Using ESC to cancel drag and drop


To escape out of a drag and drop operation we can look for the ESCAPE key in the PreTranslateMessage() and terminate the operation without moving any item..
 

BOOL CTreeCtrlX::PreTranslateMessage(MSG* pMsg)
{
	if( pMsg->message == WM_KEYDOWN && pMsg->wParam == VK_ESCAPE 
					&& m_bLDragging)
	{
		m_bLDragging = 0;
		CImageList::DragLeave(NULL);
		CImageList::EndDrag();
		ReleaseCapture();
		SelectDropTarget(NULL);
		delete m_pDragImage;
		return TRUE;		// DO NOT process further
	}

	return CTreeCtrl::PreTranslateMessage(pMsg);
}

There is one more thing you need to for this to work properly - call SetFocus() in your WM_LBUTTONDOWN handler. If the control doesn't already have focus when the user begins the drag and drop operation, then the control doesn't receive focus and if the control doesn't have the focus, it doesn't receive the WM_KEYDOWN message.



Comments

  • ignore other keys

    Posted by Legacy on 04/22/2002 12:00am

    Originally posted by: real name

    can very useful to ignore all other keys (or maybe left drag with them too) to not get unwanted situations like ctrl-a/del handling during operation
    t!

    Reply
Leave a Comment
  • Your email address will not be published. All fields are required.

Top White Papers and Webcasts

  • Organizations are increasingly gravitating toward mobile-first application development as they assess the need to revamp their application portfolios to support touch computing and mobility. Consumerization has brought higher expectations for application usability along with the mobile devices themselves. Enterprises are increasingly shifting their new application acquisitions and development efforts toward mobile platforms. With this backdrop, it is natural to expect application platform vendors to invest in …

  • Do you spend a lot of time thinking about your enemies? Attacker attribution - figuring out who's out to get you - is one of the most important things an organization can do to protect itself.  Because you have no hope of defending yourself if you don't understand who the attackers are. Good news? Every organization isn't targeted by all the attackers. Bad news? No one can identify your potential attackers as well as you. Read this graphics-rich threat summary for 2014 to determine who might be your next …

Most Popular Programming Stories

More for Developers

RSS Feeds

Thanks for your registration, follow us on our social networks to keep up-to-date