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How to move a window w/o caption bar?

asker
asker asked
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Last Modified: 2013-11-20
Hi:

I have a window without decorations (border and caption bar), only the client area. As a reaction on some user action (say, double click) I want to switch into move window mode. I tried PostMessage( WM_SYSCOMMAND, SC_MOVE, 0 ) and it works: cursor changes and the frame appears, but the window is not moved when I drag it.

I have found that it is by design: even if the window has a caption bar, it can be dragged only by the caption bar (you may try it on any window).

Does anybody how to change this and allow dragging from the client area?

Regards,
Asker.
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Hi Asker,
   I am sorry that I could not give you a tried working solution.But immediately all that I can think of is: Just try to override "OnMouseMove()" (WM_MOUSEMOVE message) function to get the units by which you have dragged the mouse on the window.Then add this much to the present windows coordinates and then do MoveWindow() or SetWindowPos().I am not sure if this will be satisfactory.There my be a flickering.But you can give it a try.

Bye!
Amaresh

Author

Commented:
I would not want that my window be always dragged as a whole (full drag).
Frankly speaking, I understand that there may be different approaches to implement move mode manually. What I am trying to do is to use the internal Windows possibilities (move mode).
Tommy HuiEngineer

Commented:
Try maintaining a flag that says whether or not the window is in move mode. Then in that window catch the WM_NCHITTEST message. If you're in the move mode, return HT_CAPTION. If not, return the base class behavior:

  CMyWindow::OnNcHitTest(CPoint point)
  {
    if (m_InMoveMode)
      return HT_CAPTION;
    else
      return CWnd::OnNcHitTest(point);
   }

Of course, you will need to turn on m_InMoveMode when the user double clicks (WM_LBUTTONDBLCLK). Also, you will need to catch WM_NCLBUTTONDOWN to turn off m_InMoveMode.

Author

Commented:
Hi, Thui:

I initiate the move mode by posting WM_SYSCOMMAND with SC_MOVE. The WM_NCHITTEST message is not sent to the window being moved after I've posted WM_SYSCOMMAND (I checked it with Spy++, you may also check this if you try Spy++ on any window, just select Move item from the system menu).
Engineer
Commented:
No, don't initiate the move mode by posting WM_SYSCOMMAND. As I mentioned, you need to handle the move mode yourself.

The WM_SYSCOMMAND message is posted to enable the window to go into a modal loop where the tracking of the mouse can occur. However, a keystroke must be hit before the tracking of the mouse can be enabled. So after posting the WM_SYSCOMMAND, try posting a WM_KEYUP and WM_KEYDOWN message immediately after and see what happens.

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Author

Commented:
Yes, this sequence lead to the success:

      PostMessage( WM_SYSCOMMAND, SC_MOVE, 0 );
      PostMessage( WM_KEYDOWN, VK_LEFT, 0 );
      PostMessage( WM_KEYUP, VK_LEFT, 0 );
      PostMessage( WM_KEYDOWN, VK_RIGHT, 0 );
      PostMessage( WM_KEYUP, VK_RIGHT, 0 );

Thank you!

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