CResizeWnd, Handle a Dialog Resizing Without Dialog Border

• Download demo - 159.4 KB
• Download source - 3.1 KB

Introduction

Sometimes, I need a custom dialog without the default border or a caption, but the dialog can't be resized without the style "WS_CAPTION" or "DS_MODALFRAME". So I try to use a transparent window to cover on the custom dialog and control the resizing behavior, that's CResizeWnd.

Using the Code

To use CResizeWnd, just declare CResizeWnd as a member in the dialog.

private:
    CResizeWnd    m_WndResize;

Then, create it at the create time, and send pointer this as parent.

int CResizeWndDemoDlg::OnCreate(LPCREATESTRUCT lpCreateStruct) 
{
    if (CDialog::OnCreate(lpCreateStruct) == -1)
        return -1;

    m_WndResize.Create(this);
    m_WndResize.ShowWindow(SW_SHOW);

    return 0;
}

And remember to fit CResizeWnd to the dialog everytime after it changes size. It will usually be OnInitDialog(), OnSize() and OnMove(). Call SetWindowPos() with the "SWP_NOACTIVATE" to avoid CResizeWnd took dialog focus.

BOOL CResizeWndDemoDlg::OnInitDialog()
{
   ....
   ....
   .... 

   CRect rcWindow;
    GetWindowRect(&rcWindow);
    m_WndResize.SetWindowPos(&wndNoTopMost, rcWindow.left, 
        rcWindow.top, rcWindow.Width(), rcWindow.Height(), SWP_NOACTIVATE);

    return TRUE;  // return TRUE  unless you set the focus to a control
}

void CResizeWndDemoDlg::OnSize(UINT nType, int cx, int cy) 
{
    CRect rcWindow;
    GetWindowRect(&rcWindow);
    m_WndResize.SetWindowPos(&wndNoTopMost, rcWindow.left, 
        rcWindow.top, rcWindow.Width(), rcWindow.Height(), SWP_NOACTIVATE);
}

void CResizeWndDemoDlg::OnMove(int x, int y)
{
    CRect rcWindow;
    GetWindowRect(&rcWindow);
    m_WndResize.SetWindowPos(&wndNoTopMost, rcWindow.left, 
        rcWindow.top, rcWindow.Width(), rcWindow.Height(), SWP_NOACTIVATE);
}

That is very easy to use. And there is a demo in the download list, I left it in a very beginning look from a new MFC project. Hope it will be easier to understand how to make it work.

History

• 2014-12-22: First published