HRGN BitmapToRegion (HBITMAP hBmp, COLORREF cTransparentColor , COLORREF cTolerance  ){	HRGN hRgn = NULL;	if (hBmp)	{		// Create a memory DC inside which we will scan the bitmap content		HDC hMemDC = CreateCompatibleDC(NULL);		if (hMemDC)		{			// Get bitmap size			BITMAP bm;			GetObject(hBmp, sizeof(bm), &bm);			// Create a 32 bits depth bitmap and select it into the memory DC 			BITMAPINFOHEADER RGB32BITSBITMAPINFO = {						sizeof(BITMAPINFOHEADER),	// biSize 					bm.bmWidth,					// biWidth; 					bm.bmHeight,				// biHeight; 					1,							// biPlanes; 					32,							// biBitCount 					BI_RGB,						// biCompression; 					0,							// biSizeImage; 					0,							// biXPelsPerMeter; 					0,							// biYPelsPerMeter; 					0,							// biClrUsed; 					0							// biClrImportant; 			};			VOID * pbits32; 			HBITMAP hbm32 = CreateDIBSection(hMemDC, (BITMAPINFO *)&RGB32BITSBITMAPINFO, DIB_RGB_COLORS, &pbits32, NULL, 0);			if (hbm32)			{				HBITMAP holdBmp = (HBITMAP)SelectObject(hMemDC, hbm32);				// Create a DC just to copy the bitmap into the memory DC				HDC hDC = CreateCompatibleDC(hMemDC);				if (hDC)				{					// Get how many bytes per row we have for the bitmap bits (rounded up to 32 bits)					BITMAP bm32;					GetObject(hbm32, sizeof(bm32), &bm32);					while (bm32.bmWidthBytes % 4)						bm32.bmWidthBytes++;					// Copy the bitmap into the memory DC					HBITMAP holdBmp = (HBITMAP)SelectObject(hDC, hBmp);					BitBlt(hMemDC, 0, 0, bm.bmWidth, bm.bmHeight, hDC, 0, 0, SRCCOPY);					// For better performances, we will use the ExtCreateRegion() function to create the					// region. This function take a RGNDATA structure on entry. We will add rectangles by					// amount of ALLOC_UNIT number in this structure.					#define ALLOC_UNIT	100					DWORD maxRects = ALLOC_UNIT;					HANDLE hData = GlobalAlloc(GMEM_MOVEABLE, sizeof(RGNDATAHEADER) + (sizeof(RECT) * maxRects));					RGNDATA *pData = (RGNDATA *)GlobalLock(hData);					pData->rdh.dwSize = sizeof(RGNDATAHEADER);					pData->rdh.iType = RDH_RECTANGLES;					pData->rdh.nCount = pData->rdh.nRgnSize = 0;					SetRect(&pData->rdh.rcBound, MAXLONG, MAXLONG, 0, 0);					// Keep on hand highest and lowest values for the "transparent" pixels					BYTE lr = GetRValue(cTransparentColor);					BYTE lg = GetGValue(cTransparentColor);					BYTE lb = GetBValue(cTransparentColor);					BYTE hr = min(0xff, lr + GetRValue(cTolerance));					BYTE hg = min(0xff, lg + GetGValue(cTolerance));					BYTE hb = min(0xff, lb + GetBValue(cTolerance));					// Scan each bitmap row from bottom to top (the bitmap is inverted vertically)					BYTE *p32 = (BYTE *)bm32.bmBits + (bm32.bmHeight - 1) * bm32.bmWidthBytes;					for (int y = 0; y < bm.bmHeight; y++)					{						// Scan each bitmap pixel from left to right						for (int x = 0; x < bm.bmWidth; x++)						{							// Search for a continuous range of "non transparent pixels"							int x0 = x;							LONG *p = (LONG *)p32 + x;							while (x < bm.bmWidth)							{								BYTE b = ((RGBQUAD *) p)->rgbRed; // GetRValue(*p);								if (b >= lr && b <= hr)								{									b = ((RGBQUAD *) p)->rgbGreen; // GetGValue(*p);									if (b >= lg && b <= hg)									{										b = ((RGBQUAD *) p)->rgbBlue ;  // GetBValue(*p);										if (b >= lb && b <= hb)											// This pixel is "transparent"											break;									}								}								p++;								x++;							}							if (x > x0)							{								// Add the pixels (x0, y) to (x, y+1) as a new rectangle in the region								if (pData->rdh.nCount >= maxRects)								{									GlobalUnlock(hData);									maxRects += ALLOC_UNIT;									hData = GlobalReAlloc(hData, sizeof(RGNDATAHEADER) + (sizeof(RECT) * maxRects), GMEM_MOVEABLE);									pData = (RGNDATA *)GlobalLock(hData);								}								RECT *pr = (RECT *)&pData->Buffer;								SetRect(&pr[pData->rdh.nCount], x0, y, x, y+1);								if (x0 < pData->rdh.rcBound.left)									pData->rdh.rcBound.left = x0;								if (y < pData->rdh.rcBound.top)									pData->rdh.rcBound.top = y;								if (x > pData->rdh.rcBound.right)									pData->rdh.rcBound.right = x;								if (y+1 > pData->rdh.rcBound.bottom)									pData->rdh.rcBound.bottom = y+1;								pData->rdh.nCount++;								// On Windows98, ExtCreateRegion() may fail if the number of rectangles is too								// large (ie: > 4000). Therefore, we have to create the region by multiple steps.								if (pData->rdh.nCount == 2000)								{									HRGN h = ExtCreateRegion(NULL, sizeof(RGNDATAHEADER) + (sizeof(RECT) * maxRects), pData);									if (hRgn)									{										CombineRgn(hRgn, hRgn, h, RGN_OR);										DeleteObject(h);									}									else										hRgn = h;									pData->rdh.nCount = 0;									SetRect(&pData->rdh.rcBound, MAXLONG, MAXLONG, 0, 0);								}							}						}						// Go to next row (remember, the bitmap is inverted vertically)						p32 -= bm32.bmWidthBytes;					}					// Create or extend the region with the remaining rectangles					HRGN h = ExtCreateRegion(NULL, sizeof(RGNDATAHEADER) + (sizeof(RECT) * maxRects), pData);					if (hRgn)					{						CombineRgn(hRgn, hRgn, h, RGN_OR);						DeleteObject(h);					}					else						hRgn = h;					// Clean up					SelectObject(hDC, holdBmp);					DeleteDC(hDC);				}				DeleteObject(SelectObject(hMemDC, holdBmp));			}			DeleteDC(hMemDC);		}		}	return hRgn;}