.net - 为 WM_MOUSEWHEEL 设置 WindowsHookEx

Question

我需要一个用 VB.NET 编写的代码示例，以使用 user32.dll 和 的低级 Hook 捕获表单外的鼠标滚轮滚动事件 WM_MOUSEWHEEL 就像 Hans Passant 在我的其他问题中回答的那样:Record mouse Middle button and wheel scroll

这是我需要做的伪示例:

Dim mousewheel_up as boolean
Dim mousewheel_down as boolean

Sub that Overides the windows messages to set the mousewheel booleans

    If mousewheel_up then msgbox("MouseWheel up")
    If mousewheel_down then msgbox("MouseWheel down")

End sub

UPDATE

试过了，但它只在表单内有效，而且我不知道如何获取增量值:

   Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Application.AddMessageFilter(New MouseWheelMessageFilter())
    End Sub

Public Class MouseWheelMessageFilter : Implements IMessageFilter

    Public Function PreFilterMessage1(ByRef m As Message) As Boolean Implements IMessageFilter.PreFilterMessage

        ' Filter out WM_MOUSEWHEEL messages, which raise the MouseWheel event,
        ' whenever the Ctrl key is pressed. Otherwise, let them through.
        Const WM_MOUSEWHEEL As Integer = &H20A

        'If m.Msg = WM_MOUSEWHEEL & My.Computer.Keyboard.CtrlKeyDown Then
        If m.Msg = WM_MOUSEWHEEL Then
            ' Process the message here.
            If Form.ActiveForm IsNot Nothing Then
                MsgBox("Mouse scrolled!")
                ' TODO: Insert your code here to adjust the size of the active form.
                ' As shown above in the If statement, you can retrieve the form that
                ' is currently active using the static Form.ActiveForm property.
                ' ...
            End If
            Return True  ' swallow this particular message
        End If
        Return False    ' but let all other messages through
    End Function

End Class

Answer 1

您需要使用 SetWindowsHookEx函数并将 Hook 类型指定为 *WH_MOUSE_LL* (14)。有以下声明。

Public Structure Point
    Public X As Integer
    Public Y As Integer
End Structure

Public Structure Msllhookstruct
    Public Location As Point
    Public MouseData As Integer
    Public Flags As Integer
    Public Time As Integer
    Public ExtraInfo As Integer
End Structure

Private Delegate Function HookProc(nCode As Integer, wParam As Integer, ByRef lParam As Msllhookstruct) As Integer

<DllImport("user32.dll", SetLastError:=True)> _
Private Function SetWindowsHookEx(ByVal hookType As Integer, ByVal lpfn As HookProc, ByVal hMod As IntPtr, ByVal dwThreadId As UInteger) As IntPtr
End Function

<DllImport("user32.dll")> _
Private Function CallNextHookEx(ByVal hhk As IntPtr, ByVal nCode As Integer, ByVal wParam As IntPtr, ByRef lParam As Msllhookstruct) As IntPtr
End Function

Private Hook As IntPtr

在您的初始化例程中，按如下方式使用它

Hook = SetWindowsHookEx(14, AddressOf Proc, Process.GetCurrentProcess().MainModule.BaseAddress.ToInt32(), 0)

其中 Proc 是一个函数回调，如下所示:

Private Function Proc(nCode As Integer, wParam As Integer, ByRef lParam As Msllhookstruct) As IntPtr
    If wParam = 522 Then
        Dim Delta = CShort(lParam.MouseData >> 16)

        If Delta > 0 Then
            ' Up
        ElseIf Delta < 0 Then
            ' Down
        End If
    End If

    Return CallNextHookEx(Hook, nCode, wParam, lParam)
End Function