ClipboardHook

There are three ways of monitoring changes to the clipboard. The oldest method is to create a clipboard viewer window. Windows 2000 added the ability to query the clipboard sequence number, and Windows Vista added support for clipboard format listeners.

A clipboard viewer window displays the current content of the clipboard, and receives messages when the clipboard content changes. A clipboard format listener is a window which has registered to be notified when the contents of the clipboard has changed.

On Windows Vista and later, ClipboardHook will create a clipboard format listener to listen for clipboard updates. On earlier versions it will create a clipboard viewer window instead.

Use this component

If you have not already added it to your project, install the package from NuGet:

Install-Package NetEx.Hooks

Use the Install method to install the clipboard hook. Then subscribe to the ClipboardUpdated event.

Example

The following example uses the Windows Forms Button control's Click event handler to install and uninstall the ClipboardHook. When the hook is installed, every change to the clipboard contents will increment the count Label.

using NetEx.Hooks;
using System;
using System.Windows.Forms;

public class ClipboardHookForm : Form
{
    [STAThread]
    public static void Main()
    {
        Application.SetCompatibleTextRenderingDefault(false);
        Application.EnableVisualStyles();
        Application.Run(new ClipboardHookForm());
    }

    private Button selectButton;
    private Label changeCountLabel;
    private int changeCount;
    private bool hooked;

    public ClipboardHookForm()
    {
        selectButton = new Button
        {
            Size = new Size(150, 20),
            Location = new Point(15, 15),
            Text = "Hook clipboard"
        };
        changeCountLabel = new Label
        {
            Size = new Size(200, 20),
            Location = new Point(15, 50),
            Text = "Clipboard change count: 0"
        };
        selectButton.Click += new EventHandler(SelectButton_Click);
        ClientSize = new Size(330, 360);
        Controls.Add(selectButton);
        Controls.Add(changeCountLabel);

        ClipboardHook.ClipboardUpdated += () =>
        {
            changeCount++;
            // Invoke back on the UI thread
            this.Invoke(() => changeCountLabel.Text = $"Clipboard change count: {changeCount}");
        };
    }
    private void SelectButton_Click(object sender, EventArgs e)
    {
        if (hooked)
        {
            if (ClipboardHook.TryUninstall())
            {
                selectButton.Text = "Hook clipboard";
                hooked = false;
            }
        }
        else
        {
            if (ClipboardHook.TryInstall())
            {
                selectButton.Text = "Unhook clipboard";
                hooked = true;
            }
        }
    }
}

Applies to

Product	Versions
.NET Framework	2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
Windows Desktop	5, 6, 7, 8, 9

See Also

Monitoring Clipboard Contents