Thread: Trouble getting snapshot of screen :(

Hey guys, I have a problem with my DirectDraw code. I'm trying to make a function that gets a snapshot of the screen, which can be later used to redraw the screen. I'm having troubles though, not sure exactly what. My function code is below (slightly modified, but not significantly).

Code:

//sfcFront and sfcBack are the front and back buffers of the screen.
IDirectDrawSurface7* GFX::getSnapshot(bool frontBuffer)
{
	IDirectDrawSurface7* surface;

	DDSURFACEDESC2 ddsd; //originally was class variable
	memset(&ddsd, 0, sizeof(ddsd));
	ddsd.dwSize = sizeof(ddsd);
	ddsd.dwFlags = DDSD_CAPS | DDSD_WIDTH | DDSD_HEIGHT;
	ddsd.ddsCaps.dwCaps = DDSCAPS_OFFSCREENPLAIN;
	ddsd.dwWidth = scrnRect.right;
	ddsd.dwHeight = scrnRect.bottom;

	//ddBltFx is a class variable of GFX.
	ddBltFx.dwSize = sizeof(ddBltFx);

	//lpdd is the DirectDraw interface/object thinger
	if(FAILED(lpdd->CreateSurface(&ddsd, &surface, NULL)))
		return NULL;

	if(frontBuffer)
	{
		if(FAILED(surface->Blt(NULL, sfcFront, NULL, DDBLT_WAIT, &ddBltFx)))
			return NULL;
	}
	else
	{
		if(FAILED(surface->Blt(NULL, sfcBack, NULL, DDBLT_WAIT, &ddBltFx)))
			return NULL;
	}

	return surface;
}

I have tested the return values, and it was never NULL. It's just that whenever I try blitting the returned surface, it doesn't blit the original screen. Can anybody see any errors in the code that I missed?

Why are you using DDSCAPS_OFFSCREENPLAIN in the DDCAPS structure?

Try DDSCAPS_PRIMARYSURFACE.

Hmm, I thought DDSCAPS_PRIMARYSURFACE meant that it was the actual screen (i.e. what gets blitted to that gets shown on the screen)? I used offscreenplain because it's supposed to be... off of the screen Am I wrong about this?