.\" Automatically generated by Pandoc 3.1.8
.\"
.TH "notcurses_channels" "3" "v3.0.9" "" ""
.SH NAME
notcurses_channels - operations on notcurses channels
.SH SYNOPSIS
\f[B]#include <notcurses/notcurses.h>\f[R]
.IP
.EX
#define NCCHANNEL_INITIALIZER(r, g, b) \[rs]
  (((uint32_t)r << 16u) + ((uint32_t)g << 8u) + (b) + NC_BGDEFAULT_MASK)

#define NCCHANNELS_INITIALIZER(fr, fg, fb, br, bg, bb) \[rs]
  ((NCCHANNEL_INITIALIZER(fr, fg, fb) << 32ull) + \[rs]
   (NCCHANNEL_INITIALIZER(br, bg, bb)))
.EE
.PP
\f[B]uint32_t ncchannel_r(uint32_t \f[R]\f[I]channel\f[R]\f[B]);\f[R]
.PP
\f[B]uint32_t ncchannel_g(uint32_t \f[R]\f[I]channel\f[R]\f[B]);\f[R]
.PP
\f[B]uint32_t ncchannel_b(uint32_t \f[R]\f[I]channel\f[R]\f[B]);\f[R]
.PP
\f[B]uint32_t ncchannel_rgb(uint32_t \f[R]\f[I]channel\f[R]\f[B]);\f[R]
.PP
\f[B]uint32_t ncchannel_rgb8(uint32_t \f[R]\f[I]channel\f[R]\f[B],
uint32_t* restrict \f[R]\f[I]r\f[R]\f[B], uint32_t* restrict
\f[R]\f[I]g\f[R]\f[B], uint32_t* restrict \f[R]\f[I]b\f[R]\f[B]);\f[R]
.PP
\f[B]int ncchannel_set_rgb8(uint32_t* \f[R]\f[I]channel\f[R]\f[B],
unsigned \f[R]\f[I]r\f[R]\f[B], unsigned \f[R]\f[I]g\f[R]\f[B], unsigned
\f[R]\f[I]b\f[R]\f[B]);\f[R]
.PP
\f[B]int ncchannel_set(uint32_t* \f[R]\f[I]channel\f[R]\f[B], uint32_t
\f[R]\f[I]rgb\f[R]\f[B]);\f[R]
.PP
\f[B]uint32_t ncchannel_alpha(uint32_t
\f[R]\f[I]channel\f[R]\f[B]);\f[R]
.PP
\f[B]int ncchannel_set_alpha(uint32_t* \f[R]\f[I]channel\f[R]\f[B],
unsigned \f[R]\f[I]alpha\f[R]\f[B]);\f[R]
.PP
\f[B]bool ncchannel_default_p(uint32_t
\f[R]\f[I]channel\f[R]\f[B]);\f[R]
.PP
\f[B]uint32_t ncchannel_set_default(uint32_t*
\f[R]\f[I]channel\f[R]\f[B]);\f[R]
.PP
\f[B]uint32_t ncchannels_fg_rgb(uint64_t
\f[R]\f[I]channels\f[R]\f[B]);\f[R]
.PP
\f[B]uint32_t ncchannels_bg_rgb(uint64_t
\f[R]\f[I]channels\f[R]\f[B]);\f[R]
.PP
\f[B]int ncchannels_set_fg_rgb(uint64_t* \f[R]\f[I]channels\f[R]\f[B],
uint32_t \f[R]\f[I]rgb\f[R]\f[B]);\f[R]
.PP
\f[B]int ncchannels_set_bg_rgb(uint64_t* \f[R]\f[I]channels\f[R]\f[B],
uint32_t \f[R]\f[I]rgb\f[R]\f[B]);\f[R]
.PP
\f[B]unsigned ncchannels_fg_alpha(uint64_t
\f[R]\f[I]channels\f[R]\f[B]);\f[R]
.PP
\f[B]unsigned ncchannels_bg_alpha(uint64_t
\f[R]\f[I]channels\f[R]\f[B]);\f[R]
.PP
\f[B]int ncchannels_set_fg_alpha(uint64_t* \f[R]\f[I]channels\f[R]\f[B],
int \f[R]\f[I]alpha\f[R]\f[B]);\f[R]
.PP
\f[B]int ncchannels_set_bg_alpha(uint64_t* \f[R]\f[I]channels\f[R]\f[B],
int \f[R]\f[I]alpha\f[R]\f[B]);\f[R]
.PP
\f[B]uint32_t ncchannels_fg_rgb8(uint64_t \f[R]\f[I]channels\f[R]\f[B],
unsigned* \f[R]\f[I]r\f[R]\f[B], unsigned* \f[R]\f[I]g\f[R]\f[B],
unsigned* \f[R]\f[I]b\f[R]\f[B]);\f[R]
.PP
\f[B]uint32_t ncchannels_bg_rgb8(uint64_t \f[R]\f[I]channels\f[R]\f[B],
unsigned* \f[R]\f[I]r\f[R]\f[B], unsigned* \f[R]\f[I]g\f[R]\f[B],
unsigned* \f[R]\f[I]b\f[R]\f[B]);\f[R]
.PP
\f[B]int ncchannels_set_fg_rgb8(uint64_t* \f[R]\f[I]channels\f[R]\f[B],
unsigned \f[R]\f[I]r\f[R]\f[B], unsigned \f[R]\f[I]g\f[R]\f[B], unsigned
\f[R]\f[I]b\f[R]\f[B]);\f[R]
.PP
\f[B]int ncchannels_set_bg_rgb8(uint64_t* \f[R]\f[I]channels\f[R]\f[B],
unsigned \f[R]\f[I]r\f[R]\f[B], unsigned \f[R]\f[I]g\f[R]\f[B], unsigned
\f[R]\f[I]b\f[R]\f[B]);\f[R]
.PP
\f[B]bool ncchannels_fg_default_p(uint64_t
\f[R]\f[I]channels\f[R]\f[B]);\f[R]
.PP
\f[B]bool ncchannels_bg_default_p(uint64_t
\f[R]\f[I]channels\f[R]\f[B]);\f[R]
.PP
\f[B]uint64_t ncchannels_set_fg_default(uint64_t*
\f[R]\f[I]channels\f[R]\f[B]);\f[R]
.PP
\f[B]uint64_t ncchannels_set_bg_default(uint64_t*
\f[R]\f[I]channels\f[R]\f[B]);\f[R]
.PP
\f[B]uint64_t ncchannels_reverse(uint64_t
\f[R]\f[I]channels\f[R]\f[B]);\f[R]
.PP
\f[B]unsigned ncchannel_palindex(uint32_t
\f[R]\f[I]channel\f[R]\f[B]);\f[R]
.PP
\f[B]bool ncchannel_palindex_p(uint32_t
\f[R]\f[I]channel\f[R]\f[B]);\f[R]
.PP
\f[B]int ncchannel_set_palindex(uint32_t* \f[R]\f[I]channel\f[R]\f[B],
unsigned \f[R]\f[I]idx\f[R]\f[B]);\f[R]
.PP
\f[B]unsigned ncchannels_fg_palindex(uint64_t
\f[R]\f[I]channels\f[R]\f[B]);\f[R]
.PP
\f[B]unsigned ncchannels_bg_palindex(uint64_t
\f[R]\f[I]channels\f[R]\f[B]);\f[R]
.PP
\f[B]int ncchannels_set_fg_palindex(uint64_t*
\f[R]\f[I]channels\f[R]\f[B], unsigned \f[R]\f[I]idx\f[R]\f[B]);\f[R]
.PP
\f[B]int ncchannels_set_bg_palindex(uint64_t*
\f[R]\f[I]channels\f[R]\f[B], unsigned \f[R]\f[I]idx\f[R]\f[B]);\f[R]
.PP
\f[B]uint64_t ncchannels_set_channels(uint64_t* \f[R]\f[I]dst\f[R]\f[B],
uint64_t \f[R]\f[I]channels\f[R]\f[B]);\f[R]
.PP
\f[B]uint64_t ncchannels_channels(uint64_t
\f[R]\f[I]channels\f[R]\f[B]);\f[R]
.PP
\f[B]uint64_t ncchannels_combine(uint32_t \f[R]\f[I]fchan\f[R]\f[B],
uint32_t \f[R]\f[I]bchan\f[R]\f[B]);\f[R]
.SH DESCRIPTION
Channels ought not be manually manipulated.
They contain several bits used \[dq]behind the scenes\[dq], and e.g.
direct assignment is likely to lead to strange and infrequent failures.
To assign one channel pair to another, use
\f[B]ncchannels_set_channels\f[R].
To assign a channel to a channel pair\[aq]s foreground, use
\f[B]ncchannels_set_fchannel\f[R].
To assign a channel to a channel pair\[aq]s background, use
\f[B]ncchannels_set_bchannel\f[R].
.PP
\f[B]ncchannel_palindex\f[R] extracts the palette index from a channel.
The channel must be palette-indexed, or the return value is meaningless.
Verify palette indexing with \f[B]ncchannel_palindex_p\f[R].
A channel can be set to palette indexed mode (and have the index set)
with \f[B]ncchannel_set_palindex\f[R].
The index must be less than \f[B]NCPALETTESIZE\f[R].
.PP
\f[B]ncchannels_combine\f[R] creates a new channel pair using
\f[B]\f[BI]fchan\f[B]\f[R] as the foreground channel and
\f[B]\f[BI]bchan\f[B]\f[R] as the background channel.
.SH RETURN VALUES
Functions returning \f[B]int\f[R] return -1 on failure, or 0 on success.
Failure is always due to invalid inputs.
Functions returning \f[B]bool\f[R] are predicates, and return the
requested value.
Functions returning \f[B]unsigned\f[R] forms return the input, modified
as requested.
.PP
\f[B]ncchannels_reverse\f[R] inverts the color components of the two
channels, while holding all other elements constant.
It\[aq]s the Notcurses approximation to reverse video.
.SH SEE ALSO
\f[B]notcurses(3)\f[R], \f[B]notcurses_cell(3)\f[R],
\f[B]notcurses_plane(3)\f[R], \f[B]notcurses_output(3)\f[R]
.SH AUTHORS
nick black <nickblack@linux.com>.