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Drag and Drop on controls in VB.NET - DragOver, MouseUp, etc.

Posted on 2008-06-10
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Last Modified: 2013-11-26
Hello,

I am attempting to write a program that allows the user to click on one control (a button) and drag across the form to another control (another button) and drop. I'm creating the buttons dynamically, and adding the event handlers when I create the buttons.

My question is, how do I determine which control the "drop" was on? When I mousedown on the 1st button, the sender is the 1st button, and I was storing that button's ID as ID1. Then, when I drag and drop onto button 2, I was trying to do a DragOver event and store ID2 as the sender in that event, but it doesn't always work. I've tried several events and can't seem to get the right combination.

These points are for the person that puts me in the right direction with links, etc. I will increase the points if you can give me a total solution here.

Thanks!
0
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Question by:paix120
5 Comments
 
LVL 27

Assisted Solution

by:planocz
planocz earned 25 total points
ID: 21751186
I do not know if this will help you but here is a sample with Addhandlers on the different controls.
'FORM 1
 

Option Strict Off

Option Explicit On 
 

Imports Microsoft.VisualBasic

Imports System

Imports System.ComponentModel

Imports System.Data

Imports System.Drawing

Imports System.Windows.Forms

Public Class Form1

    Inherits Form

    Private WithEvents dataGrid1 As Form1.DnDDataGrid

    Private WithEvents dataGrid2 As Form1.DnDDataGrid

    Private components As Container

    Private WithEvents dt As DataTable

    Private WithEvents dt2 As DataTable

    'Fields

    'Constructors

    'Events

    'Methods

    'Nested Types

    Public Sub New()

        MyBase.New()

        Me.dt = New DataTable("Table1")

        Me.dt2 = New DataTable("Table2")

        '

        ' Required for Windows Form Designer support

        '

        InitializeComponent()

        '

        ' TODO: Add any constructor code after InitializeComponent call

        '

        dt.Columns.Add("Int32", Type.GetType("System.String"))

        dt.Columns.Add("Char", Type.GetType("System.String"))

        Dim dr As DataRow

        Dim i As Integer

        i = 0
 

        Do While (i <= 10)

            dr = dt.NewRow

            dr("Int32") = "text " + i.ToString

            dr("Char") = ChrW(i + 33)

            dt.Rows.Add(dr)

            i = (i + 1)
 

        Loop

        dataGrid1.DataSource = dt

        dt2.Columns.Add("Int32", Type.GetType("System.String"))

        dt2.Columns.Add("Char", Type.GetType("System.String"))

        Dim dr1 As DataRow

        i = 0
 

        Do While (i <= 20)

            dr1 = dt2.NewRow

            dr1("Int32") = "row " + i.ToString

            dr1("Char") = ChrW(i + 33)

            dt2.Rows.Add(dr1)

            i = (i + 1)
 

        Loop

        dataGrid2.DataSource = dt2

    End Sub

    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)

        If disposing Then

            If (Not (components) Is Nothing) Then

                components.Dispose()

            End If

        End If

        MyBase.Dispose(disposing)

    End Sub

    Private Sub InitializeComponent()
 

        Me.dataGrid1 = New DataGridDnD.Form1.DnDDataGrid

        Me.dataGrid2 = New DataGridDnD.Form1.DnDDataGrid

        CType(Me.dataGrid1, System.ComponentModel.ISupportInitialize).BeginInit()

        CType(Me.dataGrid2, System.ComponentModel.ISupportInitialize).BeginInit()

        Me.SuspendLayout()

        ' 

        ' dataGrid1

        ' 

        Me.dataGrid1.AllowDrop = True

        Me.dataGrid1.DataMember = ""

        Me.dataGrid1.HeaderForeColor = System.Drawing.SystemColors.ControlText

        Me.dataGrid1.Location = New System.Drawing.Point(56, 24)

        Me.dataGrid1.Name = "dataGrid1"

        Me.dataGrid1.PreferredColumnWidth = 50

        Me.dataGrid1.Size = New System.Drawing.Size(208, 184)

        Me.dataGrid1.TabIndex = 0

        ' 

        ' dataGrid2

        ' 

        Me.dataGrid2.AllowDrop = True

        Me.dataGrid2.DataMember = ""

        Me.dataGrid2.HeaderForeColor = System.Drawing.SystemColors.ControlText

        Me.dataGrid2.Location = New System.Drawing.Point(304, 24)

        Me.dataGrid2.Name = "dataGrid2"

        Me.dataGrid2.PreferredColumnWidth = 50

        Me.dataGrid2.Size = New System.Drawing.Size(224, 184)

        Me.dataGrid2.TabIndex = 1

        ' 

        ' Form1

        ' 

        Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)

        Me.ClientSize = New System.Drawing.Size(584, 253)

        Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.dataGrid2, Me.dataGrid1})

        Me.Name = "Form1"

        Me.Text = "Form1"

        AddHandler Me.Load, New System.EventHandler(AddressOf Form1_Load)

        CType(Me.dataGrid1, System.ComponentModel.ISupportInitialize).EndInit()

        CType(Me.dataGrid2, System.ComponentModel.ISupportInitialize).EndInit()

        Me.ResumeLayout(False)
 

    End Sub

    <STAThread()> _

    Public Shared Sub Main()
 

        Application.Run(New Form1)
 

    End Sub

    Private Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs)

    End Sub

    Public Class DnDDataGrid

        Inherits DataGrid

        Private dndMouseDownRow As Integer

        Private dndMouseDownCol As Integer

        'Fields

        'Constructors

        'Events

        'Methods

        Public Sub New()

            MyBase.New()

            AddHandler Me.DragOver, New System.Windows.Forms.DragEventHandler(AddressOf HandleDragOver)

            AddHandler Me.DragDrop, New System.Windows.Forms.DragEventHandler(AddressOf HandleDragDrop)

            AddHandler Me.DragEnter, New System.Windows.Forms.DragEventHandler(AddressOf HandleDragEnter)

            AddHandler Me.MouseDown, New System.Windows.Forms.MouseEventHandler(AddressOf HandleMouseDown)

            AddHandler Me.MouseMove, New System.Windows.Forms.MouseEventHandler(AddressOf HandleMouseMove)

            AddHandler Me.MouseUp, New System.Windows.Forms.MouseEventHandler(AddressOf HandleMouseUp)

            Me.dndMouseDownRow = -(1)

            Me.dndMouseDownCol = -(1)

            Me.AllowDrop = True

        End Sub

        Private Sub HandleMouseUp(ByVal sender As Object, ByVal e As MouseEventArgs)

            Me.dndMouseDownRow = -(1)

            Me.dndMouseDownCol = -(1)

        End Sub

        Private Sub HandleMouseDown(ByVal sender As Object, ByVal e As MouseEventArgs)

            Dim ht As System.Windows.Forms.DataGrid.HitTestInfo

            ht = Me.HitTest(New Point(e.X, e.Y))

            Me.dndMouseDownRow = ht.Row

            Me.dndMouseDownCol = ht.Column

        End Sub

        Private Sub HandleMouseMove(ByVal sender As Object, ByVal e As MouseEventArgs)

            Dim ht As System.Windows.Forms.DataGrid.HitTestInfo

            ht = Me.HitTest(New Point(e.X, e.Y))

            If (e.Button = MouseButtons.Left) Then

                'Console.WriteLine(ht.ToString() );

                If (((dndMouseDownRow = -(1)) _

                            OrElse (dndMouseDownCol = -(1))) _

                            OrElse ((ht.Row = dndMouseDownRow) _

                            AndAlso (ht.Column = dndMouseDownCol))) Then

                    Return

                End If

                Dim data As [String]

                data = Me(Me.dndMouseDownRow, Me.dndMouseDownCol).ToString

                'Console.WriteLine(ht.ToString() + "\n" + data);

                Me.DoDragDrop(data, DragDropEffects.Copy)

                Me.dndMouseDownRow = -(1)

                Me.dndMouseDownCol = -(1)

            End If

        End Sub

        Private Sub HandleDragOver(ByVal sender As Object, ByVal e As DragEventArgs)

            Dim ht As System.Windows.Forms.DataGrid.HitTestInfo

            ht = Me.HitTest(Me.PointToClient(New Point(e.X, e.Y)))

            'Console.WriteLine(ht.ToString());

            If (((ht.Row = Me.dndMouseDownRow) _

                        AndAlso (ht.Column = Me.dndMouseDownCol)) _

                        OrElse Not (e.Data.GetDataPresent("Text"))) Then

                e.Effect = DragDropEffects.None

            Else

                e.Effect = DragDropEffects.Copy

            End If

        End Sub

        Private Sub HandleDragEnter(ByVal sender As Object, ByVal e As DragEventArgs)

            If e.Data.GetDataPresent("Text") Then

                e.Effect = DragDropEffects.Copy

            End If

        End Sub

        Private Sub HandleDragDrop(ByVal sender As Object, ByVal e As DragEventArgs)

            'DataGrid dg = sender as DataGrid;

            'if(dg == null) return;

            If e.Data.GetDataPresent("Text") Then

                Dim ht As System.Windows.Forms.DataGrid.HitTestInfo

                ht = Me.HitTest(Me.PointToClient(New Point(e.X, e.Y)))

                If ((ht.Row = -(1)) _

                            OrElse (ht.Column = -(1))) Then

                    Return

                Else

                    Me(ht.Row, ht.Column) = CType(e.Data.GetData("Text"), String)

                End If

            End If

        End Sub

    End Class

End Class

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0
 
LVL 69

Assisted Solution

by:Éric Moreau
Éric Moreau earned 25 total points
ID: 21751292
you can use SetData to set your own drag content. See http://www.emoreau.com/Entries/Articles/2004/02/Drag-and-Drop-in-VBNet.aspx
0
 
LVL 85

Accepted Solution

by:
Mike Tomlinson earned 250 total points
ID: 21752165
Wire up the MouseMove, DragEnter and the DragDrop events of your buttons like this:

    Private Sub btn_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs)
        If e.Button = Windows.Forms.MouseButtons.Left Then
            Dim btn As Button = DirectCast(sender, Button)
            Dim D As New DataObject("MyButtonData", btn)
            btn.DoDragDrop(D, DragDropEffects.All)
        End If
    End Sub

    Private Sub btn_DragEnter(ByVal sender As Object, ByVal e As System.Windows.Forms.DragEventArgs)
        If e.Data.GetDataPresent("MyButtonData") Then
            e.Effect = DragDropEffects.All
        Else
            e.Effect = DragDropEffects.None
        End If
    End Sub

    Private Sub btn_DragDrop(ByVal sender As Object, ByVal e As System.Windows.Forms.DragEventArgs)
        Dim target As Button = DirectCast(sender, Button)
        Dim source As Button = e.Data.GetData("MyButtonData")
        Debug.Print("Source: " & source.Name)
        Debug.Print("Target: " & target.Name)
    End Sub
0
 
LVL 3

Author Comment

by:paix120
ID: 21754328
planocz - thanks, I'll take a look at that to see if I can use it. It looks helpful.

emoreau - I'm not trying to drag text, but the functions there look helpful, thanks.

Idle_Mind - looks good, I'll try it out today!

0
 
LVL 3

Author Comment

by:paix120
ID: 21756115
Idle_Mind:

Your code works for what I asked for. Thanks!

-Renee


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