Question

在我的C＃3.5 Windows窗体应用程序中，我有一些SplitContainers。每个内部都有一个列表控件（dock fill）。当焦点在其中一个控件上并移动鼠标滚轮时，滚动显示现在聚焦的列表。

我的任务是滚动当前由鼠标悬停的列表，而不是选中的列表。是否可以在Windows窗体中？如果没有，是否可以使用PInvoke？

Answer 1

看起来您可以使用IMessageFilter和PInvoke来处理此问题。可以在Redirect Mouse Wheel Events to Unfocused Windows Forms Controls找到VB中的示例。您应该可以轻松地将其转换为C＃。

兴趣点

此类对给定任务使用以下技术：

收听控件的MouseEnter和MouseLeave事件，以确定鼠标指针何时在控件上。
实现IMessageFilter以捕获应用程序中的WM_MOUSEWHEEL消息。
PInvoke Windows API调用SendMessage将WM_MOUSEWHEEL消息重定向到控件的句柄。
IMessageFilter对象实现为MouseWheelRedirector类的单例，并由共享成员Attach，Detach和Active访问。

使用a VB.NET to C# converter，这就是你最终得到的结果：

using System;
using System.Collections;
using System.Collections.Generic;
using System.Data;
using System.Diagnostics;

using System.Windows.Forms;
using System.Runtime.InteropServices;

public class MouseWheelRedirector : IMessageFilter
{
    private static MouseWheelRedirector instance = null;
    private static bool _active = false;
    public static bool Active
    {
       get { return _active; }
       set
       { 
          if (_active != value) 
          {
             _active = value;
             if (_active)
             {
                if (instance == null)
                {
                    instance = new MouseWheelRedirector();
                }
                Application.AddMessageFilter(instance);
             }
             else
             {
                if (instance != null)
                {
                   Application.RemoveMessageFilter(instance);
                }
             }
          }
       }
    }

    public static void Attach(Control control)
    {
       if (!_active)
          Active = true;
       control.MouseEnter += instance.ControlMouseEnter;
       control.MouseLeave += instance.ControlMouseLeaveOrDisposed;
       control.Disposed += instance.ControlMouseLeaveOrDisposed;
    }

    public static void Detach(Control control)
    {
       if (instance == null)
          return;
       control.MouseEnter -= instance.ControlMouseEnter;
       control.MouseLeave -= instance.ControlMouseLeaveOrDisposed;
       control.Disposed -= instance.ControlMouseLeaveOrDisposed;
       if (object.ReferenceEquals(instance.currentControl, control))
          instance.currentControl = null;
    }

    private MouseWheelRedirector()
    {
    }


    private Control currentControl;
    private void ControlMouseEnter(object sender, System.EventArgs e)
    {
       var control = (Control)sender;
       if (!control.Focused)
       {
          currentControl = control;
       }
       else
       {
          currentControl = null;
       }
    }

    private void ControlMouseLeaveOrDisposed(object sender, System.EventArgs e)
    {
       if (object.ReferenceEquals(currentControl, sender))
       {
          currentControl = null;
       }
    }

    private const int WM_MOUSEWHEEL = 0x20a;
    public bool PreFilterMessage(ref System.Windows.Forms.Message m)
    {
       if (currentControl != null && m.Msg == WM_MOUSEWHEEL)
       {
          SendMessage(currentControl.Handle, m.Msg, m.WParam, m.LParam);
          return true;
       }
       else
       {
          return false;
       }
    }

    [DllImport("user32.dll", SetLastError = false)]
    private static extern IntPtr SendMessage(
       IntPtr hWnd, int msg, IntPtr wParam, IntPtr lParam);
 }

Answer 2

我有类似的问题并找到了这个帖子......所以发布我迟到的答案给其他可能找到这个帖子的人。在我的情况下，我只是希望鼠标滚轮事件转到光标下的任何控件...就像右键单击一样（如果右键单击转到焦点控件而不是光标下的控件，那将会很困惑...我认为鼠标滚轮也是如此，除非我们已经习惯了它。）

无论如何，答案非常简单。只需将PreFilterMessage添加到您的应用程序中，并将鼠标滚轮事件重定向到鼠标下的控件：

    public bool PreFilterMessage(ref Message m)
    {
        switch (m.Msg)
        {
            case WM_MOUSEWHEEL:   // 0x020A
            case WM_MOUSEHWHEEL:  // 0x020E
                IntPtr hControlUnderMouse = WindowFromPoint(new Point((int)m.LParam));
                if (hControlUnderMouse == m.HWnd)
                    return false; // already headed for the right control
                else
                {
                    // redirect the message to the control under the mouse
                    SendMessage(hControlUnderMouse, m.Msg, m.WParam, m.LParam);
                    return true;
                } 
             default: 
                return false; 
           } 
}

Answer 3

使用Control.MouseEnter Event将焦点设置为控件。例如。使用ActiveControl Property

Answer 4

Brian Kennedy 的回答以 Hank Schultz 评论完成：

首先，你应该让一个类实现 IMessageFilter ：

public class MessageFilter : IMessageFilter
{
    private const int WM_MOUSEWHEEL = 0x020A;
    private const int WM_MOUSEHWHEEL = 0x020E;

    [DllImport("user32.dll")]
    static extern IntPtr WindowFromPoint(Point p);
    [DllImport("user32.dll", CharSet = CharSet.Auto)]
    static extern IntPtr SendMessage(IntPtr hWnd, UInt32 Msg, IntPtr wParam, IntPtr lParam);

    public bool PreFilterMessage(ref Message m)
    {
        switch (m.Msg)
        {
            case WM_MOUSEWHEEL:
            case WM_MOUSEHWHEEL:
                IntPtr hControlUnderMouse = WindowFromPoint(new Point((int)m.LParam));
                if (hControlUnderMouse == m.HWnd)
                {
                    //Do nothing because it's already headed for the right control
                    return false;
                }
                else
                {
                    //Send the scroll message to the control under the mouse
                    uint u = Convert.ToUInt32(m.Msg);   
                    SendMessage(hControlUnderMouse, u, m.WParam, m.LParam);
                    return true;
                }
            default:
                return false;
        }
    }
}

使用示例：

public partial class MyForm : Form
{
    MessageFilter mf = null;

    private void MyForm_Load(object sender, EventArgs e)
    {
        mf= new MessageFilter();
        Application.AddMessageFilter(mf);
    }

    private void MyForm_FormClosing(object sender, FormClosingEventArgs e)
    {
        Application.RemoveMessageFilter(mf);
    }
}

鼠标滚轮事件与悬停控件一起使用

4 个答案: