Trapping a mouse click on a TreeView

[Scott Wolfington]

Sorry if this is a lame question...

I can't seem to figure out how to trap the mouse button
click on a treeview. What messages should I be looking for
in the dialog callback?

Thanks,
Scott


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Scott Wolfington
http://www.boogietools.com


[This message has been edited by Scott Wolfington (edited March 05, 2003).]

[Cecil Williams]

These few come to mind:

WM_LBUTTONDOWN
WM_RBUTTONDOWN
WM_MBUTTONDOWN
WM_LBUTTONUP
WM_RBUTTONUP
WM_MBUTTONUP
WM_LBUTTONDBLCLK
WM_RBUTTONDBLCLK
WM_MBUTTONDBLCLK
WM_MOUSEMOVE
WM_MOUSEWHEEL

Cheers,
Cecil

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[Eric Pearson]

Scott --

Microsoft didn't make this one easy. In your window proc...

    DIM tpNotify AS LOCAL NMHDR PTR
 	
    ...ELSEIF wMsg = %WM_NOTIFY THEN
     
        tpNotify = lParam
 
        IF @tpNotify.Code = %NM_CLICK THEN
        	'somebody clicked a tree item
        END IF

(I use the "tp" prefix to mean "type pointer". It's optional.)

It gets worse... Then you have to use %TVM_HITTEST to get the handle of the tree item at the current cursor location, then %TVM_GETITEM to get the item number that goes with that item.

Are you really trying to detect the click, or detect that an item has been selected? Remember that item selection can be done with the keyboard too...

-- Eric


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Perfect Sync: Perfect Sync Development Tools
Email: mailto:[email protected][email protected]</A>



[This message has been edited by Eric Pearson (edited February 22, 2001).]

[Semen Matusovski]

Very doubt that Scott is interesting exactly in mouse down.
Typically %TVN_SELCHANGED is enough.
But coming back to click.
WM_PARENTNOTIFY with Lowrd(CbWparam) = WM_.BUTTONDOWN occurs before WM_NOTIFY.


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[Eric Pearson]

Semen --

It really makes very little difference which technique you use, if all you are doing is detecting an item-click. But the WM_NOTIFY system is much more flexible that WM_PARENTNOTIFY -- it provides notification about many more events -- so in real-world treeview apps I tend to use it for everything.

-- Eric

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Perfect Sync: Perfect Sync Development Tools
Email: mailto:[email protected][email protected]</A>

[This message has been edited by Eric Pearson (edited February 22, 2001).]

[Semen Matusovski]

About real programs - agree.
I added some statements to Peter's sample to illustrate my previous post.
Selected item is shown in caption.

   #Compile Exe
   #Dim All
   #Register None
   #Include "win32api.inc"
   #Include "commctrl.inc"

   Function TVInsertItem(ByVal hTree As Long, ByVal hParent As Long, sTxt As String) As Long
      Local tv_insert As TV_INSERTSTRUCT
      Local tv_item As TV_ITEM
      If hParent Then
         tv_item.mask = %TVIF_CHILDREN Or %TVIF_HANDLE
         tv_item.hItem = hParent
         tv_item.cchildren = 1
         TreeView_SetItem hTree, tv_item
      End If
      tv_insert.hParent = hParent
      tv_insert.Item.Item.mask = %TVIF_TEXT
      tv_insert.Item.Item.pszText = StrPtr(sTxt)
      tv_insert.Item.Item.cchTextMax = Len(sTxt)
      Function = TreeView_InsertItem(hTree, tv_insert)
   End Function

   CallBack Function DlgProc
      %ID_TREE = 100
      Dim hParent As Long, hRoot As Long, hTree As Static Long
      Dim lpNmh As NMHDR Ptr, hItem As Long, lpTV As NM_TREEVIEW Ptr, pitem As TV_ITEM
      Dim TmpAsciiz As Asciiz * %MAX_PATH, i As Long, j As Long, Answer As String

      Select Case CbMsg
         Case %WM_INITDIALOG
            Control Add "SysTreeView32", CbHndl, %ID_TREE, "", 5, 5, 190, 90, _
                %WS_CHILD Or %WS_VISIBLE Or %TVS_HASBUTTONS Or %TVS_HASLINES Or _
                %TVS_LINESATROOT Or %TVS_SHOWSELALWAYS, %WS_EX_CLIENTEDGE
            Control Handle CbHndl, %ID_TREE To hTree
  
            hRoot = TVInsertItem(hTree, 0, "Root")
            For i = 1 To 10
               hParent = TVInsertItem(hTree, hRoot,  "Item" + Format$(i))
               For j = 1 To 10
                  TVInsertItem hTree, hParent, "Subitem" + Format$(i) + "." + Format$(j)
               Next
            Next
            
         Case %WM_NOTIFY
            lpNmh = CbLparam
            If (@lpNmh.Code = %TVN_SELCHANGED) And (@lpNmh.idFrom = %ID_TREE) Then
                lpTV = CbLparam
                i = @lpTV.ItemNew.hItem
                While i
                   pItem.hitem = i
                   pItem.mask = %TVIF_TEXT
                   pItem.pszText = VarPtr(TmpAsciiz)
                   pItem.cchTextMax = SizeOf(TmpAsciiz)
                   TreeView_GetItem hTree, pItem
                   If Answer <> "" Then Answer = Trim$(TmpAsciiz) + "; " + Answer Else Answer = Trim$(TmpAsciiz)
                   i = TreeView_GetParent (hTree, pitem.hitem)
                Wend
                SetWindowText CbHndl, ByVal StrPtr(Answer)
             End If
      End Select

   End Function

   Function PbMain
      Local hDlg As Long
      Dialog New 0, "TreeView32",,, 200, 100, %WS_SYSMENU Or %WS_MINIMIZEBOX Or %WS_CAPTION To hDlg
      Dialog Show Modal hDlg Call DlgProc
   End Function

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[Scott Wolfington]

Thanks guys,

Eric, you're right... I need to detect an item selection
and like you said, item selection can be done with the
keyboard too. How would I go about handling keyboard selection
of an item?

The example you gave me is definitely still useful because I
need it for trapping right clicks (%NM_RCLICK) to pop up
context sensitive menus. Again, I'll still need to know which
item I'm on though, so I'll take a look at the %TVM_HITTEST
and %TVM_GETITEM you mentioned. Thanks for your help on this!

Regards,
Scott


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Scott Wolfington
http://www.boogietools.com


[This message has been edited by Scott Wolfington (edited March 05, 2003).]

[Scott Wolfington]

Semen-

Great example. You posted that like seconds before my
last post. Thank you very much!

Scott


------------------
Scott Wolfington
http://www.boogietools.com


[This message has been edited by Scott Wolfington (edited March 05, 2003).]