Re: Gtk3 and theming - a proposal (with code)

["Alberto Ruiz" <aruiz gnome org>]

2008/10/13 Robert Staudinger <robert staudinger gmail com>:
> On Mon, Oct 13, 2008 at 4:58 PM, Alberto Ruiz <aruiz gnome org> wrote:
>
> [...]
>
>>> It would also be possible to introduce aliases for the sake of
>>> theming, e.g. "GtkTreeViewColumnHeader" for a GtkButton inside a
>>> treeview. Maybe such an approach would be feasible to bridge the gaps
>>> between the "widget access" and the "no widget access" camps?
>>
>> That's exactly the kind of thing that we want to propose. That's why
>> we need something richer and more flexible than the detail string. If
>> a column header button is rendered, the engine should not by any means
>> crawl the structure to figure it out. The api call should have that
>> information out of the box.
>
> There are two different cases of parent-matching to consider. One is
> for composite widget where, agreed, it may not be desireable to depend
> on implementation details. QT introduces the notion of "sub-controls"
> [1] for that, a thing we are also discussing for the CSS engine.
>
> The other case is "legitimate" parent/position matching, for example
> to theme buttons inside a button box (see [2] for a mockup) or
> even/odd row colouring in a treeview. It would be on the one hand
> prone to limit designers' possibilities by restricting that second
> variant in any way, and on the other hand hard to provide a complete
> representation of a window's widget hierarchy. Here iteration through
> parent widgets is needed.

I can't see why iteration over parents containers is needed in any of
those cases with the proper tools in place. Our current idea is that
containers push that context information into a the widget's context
object before they delegate the rendering of their childs.

Odd/even an order information is precisely one of those cases. As an
example, figuring out if a tab of a notebook is the last one, is
pretty much impossible at the moment even crowling unless you push
that information from the notebook itself. Thing is, we have nowhere
to push it at the moment.


>
> [1] http://doc.trolltech.com/4.5/stylesheet-syntax.html#sub-controls
> [2] http://www.gnome.org/~robsta/gtk-css-engine/screenshots/child-index-selector.png
>
> - Rob
>



-- 
Un saludo,
Alberto Ruiz