Firefox ONPASTE: Get the text to be pasted?

[Jim Douglas]

I'm in the process of implementing a text control from Swing
(JFormattedTextField) to GWT.  One of the requirements is that when
the user pastes in a block of text, I can't just let the default
action occur; I have to filter the text through a mask.  Given that
requirement, I need to be able to intercept the text the user is about
to paste into a TextBox.

I've got a solution that seems to be working perfectly in IE and
WebKit (Chrome/Safari).  There's an open Mozilla bug requesting this
feature (https://bugzilla.mozilla.org/show_bug.cgi?id=407983), but
it's not clear when it will be resolved.

Here's what I have so far, plugged in to the StockWatcher sample app
for ease of testing.  Does anyone know of a reliable way to make this
work in Firefox?

(1) Create the nameField TextBox like this:

    final TextBox nameField = new TextBox()
    {
        @Override
        public void onBrowserEvent(Event event)
        {
            super.onBrowserEvent(event);
            switch (event.getTypeInt())
            {
                case Event.ONPASTE:
                {
                    event.preventDefault();
                    String text = getPastedText(event);
                    if (text.length() > 0)
                    {
                        Window.alert("Pasted: "+text);
                    }
                    break;
                }
            }
        }
    };
    nameField.sinkEvents(Event.ONPASTE);

(2) Add this methodt:

    public static native String getPastedText(Event event)
    /*-{

        var text = "";

        if (event.clipboardData) // WebKit/Chrome/Safari
        {
            try
            {
                text = event.clipboardData.getData("Text");
                return text;
            }
            catch (e)
            {
                // Hmm, that didn't work.
            }
        }

        if ($wnd.clipboardData) // IE
        {
            try
            {
                text = $wnd.clipboardData.getData("Text");
                return text;
            }
            catch (e)
            {
                // Hmm, that didn't work.
            }
        }

        // Ok, last chance.  Firefox refuses to make this easy:
        // https://bugzilla.mozilla.org/show_bug.cgi?id=407983
        // And this ridiculous approach is unlikely to work.
        // But try it anyway; we have nothing to lose.
        // We can ignore Opera; it doesn't even fire ONPASTE.

        try
        {
            if (netscape.security.PrivilegeManager.enablePrivilege)
            {
 
netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");
            }
            else
            {
                return "";
            }
        }
        catch (ex)
        {
            return "";
        }

        var clip = Components.classes["@mozilla.org/widget/clipboard;
1"].getService(Components.interfaces.nsIClipboard);
        if (!clip) return "";

        var trans = Components.classes["@mozilla.org/widget/
transferable;
1"].createInstance(Components.interfaces.nsITransferable);
        if (!trans) return "";

        trans.addDataFlavor("text/unicode");
        clip.getData(trans, clip.kGlobalClipboard);

        var str = new Object();
        var strLength = new Object();

        trans.getTransferData("text/unicode", str, strLength);
        if (str) str =
str.value.QueryInterface(Components.interfaces.nsISupportsString);
        if (str) text = str.data.substring(0, strLength.value / 2);

        return text;

    }-*/;

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