Re: Exposing cairo based implementation of CSS as an API in GTK+/gtkmm

[Emmanuele Bassi <ebassi gmail com>]

Hi;

On 25 June 2016 at 12:45, Samik Ganguly <sganguly87 gmail com> wrote:
> Hello Gtk+ developers,

if you're trying to reach the GTK+ developers you're using the wrong
mailing list; you want to use gtk-devel-list. I've added the list to
the Cc:

>     Gtk+ implements various CSS3 functionality so that widgets can be styled
> with CSS. As far as I understand these effects are implemented with cairo
> drawing API. Is there any chance to expose some of the effects such as
> blurred shadow, transitions etc. as generic functions in Gtk+ API so that
> they can be used without CSS?

No, there are no plans.

The CSS-based drawing is heavily tied to the state defined by the CSS
machinery, and that section of the API is private (for good reasons,
given the speed with which it's been changing and it's supposed to
change in the future).

> For example, if someone is doing some custom drawing with cairo on Gtk+ such
> as non rectangular widgets, curves with shadow etc. then they can take
> advantages of such API instead having to implement those effects with cairo
> themselves. For rectangular widgets StyleProvider's draw_background,
> draw_frame methods can be used to specify such effects in CSS, but for
> others I'm guessing they're probably not suitable.

The overall plan is to make widgets more lightweight and easier to
compose — similar to "<div>" elements in HTML. The idea is that if you
want something that draws with CSS semantics, you will be able to use
widgets.

Additionally, the plan is to add a Clutter-like scene graph that sits
below GTK, for UIs that do not rely on complex widget semantics (like
media player UIs or games).

Ciao,
 Emmanuele.

-- 
https://www.bassi.io
[ ] ebassi [ gmail com]