Intercept Ctrl-V or WM_PASTE in AxSHDocVw.AxWebBrowser and do cleanup

Question

I am using a winform HTML Editor which uses AxSHDocVw.AxWebBrowser. User are copying and pasting text from other software into this control. The problem is that, on paste Ctrl-V it add few font tags to preserve formatting. I do not want to preserve formatting, it should paste clean text without formatting or at least should not add there FONT tags. What i think is to intercept Ctrl-V and before pasting cleanup clipboard text.

So, I tried to intercept WM_PASTE message and replace clipboard content with fixed test (just to check) as below

class myWB : AxSHDocVw.AxWebBrowser
{
    protected override void WndProc(ref Message m)
    {
        if (m.Msg == 0x302)     // Trap WM_PASTE:
        {
            Clipboard.Clear();
            Clipboard.SetText("some text");
            return;
        }
        base.WndProc(ref m);
    }
}

But it was not working. I added following before IF block to see if it is receiving WM_PASTE message.

Debug.WriteLine(m.Msg);

On run, i didn't see there 0x302 (770) in output window even after multiple Ctrl-V.

Is it not receiving that message?

Then what is the way to do it? How do i cleanup text before paste?

Answer 1

WM_PASTE is not a notification, it is a command. That you'd send to an EDIT control to have it paste the clipboard into the control.

Of course a web browser is not an edit box so doesn't do it the same way. You will need to intercept the IHtmlElement2.onpaste event instead.