Each plane has a "base cell", which like all other cells is
initialized to the null glyph, opaque default foreground color,
and opaque default background color. Prior to this change, at
each cell of a plane, we decided whether to use that cell (the
"viscell") or the base cell depending on whether the viscell had
a non-null glyph. We now evaluate each component independently.
If the viscell has a null glyph, we use the base cell's glyph.
If the viscell has a default foreground, we use the base's fg.
If the viscell has a default background, we use the base's bg.
This was done because (a) it seems more intuitive (if I set a cell
to red, I expect red, not red iff there's a glyph in that cell
for this plane), and (b) because otherwise it was impossible to
do a multicolor overlay without blowing away underlying glyphs
(since without a glyph, you always reduced to the same base cell,
which could have only one fore- and background per render).
Existing code will need to change any instances where cells
lacking glyphs are colored, and those colors are not desired.
Since any such coloring had no effect before, it seems unlikely
that any ought exist (this did bring to light an instance in
the "qrcode" demo where we were staining overmuch of the plane).
This closes#395, the last big open worry regarding our API.
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).
Very simple take at ncplane_puttext(), a new function for linebroken text. Also some very basic unit tests. I doubt this works very well yet, but it handles the simplest cases #682. Added nclog(), internal function for logging. #520
