notcurses_channels(3)

NAME
notcurses_channels - operations on notcurses channels

SYNOPSIS
#include <notcurses/notcurses.h>

        #define NCCHANNEL_INITIALIZER(r, g, b) \
          (((uint32_t)r << 16u) + ((uint32_t)g << 8u) + (b) + NC_BGDEFAULT_MASK)
        #define NCCHANNELS_INITIALIZER(fr, fg, fb, br, bg, bb) \
          ((NCCHANNEL_INITIALIZER(fr, fg, fb) << 32ull) + \
           (NCCHANNEL_INITIALIZER(br, bg, bb)))

uint32_t ncchannel_r(uint32_t channel);

uint32_t ncchannel_g(uint32_t channel);

uint32_t ncchannel_b(uint32_t channel);

uint32_t ncchannel_rgb(uint32_t channel);

uint32_t ncchannel_rgb8(uint32_t channel, uint32_t* restrict r, uint32_t* restrict g, uint32_t* restrict b);

int ncchannel_set_rgb8(uint32_t* channel, unsigned r, unsigned g, unsigned b);

int ncchannel_set(uint32_t* channel, uint32_t rgb);

uint32_t ncchannel_alpha(uint32_t channel);

int ncchannel_set_alpha(uint32_t* channel, unsigned alpha);

bool ncchannel_default_p(uint32_t channel);

uint32_t ncchannel_set_default(uint32_t* channel);

uint32_t ncchannels_fg_rgb(uint64_t channels);

uint32_t ncchannels_bg_rgb(uint64_t channels);

int ncchannels_set_fg_rgb(uint64_t* channels, uint32_t rgb);

int ncchannels_set_bg_rgb(uint64_t* channels, uint32_t rgb);

unsigned ncchannels_fg_alpha(uint64_t channels);

unsigned ncchannels_bg_alpha(uint64_t channels);

int ncchannels_set_fg_alpha(uint64_t* channels, int alpha);

int ncchannels_set_bg_alpha(uint64_t* channels, int alpha);

uint32_t ncchannels_fg_rgb8(uint64_t channels, unsigned* r, unsigned* g, unsigned* b);

uint32_t ncchannels_bg_rgb8(uint64_t channels, unsigned* r, unsigned* g, unsigned* b);

int ncchannels_set_fg_rgb8(uint64_t* channels, unsigned r, unsigned g, unsigned b);

int ncchannels_set_bg_rgb8(uint64_t* channels, unsigned r, unsigned g, unsigned b);

bool ncchannels_fg_default_p(uint64_t channels);

bool ncchannels_bg_default_p(uint64_t channels);

uint64_t ncchannels_set_fg_default(uint64_t* channels);

uint64_t ncchannels_set_bg_default(uint64_t* channels);

uint64_t ncchannels_reverse(uint64_t channels);

unsigned ncchannel_palindex(uint32_t channel);

bool ncchannel_palindex_p(uint32_t channel);

int ncchannel_set_palindex(uint32_t* channel, unsigned idx);

unsigned ncchannels_fg_palindex(uint64_t channels);

unsigned ncchannels_bg_palindex(uint64_t channels);

int ncchannels_set_fg_palindex(uint64_t* channels, unsigned idx);

int ncchannels_set_bg_palindex(uint64_t* channels, unsigned idx);

uint64_t ncchannels_set_channels(uint64_t* dst, uint64_t channels);

uint64_t ncchannels_channels(uint64_t channels);

uint64_t ncchannels_combine(uint32_t fchan, uint32_t bchan);

DESCRIPTION
Channels ought not be manually manipulated. They contain several bits used "behind the scenes", and e.g. direct assignment is likely to lead to strange and infrequent failures. To assign one channel pair to another, use ncchannels_set_channels. To assign a channel to a channel pair's foreground, use ncchannels_set_fchannel. To assign a channel to a channel pair's background, use ncchannels_set_bchannel.

ncchannel_palindex extracts the palette index from a channel. The channel must be palette-indexed, or the return value is meaningless. Verify palette indexing with ncchannel_palindex_p. A channel can be set to palette indexed mode (and have the index set) with ncchannel_set_palindex. The index must be less than NCPALETTESIZE.

ncchannels_combine creates a new channel pair using fchan as the foreground channel and bchan as the background channel.

RETURN VALUES
Functions returning int return -1 on failure, or 0 on success. Failure is always due to invalid inputs. Functions returning bool are predicates, and return the requested value. Functions returning unsigned forms return the input, modified as requested.

ncchannels_reverse inverts the color components of the two channels, while holding all other elements constant. It's the Notcurses approximation to reverse video.

SEE ALSO
notcurses(3), notcurses_cell(3), notcurses_plane(3), notcurses_output(3)

AUTHORS
nick black nickblack@linux.com