Thread: Why UpdateWindow() after ShowWindow()?

  1. #1
    the Corvetter
    Join Date
    Sep 2001

    Why UpdateWindow() after ShowWindow()?

    In WinMain after you CreateWindow, there is:
    ShowWindow(hwnd, nCmdShow);
    I wasn't sure why UpdateWindow was there, so I temporarily took it out and the program did the same exact thing.

    Can somebody explain this? I realize what UpdateWindow does (If there is an invalid region on the client area and UpdateWindow is called, then a WM_PAINT message bypasses the message queue and the WndProc proccesses the WM_PAINT message).


    1978 Silver Anniversary Corvette

  2. #2
    Skunkmeister Stoned_Coder's Avatar
    Join Date
    Aug 2001
    ShowWindow() only sets the "show-state". It doesn't actually force a painting so we do that by calling UpdateWindow() which forces the window to be painted.
    Free the weed!! Class B to class C is not good enough!!
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  3. #3
    Just one more wrong move. -KEN-'s Avatar
    Join Date
    Aug 2001
    exactly, so if you had to draw buttons or something on your window and you didn't have UpdateWindow() in there, you would have to force a repaint by dragging the window/minimizing it, etc. you could probably replace that with SendMessage(hwnd, WM_PAINT, 0, 0);

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