We always create a SSD for 0x0 window since decorations are usually
requested before a window is mapped. Thus the sizes of some buffers/rects
like edge shadows could be negative, which is asserted in wlroots 0.19.
For example, variables:
`theme->window_inactive_border_color`
`theme->window_active_border_color`
are converted to:
`theme->window[THEME_INACTIVE].border_color`
`theme->window[THEME_ACTIVE].border_color`
Add buffer_adopt_cairo_surface(), which allows wrapping an existing
cairo image surface in a struct lab_data_buffer. This is useful when
loading PNGs since most will be loaded as ARGB32 already.
Fix a memory leak in the non-ARGB32 PNG case, where we do still need to
paint to a new image surface -- we were leaking the original surface.
Eliminate an unnecessary temporary image surface in SVG loading and just
render the SVG to the image surface held by the lab_data_buffer.
I also cleaned up and clarified the buffer API a bit:
- Add a pointer to the held cairo_surface_t (so we can still access it
if there is no cairo_t).
- Remove the free_on_destroy bool (it was always true).
- Rename unscaled_width/height to logical_width/height and add an
explanatory comment. It was unclear what "unscaled" meant.
- Rename buffer_create_wrap() to buffer_create_from_data().
This is laying groundwork for some more icon fixes I am working on
(making sure icons are loaded and rendered at the correct scale).
Before this patch, we were leaking memory [0] because the
shadow implementation did not free the ssd_parts on destruction.
There was also no check if shadows were actually enabled via
rc.xml or not so this also impacted people who were not using
shadows but were not setting the shadow size via their theme to 0.
[0] 44 bytes per ssd_part * 8 parts * 2 states == 704 bytes per
view closed. Note that Reconfigure also re-creates the SSD, thus
we were also leaking 704 bytes * nr_views per Reconfigure.
