TreeView Walkthrough in just 15 lines of code - PBWin9

[Gary Beene]

In an earlier thread, I gave a ~25 line code for a traversing a TreeView control. While it worked, it wasn't "satisfying". Plus, jcfuller hurt my feelings by not embracing the code - kind of like a mother who is hurt when someone says her baby is ugly! (ok, he didn't really hurt my feelings, but he did say my baby was ugly!).

It got me to thinking about a better solution. Here's the result - just 15 lines of code. It fixes some of the objections I heard last time - there are no globals (do equates count as globals?), no arrays, and no recursive calls. It starts at any node and does not have to traverse the whole tree (it can be stopped at any node).

Sub TreeWalk(ByVal hWnd As Dword, ByVal hNode As Dword)
   Dim iReturn As Dword, hParent As Dword, hSibling As Dword
   Do
        Treeview Get Child hWnd, %ID_Treeview, hNode To iReturn                    'get child (1st choice)
        If iReturn = 0 Then Treeview Get Next hWnd, 100, hNode To iReturn 'or sibling (2nd choice)
        If iReturn = 0 Then                                               'no child or sibling
            Do      'get sibling of first parent with sibling
               Treeview Get Parent hWnd, %ID_TreeView, hNode To hParent            'parent
               Treeview Get Next hWnd, %ID_TreeView, hParent To hSibling           'child of parent
               hNode = hParent
            Loop Until hSibling Or (hParent = 0)  'stop when find parent with sibling (or no more choices)
            If hSibling Then iReturn = hSibling   'otherwise iReturn remains zero
        End If
        hNode = iReturn
        Sleep 250 : If iReturn Then Treeview Select hWnd, %ID_TreeView, hNode
   Loop While hNode
End Sub

It gives this kind of walkthrough.

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Here's a compilable version to play with.

 #Compile Exe
 #Dim All
 %ID_TreeView = 100
 Function PBMain() As Long
    Local hDlg As Dword, hItem As Dword
    Local hTemp As Dword, hTemp2 As Dword, hTemp3 As Dword
    Dialog New Pixels, 0, "TreeView",200,200,155,250, %WS_SysMenu, 0 To hDlg
    Control Add Treeview, hDlg, 100, "", 10,10,130,200
    Treeview Insert Item hDlg, 100, 0, %TVI_Last, 2,2,"Top" To hItem

    Treeview Insert Item hDlg, 100, hItem, %TVI_Last, 2,4,"Mother" To hTemp
       Treeview Insert Item hDlg, 100, hTemp, %TVI_Last, 2,4,"Dan" To hTemp2
       Treeview Insert Item hDlg, 100, hTemp, %TVI_Last, 1,4,"Bob" To hTemp3
          Treeview Insert Item hDlg, 100, hTemp3, %TVI_Last, 2,4,"Foot" To hTemp2
          Treeview Insert Item hDlg, 100, hTemp3, %TVI_Last, 1,4,"Arm" To hTemp2

    Treeview Insert Item hDlg, 100, hItem, %TVI_Last, 1,4,"Father" To hTemp
       Treeview Insert Item hDlg, 100, hTemp, %TVI_Last, 2,4,"Helen" To hTemp2
       Treeview Insert Item hDlg, 100, hTemp, %TVI_Last, 1,4,"Any" To hTemp3
          Treeview Insert Item hDlg, 100, hTemp3, %TVI_Last, 2,4,"Leg" To hTemp2
          Treeview Insert Item hDlg, 100, hTemp3, %TVI_Last, 1,4,"Finger" To hTemp2
    Control Add Button, hDlg, 200, "Walk", 10,220,40,20

    Dialog Show Modal hDlg Call DlgProc
 End Function


 CallBack Function DlgProc() As Long
 Dim hTreeView As Dword, hNode As Dword
    If Cb.Msg = %WM_Command And Cb.Ctl = 200 Then
       Treeview Get Select Cb.Hndl, 100 To hNode
       TreeWalk Cb.Hndl, hNode
    End If
 End Function

Sub TreeWalk(ByVal hWnd As Dword, ByVal hNode As Dword)
   Dim iReturn As Dword, hParent As Dword, hSibling As Dword
   Do
        Treeview Get Child hWnd, %ID_Treeview, hNode To iReturn                    'get child (1st choice)
        If iReturn = 0 Then Treeview Get Next hWnd, 100, hNode To iReturn 'or sibling (2nd choice)
        If iReturn = 0 Then                                               'no child or sibling
            Do      'get sibling of first parent with sibling
               Treeview Get Parent hWnd, %ID_TreeView, hNode To hParent            'parent
               Treeview Get Next hWnd, %ID_TreeView, hParent To hSibling           'child of parent
               hNode = hParent
            Loop Until hSibling Or (hParent = 0)  'stop when find parent with sibling (or no more choices)
            If hSibling Then iReturn = hSibling   'otherwise iReturn remains zero
        End If
        hNode = iReturn
        Sleep 250 : If iReturn Then Treeview Select hWnd, %ID_TreeView, hNode
   Loop While hNode
End Sub

[Gary Beene]

And without being too Perl-ish about it, I was just looking at the earlier version and realized I could take out another 2 lines and a variable declaration.

Here's the revised version. Now we're talking about minimal code - only 11 lines of code if you don't count the SUB/DIM/End Sub statements!

Sub TreeWalk2(ByVal hWnd As Dword, ByVal hNode As Dword)
   Dim iReturn As Dword, hSibling As Dword
   Do
        Treeview Get Child hWnd, %ID_Treeview, hNode To iReturn                    'get child (1st choice)
        If iReturn = 0 Then Treeview Get Next hWnd, 100, hNode To iReturn 'or sibling (2nd choice)
        If iReturn = 0 Then                                               'no child or sibling
            Do      'get sibling of first parent with sibling
               Treeview Get Parent hWnd, %ID_TreeView, hNode To hNode            'parent
               Treeview Get Next hWnd, %ID_TreeView, hNode To iReturn            'sibling child of parent
            Loop Until iReturn Or (hNode = 0)  'stop when find sibling of parent with sibling, or no more choices
        End If
        hNode = iReturn    'possible values: 0, zero (no parent/no sibling), <>0 (parent or sibling)
        Sleep 250 : If iReturn Then Treeview Select hWnd, %ID_TreeView, hNode
   Loop While hNode
End Sub

I posted a thread in the Programming forum that has more description of how the code works.