This borrows heavily from the CSS4 fonts draft's font-palette, currently
found at https://drafts.csswg.org/css-fonts-4/#font-palette-control
The palette is mainly meant to trigger invalidations when colors used for
symbolic icons change, to potentially allow extending supported colors
in symbolic icons and to recolor all colors of a symbolic icon, not just
the main one.
The syntax for the property goes like this:
Name: -gtk-icon-palette
Value: default | name <color> [ , name <color> ]*
Initial: default
Applies to: all elements with icons
Inherited: yes
Animatable: yes, each color animated separately
The property defines a list of named colors to be used when looking up
icons. If a name is not defined, the value of the current "color"
property is used. Which names are relevant depends on the icons in use.
Currently symbolic icons make use of the names "success", "warning" and
"error".
"default" is the current behavior of the GTK when coloring symbolic
icons and is equal to the string
success @success_color, warning @warning_color, error @error_color
Animation is crudely implemented by animating colors that are in both
palettes that are animated and otherwise keeping the color from the
palette that defined it. Note that this can cause a sharp cut at the
beginning or end of the animation when the color goes away and will
therefore be replaced with the color property.
You can see an example of animations at
http://gfycat.com/CautiousPeacefulIaerismetalmark
When we start a drag cancel animation, we can just keep the existing
window. The reset was only necessary to convert from cursor icon to
window and we removed the cursor handling.
Just like we did for the default size, that reduces the chances of
having the headerbar missing or wrongly sized when computing the client
side decorations controls.
https://bugzilla.gnome.org/show_bug.cgi?id=756618
The Wayland dnd surface must remain in place until the drag
is over. Setting it directly as the hardcoded window of the
widget we construct carries the danger that it might get
destroyed prematurely, e.g. when the application calls
gtk_drag_set_icon_name more than once and we recreate the
widget.
Instead, create a dedicated toplevel, and reparent the widget
into it. To keep the code simple, we use the same approach
under X11 as well, and make it the responsibility of the
GDK dnd code to keep the window position updated. We already
pass the current pointer position to gdk_drag_motion, which
makes this very easy.
As a side-effect of these changes, it is now possible to use
non-toplevel widgets as drag icons.
https://bugzilla.gnome.org/show_bug.cgi?id=748763
If that sounds confusing, it's because GTK and CSS can sometimes not
agree on naming.
:active for CSS means that a button is currently pressed on an element.
And that is clearly not the case for spinning spinners.
This removes the dependency on state, which should be used for selection
CSS styles, not for actually applying them.
And image-effect does exactly what we want already, so we can start
using it.
The size of icons is a property that is relevant to who is rendering the
icon, not to the icon itself.
Example: Starting a DND operation from an entry icon should cause the
icon to resize (from the entr icon's size to the DND icon size).
Make gtk_icon_helper_ensure_surface() a private function that just
ensures the surface was loaded.
Add gtk_icon_helper_load_surface() that is called by the above function
and the dnd code to actually load the surface.
