Capture .bmp from hidden desktop

Question

Hi , I'm trying to capture a desktop created with the "CreateDesktop" methode.
But I have some problems. I only get the capture .bmp from the desktop, when
it is active. This desktop runs on vm,and I connect to it through remote desktop.
Well, as I said, I only get the bitmap of the desktop when the vm is open. When I mnimize
or close the remote desktop connection, I dont get any bmp from the desktop.
For me is important,because the machine were the vm runs,doesnt have any monitor
to display the desktop.I only want to make this vm to stream its desktop to other computers,
but the vm wont have any monitor.
Is there the posibility to set the desktop as active, or to get the bitmap of the desktop from somewhere else ?
Thank you

Answer 1

Well, I was passing the wrong DC to the PrintWindow function (the one which I retrieved by using GetWindowDC) and then tried to BitBlt it to the memory DC. But the right solution is to get window DC using GetWindowDC then create compatible DC and PrintWindow
to it and not use BitBlt on that stage at all.
Following is a right approach:
// Some code where you get appropriate HWD
HDC wndDc = GetWindowDC(hwnd);
HDC memDc = CreateCompatibleDC(wndDc);
CRect rc;
GetWindowRect(hwnd, &rc);
HBITMAP memBmp = CreateCompatibleBitmap(wndDc, rc.Width(), rc.Height());
HBITMAP oldBmp = reinterpret_cast<HBITMAP>(SelectObject(memDc, memBmp));
// Print window to the memory DC.
PrintWindow(hwnd, memDc, 0);
// Here you can use memDc of the window
// (e.g. BitBlt it to the DC of the merged desktop screen)
DeleteObject(memBmp);
DeleteDC(wndDc);SelectObject(memDc, oldBmp);
DeleteDC(memDc);