|
|
The following code segment can be used
to copy a portion or full screen in to a HBITMAP GDI object in
visual C++. This code is tested on Visual C++ 6.0
HBITMAP CopyScreenToBitmap(int x1, int y1, int x2, int y2)
{
HDC hScrDC, hMemDC; // screen DC and memory DC
HBITMAP hBitmap, hOldBitmap; // handles to deice-dependent bitmaps
int nX, nY, nX2, nY2; // coordinates of rectangle to grab
int nWidth, nHeight; // DIB width and height
int xScrn, yScrn; // screen resolution
// create a DC for the screen and create
// a memory DC compatible to screen DC
if((hScrDC = CreateDC("DISPLAY", NULL, NULL, NULL))==NULL){
AfxMessageBox("Can not create display DC");
return NULL;
}
if((hMemDC = CreateCompatibleDC(hScrDC))==NULL)
{
AfxMessageBox("Can not create compatible DC");
return NULL;
}
// get points of rectangle to grab
nX = x1;
nY = y1;
nX2 = x2;
nY2 = y2;
// get screen resolution
xScrn = GetDeviceCaps(hScrDC, HORZRES);
yScrn = GetDeviceCaps(hScrDC, VERTRES);
//make sure bitmap rectangle is visible
if (nX < 0)
nX = 0;
if (nY < 0)
nY = 0;
if (nX2 > xScrn)
nX2 = xScrn;
if (nY2 > yScrn)
nY2 = yScrn;
nWidth = nX2 - nX;
nHeight = nY2 - nY;
// create a bitmap compatible with the screen DC
if((hBitmap = CreateCompatibleBitmap(hScrDC, nWidth, nHeight))==NULL)
{
AfxMessageBox("Can not create compatible bitmap");
return NULL;
}
// select new bitmap into memory DC
hOldBitmap = (HBITMAP)SelectObject(hMemDC, hBitmap);
if(hOldBitmap == NULL)
{
AfxMessageBox("Can not select old object");
return NULL;
}
// bitblt screen DC to memory DC
if(!BitBlt(hMemDC, 0, 0, nWidth, nHeight, hScrDC, nX, nY, SRCCOPY))
{
AfxMessageBox("Can not read screen memory");
return NULL;
}
// select old bitmap back into memory DC and get handle to bitmap of
the screen
hBitmap = (HBITMAP)SelectObject(hMemDC, hOldBitmap);
if(hBitmap == NULL)
{
AfxMessageBox("Can not select object");
return NULL;
}
// clean up
DeleteDC(hScrDC);
DeleteDC(hMemDC);
// return handle to the bitmap
return hBitmap;
}
|
|
