This indicates that empty pixels should "remain at their current
color". I.e. it makes them transparent.
This is in contrast to P2=0|2, where empty pixels are filled with the
"current background color" (which is either sixel color register #0,
or the current ANSI background color, depending on terminal and its
sixel implementation).
Note that due to what is most likely a bug, XTerm will behave as if
P2=1 if P2 is either left unset, or explicitly set to 0 or 2, as long
as we do *not* emit a "Set Raster Attributes" command.
- separate the methods into its own module.
- add constants NCVISUAL_OPTION_ADDALPHA, NCVISUAL_OPTION_HORALIGNED, NCVISUAL_OPTION_VERALIGNED
- add NcRgba type.
- update the docs.
the media code that makes up non-core libnotcurses called
into lookup_rgba(). instead, have them use the new
funtion ncvisual_blitter_geom() to access the actual blitter
being used. we can then hide lookup_blitset(), which ought
never have been exported. closes#1519.
Require a known-good TERM heuristic match to enable
quadrants (NCBLIT_2x2); they otherwise decay to halves
(NCBLIT_2x1). The only terminal that supports quadrants
but does not support sextants is the Linux console, where
we program quadrants directly into the font table,
like a beast. Closes#1517, and #1298 if we're lucky.
deprecate ncvisual_geom() in favor of new ncvisual_blitter_geom(), which allows caller to get the blitter used. replace the checks and calculations in ncvisual_render() with a call to ncvisual_blitter_geom(), unifying the two paths (and eliminating several bugs in the unloved ncvisual_geom()).
if we go into ncvisual_render() looking to render a number
of rows not evenly divisible by the scaling factor, we need
to get an extra row (duh). correct ncvisual_render_cell() to
reflect this. the blitters already know to fill this line in
with transparency wherever the image is not defined. fix up
rotation unit tests to reflect this. closes#1513.
- improve NcVisual.from_rgba documentation.
- fix Notcurses.term_dim_yx documentation.
- new example `poc-planebase` to help find the bug.
- improve full-capabilities example a little.