VB.NET DragEventArgs.Effect属性代码示例

Private Sub ListDragTarget_DragOver(ByVal sender As Object, ByVal e As DragEventArgs) Handles ListDragTarget.DragOver
    ' Determine whether string data exists in the drop data. If not, then
    ' the drop effect reflects that the drop cannot occur.
    If Not (e.Data.GetDataPresent(GetType(System.String))) Then

        e.Effect = DragDropEffects.None
        DropLocationLabel.Text = "None - no string data."
        Return
    End If

    ' Set the effect based upon the KeyState.
    If ((e.KeyState And (8 + 32)) = (8 + 32) And _
        (e.AllowedEffect And DragDropEffects.Link) = DragDropEffects.Link) Then
        ' KeyState 8 + 32 = CTL + ALT

        ' Link drag-and-drop effect.
        e.Effect = DragDropEffects.Link

    ElseIf ((e.KeyState And 32) = 32 And _
        (e.AllowedEffect And DragDropEffects.Link) = DragDropEffects.Link) Then

        ' ALT KeyState for link.
        e.Effect = DragDropEffects.Link

    ElseIf ((e.KeyState And 4) = 4 And _
        (e.AllowedEffect And DragDropEffects.Move) = DragDropEffects.Move) Then

        ' SHIFT KeyState for move.
        e.Effect = DragDropEffects.Move

    ElseIf ((e.KeyState And 8) = 8 And _
        (e.AllowedEffect And DragDropEffects.Copy) = DragDropEffects.Copy) Then

        ' CTL KeyState for copy.
        e.Effect = DragDropEffects.Copy

    ElseIf ((e.AllowedEffect And DragDropEffects.Move) = DragDropEffects.Move) Then

        ' By default, the drop action should be move, if allowed.
        e.Effect = DragDropEffects.Move

    Else
        e.Effect = DragDropEffects.None
    End If

    ' Gets the index of the item the mouse is below. 

    ' The mouse locations are relative to the screen, so they must be 
    ' converted to client coordinates.

    indexOfItemUnderMouseToDrop = _
        ListDragTarget.IndexFromPoint(ListDragTarget.PointToClient(New Point(e.X, e.Y)))

    ' Updates the label text.
    If (indexOfItemUnderMouseToDrop <> ListBox.NoMatches) Then

        DropLocationLabel.Text = "Drops before item #" & (indexOfItemUnderMouseToDrop + 1)
    Else
        DropLocationLabel.Text = "Drops at the end."
    End If

End Sub

' 导入命名空间
Imports System
Imports System.Runtime.InteropServices
Imports System.Drawing
Imports System.ComponentModel
Imports System.Windows.Forms
Imports System.IO

Public Class MainClass
    
    Shared Sub Main(ByVal args As String())
        Dim myform As New Form1()
        Application.Run(myform)            

    End Sub

End Class
Public Class Form1
    ' Allow Copy if there is FileDrop data.
    Private Sub lblDropTarget_DragEnter(ByVal sender As Object, ByVal e As System.Windows.Forms.DragEventArgs) Handles lblDropTarget.DragEnter
        If e.Data.GetDataPresent(DataFormats.FileDrop) Then
            e.Effect = DragDropEffects.Copy
        Else
            e.Effect = DragDropEffects.None
        End If
    End Sub

    ' Display the dropped file names.
    Private Sub lblDropTarget_DragDrop(ByVal sender As Object, ByVal e As System.Windows.Forms.DragEventArgs) Handles lblDropTarget.DragDrop
        lstFiles.Items.Clear()
        Dim file_names As String() = DirectCast(e.Data.GetData(DataFormats.FileDrop), String())
        For Each file_name As String In file_names
            lstFiles.Items.Add(file_name)
        Next file_name
    End Sub
End Class

<Global.Microsoft.VisualBasic.CompilerServices.DesignerGenerated()> _
Partial Public Class Form1
    Inherits System.Windows.Forms.Form

    'Form overrides dispose to clean up the component list.
    <System.Diagnostics.DebuggerNonUserCode()> _
    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
        If disposing AndAlso components IsNot Nothing Then
            components.Dispose()
        End If
        MyBase.Dispose(disposing)
    End Sub

    'Required by the Windows Form Designer
    Private components As System.ComponentModel.IContainer

    'NOTE: The following procedure is required by the Windows Form Designer
    'It can be modified using the Windows Form Designer.  
    'Do not modify it using the code editor.
    <System.Diagnostics.DebuggerStepThrough()> _
    Private Sub InitializeComponent()
        Me.lstFiles = New System.Windows.Forms.ListBox
        Me.lblDropTarget = New System.Windows.Forms.Label
        Me.SuspendLayout()
        '
        'lstFiles
        '
        Me.lstFiles.Dock = System.Windows.Forms.DockStyle.Fill
        Me.lstFiles.FormattingEnabled = True
        Me.lstFiles.Location = New System.Drawing.Point(0, 48)
        Me.lstFiles.Name = "lstFiles"
        Me.lstFiles.Size = New System.Drawing.Size(274, 160)
        Me.lstFiles.TabIndex = 3
        '
        'lblDropTarget
        '
        Me.lblDropTarget.AllowDrop = True
        Me.lblDropTarget.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D
        Me.lblDropTarget.Dock = System.Windows.Forms.DockStyle.Top
        Me.lblDropTarget.Location = New System.Drawing.Point(0, 0)
        Me.lblDropTarget.Name = "lblDropTarget"
        Me.lblDropTarget.Size = New System.Drawing.Size(274, 48)
        Me.lblDropTarget.TabIndex = 2
        Me.lblDropTarget.Text = "Drop Target"
        Me.lblDropTarget.TextAlign = System.Drawing.ContentAlignment.MiddleCenter
        '
        'Form1
        '
        Me.AutoScaleDimensions = New System.Drawing.SizeF(6.0!, 13.0!)
        Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font
        Me.ClientSize = New System.Drawing.Size(274, 210)
        Me.Controls.Add(Me.lstFiles)
        Me.Controls.Add(Me.lblDropTarget)
        Me.Name = "Form1"
        Me.Text = "AcceptFiles"
        Me.ResumeLayout(False)

    End Sub
    Friend WithEvents lstFiles As System.Windows.Forms.ListBox
    Friend WithEvents lblDropTarget As System.Windows.Forms.Label

End Class