Lock / unlock clipboard from different applications

Question

I have a two office add-in which communicates using clipboard, for example: copy and paste table or picture from excel to word. While copy\paste operation running, user can corrupt data in clipboard if he copy something in clipboard. I tried lock clipboard after copy in first application and unlock clipboard before paste in second application.

I can lock Clipboard in one application, but can't unlock it in another application

This is class with wrappers for Clipboard

public class MyClipboard
    {
        [DllImport("user32.dll", SetLastError = true)]
        [return: MarshalAs(UnmanagedType.Bool)]
        private static extern bool OpenClipboard(IntPtr hwnd);

        [DllImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        private static extern bool CloseClipboard();

        public void Close()
        {
            CloseClipboard();
        }

        public void Open()
        {
            OpenClipboard(IntPtr.Zero);
        }
    }

First application :

    MyClipboard clipboard = new MyClipboard();
                clipboard.Open();
    ...

Second application :

 MyClipboard clipboard = new MyClipboard();
                clipboard.Close();
    ...

What should I do to Open clipboard from one application, and close clipboard from another application?

Thanks!

Please share a bool result of the `CloseClipboard()` and the corresponding `GetLastError()`. Maybe `CloseClipboard` can only be called from the same `HWND` which was specified in the `OpenClipboard`. — Dmitry, Mar 21 '14 at 11:41
Keep in mind the the clipboard is provided for the convenience of the USER, not the PROGRAMMER. What you are attempting to do (block users from using the clipboard) is just wrong. — Chris Thornton, Mar 23 '14 at 21:50
@ChrisThornton although your point is generally valid, office add-ins access more-or-less the same API as VBA scripts, which means it's basically just for user automation. There are marshalled COM objects which are not properly exposed to your code but are copy-pastable (for example you can move a PPT slide by copy-paste but good luck moving it in any other way). — vinczemarton, Jul 04 '17 at 12:26

score 1 · Answer 1 · edited May 23 '17 at 10:31

Rather than using the clipboard to share data between your apps (as you say the user could modify the clipboard) I'd use something like a

Shared known file (with some file watching) could be slow
Named Pipes (could be over complex)
WCF (massive overkill)
Memory Mapped files (Could be hard in .NET) http://msdn.microsoft.com/en-us/library/ms810613.aspx

Here is someothers ideas.. What is the simplest method of inter-process communication between 2 C# processes?

If you really want to use the clipboard you could put in some extra custom attributes to the format to make sure that user has not used the clipboard themselves. But it seems like bad practice to use the clipboard in this way, but that's my opion.

HTH. David

Lock / unlock clipboard from different applications

1 Answers1