C# 监视粘贴板

public partial class FrmMain : Form{private const int WM_DRAWCLIPBOARD = 0x308;private const int WM_CHANGECBCHAIN = 0x30D;private IntPtr nextClipHwnd;[DllImport("user32")]private static extern IntPtr SetClipboardViewer(IntPtr hwnd);[DllImport("user32")]private static extern IntPtr ChangeClipboardChain(IntPtr hwnd, IntPtr hWndNext);[DllImport("user32")]private static extern int SendMessage(IntPtr hwnd, int wMsg, IntPtr wParam, IntPtr lParam);public FrmMain(){InitializeComponent();}private void FrmMain_Load(object sender, EventArgs e){nextClipHwnd = SetClipboardViewer(this.Handle);}protected override void WndProc(ref Message m){switch (m.Msg){case WM_DRAWCLIPBOARD://将WM_DRAWCLIPBOARD消息传递到下一个观察链中的窗口SendMessage(nextClipHwnd, m.Msg, m.WParam, m.LParam);IDataObject data = Clipboard.GetDataObject();if (data.GetDataPresent(DataFormats.Text) | data.GetDataPresent(DataFormats.OemText)){this.richTextBox1.Text = (String)data.GetData(DataFormats.Text);}break;default:base.WndProc(ref m);break;}}private void FrmMain_FormClosed(object sender, FormClosedEventArgs e){//从观察链中删除本观察窗口ChangeClipboardChain(this.Handle, nextClipHwnd);//将WM_DRAWCLIPBOARD消息传递到下一个观察链中的窗口 SendMessage(nextClipHwnd, WM_CHANGECBCHAIN, this.Handle, nextClipHwnd);}}