[LAD] pixmap based knob widgets and theme integration.

[Olivier Guilyardi]

On 09/28/2010 07:28 AM, hermann wrote:
> Am Montag, den 27.09.2010, 16:57 +0200 schrieb Olivier Guilyardi:
>> My point was that widgets drawn directly with Cairo bypass the
>> gtk_paint_*()
>> drawing abstraction layer, which would forbid engine to provide their
>> own knob
>> drawing implementation, as it's done for buttons, etc...
>>
>> Therefore, such Cairo-based knobs wouldn't support the full GTK
>> theming
>> capabilities. 
> 
> In Gtk+3 many GDK functions are replaced by cairo. 
> gtk_widget_draw() will take any cairo surface then.
> 
> http://live.gnome.org/GnomeGoals/GTKRenderingCleanup

Okay, it says "All GtkStyle drawing functions (gtk_paint_box(), etc) have been
changed to take a #cairo_t instead of a window and a clip area. ::draw
implementations will usually just use the cairo context that has been passed in
for this."

I'm not a gtk engine wizard, but the problem is still here IIUC.

If you draw directly with Cairo within your widget, your bypass the drawing
"driver" layer, for example used by ClearLooks which overloads the old
gtk_draw_*() functions in clearlooks_style_class_init():
http://clearlooks.cvs.sourceforge.net/viewvc/clearlooks/clearlooks/src/clearlooks_style.c?revision=1.100&view=markup

Whether gtk or a specific engine draw internally with Cairo or not doesn't
change the situation.

I suppose that the only solution would be to add some knob drawing primitives to
the GtkStyle class itself. That would allow gtk engines developers to provide
their own knob drawing implementation, and also separate the rendering code from
the knob logic.

But that might be a lot of trouble.

--
  Olivier