C # implement the Windows clipboard monitor,

C # implement the Windows clipboard monitor,
Windows clipboard

ClipBoard is an area in memory and a very useful tool built into Windows. It uses a small ClipBoard to build a color bridge between various applications, it is possible to transmit and share information. However, in the United States, the clipboard can only retain one copy of data. When new data is imported, the old one will be overwritten.

Related Windows APIs

The most important thing is SetClipboardViewer. Whenever the content of the clipboard changes, this function adds the window to the notified window chain through the WM_DRAWCLIPBOARD message.
Because the handle of the next window in the clipboard observer chain has not been returned, the application should not pass it in SetClipboardViewer
The WM_DRAWCLIPBOARD message received during the call.
If you want to remove the window chain from the clipboard observer chain, the application must call the changyunboard member function.

        #region Definitions        //Constants for API Calls...        private const int WM_DRAWCLIPBOARD = 0x308;        private const int WM_CHANGECBCHAIN = 0x30D;        //Handle for next clipboard viewer...        private IntPtr mNextClipBoardViewerHWnd;        //API declarations...        [DllImport("user32.dll", CharSet = CharSet.Auto)]        static public extern IntPtr SetClipboardViewer(IntPtr hWndNewViewer);        [DllImport("user32.dll", CharSet = CharSet.Auto)]        static public extern bool ChangeClipboardChain(IntPtr HWnd, IntPtr HWndNext);        [DllImport("user32.dll", CharSet = CharSet.Auto)]        public static extern int SendMessage(IntPtr hWnd, int msg, int wParam, int lParam);        #endregion

Wndproc Function

The operating system sends a series of messages to the application, such as left-click and left-click lifting. The application finally submits the messages to the window through GetMessage (WndProc [windows process]). pointer to the window process defined by an application.

We need to rewrite this function to handle the clipboard content change event:

# Region Message Process // Override WndProc to get messages... protected override void WndProc (ref Message m) {switch (m. msg) {case WM_DRAWCLIPBOARD: {// The clipboard has changed... //###################################### #####################################// Process Clipboard here :)........................ //###################################### ################################### SendMessage (mNextClipBoardViewerHWnd, m. msg, m. WParam. toInt32 (), m. LParam. toInt32 (); // display the text information in the Clipboard if (Clipboard. containsText () {label1.Text = Clipboard. getText ();} // display the image information in the Clipboard if (Clipboard. containsImage () {pictureBox1.Image = Clipboard. getImage (); pictureBox1.Update ();} break;} case WM_CHANGECBCHAIN: {// Another clipboard viewer has removed itself... if (m. WParam = (IntPtr) mNextClipBoardViewerHWnd) {mNextClipBoardViewerHWnd = m. LParam;} else {SendMessage (mNextClipBoardViewerHWnd, m. msg, m. WParam. toInt32 (), m. LParam. toInt32 ();} break;} base. wndProc (ref m);} # endregion

Effect:

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