How do I monitor clipboard content changes in C#?

Question

I want to have this feature in my C# program: When the user do Ctrl + C or Copy anywhere (i.e. when the clipboard content changes), my program will get notified, and check whether the content met certain criteria, if so, become the active program, and process the content, etc.

I can get the contents out from System.Windows.Forms.Clipboard, however, I don't know how to monitor the content changes from the clipboard.

If using Windows Vista or later, use AddClipboardFormatListener as in John Knoeller's answer, for Windows XP, I have to use the older, more fragile SetClipboardViewer API, as in the accepted answer.

How to do this in WPF is here: http://stackoverflow.com/a/33018459/2122718 — marbel82, Jul 05 '16 at 12:17
[SharpClipboard](https://github.com/Willy-Kimura/SharpClipboard) as a library could be of more benefit as it encapsulates the same features into one fine component library. You can then access its `ClipboardChanged` event and detect various data-formats when they're cut/copied. — Willy Kimura, Feb 07 '19 at 10:38

score 57 · Answer 1 · answered Aug 10 '12 at 12:29

I've written up a small utility class that uses the AddClipboardFormatListener function function with a Message-only window to do just this.

/// <summary>
/// Provides notifications when the contents of the clipboard is updated.
/// </summary>
public sealed class ClipboardNotification
{
    /// <summary>
    /// Occurs when the contents of the clipboard is updated.
    /// </summary>
    public static event EventHandler ClipboardUpdate;

    private static NotificationForm _form = new NotificationForm();

    /// <summary>
    /// Raises the <see cref="ClipboardUpdate"/> event.
    /// </summary>
    /// <param name="e">Event arguments for the event.</param>
    private static void OnClipboardUpdate(EventArgs e)
    {
        var handler = ClipboardUpdate;
        if (handler != null)
        {
            handler(null, e);
        }
    }

    /// <summary>
    /// Hidden form to recieve the WM_CLIPBOARDUPDATE message.
    /// </summary>
    private class NotificationForm : Form
    {
        public NotificationForm()
        {
            NativeMethods.SetParent(Handle, NativeMethods.HWND_MESSAGE);
            NativeMethods.AddClipboardFormatListener(Handle);
        }

        protected override void WndProc(ref Message m)
        {
            if (m.Msg == NativeMethods.WM_CLIPBOARDUPDATE)
            {
                OnClipboardUpdate(null);
            }
            base.WndProc(ref m);
        }
    }
}

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);

    // See http://msdn.microsoft.com/en-us/library/ms633541%28v=vs.85%29.aspx
    // See http://msdn.microsoft.com/en-us/library/ms649033%28VS.85%29.aspx
    [DllImport("user32.dll", SetLastError = true)]
    public static extern IntPtr SetParent(IntPtr hWndChild, IntPtr hWndNewParent);
}

This class assumes that the notifications are always needed for the duration of the applications lifetime, however it could be modified to provide the ability to unsubscribe via the RemoveClipboardFormatListener function if required.

@tofutim No, I'm not sure what API is available on XP machines which can do this — Justin, May 15 '13 at 22:53
[this is for XP](http://stackoverflow.com/a/2226957/3331861) — Nilay Vishwakarma, Dec 29 '16 at 09:33
Likewise, you can also try [SharpClipboard](https://github.com/Willy-Kimura/SharpClipboard). It provides a `ClipboardChanged` event that allows you to filter various data-formats whenever they're cut/copied and get the clipboard content. — Willy Kimura, Feb 07 '19 at 10:40
Note: You should always remove your window from the clipboard notification change before you exit your app. — dynamichael, Jul 24 '22 at 01:13

John Knoeller · Answer 2 · 2010-02-09T10:57:37.057

16

You can do this with pinvoke to the Win32 API AddClipboardFormatListener

The listener is a window handle (Form.Handle), and the form will be notified of changes with a WM_CLIPBOARDUPDATE notification

It is a more robust replacement for the older SetClipboardViewer API.

edited Feb 09 '10 at 10:57

answered Feb 09 '10 at 05:29

John Knoeller

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Thanks. but on the msdn page, the minimum OS requirement for this API is Vista. is that true? (I'm still under XP though. in fact, my users will be using XP, too.) – Weiming Feb 09 '10 at 22:58
2

Yes, minimum requirement is Vista. If you are on XP then you have no choice than to use SetClipboarViewer. Be aware that SetClipboardViewer is fragile, although you should have no problems if _your_ code is correct and you are the _only_ viewer. – John Knoeller Feb 09 '10 at 23:32
Ok, I will be very cautious. Your answer would otherwise be the best. Thanks! – Weiming Feb 10 '10 at 00:03

score 14 · Accepted Answer · edited Jul 08 '19 at 20:25

14

You could use SetClipboardViewer provided by Win32 API (through P/Invoke).

Here is a page which contains code to set one up in C#: http://www.codeguru.com/csharp/.net/net_general/tipstricks/article.php/c7315/

edited Jul 08 '19 at 20:25

Peter Mortensen

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answered Feb 09 '10 at 05:30

10

SetClipboardViewer is an fragile, older API, you should not be using it in new code. use AddClipboardFormatListener instead. – John Knoeller Feb 09 '10 at 10:52
1

Likewise, you can also try [SharpClipboard](https://github.com/Willy-Kimura/SharpClipboard). It provides a `ClipboardChanged` event that allows you to filter various data-formats whenever they're cut/copied and get the clipboard content. – Willy Kimura Feb 07 '19 at 10:41
2

The second link is broken. – Peter Mortensen Jul 08 '19 at 20:25

score 3 · Answer 4 · answered Feb 09 '10 at 05:31

3

The Win32 API contains a function SetClipboardViewer.

Here is a pretty good (from a quick glance) write up.

answered Feb 09 '10 at 05:31

µBio

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that's a good example, too. Thanks! – Weiming Feb 09 '10 at 23:00

How do I monitor clipboard content changes in C#?

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