Question

我已经在表单属性中将 KeyPreview 设置为true

我正在开发一个小程序，我遇到一个问题，当我按下并释放任何箭头键时，看起来它在groupboxes中的某些控件没有触发我表单上的KeyDown事件KeyUp事件。我的代码是否有可能导致此问题？

具体来说，我在表单上启用了KeyPreview，并在两个子例程中的e.SuppressKeyPress = True上设置断点，只有frmMain_KeyUp的断点到达断点。

我在两个GroupBox事件中添加了希望可以缓解这个问题，但没有这样的运气。但是，我在表单上有一个自定义控件，专门编码忽略这些按键，代码按预期工作。

  Private Sub frmMain_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles Me.KeyDown, GroupBox1.KeyDown, GroupBox2.KeyDown
      e.SuppressKeyPress = True
      Select Case e.KeyCode
          Case Keys.Left
              ScrollDir = ScrollDir Or 1
          Case Keys.Right
              ScrollDir = ScrollDir Or 2
          Case Keys.Down
              ScrollDir = ScrollDir Or 4
          Case Keys.Up
              ScrollDir = ScrollDir Or 8
          Case Else
              e.SuppressKeyPress = False
      End Select
      tScroll.Enabled = True
      tScroll_Tick(Nothing, Nothing)
  End Sub

  Private Sub frmMain_KeyUp(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles Me.KeyUp, GroupBox1.KeyUp, GroupBox2.KeyUp

      e.SuppressKeyPress = True
      Select Case e.KeyCode
          Case Keys.Left
              ScrollDir = ScrollDir And (Not 1)
          Case Keys.Right
              ScrollDir = ScrollDir And (Not 2)
          Case Keys.Down
              ScrollDir = ScrollDir And (Not 4)
          Case Keys.Up
              ScrollDir = ScrollDir And (Not 8)
          Case Else
              e.SuppressKeyPress = False
      End Select
      If ScrollDir = 0 Then tScroll.Enabled = False
  End Sub

用户控件中“忽略”按键的代码如下：

    Private Sub TileDropDown_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles Me.KeyDown
        If e.KeyValue = 40 OrElse e.KeyValue = 38 OrElse e.KeyValue = 39 OrElse e.KeyValue = 37 Then

            e.SuppressKeyPress = True
        End If
    End Sub

Answer 1

某些控件拦截keydown事件中的箭头键，但不在keyup事件中。一种解决方案是派生控件类并重写ProcessCmdKey：

Protected Overrides Function ProcessCmdKey(ByRef msg As Message, ByVal keydata As Keys) As Boolean

If keydata = Keys.Right Or keydata = Keys.Left Or keydata = Keys.Up Or keydata = Keys.Down Then
  OnKeyDown(New KeyEventArgs(keydata))
  ProcessCmdKey = True
Else
  ProcessCmdKey = MyBase.ProcessCmdKey(msg, keydata)
  End If
End Function

Answer 2

无需做太多事情，只需在加载函数中使用Me.KeyPreview = True并在vb.net的Target函数中为箭头键使用（处理Me.KeyUp）

KeyDown事件没有使用.NET WinForms触发？

2 个答案: