ASSERT(hBmp);
if (hBmp)
{
// Create a memory DC inside which we will scan the bitmap content
HDC hMemDC = CreateCompatibleDC(NULL);
ASSERT(hMemDC);
if (hMemDC)
{
// Get bitmap siz
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);
ASSERT(hbm32);
if (hbm32)
{
HBITMAP holdBmp = (HBITMAP)SelectObject(hMemDC, hbm32);
// Create a DC just to copy the bitmap into the memory DC
HDC hDC = CreateCompatibleDC(hMemDC);
ASSERT(hDC);
if (hDC)
{
// Get how many bytes per row we have for the bitmap bits (rounded up to 32 bits
BITMAP bm32;
VERIFY(GetObject(hbm32, sizeof(bm32), &bm32));
while (bm32.bmWidthBytes % 4)
bm32.bmWidthBytes++;
// Copy the bitmap into the memory DC
HBITMAP holdBmp = (HBITMAP)SelectObject(hDC, hBmp);
cTransparentColor = ::GetPixel(hDC, 0, 0);
TRACE("%d, %d, %d : Color R G B\n",GetRValue(cTransparentColor),
GetGValue(cTransparentColor),
GetBValue(cTransparentColor)
);
VERIFY(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 b
// 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);
// Scan each bitmap row from bottom to top (the bitmap is inverted vertically
BYTE *p32 = (BYTE *)bm32.bmBits + (bm32.bmHeight - 1) * bm32.bmWidthBytes; // go to bottom
for (int y = 0; y < bm.bmHeight; y++)
{
// Scan each bitmap pixel from left to righ
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)
{
if(*p == cTransparentColor)
break;
p++;
x++;
}
if (x > x0) // the first pixel is not transparent color
{
// Add the pixels (x0, y) to (x, y+1) as a new rectangle in the regio
if (pData->rdh.nCount >= maxRects)
{
GlobalUnlock(hData);
maxRects += ALLOC_UNIT;
VERIFY(hData = GlobalReAlloc(hData, sizeof(RGNDATAHEADER) + (sizeof(RECT) * maxRects), GMEM_MOVEABLE));
pData = (RGNDATA *)GlobalLock(hData);
ASSERT(pData);
}
RECT *pr = (RECT *)&pData->Buffer;
SetRect(&pr[pData->rdh.nCount], x0, y, x, y+1);
// follow lines may be never occured
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;
// above lines may be never occured
pData->rdh.nCount++;
// On Windows98, ExtCreateRegion() may fail if the number of rectangles is to
// 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);
ASSERT(h);
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 rectangle
HRGN h = ExtCreateRegion(NULL, sizeof(RGNDATAHEADER) + (sizeof(RECT) * maxRects), pData);
ASSERT(h);
if (hRgn)
{
// AfxMessageBox("Not null");
CombineRgn(hRgn, hRgn, h, RGN_OR);
DeleteObject(h);
}
else
{
// AfxMessageBox("hrgn is null");
hRgn = h;
}
// Clean u
GlobalFree(hData);
SelectObject(hDC, holdBmp);
DeleteDC(hDC);
}