.Net TrackMouseEvent 不适用于子菜单项答案

【问题标题】：.Net TrackMouseEvent not working with Sub Menu Items.Net TrackMouseEvent 不适用于子菜单项
【发布时间】：2011-09-07 15:31:28
【问题描述】：

我正在向我创建的自定义 ContextMenuStrip 控件添加一些功能。

我需要做的第一件事是增加鼠标悬停在子菜单上下文项上的时间。以下代码适用于主要上下文项，但不会触发子菜单项的鼠标悬停事件。

我认为问题在于我需要将 tme.hWnd 句柄设置为子菜单。如果是这种情况，我如何在打开子菜单时获取子菜单的句柄？

谢谢！

    Friend Const WM_MOUSEMOVE As Integer = &H200
    Friend Const WM_MOUSELEAVE As Integer = &H2A3
    Friend Const TME_LEAVE As Integer = &H2

    Private _mouseOver As Boolean = False
    Private _mouseOverHandel As IntPtr = Me.Handle

    Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)

        Select Case m.Msg
            Case WM_MOUSEMOVE
                If Not _mouseOver Then

                    Dim tme As New TRACKMOUSEEVENTR()
                    tme.hWnd = _mouseOverHandel
                    tme.cbSize = Marshal.SizeOf(GetType(TRACKMOUSEEVENTR))
                    tme.dwFlags = TMEFlags.TME_HOVER
                    tme.dwHoverTime = 1000 * 3
                    TrackMouseEvent(tme)

                    _mouseOver = True
                End If

                MyBase.WndProc(m)
                Exit Select

            Case WM_MOUSELEAVE
                _mouseOver = False
                MyBase.WndProc(m)
                Exit Select

            Case Else
                MyBase.WndProc(m)
        End Select

    End Sub


    <DllImport("user32.dll")> _
    Private Shared Function TrackMouseEvent(ByRef lpEventTrack As TRACKMOUSEEVENTR) As Integer
    End Function

    <StructLayout(LayoutKind.Sequential)> _
    Public Structure TRACKMOUSEEVENTR
        Public cbSize As Int32
        ' using Int32 instead of UInt32 is safe here, and this avoids casting the result  of Marshal.SizeOf()
        <MarshalAs(UnmanagedType.U4)> _
        Public dwFlags As TMEFlags
        Public hWnd As IntPtr
        Public dwHoverTime As UInt32

        Public Sub New(dwFlags As Int32, hWnd As IntPtr, dwHoverTime As UInt32)
            Me.cbSize = Marshal.SizeOf(GetType(TRACKMOUSEEVENTR))
            Me.dwFlags = dwFlags
            Me.hWnd = hWnd
            Me.dwHoverTime = dwHoverTime
        End Sub
    End Structure

    ''' <summary>
    ''' The services requested. This member can be a combination of the following values. 
    ''' </summary>
    <Flags()> _
    Public Enum TMEFlags As UInteger
        TME_CANCEL = &H80000000UI
        TME_HOVER = &H1
        TME_LEAVE = &H2
        TME_NONCLIENT = &H10
        TME_QUERY = &H40000000
    End Enum

【问题讨论】：

子菜单项没有句柄。解决这个问题并不容易，它们的鼠标处理被锁定在 Winforms 中。

标签： vb.net winapi custom-controls contextmenu

【解决方案1】：

我不得不用另一种方法来解决这个问题。我会把它留在这里给需要的人。

我为我的动态子菜单项创建了一个 MouseMove 和 MouseLeave 处理程序。

MouseMove 内部

If Not _mouseSubOver Then

    _tsmi = sender

    _itemDelayTimer = New Timer()
    _itemDelayTimer.Interval = Math.Max(1, 1500)
    AddHandler _itemDelayTimer.Tick, AddressOf OnDelayTimerExpire
    _itemDelayTimer.Start()

    _mouseSubOver = True

End If

鼠标离开内部

If _itemDelayTimer IsNot Nothing Then
    _itemDelayTimer.Stop()
    _itemDelayTimer.Dispose()
    _itemDelayTimer = Nothing
End If

_mouseSubOver = False

OnDelayTimerExpire 内

 Private Sub OnDelayTimerExpire(sender As Object, e As EventArgs)
        If _itemDelayTimer IsNot Nothing Then

            _itemDelayTimer.Stop()
            _itemDelayTimer.Dispose()
            _itemDelayTimer = Nothing

        End If

        'Do your sub menu stuff here
 End Sub

【讨论】：