Re: Problem in pango_layout_index_to_pos()

["Padraig O'Briain" <Padraig Obriain Sun COM>]

I was here last week. see 
http://mail.gnome.org/archives/gtk-devel-list/2001-September/msg00373.html
and bug 60630.

I have not received any feedback yet.

Padraig

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> Subject: Problem in pango_layout_index_to_pos()
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> 
> I've been trying to solve some bugs in the gtktextviewer widget, 
> and I have stumbled upon a problem in pango.
> 
> The problem I'm looking at occurs in the following scenario:
> 
>     * Wrap is off
>     * The line is longer than the "screen" (widget width) and thus
>       a horizontal scrollbar is shown.
>     * The insert mark is at the end of the line.
>     * Control-E is pressed.
> 
> What happens then is that scrolling jumps to display the start of
> the line instead of the end of the line. (The same behaviour occurs
> if trying to type, the scrolling jumps back and forth between the
> beginning and the end of the buffer.)
> 
> I eventually traced down the problem to the following lines in 
> pango-layout.c:pango_layout_index_to_pos():
> 
>     if (notfound)
>       {
> 	/* Iterator should now be on the "NULL" run at the end of the last
> 	 * line, which is a zero-width rectangle. Return the extents of
> 	 * that run.
> 	 */
> 
> 	pango_layout_iter_get_run_extents (iter, NULL, pos);
>       }
> 
> The problem is that pango_layout_iter_get_run_extents() does
> not return a zero-width rectangle, but rather a rectangle of the 
> complete row. Since the scrolling is done to the start of the rectangle
> this causes the widget to be scrolled to the beginning of the line.
> 
> My question is what function should fullfill the creation of the zero-
> width rectangle mentioned in the comment? pango_layout_index_to_pos()
> or pango_layout_iter_get_run_extents()?
> 
> Regards,
> Dov
> 
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