CTreeViewEdit – A class for enhanced treeview node editing

CTreeViewEdit – A class for enhanced treeview node editing

'-------------------------------------------------------' The CTREEVIEWEDIT Class module'' This class lets you use a regular TextBox control to' edit a treeview node's label. All you have to do to' use this class is adding a TextBox control to the same' form that hosts the TreeView control, and initialize' an instance of the class from inside the form's Load' event. In the following example we have a treeview' control named tvwHierarchy and a support textbox control' named txtSupport'  Dim TVEdit As New CTreeViewEdit''  Private Sub Form_Load()'      TVEdit.Init tvwHierarchy, txtSupport'  End Sub' You can then write code in the event procs of txtSupport,' as you would do with a regular textbox. For example you' can filter out invalid keys. You can also terminate the' edit mode by invoking the class's EndLabelEdit method' (pass True to accept the new value, False to reject it)'Private Sub txtSupport_KeyPress(KeyAscii As Integer)'    If KeyAscii >= 48 And KeyAscii <= 57 Then'        ' filter out numeric keys'        KeyAscii = 0'    ElseIf KeyAscii = 8 Then'        ' the backspace cancels the operation'        TVEdit.EndLabelEdit False'    End If'End Sub'-------------------------------------------------------'-------------------------------------------------------' API Declares'-------------------------------------------------------Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal _    hWnd As Long, ByVal wMsg As Long, ByVal wParam As Long, _    lParam As Any) As LongPrivate Declare Function GetClientRect Lib "user32" (ByVal hWnd As Long, _    lpRect As RECT) As LongPrivate Declare Function SetCapture Lib "user32" (ByVal hWnd As Long) As LongPrivate Declare Function ReleaseCapture Lib "user32" () As LongPrivate Type RECT    Left As Long    Top As Long    Right As Long    Bottom As LongEnd TypePrivate Const TV_FIRST = &H1100Private Const TVM_GETITEMRECT = (TV_FIRST + 4)Private Const TVM_GETNEXTITEM = (TV_FIRST + 10)Private Const TVGN_CARET = 9'-------------------------------------------------------' module variables'-------------------------------------------------------' the TreeView controlDim WithEvents TreeView As TreeView' the hidden textbox controlDim WithEvents TextBox As TextBox' the parent form (can be anything)Dim Parent As Object' these variables are active when the user is editing the node label' the previous value of the Node's Text propertyDim saveText As String' the control that had Default = TrueDim defaultCtrl As Object' the control that had Cancel = TrueDim cancelCtrl As Object' Initialize this instanceSub Init(TView As TreeView, TBox As TextBox)    Set TreeView = TView    Set TextBox = TBox    Set Parent = TextBox.Parent    TextBox.Visible = FalseEnd Sub'-------------------------------------------------------' event procedures'-------------------------------------------------------' when the user clicks on a treeview's item' this procedure gets the control and cancels' the default operationPrivate Sub TreeView_BeforeLabelEdit(Cancel As Integer)    Cancel = True    StartLabelEditEnd Sub' when the user types in the textbox, grow or shrink itPrivate Sub TextBox_Change()    Dim saveFont As StdFont    Dim wi As Single    Dim borderWidth As Single        ' temporarily change the parent form's font,    ' to use its TextWidth method    Set saveFont = Parent.Font    Set Parent.Font = TextBox.Font    wi = Parent.TextWidth(TextBox.Text) + Parent.ScaleX(20, vbPixels, _        Parent.ScaleMode)    Set Parent.Font = saveFont    ' this is the Treeview's border, in the same coordinate    ' system as the parent form    borderWidth = Parent.ScaleX(2, vbPixels, Parent.ScaleMode)        ' don't let the textbox grow larger than the treeview    If TextBox.Left + wi > TreeView.Left + TreeView.Width - borderWidth Then        wi = TreeView.Left + TreeView.Width - TextBox.Left - borderWidth    End If        TextBox.Width = wi    End Sub' terminate the edit mode when the user types' Enter or Escape keysPrivate Sub TextBox_KeyPress(KeyAscii As Integer)    Select Case KeyAscii        Case 13            EndLabelEdit True            KeyAscii = 0        Case 27            EndLabelEdit False            KeyAscii = 0    End SelectEnd Sub' terminate the edit mode when the user clicks' outside of the textbox controlPrivate Sub TextBox_MouseDown(Button As Integer, Shift As Integer, X As Single, _    Y As Single)    If X < 0 Or Y < 0 Or X > TextBox.Width Or Y > TextBox.Height Then        EndLabelEdit True    End IfEnd Sub'-------------------------------------------------------' Support routines'-------------------------------------------------------' enter edit modePrivate Sub StartLabelEdit()    ' get the edit rectangle for the selected item    Dim lpRect As RECT, lpClientRect As RECT    Dim hNode As Long        ' get the handle of the selected node    hNode = SendMessage(TreeView.hWnd, TVM_GETNEXTITEM, TVGN_CARET, ByVal 0&)    ' get the bounding rectangle for this node    ' the function expects in input the handle of the item    ' at the beginning of the RECT structure    lpRect.Left = hNode    If SendMessage(TreeView.hWnd, TVM_GETITEMRECT, True, lpRect) = 0 Then        ' a zero value means error        Exit Sub    End If    ' convert coordinates into form coordinates    With lpRect        .Left = TreeView.Left + Parent.ScaleX(.Left, vbPixels, Parent.ScaleMode)        .Top = TreeView.Top + Parent.ScaleY(.Top, vbPixels, Parent.ScaleMode)        .Right = TreeView.Left + Parent.ScaleX(.Right, vbPixels, _            Parent.ScaleMode)        .Bottom = TreeView.Top + Parent.ScaleY(.Bottom, vbPixels, _            Parent.ScaleMode)    End With        ' move the textbox in front of the TreeView    With TextBox        ' move the textbox in the right position        .Move lpRect.Left, lpRect.Top, lpRect.Right - lpRect.Left + 200, _            lpRect.Bottom - lpRect.Top        .ZOrder                ' transfer the node's text to the TextBox control        .Text = TreeView.SelectedItem.Text        .SelStart = 0        .SelLength = Len(.Text)        Set .Font = TreeView.Font                ' make the textbox visible and give it the focus        .Visible = True        .SetFocus                ' grab the mouse capture        SetCapture .hWnd                ' disable any button with Default or Cancel property        ' this is necessary because we want to trap the Enter        ' and Cancel keys while the user is editing the        ' node's label.        Set defaultCtrl = Nothing        Set cancelCtrl = Nothing        Dim ctrl As Control                On Error Resume Next                For Each ctrl In Parent.Controls            If ctrl.Default = False Then                ' not supported or Default = False            Else                Set defaultCtrl = ctrl                ctrl.Default = False            End If            If ctrl.Cancel = False Then                ' not supported or Cancel = False            Else                Set cancelCtrl = ctrl                ctrl.Cancel = False            End If        Next            ' save node's text, then clear it - this is necessary to avoid the         ' original        ' text appears if the editing textbox shrinks        saveText = TreeView.SelectedItem.Text        TreeView.SelectedItem.Text = ""        End WithEnd Sub' this procedure is called from TextBox event procs' or by the client applicationSub EndLabelEdit(AcceptIt As Boolean)    If AcceptIt Then        ' if not canceled, assign the text to the underlying node        TreeView.SelectedItem.Text = TextBox.Text    Else        ' else restore original text        TreeView.SelectedItem.Text = saveText    End If    ' release mouse capture, and restore form's font    ReleaseCapture        ' make the TextBox invisible and clear it    TextBox.Visible = False    TextBox.Text = ""    TreeView.SetFocus        ' restore Default and Cancel buttons, if any    On Error Resume Next    defaultCtrl.Default = True    cancelCtrl.Cancel = TrueEnd Sub


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