VB.Net Get The Control That Is Used To Show The Contextmenu Strip

问题

i am attaching a single context menu to multiple text box. so, i need to get the control name/reference that used to show the context menu.

below is the sample image of my context menu:

Below is the code for green marked "paste" item click event:

    Dim objTSMI As ToolStripMenuItem
    Dim objCMS As ContextMenuStrip
    Dim objTxtBox As System.Windows.Forms.TextBox
    objTSMI = CType(sender, ToolStripMenuItem)
    objCMS = CType(objTSMI.Owner, ContextMenuStrip)
    objTxtBox = CType(objCMS.SourceControl, System.Windows.Forms.TextBox)
    If Clipboard.ContainsText(TextDataFormat.Text) = True Then
        objTxtBox.SelectedText = Clipboard.GetText(TextDataFormat.Text)
    End If

it works very fine.

but below is my code for red marked "Page count" item click event:

    Dim objTSMI As ToolStripMenuItem
    Dim objCMS As ContextMenuStrip
    Dim objTxtBox As System.Windows.Forms.TextBox
    objTSMI = CType(sender, ToolStripMenuItem)
    objCMS = CType(objTSMI.Owner, ContextMenuStrip)
    objTxtBox = CType(objCMS.SourceControl, System.Windows.Forms.TextBox)
    MessageBox.Show(objTxtBox.Name)

but above throws following error :

Unable to cast object of type 'System.Windows.Forms.ToolStripDropDownMenu' to type 'System.Windows.Forms.ContextMenuStrip'.

here is the screenshot of the error:

so, i can't figure it out what is the issue.

any help would be highly appreciated

回答1:

If you check this C# thread the accepted answer notes it is a bug. The workaround presented there uses a private variable to store the SourceControl on the Opening event of the ContextMenuStrip. I've converted to VB.NET and used the Tag of the ContextMenuStrip instead of using the variable. You then refer to the Tag property instead of the faulty SourceControl property:

Imports System.ComponentModel

Public Class Form1

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Me.TextBox1.ContextMenuStrip = Me.ContextMenuStrip1
        Me.TextBox2.ContextMenuStrip = Me.ContextMenuStrip1
    End Sub

    Private Sub ContextMenuStrip1_Opening(sender As Object, e As CancelEventArgs) Handles ContextMenuStrip1.Opening
        Me.ContextMenuStrip1.Tag = CType(Me.ContextMenuStrip1.SourceControl, Control)
    End Sub

    Private Sub TestToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles TestToolStripMenuItem.Click
        ' first level of context menu strip
        Dim Strip As ContextMenuStrip = CType(sender, ToolStripMenuItem).Owner
        Dim Box As TextBox = Strip.Tag

        MessageBox.Show(Box.Name)
    End Sub

    Private Sub ChildToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles ChildToolStripMenuItem.Click
        ' second level of context menu strip
        Dim Strip As ContextMenuStrip = CType(sender, ToolStripMenuItem).OwnerItem.Owner
        Dim Box As TextBox = Strip.Tag

        MessageBox.Show(Box.Name)
    End Sub

End Class

来源：https://stackoverflow.com/questions/37703891/how-to-get-parent-control-from-context-menu-item-vb-net

标签

vb.net

winforms

contextmenu