CODEWITHSUNDEEP
c++winapi
georgeT
georgeT

Reputation: 11

Changing the style of a window from standard to not having a title bar and back

I am writing an APP (c++, win32 ) where I want to create the main window as a) a standard one, or b) without a title bar but resizable/movable and I want to switch between the two styles at run time.

I am using the following code to create the window :

bool   bare        = false ;
DWORD  style_bare  = WS_POPUP  | WS_SIZEBOX | WS_THICKFRAME ;
DWORD  style_std   = WS_OVERLAPPEDWINDOW     ;
DWORD  win_style   = bare ? style_bare : style_std ;
DWORD  win_exstyle = WS_EX_ACCEPTFILES | WS_EX_CLIENTEDGE | WS_EX_APPWINDOW;
...
HWND main = CreateWindowEx( win_exstyle ,  className , applName ,  win_style,  x, y, cx, cy, NULL, NULL, hInstance, NULL);

and later, in the MainWndProc(), to change the style 

bare = ! bare ;
if ( bare ) 
    SetWindowLongPtr( hwnd , GWL_STYLE,   style_bare ) ;
else 
    SetWindowLongPtr( hwnd , GWL_STYLE,   style_std  ) ;
InvalidateRect( hwnd, NULL , TRUE ) ;

and while in 'bare' mode I handle the WM_NCHITEST message which makes the bare window movable, as follows:

   if ( bare && WM_NCHITTEST == message )
   {
        LRESULT rc = DefWindowProc( hwnd, message, wParam, lParam ) ;
        if ( HTCLIENT  == rc ) return HTCAPTION  ;
        return rc ;
  }

The code works fine when I create the window in either mode, but when I switch mode the window is drawn as expected, but is not "selectable"... When I click on it, it moves behind all windows that might be there, and when I close all windows to find my APP and click on it, icons from the desktop are selected.

What I am missing ...

Upvotes: 0

Views: 842

Answers (1)

Drake Wu
Drake Wu

Reputation: 7170

Don't forget to call SetWindowPos when using SetWindowLongPtr to change the window frame. Your SetWindowLongPtr sets a value of window frame at the specified offset in the extra window memory. And the information of frame changing is cached. SetWindowPos will make it effective.

bare = !bare;
if (bare)
    SetWindowLongPtr(hwnd, GWL_STYLE, style_bare);
else
    SetWindowLongPtr(hwnd, GWL_STYLE, style_std);
SetWindowPos(hwnd,0,0,0,0,0, SWP_FRAMECHANGED| SWP_NOMOVE| SWP_NOOWNERZORDER| SWP_NOSIZE| SWP_NOZORDER| SWP_SHOWWINDOW);
InvalidateRect(hWnd, NULL, TRUE);

Upvotes: 1

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