How to lock the clipboard?

Question

I was wondering if there is anyway to lock and unlock the clipboard from C#. Basically, I'd be writing something into it and I do not want anyone else to write to it before I pick up my stuff.

How can I do this?

Answer 1

The OpenClipboard() API function, followed by EmptyClipboard() locks the clipboard until CloseClipboard is called. You should probably pass a window handle of a window in the target process, but zero works.

Here's a C# console app that worked for me when I wanted to test that my application gracefully handled a rogue application locking the clipboard.

class Program
{
    [DllImport("user32.dll", EntryPoint = "OpenClipboard", SetLastError = true)]
    private static extern bool OpenClipboard(IntPtr hWndNewOwner);

    [DllImport("user32.dll", SetLastError = true)]
    private static extern bool CloseClipboard();

    [DllImport("user32.dll", SetLastError = true)]
    private static extern bool EmptyClipboard();

    static void Main(string[] args)
    {
        OpenClipboard(new IntPtr(0));
        EmptyClipboard();
        Console.WriteLine("Clipboard locked. Press enter to unlock and exit.");
        Console.ReadLine();
        CloseClipboard();
    }
}

These declarations came from pinvoke.net.