bmiHeader.biBitCount = 24;
   infoheader.bmiHeader.biCompression = BI_RGB;
   infoheader.bmiHeader.biSizeImage = size;
   // allocate Memory for Icon RGB data plus Icon mask plus ARGB buffer for the resulting image
   MemoryBlock* pMemBlock = new MemoryBlock((size*2+height*width*4)*sizeof(uint8));
   uint8* pixelsIconRGB = (uint8*)pMemBlock->getData();
   uint8* alphaPixels    = (uint8*)(pixelsIconRGB+size);
   uint32* imagePixels   = (uint32*)(alphaPixels+size);
   HDC hDC = CreateCompatibleDC(NULL);
   // Get Icon RGB data
   HBITMAP hBmpOld = (HBITMAP)SelectObject(hDC, (HGDIOBJ)iconInfo.hbmColor);
   if(!GetDIBits(hDC, iconInfo.hbmColor, 0, height, (LPVOID) pixelsIconRGB, &infoheader, DIB_RGB_COLORS))
      return NULL;
   SelectObject(hDC, hBmpOld);
   // now get the mask
   if(!GetDIBits(hDC, iconInfo.hbmMask, 0,height,(LPVOID)alphaPixels, &infoheader, DIB_RGB_COLORS))
      return NULL;
   int x=0;
   int currentSrcPos=0;
   int currentDestPos=0;
   int linePosSrc = 0;
   int linePosDest = 0;
   int lsSrc = width*3;
   int vsDest = height-1;
   for(int y=0; y<height; y++)
   {
      linePosSrc = (vsDest-y)*lsSrc;
      linePosDest = y*width;
      for(x=0; x<width; x++)
      {
         //pixels from Icon are stored in BGR vertical and horizontal flipped order
         currentDestPos = linePosDest+x;
         currentSrcPos  = linePosSrc+x*3;
         // BGR -> ARGB
         imagePixels[currentDestPos]=(((uint32)((((pixelsIconRGB[currentSrcPos+2] << 0x10 /*Red*/) | (pixelsIconRGB[currentSrcPos+1] << 8 /*Green*/))
            | pixelsIconRGB[currentSrcPos] /*Blue*/) | ((alphaPixels[currentSrcPos]?0:255) << 0x18))) & 0xffffffffL);
      }
   }
   Image *pImage = new Image(Image::ARGB, width, height,true);
   pImage->setPixelData (0, 0, width, height, (uint8*)imagePixels, width*4);
   deleteAndNull(pMemBlock)
   DeleteDC(hDC);
   return pImage;
}

[jules]

Thanks Thomas!

Just one thing to note though - its return type should be a const Image, not an Image*. Images are designed to be pass-by-value these days.