Add `notcurses_check_pixel_support()` and
`ncdirect_check_pixel_support()` per #1367. Removes
NCOPTION_VERIFY_SIXEL, again per #1367. Adds
`free_terminfo_cache()`, and calls it from both
`notcurses_stop_minimal()` and `ncdirect_stop()`.
Update all documentation. Closes#1371 and #1367.
This completes the work for #1068. This addressed a subtle issue.
When we're using pixel->semigraphic art, we want slightly different
rendering. Essentially, imagine that we have two images, each two
pixels tall and one pixel wide. The top image is a transparent pixel
above a white pixel. The bottom image is a white pixel above a black
pixel. We'd expect the result to be two white pixels, but we can
instead get a black pixel above a white pixel. This is because the
*background* color is being merged from the bottom plane, but really
we want the *top* color. Ncvisuals are now blitted along with
information regarding which quadrants they draw over, and when
appropriate, we invert the foreground and background. Closes#1068.
In order to properly determine the scaling of an ncvisual to
be rendered, ncvisual_geom() needs know the blitting method.
For this reason, it took an ncblitter_e argument. It also,
however, needs handle degradation, which means knowing whether
NCVISUAL_OPTIONS_NODEGRADE is in use. It thus really wants the
struct ncvisual_options. Pass and accept it. Closes#697, and
fixes the "yield" demo in ASCII mode (#696).
If we're in ASCII mode, no blitter except for NCBLIT_1x1 is going to
work. Whenever NCBLIT_DEFAULT is provided, select NCBLIT_1x1 if we're
in ASCII mode. Add NCVISUAL_OPTIONS_MAYDEGRADE and
NCPLOT_OPTIONS_MAYDEGRADE. Both serve to allow smooth degradation when a
blitter other than NCBLIT_DEFAULT has been provided. Closes#637.
Make calc_gradient_cell() static inline so our templated ncppplot
implementation can use it (ugh). When using NCBLIT_1x1 for plots in
ASCII mode, use space rather than full block, and invert colors.
Use NCBLIT_DEFAULT in the demo for the FPS plot.
nick black