This lets us do fallback in case an image format is not
supported, and also lets us provide solid-color images.
We don't support image fragment notations.
See ttps://www.w3.org/TR/css3-images/#image-notation
https://bugzilla.gnome.org/show_bug.cgi?id=761318
Since a lot of Adwaita sets transition: all, it's easy to end up in a
state where we're making dummy transitions for all of the icons, most of
which we'll never be showing.
For images without a concrete size but with an aspect ratio, we took the
wrong code path.
(I even copied the documentation that said "Otherwise" but didn't put an
else clause there, go me!)
This allows using icons from the icontheme as images in CSS. The
reasoning is that this allows to give the image control about how it's
scaled (by using the icon theme's scaling method. So we can get crisp
images at different resolutions.
The version of device scale that landed in upstream cairo
master already inherits the device scale in cairo_create_similar,
so no need to do that in gtk anymore.
To handle hidpi support we need to make sure we don't
downscale scaled css images.
Note: If cairo_surface_create_similar starts doing this
by itself we need to back this out.
We need to be able to compute different GtkCssImage values
depending on the scale, and we need this at compute time so that
we don't need to read any images other than the scale in used (to
e.g. calculate the image size). GtkStyleProviderPrivate is shared
for all style contexts, so its not right.
Also remove the starting underscore from function names where
appropriate, as those functions are static now and not exported anymore.
This is part of a bunch of fixes for gcc complaining about
-Wmissing-declarations.
Here's the shortest description of the bug I can come up with:
When computing values, we have 3 kinds of dependencies:
(1) other properties ("currentColor" or em values)
(2) inherited properties ("inherit")
(3) generic things from the theme (@keyframes or @define-color)
Previously, we passed the GtkStyleContext as an argument, because it
provided these 3 things using:
(1) _gtk_style_context_peek_property()
(2) _gtk_style_context_peek_property(gtk_style_context_get_parent())
(3) context->priv->cascade
However, this makes it impossible to lookup values other than the ones
accessible via _gtk_style_context_peek_property(). And this is exactly
what we are doing in gtk_style_context_update_cache(). So when the cache
updates encountered case (1), they were looking up the values from the
wrong style data.
So this large patch essentially does nothing but replace the
context argument in all compute functions with new arguments for the 3
cases above:
(1) values
(2) parent_values
(3) provider
We apparently have a lot of computing code.
This is a reorganization of how value computing should be done.
Previously the GtkCssStyleProperty.compute vfunc was supposed to take
care of special cases when it needed those for computation. However,
this proved to be very complicated in cases where values were nested and
only the last value (of a common type) needed to be special cased.
A common example for this was the fallback handling for unresolvable
colors.
Now, we pass the property's ID along with all compute functions so we
can do the special casing where it's necessary.
Note that no actual changes happen in this commit. This will happen in
follow-ups.
