CODEWITHSUNDEEP
c++winapi
Tyler Gaona
Tyler Gaona

Reputation: 489

WM_CREATE doesn't seem to be processed in child window

I have a window HWND assignWnd that is a child window of the main window. This window doesn't seem to process the WM_CREATE message. For example, here is the WM_CREATE message within my window procedure.

case WM_CREATE:
    {
        hdc = GetDC(assignWnd);

        GetTextMetrics(assignWnd,&tm);
        cyChar = tm.tmHeight + tm.tmExternalLeading;

        ReleaseDC(assignWnd,hdc);
        return 0;
    }

The variable cyChar is an int and is declared within the window procedure. It is used later in the WM_PAINT message. Whenever I compile the program, I get a run-time error stating that cyChar is being used before it initialized. If I place the above code within the WM_PAINT message however, the program works as expected.

The obvious problem is that I don't want these calls to be made every time the window is painted. I would like these commands (and others later on) to be processed during the WM_CREATE message.

Any explanation as to why the WM_CREATE message is not being processed in this child window be greatly appreciated.

Upvotes: 1

Views: 541

Answers (1)

Jonathan Potter
Jonathan Potter

Reputation: 37122

Presumably cyChar is local to the window procedure. It's not a question of WM_CREATE not being processed, it's that the cyChar you assign in WM_CREATE is not the same cyChar that you use in WM_PAINT. You need to make your variable global or static so that it survives from one call to the window procedure to another.

Upvotes: 1

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