CopyingHandler OnCopy method in RichTextBox does not work as expected about emoji.wpf HOT 5 CLOSED

 protected void OnCopy(object o, DataObjectCopyingEventArgs e)
{
    string clipboard = "";

    for (TextPointer p = MsgViewer.Selection.Start, next = null;
            p != null && p.CompareTo(MsgViewer.Selection.End) < 0;
            p = next)
    {
        next = p.GetNextInsertionPosition(LogicalDirection.Forward);
        if (next == null)
            break;

        var t = new TextRange(p, next);
        var emoji = (next.Parent as Run)?.PreviousInline as Emoji.Wpf.EmojiInline;
        if (next.Parent != p.Parent && emoji == null) emoji = (p.Parent as Run)?.NextInline as Emoji.Wpf.EmojiInline;
        if ((p.Parent as Run).PreviousInline != emoji && emoji != null) clipboard += emoji?.Text;
        else clipboard += t.Text;
    }

    Clipboard.SetText(clipboard);
    e.Handled = true;
    e.CancelCommand();
}