Determine which process is locking the clipboard

Question

I have a peculiar error where some process occasionally appears to be using the clipboard when my application goes to handle copy & paste operations. There are some ret

Answer 1

Based on Jeff Roe's answer, but shows how to get the text length, so could be > 500. Also handles case where window is not found.

[System.Runtime.InteropServices.DllImport("user32.dll")]
static extern IntPtr GetOpenClipboardWindow();

[System.Runtime.InteropServices.DllImport("user32.dll")]
static extern int GetWindowText(int hwnd, StringBuilder text, int count);

[System.Runtime.InteropServices.DllImport("user32.dll")]
private static extern int GetWindowTextLength(int hwnd);

private static string GetOpenClipboardWindowText()
{
    var hwnd = GetOpenClipboardWindow();
    if (hwnd == IntPtr.Zero)
    {
        return "Unknown";
    }
    var int32Handle = hwnd.ToInt32();
    var len = GetWindowTextLength(int32Handle);
    var sb = new StringBuilder(len);
    GetWindowText(int32Handle, sb, len);
    return sb.ToString();
}

Answer 2

To diagnose something like this I would suggest starting with Process Explorer, http://technet.microsoft.com/en-us/sysinternals/bb896653

Answer 3

I've wrapped my solution into an easy-to-use method (and some declarations):

[DllImport("user32.dll", SetLastError = true)]
static extern IntPtr GetOpenClipboardWindow();

[DllImport("user32.dll", SetLastError = true)]
static extern int GetWindowThreadProcessId(IntPtr hWnd, out int lpdwProcessId);

private static Process GetProcessLockingClipboard()
{
    int processId;
    GetWindowThreadProcessId(GetOpenClipboardWindow(), out processId);

    return Process.GetProcessById(processId);
}

Enjoy!

Answer 4

Here's a similar solution, but this gives you a string you can show the user:

[System.Runtime.InteropServices.DllImport("user32.dll")]
static extern IntPtr GetOpenClipboardWindow();

[System.Runtime.InteropServices.DllImport("user32.dll")]
static extern int GetWindowText(int hwnd, StringBuilder text, int count);

private string getOpenClipboardWindowText()
{
    IntPtr hwnd = GetOpenClipboardWindow();
    StringBuilder sb = new StringBuilder(501);
    GetWindowText(hwnd.ToInt32(), sb, 500);
    return sb.ToString();
}