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How get a checked/unchecked message from CTreeCtrl?

Posted on 2004-03-25
Medium Priority
Last Modified: 2013-11-20
How do I determine when the user is un/cheking a check box in a
 tree. What  notification message is sent?

Question by:robter_x
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LVL 16

Accepted Solution

nonubik earned 150 total points
ID: 10686858
I presume you use a CTreeCtrl with TVS_CHECKBOXES.
I couldn't find any standard notification message, but I have an workarround: you may wait NM_CLICK and verify wether the checkbos is checked or not  (http://msdn.microsoft.com/library/default.asp?url=/library/en-us/shellcc/platform/commctls/treeview/treeview.asp ,the last example in "Working with state image indexes") .
LVL 14

Expert Comment

ID: 14541570
I know it must be way too late now, but anyway, for the knowledgebase:
There is a better way - derive a class from CTreeCtrl and override with this one:

void CTreeCtrlEx::OnLButtonDown(UINT nFlags, CPoint point)
      UINT uFlags=0;
      HTREEITEM hItem = HitTest(point,&uFlags);

      if( uFlags & TVHT_ONITEMSTATEICON )
            // determine by using GetCheck(hItem)
            // you can send a custom message if you want.

      CTreeCtrl::OnLButtonDown(nFlags, point);


Expert Comment

ID: 21309279
Hi Stilgar,

I was just looking over these responses - it's been a long time, but maybe you can remember...  I subclassed CTreeCtrl and provided the virtual function to override OnLButtonDown as you said to do, but my function is not being called.  Do I absolutely need a message map so that it is called?  I'm not sure what to use as a message map if that's the case - how do you determine which dialog ID to use and still have a generic class?

Thanks for your help,
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LVL 14

Expert Comment

ID: 21316759

Its been a while since I touched MFC GUI controls... AFAIR just overriding the function should do, but I may as well be wrong. Try creating the OnLButtonDown function in your sub-class using the MFC wizards - this should create whatever is needed for this function to work. Also, make sure you're not overriding this message elsewhere (for example in PreTranslateMessage).


Expert Comment

ID: 21318011
Thanks Stilgar, I'll give that a try..

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