How to make a Win32 control created without WS_VISIBLE visible? - c++

Question

Suppose hCtl is a handle to a control created without the WS_VISIBLE flag such as:
HWND hCtl = CreateWindowEx(0, WC_STATIC, L"some text",
WS_CHILD | SS_NOTIFY, // no WS_VISIBLE flag
0, 0, 0, 0, hWndParent, (HMENU)IDC_STATIC1, g_hInst, 0);
Is there a more straightforward way to make it visible than the following?
void make_visible(HWND hCtl, HWND hWndParent) {
SetWindowLongPtr(hCtl, GWL_STYLE,
GetWindowLongPtr(hCtl, GWL_STYLE) | WS_VISIBLE);
RECT rc{};
GetClientRect(hCtl, &rc);
MapWindowRect(hCtl, hWndParent, &rc);
InvalidateRect(hWndParent, &rc, TRUE);
UpdateWindow(hWndParent);
//ShowWindow(hCtl, SW_SHOW); // no use: does not update window
//SetWindowPos(hCtl, HWND_TOP, 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE | SWP_NOZORDER | SWP_FRAMECHANGED); // no use: does not update window
}

Answer 1

To make a child control visible, call SetWindowPos like this:
SetWindowPos(hCtl, 0, 0, 0, 0, 0,
SWP_NOSIZE | SWP_NOMOVE | SWP_NOZORDER | SWP_NOACTIVATE | SWP_SHOWWINDOW);
Your code to call MapWindowRect, InvalidateRect, UpdateRect etc. should be removed.
Perhaps the real problem you have is that you have created the static control with zero width and height.

Answer 2

The normal way to make a window visible is only the function ShowWindow. There is no need dealing with flags and so on. Usually you use SW_SHOW as a parameter for a child window. Check the other values and use what you think is appropriate.
If the window has a visible rectangle and isn't covered by another window it will show up. Even UpdateWindow calls are not needed. The window will show up in the next paint cycle. If your control has a size of 0,0,0,0 (as it was created) it will never show up.
There is also a ShowWindowAsync function for the use if the window is on a different thread to avoid blocking.
BTW: I don't understand what you try with invalidating the parent window area. If there is a child window clipping (WS_CLIPCHILDREN) it has no effect.

Answer 3

I believe your problem is that you're explicitly setting the WS_VISIBLE style yourself and then calling ShowWindow, which confuses Windows into believing that the window is already visible and doesn't need to be repainted.
Just call ShowWindow. There should be no need to explicitly set WS_VISIBLE yourself because ShowWindow already does it. You should not need to forcibly repaint your control.
Additionally, if you find some need to explicitly invalidate your control, it should be sufficient to just do InvalidateRect(hCtl, NULL) and not bother with GetClientRect and MapWindowRect.