Win32 - how delete some Region points?

Question

i have 1 Region:
HRGN hRgn = CreateRectRgn(0,0,wBmpWidth,wBmpHeight);
heres how i remove some points:
if (pixelcolor==backcolor)
SetWindowText(ActivatedForm,"match");
// remove transparent color from region
hTmpRgn = CreateRectRgn(x,y,x+1,y+1);
CombineRgn(hRgn, hRgn, hTmpRgn, RGN_XOR);
DeleteObject(hTmpRgn);
i belive that the CombineRgn() isn't right, because the points aren't removed :(
what can advice me?

Answer 1

finally it's working:
BYTE* Get24BitPixels(HBITMAP pBitmap, WORD *pwWidth, WORD *pwHeight)
// a bitmap object just to get bitmap width and height
BITMAP bmpBmp;
// pointer to original bitmap info
LPBITMAPINFO pbmiInfo;
// bitmap info will hold the new 24bit bitmap info
BITMAPINFO bmiInfo;
// width and height of the bitmap
WORD wBmpWidth, wBmpHeight;
// get some info from the bitmap
GetObject(pBitmap, sizeof(bmpBmp),&bmpBmp);
pbmiInfo = (LPBITMAPINFO)&bmpBmp;
// get width and height
wBmpWidth = (WORD)pbmiInfo->bmiHeader.biWidth;
wBmpWidth -= (wBmpWidth%4); // width is 4 byte boundary aligned.
wBmpHeight = (WORD)pbmiInfo->bmiHeader.biHeight;
// copy to caller width and height parms
*pwWidth = wBmpWidth;
*pwHeight = wBmpHeight;
// allocate width * height * 24bits pixels
BYTE *pPixels = new BYTE[wBmpWidth*wBmpHeight*3];
if (!pPixels) return NULL;
// get user desktop device context to get pixels from
HDC hDC = GetWindowDC(NULL);
// fill desired structure
bmiInfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
bmiInfo.bmiHeader.biWidth = wBmpWidth;
bmiInfo.bmiHeader.biHeight = -wBmpHeight;
bmiInfo.bmiHeader.biPlanes = 1;
bmiInfo.bmiHeader.biBitCount = 24;
bmiInfo.bmiHeader.biCompression = BI_RGB;
bmiInfo.bmiHeader.biSizeImage = wBmpWidth*wBmpHeight*3;
bmiInfo.bmiHeader.biXPelsPerMeter = 0;
bmiInfo.bmiHeader.biYPelsPerMeter = 0;
bmiInfo.bmiHeader.biClrUsed = 0;
bmiInfo.bmiHeader.biClrImportant = 0;
// get pixels from the original bitmap converted to 24bits
int iRes = GetDIBits(hDC,pBitmap,0,wBmpHeight,(LPVOID)pPixels,&bmiInfo,DIB_RGB_COLORS);
// release the device context
ReleaseDC(NULL,hDC);
// if failed, cancel the operation.
if (!iRes)
delete pPixels;
return NULL;
// return the pixel array
return pPixels;
HRGN ScanRegion(HBITMAP pBitmap,COLORREF clrTransparent )
BYTE jTranspR = GetRValue(clrTransparent), jTranspG=GetGValue(clrTransparent), jTranspB=GetBValue(clrTransparent);
// bitmap width and height
WORD wBmpWidth,wBmpHeight;
// the final region and a temporary region
HRGN hRgn, hTmpRgn;
// 24bit pixels from the bitmap
BYTE *pPixels = Get24BitPixels(pBitmap, &wBmpWidth, &wBmpHeight);
if (!pPixels) return NULL;
// create our working region
hRgn = CreateRectRgn(0,0,wBmpWidth,wBmpHeight);
if (!hRgn) { delete pPixels; return NULL; }
// scan the bitmap
DWORD p=0;
for (WORD y=0; y<wBmpHeight; y++)
for (WORD x=0; x<wBmpWidth; x++)
BYTE jRed = pPixels[p+2];
BYTE jGreen = pPixels[p+1];
BYTE jBlue = pPixels[p+0];
if ((jRed == jTranspR && jGreen == jTranspG && jBlue == jTranspB))
// remove transparent color from region
hTmpRgn = CreateRectRgn(x,y,x+1,y+1);
CombineRgn(hRgn, hRgn, hTmpRgn, RGN_XOR);
DeleteObject(hTmpRgn);
// next pixel
p+=3;
// release pixels
delete pPixels;
// return the region
return hRgn;
if(inst->blnTransparent==true)
TransparentBlt(test.hdc,0,0,imglabel.width(),imglabel.height(),imglabel,0,0, imglabel.width(),imglabel.height(), inst->clrBackColor);
inst->LabelRegion=ScanRegion(imglabel, inst->clrBackColor);
SetWindowRgn(inst->hwnd,inst->LabelRegion,TRUE);
else
SetWindowRgn(inst->hwnd,NULL,TRUE);
BitBlt(test.hdc,0,0,imglabel.width(),imglabel.height(),imglabel,0,0,SRCCOPY);
inst is the subclass pointer;
imglabel is the image class object.
maybe you can't see the diference... sorry. but works fine now.
thanks for all