Problème avec Drag And Drop TreeWiew

Version imprimable

Salut,

J'ai trouvé un exemple sur le forum MDSN sur le drag and drop avec un TreeWiew.
Ceci fonctionne très bien si ce n'est que si je drag and drop tous en bas du TreeWiew et bien j'ai
une erreur:

L'exception System.NullReferenceException n'a pas été gérée par le code utilisateur
HResult=-2147467261
Message=La référence d'objet n'est pas définie à une instance d'un objet.
Source=WindowsApplication1
StackTrace:
à WindowsApplication1.FenêtreMenuMaker.ContainsNode(TreeNode node1, TreeNode node2) dans C:\Users\Dayvid\AppData\Local\Temporary Projects\WindowsApplication1\Fenêtre Menu Maker.vb:ligne 80
à WindowsApplication1.FenêtreMenuMaker.treeView1_DragDrop(Object sender, DragEventArgs e) dans C:\Users\Dayvid\AppData\Local\Temporary Projects\WindowsApplication1\Fenêtre Menu Maker.vb:ligne 52
à System.Windows.Forms.Control.OnDragDrop(DragEventArgs drgevent)
à System.Windows.Forms.Control.System.Windows.Forms.IDropTarget.OnDragDrop(DragEventArgs drgEvent)
à System.Windows.Forms.DropTarget.System.Windows.Forms.UnsafeNativeMethods.IOleDropTarget.OleDrop(Object pDataObj, Int32 grfKeyState, POINTSTRUCT pt, Int32& pdwEffect)
InnerException:

Je suppose que c'est parce que je drag and drop sur rien ?
Voici le code, il vous faudra créer une fenêtre avec un TreeWiew, ajouter des éléments dans
celui-ci puis exécutez, drag and drop un item vers le bas ou ya rien et la magie -> erreur :'(
Coller ce code dans votre classe form.

Je vous remercie de votre aide par avance.

Code:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
Private Sub treeView1_ItemDrag(ByVal sender As Object, ByVal e As ItemDragEventArgs) Handles TreeView1.ItemDrag
 
        ' Move the dragged node when the left mouse button is used.
        If e.Button = MouseButtons.Left Then
            DoDragDrop(e.Item, DragDropEffects.Move)
 
            ' Copy the dragged node when the right mouse button is used.
        ElseIf e.Button = MouseButtons.Right Then
            DoDragDrop(e.Item, DragDropEffects.Copy)
 
        End If
 
    End Sub 'treeView1_ItemDrag
 
    ' Set the target drop effect to the effect 
    ' specified in the ItemDrag event handler.
    Private Sub treeView1_DragEnter(ByVal sender As Object, ByVal e As DragEventArgs) Handles TreeView1.DragEnter
        e.Effect = e.AllowedEffect
    End Sub 'treeView1_DragEnter
 
    ' Select the node under the mouse pointer to indicate the 
    ' expected drop location.
    Private Sub treeView1_DragOver(ByVal sender As Object, ByVal e As DragEventArgs) Handles TreeView1.DragOver
 
        ' Retrieve the client coordinates of the mouse position.
        Dim targetPoint As Point = TreeView1.PointToClient(New Point(e.X, e.Y))
 
        ' Select the node at the mouse position.
        TreeView1.SelectedNode = TreeView1.GetNodeAt(targetPoint)
 
    End Sub 'treeView1_DragOver
 
    Private Sub treeView1_DragDrop(ByVal sender As Object, ByVal e As DragEventArgs) Handles TreeView1.DragDrop
 
        ' Retrieve the client coordinates of the drop location.
        Dim targetPoint As Point = TreeView1.PointToClient(New Point(e.X, e.Y))
 
        ' Retrieve the node at the drop location.
        Dim targetNode As TreeNode = TreeView1.GetNodeAt(targetPoint)
 
        ' Retrieve the node that was dragged.
        Dim draggedNode As TreeNode = CType(e.Data.GetData(GetType(TreeNode)), TreeNode)
 
        ' Confirm that the node at the drop location is not 
        ' the dragged node or a descendant of the dragged node.
        If Not draggedNode.Equals(targetNode) AndAlso Not ContainsNode(draggedNode, targetNode) Then
 
            ' If it is a move operation, remove the node from its current 
            ' location and add it to the node at the drop location.
            If e.Effect = DragDropEffects.Move Then
                draggedNode.Remove()
                targetNode.Nodes.Add(draggedNode)
 
                ' If it is a copy operation, clone the dragged node 
                ' and add it to the node at the drop location.
            ElseIf e.Effect = DragDropEffects.Copy Then
                targetNode.Nodes.Add(CType(draggedNode.Clone(), TreeNode))
 
            End If
 
            ' Expand the node at the location 
            ' to show the dropped node.
            targetNode.Expand()
 
        End If
 
    End Sub 'treeView1_DragDrop
 
    ' Determine whether one node is a parent 
    ' or ancestor of a second node.
    Private Function ContainsNode(ByVal node1 As TreeNode, ByVal node2 As TreeNode) As Boolean
 
        ' Check the parent node of the second node.
        If node2.Parent Is Nothing Then
            Return False
        End If
 
        If node2.Parent.Equals(node1) Then
            Return True
        End If
 
        ' If the parent node is not null or equal to the first node, 
        ' call the ContainsNode method recursively using the parent of 
        ' the second node.
        Return ContainsNode(node1, node2.Parent)
 
    End Function 'ContainsNode

Bonsoir,

voici une solution qui marche avec un ListBox:

Code:

1
2
3
4
5
6
7
Private Sub ListBox1_DragEnter(sender As System.Object, e As System.Windows.Forms.DragEventArgs) Handles ListBox1.DragEnter
        If e.Data.GetDataPresent(DataFormats.FileDrop) Then
            e.Effect = DragDropEffects.Copy
        Else
            e.Effect = DragDropEffects.None
        End If
    End Sub

Code:

1
2
3
4
5
6
Private Sub ListBox1_DragDrop(sender As System.Object, e As System.Windows.Forms.DragEventArgs) Handles ListBox1.DragDrop
        Dim data As String() = DirectCast(e.Data.GetData(DataFormats.FileDrop), String())
        For Each str In data
            'Ton code pour lire ton fichier avec treeview
        Next
    End Sub

ce code fonction car je l'applique avec une application.
bonsoir,

19/11/2015, 01h20
Dayvid

Bonjour, merci de ton aide mais là ça ne fonctionne pas pour moi.
Moi, le drag et drop, c'est pour réorganiser les éléments ou les copier...

Si je lâche l’élément sur "Rien", c'est ici qu'intervient le problème.
19/11/2015, 06h54
hacker59

Bonjour,

Regarde ce lien c'est peut être la solution que du chercher :
http://www.telerik.com/help/winforms...-and-drop.html

cordialement,

Merci de ton aide.

Alors je ne sais pas si c'est bien mais j'ai fais comme ça, c'est du bricolage mais ça marche:

Code:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
 Private Sub treeView1_ItemDrag(ByVal sender As Object, ByVal e As ItemDragEventArgs) Handles TreeView1.ItemDrag
 
        ' Move the dragged node when the left mouse button is used.
        If e.Button = MouseButtons.Left Then
            DoDragDrop(e.Item, DragDropEffects.Move)
 
            ' Copy the dragged node when the right mouse button is used.
        ElseIf e.Button = MouseButtons.Right Then
            DoDragDrop(e.Item, DragDropEffects.Copy)
 
        End If
 
    End Sub 'treeView1_ItemDrag
 
    ' Set the target drop effect to the effect 
    ' specified in the ItemDrag event handler.
    Private Sub treeView1_DragEnter(ByVal sender As Object, ByVal e As DragEventArgs) Handles TreeView1.DragEnter
        e.Effect = e.AllowedEffect
    End Sub 'treeView1_DragEnter
 
    ' Select the node under the mouse pointer to indicate the 
    ' expected drop location.
    Private Sub treeView1_DragOver(ByVal sender As Object, ByVal e As DragEventArgs) Handles TreeView1.DragOver
 
        ' Retrieve the client coordinates of the mouse position.
        Dim targetPoint As Point = TreeView1.PointToClient(New Point(e.X, e.Y))
 
        ' Select the node at the mouse position.
        TreeView1.SelectedNode = TreeView1.GetNodeAt(targetPoint)
 
    End Sub 'treeView1_DragOver
 
    Private Sub treeView1_DragDrop(ByVal sender As Object, ByVal e As DragEventArgs) Handles TreeView1.DragDrop
 
        ' Retrieve the client coordinates of the drop location.
        Dim targetPoint As Point = TreeView1.PointToClient(New Point(e.X, e.Y))
 
        ' Retrieve the node at the drop location.
        Dim targetNode As TreeNode = TreeView1.GetNodeAt(targetPoint)
 
        ' Retrieve the node that was dragged.
        Dim draggedNode As TreeNode = CType(e.Data.GetData(GetType(TreeNode)), TreeNode)
 
        ' Confirm that the node at the drop location is not 
        ' the dragged node or a descendant of the dragged node.
        If Not draggedNode.Equals(targetNode) AndAlso Not ContainsNode(draggedNode, targetNode) Then
 
            If Not targetNode Is Nothing Then
 
                ' If it is a move operation, remove the node from its current 
                ' location and add it to the node at the drop location.
                If e.Effect = DragDropEffects.Move Then
                    draggedNode.Remove()
                    targetNode.Nodes.Add(draggedNode)
 
                    ' If it is a copy operation, clone the dragged node 
                    ' and add it to the node at the drop location.
                ElseIf e.Effect = DragDropEffects.Copy Then
                    targetNode.Nodes.Add(CType(draggedNode.Clone(), TreeNode))
 
                End If
 
                ' Expand the node at the location 
                ' to show the dropped node.
                targetNode.Expand()
 
            End If
 
        End If
 
    End Sub 'treeView1_DragDrop
 
    ' Determine whether one node is a parent 
    ' or ancestor of a second node.
    Private Function ContainsNode(ByVal node1 As TreeNode, ByVal node2 As TreeNode) As Boolean
 
        If Not node2 Is Nothing Then
 
            ' Check the parent node of the second node.
            If node2.Parent Is Nothing Then
                Return False
            End If
 
            If node2.Parent.Equals(node1) Then
                Return True
            End If
 
            ' If the parent node is not null or equal to the first node, 
            ' call the ContainsNode method recursively using the parent of 
            ' the second node.
            Return ContainsNode(node1, node2.Parent)
 
        Else
            Return 0
        End If
 
    End Function 'ContainsNode
 
    Private Sub ButtonSupprimerElements_Click(sender As System.Object, e As System.EventArgs) Handles ButtonSupprimerElements.Click
        TreeView1.Nodes.Remove(TreeView1.SelectedNode)
    End Sub

23/11/2015, 08h15
Dayvid

Bonjour,

Est-ce que quelqu'un peut me dire si ma méthode est bonne ou pas ?
Merci :)