A simple way to make a dialog “dragable” without using Title Bar





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Mar 30, 2004
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A simple way to make a dialog “dragable” without using Title Bar
Introduction
I often make dialogs in my projects in random shapes. This will make the dialog’s title bar missing, or actually, I miss it in purpose (he he). By default, a dialog can only be moved by dragging the mouse on the title bar. But what will you do if you don’t have any title bar? This short article will show you how.
How It Works
If we don’t have any client
windows in our dialog, we can simply use OnMouseMove
function which will
receive the WM_MOUSEMOVE
from the system. But in this article, I assume that
the dialog is filled with many controls, and because of that, the OnMouseMove
function cannot be used.
Then, what’s the solution?
Since usually, the cursor is within the dialog itself in order to move it, I
chose to block the message before it reached the child. Then if the message has
fulfill the condition (that is: mouse pressed, then
mouse moved), the window position should change. So, we can then use the PreTranslateMessage(..)
to do this. Just filter the
necessary message, do something with it, and it’s done.
Note: for some controls, the method I used is not very friendly. So, just modify it as you need. This can easily be done by retrieving the control’s rectangle, and do some necessary filters by checking the current cursor position (is it within the rectangle? Or not?) so that it won’t reach the main code (that will move the window).
A very simple code
Here is the code I used to make a dialog dragable.
BOOL CYourClassDlg::PreTranslateMessage(MSG* pMsg) { //The code starts here static bool mouse_down = false; static CRect MainRect; static HCURSOR cursor; // use this if you want the // “dragging” cursor different from the normal one static CPoint point; switch(pMsg->message) { case WM_LBUTTONDOWN: //save current dialog’s rectangle GetWindowRect(&MainRect); //save current cursor coordinate point = pMsg->pt; ScreenToClient(&point); //change the sign mouse_down = true; cursor = ::AfxGetApp()->LoadCursor(IDC_CURSOR1); break; case WM_LBUTTONUP: //stop the sign mouse_down = false; //gimme a standard cursor now!! cursor = ::AfxGetApp()->LoadStandardCursor(IDC_ARROW); break; case WM_MOUSEMOVE : cursor = ::AfxGetApp()->LoadStandardCursor(IDC_ARROW); if(mouse_down) { //if here, then the mouse is dragging cursor = ::AfxGetApp()->LoadCursor(IDC_CURSOR1); //finally, move the window MoveWindow( pMsg->pt.x - point.x, //count the relative position pMsg->pt.y - point.y, MainRect.Width(), //if the width doesn’t change MainRect.Height(), //if the height doesn’t change TRUE); } } SetCursor(cursor); //The code ends here return CDialog::PreTranslateMessage(pMsg); }
That’s it. That’s the only code you need to add to your project. I Hope this is useful.