double buffering

[EvIl_DeViL]

hi! i'm trying to make a double buffering to avoid the slow refresh
my code looks like this:

void draw(HDC hdc)
{
	HDC dc = CreateCompatibleDC(hdc);
	HBITMAP hBitmap = CreateCompatibleBitmap (hdc, 400, 240);
	SelectObject(dc, hBitmap);

	/*draw all the stuff on dc*/

	BitBlt(hdc, 0, 0, 400, 240, dc, 0, 0, SRCCOPY);

	ReleaseDC(0, dc);
	DeleteObject(hBitmap);
	DeleteDC(dc);

	return;
}

where the hdc passed is the main hdc.
it draws but the refresh is slow. i know that is a working method because if i comment out BitBlt(hdc, 0, 0, 400, 240, dc, 0, 0, SRCCOPY); i get a black screen...

[hoxsiew]

Your missing the part where "/*draw all the stuff on dc*/" is. That's probably where you're bogging down.

[EvIl_DeViL]

wooo! solved!
good double buffering script bad asking-to-refresh!
i was

InvalidateRect(hWnd, NULL, TRUE);

instead

InvalidateRect(hWnd, NULL, FALSE);
UpdateWindow(hWnd);

well... i think is a good code... feel free to use and give suggestion! (i didn't find something that do this elsewhere o.o)
thanks for reply

p.s. i'm working on windows mobile so this code runs over it too!

[olivthill2]

get a black screen[...]feel free to use and give suggestion!

Just a little suggestion: If you have a message loop, and if you repaint the entire client area of your window, then you don't need Windows to paint a (black in your case) background. So you could write:

      case WM_ERASEBKGND:
         return(1); // Prevent erasing the background to reduce flickering
         break;

[EvIl_DeViL]

I read on msdn to pass FALSE as last parameter when I do:

InvalidateRect(hWnd, NULL, FALSE);

shouldn't this avoid the WM_ERASEBKGND message queuing?