gtk_text_buffer_delete ?

[Pierre Wieser <pwieser trychlos org>]

Hello, 

On the application I'm currently working on [1], I want limit the size of the
text entered in a GtkTextBuffer to those saved in the DBMS, so 4096 chars.

I so connected to the 'changed' signal of the GtkTextBuffer, and the handler
is :

static void
on_notes_changed( GtkTextBuffer *buffer, void *empty )
{
        static const gchar *thisfn = "my_utils_on_notes_changed";
        static const gint MAX_LENGTH = 4096;
        static gboolean in = FALSE;
        gint count;
        GtkTextIter start, end;

        /* prevent an infinite recursion */
        if( !in ){
                count = gtk_text_buffer_get_char_count( buffer );
                if( count >= MAX_LENGTH ){
                        /*
                         * this code works, but emit the following Gtk-Warning:
                         *
                         * Invalid text buffer iterator: either the iterator is
                         * uninitialized, or the characters/pixbufs/widgets in the
                         * buffer have been modified since the iterator was created.
                         * You must use marks, character numbers, or line numbers to
                         * preserve a position across buffer modifications.
                         * You can apply tags and insert marks without invalidating
                         * your iterators, but any mutation that affects 'indexable'
                         * buffer contents (contents that can be referred to by character
                         * offset) will invalidate all outstanding iterators
                         */
                        gtk_text_buffer_get_iter_at_offset( buffer, &start, MAX_LENGTH-1 );
                        /*gtk_text_iter_backward_char( &start );*/
                        /*gtk_text_buffer_get_iter_at_offset( buffer, &end, count );*/
                        gtk_text_buffer_get_end_iter( buffer, &end );
                        /*gtk_text_iter_backward_char( &end );*/
                        in = TRUE;
                        g_debug( "%s: count=%d, start=%d, end=%d",
                                        thisfn, count, gtk_text_iter_get_offset( &start ), 
gtk_text_iter_get_offset( &end ));
                        gtk_text_buffer_delete( buffer, &start, &end );
                        in = FALSE;
                }
        }
}

As stated in the comment, the code works (the size if actually limited to 4095 chars),
but each execution of gtk_text_buffer_delete() triggers the well-known warning
"Invalid text buffer iterator".

I am a bit stucked here, because I do not understand why this happens, as the buffer
is not modified between taking the iters and deleting the content...

Can anyone help me in this matter ?

Thanks in advance.
Regards
Pierre