Which handles:
- conversion from other pixel formats to ARGB32
- setting the logical size to the desired display size
- downscaling very large images using CAIRO_FILTER_GOOD
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).
Made all header files to have LABWC_ prefix in include guard identifers.
Converted from __LABWC_ in 35 include/ files.
Converted from __LAB_ in 5 include/ files.
Added LABWC prefix to 3 include/ files.
Added include guards to 3 include/ files.
The double underscores were removed since according to C standard
those "are always reserved for any use".
