不管控件如何处理mousedown事件

这很不寻常,你几乎总是 真正地 注意单击了哪个控件。并有一个mousedown事件,根据单击的控件执行特定操作。但是,您可以在将输入事件发送到控件本身之前捕获它们。您需要使用IMessageFilter接口。最好用代码示例解释:

Public Class Form1
  Implements IMessageFilter

  Public Sub New()
    InitializeComponent()
    Application.AddMessageFilter(Me)
  End Sub

  Protected Overrides Sub OnFormClosed(ByVal e As System.Windows.Forms.FormClosedEventArgs)
    Application.RemoveMessageFilter(Me)
  End Sub

  Public Function PreFilterMessage(ByRef m As System.Windows.Forms.Message) As Boolean Implements System.Windows.Forms.IMessageFilter.PreFilterMessage
    REM catch WM_LBUTTONDOWN
    If m.Msg = &H201 Then
      Dim pos As New Point(m.LParam.ToInt32())
      Dim ctl As Control = Control.FromHandle(m.HWnd)
      If ctl IsNot Nothing Then
        REM do something...
      End If
      REM next line is optional
      Return False
    End If
  End Function
End Class

请注意,此筛选器在 全部的 应用程序中的表单。如果只想使ctl值特定于一个表单,则需要对其进行筛选。

Private Sub Form1_Load(ByVal sender As System.Object, _
                       ByVal e As System.EventArgs) Handles MyBase.Load
    'note - this will NOT work for containers i.e. tabcontrols, etc
    For Each c In Me.Controls
        Try
            AddHandler DirectCast(c, Control).MouseDown, AddressOf Global_MouseDown
        Catch ex As Exception
            Debug.WriteLine(ex.Message)
        End Try
    Next
End Sub

Private Sub Global_MouseDown(ByVal sender As Object, _
                              ByVal e As System.Windows.Forms.MouseEventArgs)
    Debug.WriteLine(DirectCast(sender, Control).Name)
End Sub