Clipboard event C#

Question

Is there a clipboard changed or updated event that i can access through C#?

Answer 1

There are multiple ways of doing this but this is my favorite and works for me. I've created a class library so that others may add the project and include the DLL then simply call on it and use it wherever they want within their applications.

This answer was made with the help of this one.

1. Create Class Library project and name it ClipboardHelper.
2. Replace the Class1 name with ClipboardMonitor.
3. Add the below code into it.
4. Add System.Windows.Forms reference.

More steps under code.

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

namespace ClipboardHelper
{
    public static class ClipboardMonitor
    {
        public delegate void OnClipboardChangeEventHandler(ClipboardFormat format, object data);
        public static event OnClipboardChangeEventHandler OnClipboardChange;

        public static void Start()
        {
            ClipboardWatcher.Start();
            ClipboardWatcher.OnClipboardChange += (ClipboardFormat format, object data) =>
            {
                if (OnClipboardChange != null)
                    OnClipboardChange(format, data);
            };
        }

        public static void Stop()
        {
            OnClipboardChange = null;
            ClipboardWatcher.Stop();
        }

        class ClipboardWatcher : Form
        {
            // static instance of this form
            private static ClipboardWatcher mInstance;

            // needed to dispose this form
            static IntPtr nextClipboardViewer;

            public delegate void OnClipboardChangeEventHandler(ClipboardFormat format, object data);
            public static event OnClipboardChangeEventHandler OnClipboardChange;

            // start listening
            public static void Start()
            {
                // we can only have one instance if this class
                if (mInstance != null)
                    return;

                var t = new Thread(new ParameterizedThreadStart(x => Application.Run(new ClipboardWatcher())));
                t.SetApartmentState(ApartmentState.STA); // give the [STAThread] attribute
                t.Start();
            }

            // stop listening (dispose form)
            public static void Stop()
            {
                mInstance.Invoke(new MethodInvoker(() =>
                {
                    ChangeClipboardChain(mInstance.Handle, nextClipboardViewer);
                }));
                mInstance.Invoke(new MethodInvoker(mInstance.Close));

                mInstance.Dispose();

                mInstance = null;
            }

            // on load: (hide this window)
            protected override void SetVisibleCore(bool value)
            {
                CreateHandle();

                mInstance = this;

                nextClipboardViewer = SetClipboardViewer(mInstance.Handle);

                base.SetVisibleCore(false);
            }

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

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

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

            // defined in winuser.h
            const int WM_DRAWCLIPBOARD = 0x308;
            const int WM_CHANGECBCHAIN = 0x030D;

            protected override void WndProc(ref Message m)
            {
                switch (m.Msg)
                {
                    case WM_DRAWCLIPBOARD:
                        ClipChanged();
                        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;
                }
            }

            static readonly string[] formats = Enum.GetNames(typeof(ClipboardFormat));

            private void ClipChanged()
            {
                IDataObject iData = Clipboard.GetDataObject();

                ClipboardFormat? format = null;

                foreach (var f in formats)
                {
                    if (iData.GetDataPresent(f))
                    {
                        format = (ClipboardFormat)Enum.Parse(typeof(ClipboardFormat), f);
                        break;
                    }
                }

                object data = iData.GetData(format.ToString());

                if (data == null || format == null)
                    return;

                if (OnClipboardChange != null)
                    OnClipboardChange((ClipboardFormat)format, data);
            }
        }
    }

    public enum ClipboardFormat : byte
    {
        /// <summary>Specifies the standard ANSI text format. This static field is read-only.
        /// </summary>
        /// <filterpriority>1</filterpriority>
        Text,
        /// <summary>Specifies the standard Windows Unicode text format. This static field
        /// is read-only.</summary>
        /// <filterpriority>1</filterpriority>
        UnicodeText,
        /// <summary>Specifies the Windows device-independent bitmap (DIB) format. This static
        /// field is read-only.</summary>
        /// <filterpriority>1</filterpriority>
        Dib,
        /// <summary>Specifies a Windows bitmap format. This static field is read-only.</summary>
        /// <filterpriority>1</filterpriority>
        Bitmap,
        /// <summary>Specifies the Windows enhanced metafile format. This static field is
        /// read-only.</summary>
        /// <filterpriority>1</filterpriority>
        EnhancedMetafile,
        /// <summary>Specifies the Windows metafile format, which Windows Forms does not
        /// directly use. This static field is read-only.</summary>
        /// <filterpriority>1</filterpriority>
        MetafilePict,
        /// <summary>Specifies the Windows symbolic link format, which Windows Forms does
        /// not directly use. This static field is read-only.</summary>
        /// <filterpriority>1</filterpriority>
        SymbolicLink,
        /// <summary>Specifies the Windows Data Interchange Format (DIF), which Windows Forms
        /// does not directly use. This static field is read-only.</summary>
        /// <filterpriority>1</filterpriority>
        Dif,
        /// <summary>Specifies the Tagged Image File Format (TIFF), which Windows Forms does
        /// not directly use. This static field is read-only.</summary>
        /// <filterpriority>1</filterpriority>
        Tiff,
        /// <summary>Specifies the standard Windows original equipment manufacturer (OEM)
        /// text format. This static field is read-only.</summary>
        /// <filterpriority>1</filterpriority>
        OemText,
        /// <summary>Specifies the Windows palette format. This static field is read-only.
        /// </summary>
        /// <filterpriority>1</filterpriority>
        Palette,
        /// <summary>Specifies the Windows pen data format, which consists of pen strokes
        /// for handwriting software, Windows Forms does not use this format. This static
        /// field is read-only.</summary>
        /// <filterpriority>1</filterpriority>
        PenData,
        /// <summary>Specifies the Resource Interchange File Format (RIFF) audio format,
        /// which Windows Forms does not directly use. This static field is read-only.</summary>
        /// <filterpriority>1</filterpriority>
        Riff,
        /// <summary>Specifies the wave audio format, which Windows Forms does not directly
        /// use. This static field is read-only.</summary>
        /// <filterpriority>1</filterpriority>
        WaveAudio,
        /// <summary>Specifies the Windows file drop format, which Windows Forms does not
        /// directly use. This static field is read-only.</summary>
        /// <filterpriority>1</filterpriority>
        FileDrop,
        /// <summary>Specifies the Windows culture format, which Windows Forms does not directly
        /// use. This static field is read-only.</summary>
        /// <filterpriority>1</filterpriority>
        Locale,
        /// <summary>Specifies text consisting of HTML data. This static field is read-only.
        /// </summary>
        /// <filterpriority>1</filterpriority>
        Html,
        /// <summary>Specifies text consisting of Rich Text Format (RTF) data. This static
        /// field is read-only.</summary>
        /// <filterpriority>1</filterpriority>
        Rtf,
        /// <summary>Specifies a comma-separated value (CSV) format, which is a common interchange
        /// format used by spreadsheets. This format is not used directly by Windows Forms.
        /// This static field is read-only.</summary>
        /// <filterpriority>1</filterpriority>
        CommaSeparatedValue,
        /// <summary>Specifies the Windows Forms string class format, which Windows Forms
        /// uses to store string objects. This static field is read-only.</summary>
        /// <filterpriority>1</filterpriority>
        StringFormat,
        /// <summary>Specifies a format that encapsulates any type of Windows Forms object.
        /// This static field is read-only.</summary>
        /// <filterpriority>1</filterpriority>
        Serializable,
    }
}

5. In your other projects right click on solution and Add -> Exiting Project -> ClipboardHelper.csproj
6. On your project go to and right click References -> Add Reference -> Solution -> Select ClipboardHelper.
7. In your class file of the project type using ClipboardHelper.

8. You may now type ClipboardMonitor.Start or .Stop or .OnClipboardChanged

   using ClipboardHelper;
   
   namespace Something.Something.DarkSide
   {
       public class MainWindow
       {
   
           public MainWindow()
           {
               InitializeComponent();
   
               Loaded += MainWindow_Loaded;
           }
   
           void MainWindow_Loaded(object sender, RoutedEventArgs e)
           {
               ClipboardMonitor.OnClipboardChange += ClipboardMonitor_OnClipboardChange;
               ClipboardMonitor.Start();
           }               
   
           private void ClipboardMonitor_OnClipboardChange(ClipboardFormat format, object data)
           {
               // Do Something...
           }
   }
   

Answer 2

Ok so this is an old post but we found a solution that seems very simple compared to the current set of answers. We are using WPF and we wanted to have our own custom Commands (in a ContextMenu) enable and disable if the Clipboard contains text. There is already an ApplicationCommands.Cut, Copy and Paste and these commands respond correctly to the clipboard changing. So we just added the following EventHandler.

ApplicationCommands.Paste.CanExecuteChanged += new EventHandler(Paste_CanExecuteChanged);

private void Paste_CanExecuteChanged(object sender, EventArgs e) {
  ourVariable= Clipboard.ContainsText();
}

We actually are controlling the CanExecute on our own Command this way. Works for what we needed and maybe it will help others out there.

Answer 3

here is a good example of using AddClipboardFormatListener.

In order to do that we need to pinvoke the AddClipboardFormatListener and RemoveClipboardFormatListener.

/// <summary>
/// Places the given window in the system-maintained clipboard format listener list.
/// </summary>
[DllImport("user32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool AddClipboardFormatListener(IntPtr hwnd);

/// <summary>
/// Removes the given window from the system-maintained clipboard format listener list.
/// </summary>
[DllImport("user32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool RemoveClipboardFormatListener(IntPtr hwnd);

/// <summary>
/// Sent when the contents of the clipboard have changed.
/// </summary>
private const int WM_CLIPBOARDUPDATE = 0x031D;

Then we need to add our window to the clipboard format listener list by calling the AddClipboardFormatListener method with our window’s handle as a parameter. Place the following code in your main window form constructor or any of its load events.

AddClipboardFormatListener(this.Handle);    // Add our window to the clipboard's format listener list.

Override the WndProc method so we can catch when the WM_CLIPBOARDUPDATE is send.

protected override void WndProc(ref Message m)
{
    base.WndProc(ref m);

    if (m.Msg == WM_CLIPBOARDUPDATE)
    {
        IDataObject iData = Clipboard.GetDataObject();      // Clipboard's data.

        /* Depending on the clipboard's current data format we can process the data differently.
         * Feel free to add more checks if you want to process more formats. */
        if (iData.GetDataPresent(DataFormats.Text))
        {
            string text = (string)iData.GetData(DataFormats.Text);
            // do something with it
        }
        else if (iData.GetDataPresent(DataFormats.Bitmap))
        {
            Bitmap image = (Bitmap)iData.GetData(DataFormats.Bitmap);
            // do something with it
        }
    }
}

And finally make sure to remove your main window from the clipboard format listener list before closing your form.

private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
    RemoveClipboardFormatListener(this.Handle);     // Remove our window from the clipboard's format listener list.
}

Answer 4

I had this challenge in WPF and ended up using the approach described below. For windows forms there are excellent examples elsewhere in this answer, such as the ClipboardHelper control.

For WPF we cannot override WndProc, so we have to hook it explicitly with an HwndSource AddHook call using the Source from a window. The clipboard listener still uses the AddClipboardFormatListener native interop call.

Native methods:

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);
}

Clipboard Manager class:

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;
    }
}

This gets used in a WPF window by adding the event in OnSourceInitialized or later such as the Window.Loaded event or during operation. (when we have enough information to use the native hooks):

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());
        }
    }
}

I'm using this approach in a Path of Exile item analyzer project, as the game exposes item information via the clipboard when you hit Ctrl-C.

https://github.com/ColinDabritz/PoeItemAnalyzer

I hope this helps someone with WPF clipboard change handling!

Answer 5

I think you'll have to use some p/invoke:

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

See this article on how to set up a clipboard monitor in c#

Basically you register your app as a clipboard viewer using

_ClipboardViewerNext = SetClipboardViewer(this.Handle);

and then you will recieve the WM_DRAWCLIPBOARD message, which you can handle by overriding WndProc:

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

(There's more to be done; passing things along the clipboard chain and unregistering your view, but you can get that from the article)

Answer 6

I believe one of the earlier solutions doesn't check for a null on the dispose method:

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)
    {
        if(nextClipboardViewer != null)
            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;
        }
    }
}