winapi window doesn't refresh after painting

Question

Hi I created a window with this:

WNDCLASSEX WndClass = {0};

if (WndClass.cbSize == 0)
{
    WndClass.cbSize = sizeof(WNDCLASSEX);
    WndClass.style = CS_DBLCLKS;
    WndClass.lpfnWndProc = WindowProcedure;
    WndClass.cbClsExtra = 0;
    WndClass.cbWndExtra = 0;
    WndClass.hInstance = GetModuleHandle(NULL);
    WndClass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    WndClass.hCursor = LoadCursor(NULL, IDC_ARROW);
    WndClass.hbrBackground = HBRUSH(COLOR_WINDOW+1);
    WndClass.lpszMenuName = NULL;
    WndClass.lpszClassName = ClassName.c_str();
    WndClass.hIconSm = LoadIcon( NULL, IDI_APPLICATION);
}

if (RegisterClassEx(&WndClass))
{

    WindowHandle = CreateWindowEx(0, ClassName.c_str(), WindowName.c_str(), WS_OVERLAPPEDWINDOW | WS_VSCROLL | WS_HSCROLL,
        CW_USEDEFAULT, CW_USEDEFAULT, Width, Height, NULL, NULL, GetModuleHandle(NULL), NULL);
    if(WindowHandle)
    {
        ShowWindow(WindowHandle, SW_SHOWDEFAULT);
    }
}

And try to add a button. Use this:

HWND child = CreateWindowEx(0, L"BUTTON", NULL, WS_CHILD | WS_VISIBLE, n * CHILDS_OFSET, posY, GetWidth(), h, window, NULL, NULL, NULL);

After code executed my window stays clear, but if I move it or resize it, button becomes visible, what the issue might be?

I tried:

RECT rc;
GetClientRect(window, &rc);
InvalidateRect(window, &rc, TRUE);

Tried if window is handle to the main window and to the button.

Answer 1

This could happen if your window procedure does not handle WM_PAINT properly. The minimum thing you must have is

...
    case WM_PAINT:
    {
        PAINTSTRUCT ps;
        BeginPaint( wnd, &ps );
        EndPaint( wnd, &ps );
        return 0;
    }

Answer 2

我认为您需要在ShowWindow之后调用UpdateWindow ，请参见此处 。