We avoid an offscreen if we know the child node
can 'handle' the transform. Shadow nodes can if their
child node does - either the child node is a text node
in which case the shortcuts we take for shadow nodes
will work fine with the transform (we just render the
text node offset), or the child is not a text node,
in which case we render the shadow to an offscreen
anyway.
This change makes the label-shadows reftest pass with
the GL renderer, not by fixing the issue but by avoiding
it.
For shadow nodes, we try pretty hard to avoid
rendering shadows, and and we have a shortcut
that just renders text offset, but we can try
harder to do nothing - if the text is offset
by zero, we don't need to draw it at all.
We need to use an offscreen whenever there is overlapping
children somewhere in the tree below, just checking the
direct child of the opacity node is not enough.
Fixes: #4261
The cairo_t that we create to render glyphs for
the glyph cache needs to match the font options
that are supposedly governing how glyphs are
drawn.
Since we allow font options to be different per
widget in gtk, we need to have them at least at
the level of individual render nodes. Adding them
to the lookup key for the glyph cache has the
side effect of solving another problem: We are
not flushing the cache when font options change.
Since font options affect how the glyphs get rendered,
we need to pass the font options down from the gtk level
to where the glyph cache is populated.
Add a new gsk_text_node_new_full api that takes a
cairo_font_options_t in addition to the other parameters.
This is needed as GskRenderNode is its own fundamental type and has its
own GValue infrastructure. And I want to put render nodes into the
clipboard which uses GValues.
Long time ago, Cairo shadows in both GTK3 and 4 were drawn at a size about
twice their radius. Eventually this was fixed but the shadow extents are
still calculated for the previous size and appear unreasonably large: for
example, 141px for a 50px radius shadow. This can get very noticeable in
places such as invisible window frame which gets included into screenshots.
https://gitlab.gnome.org/GNOME/gtk/-/merge_requests/3419 just divides the
radius by 2 when drawing a shadow with Cairo, do the same when calculating
extents.
See https://gitlab.gnome.org/GNOME/gtk/-/issues/3841
harfbuzz has all the information we need, so we
can avoid poking directly at freetype apis. Also
drop the caching of color glyph information until
it turns out to be a problem.
The vfunc is called to initialize GL and it returns a "base" context
that GDK then uses as the context all others are shared with. So the GL
context share tree now looks like:
+ context from init_gl
- context1
- context2
...
So this is a flat tree now, the complexity is gone.
The only caveat is that backends now need to create a GL context when
initializing GL so some refactoring was needed.
Two new functions have been added:
* gdk_display_prepare_gl()
This is public API and can be used to ensure that GL has been
initialized or if not, retrieve an error to display (or debug-print).
* gdk_display_get_gl_context()
This is a private function to retrieve the base context from
init_gl(). It replaces gdk_surface_get_shared_data_context().
