问如何在C#中监视剪贴板更改？

EN

[DllImport("User32.dll", CharSet=CharSet.Auto)]
public static extern IntPtr SetClipboardViewer(IntPtr hWndNewViewer);

_ClipboardViewerNext = SetClipboardViewer(this.Handle);

protected override void WndProc(ref Message m)
{
    switch ((Win32.Msgs)m.Msg)
    {
        case Win32.Msgs.WM_DRAWCLIPBOARD:
        // Handle clipboard changed
        break;
        // ... 
   }
}

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

namespace ClipboardAssist {

// Must inherit Control, not Component, in order to have Handle
[DefaultEvent("ClipboardChanged")]
public partial class ClipboardMonitor : Control 
{
    IntPtr nextClipboardViewer;

    public ClipboardMonitor()
    {
        this.BackColor = Color.Red;
        this.Visible = false;

        nextClipboardViewer = (IntPtr)SetClipboardViewer((int)this.Handle);
    }

    /// <summary>
    /// Clipboard contents changed.
    /// </summary>
    public event EventHandler<ClipboardChangedEventArgs> ClipboardChanged;

    protected override void Dispose(bool disposing)
    {
        ChangeClipboardChain(this.Handle, nextClipboardViewer);
    }

    [DllImport("User32.dll")]
    protected static extern int SetClipboardViewer(int hWndNewViewer);

    [DllImport("User32.dll", CharSet = CharSet.Auto)]
    public static extern bool ChangeClipboardChain(IntPtr hWndRemove, IntPtr hWndNewNext);

    [DllImport("user32.dll", CharSet = CharSet.Auto)]
    public static extern int SendMessage(IntPtr hwnd, int wMsg, IntPtr wParam, IntPtr lParam);

    protected override void WndProc(ref System.Windows.Forms.Message m)
    {
        // defined in winuser.h
        const int WM_DRAWCLIPBOARD = 0x308;
        const int WM_CHANGECBCHAIN = 0x030D;

        switch (m.Msg)
        {
            case WM_DRAWCLIPBOARD:
                OnClipboardChanged();
                SendMessage(nextClipboardViewer, m.Msg, m.WParam, m.LParam);
                break;

            case WM_CHANGECBCHAIN:
                if (m.WParam == nextClipboardViewer)
                    nextClipboardViewer = m.LParam;
                else
                    SendMessage(nextClipboardViewer, m.Msg, m.WParam, m.LParam);
                break;

            default:
                base.WndProc(ref m);
                break;
        }
    }

    void OnClipboardChanged()
    {
        try
        {
            IDataObject iData = Clipboard.GetDataObject();
            if (ClipboardChanged != null)
            {
                ClipboardChanged(this, new ClipboardChangedEventArgs(iData));
            }

        }
        catch (Exception e)
        {
            // Swallow or pop-up, not sure
            // Trace.Write(e.ToString());
            MessageBox.Show(e.ToString());
        }
    }
}

public class ClipboardChangedEventArgs : EventArgs
{
    public readonly IDataObject DataObject;

    public ClipboardChangedEventArgs(IDataObject dataObject)
    {
        DataObject = dataObject;
    }
}
}

internal static class NativeMethods
{
    // See http://msdn.microsoft.com/en-us/library/ms649021%28v=vs.85%29.aspx
    public const int WM_CLIPBOARDUPDATE = 0x031D;
    public static IntPtr HWND_MESSAGE = new IntPtr(-3);

    // See http://msdn.microsoft.com/en-us/library/ms632599%28VS.85%29.aspx#message_only
    [DllImport("user32.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    public static extern bool AddClipboardFormatListener(IntPtr hwnd);
}

using System.Windows;
using System.Windows.Interop;

public class ClipboardManager
{
    public event EventHandler ClipboardChanged;

    public ClipboardManager(Window windowSource)
    {
        HwndSource source = PresentationSource.FromVisual(windowSource) as HwndSource;
        if(source == null)
        {
            throw new ArgumentException(
                "Window source MUST be initialized first, such as in the Window's OnSourceInitialized handler."
                , nameof(windowSource));
        }

        source.AddHook(WndProc);

        // get window handle for interop
        IntPtr windowHandle = new WindowInteropHelper(windowSource).Handle;

        // register for clipboard events
        NativeMethods.AddClipboardFormatListener(windowHandle);
    }

    private void OnClipboardChanged()
    {
        ClipboardChanged?.Invoke(this, EventArgs.Empty);
    }

    private static readonly IntPtr WndProcSuccess = IntPtr.Zero;

    private IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
    {
        if (msg == NativeMethods.WM_CLIPBOARDUPDATE)
        {
            OnClipboardChanged();
            handled = true;
        }

        return WndProcSuccess;
    }
}

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }

    protected override void OnSourceInitialized(EventArgs e)
    {
        base.OnSourceInitialized(e);

        // Initialize the clipboard now that we have a window soruce to use
        var windowClipboardManager = new ClipboardManager(this);
        windowClipboardManager.ClipboardChanged += ClipboardChanged;
    }

    private void ClipboardChanged(object sender, EventArgs e)
    {
        // Handle your clipboard update here, debug logging example:
        if (Clipboard.ContainsText())
        {
            Debug.WriteLine(Clipboard.GetText());
        }
    }
}