notcurses/doc/man/man3/notcurses_cell.3.md

% notcurses_cell(3) % nick black nickblack@linux.com % v1.6.17

NAME

notcurses_cell - operations on notcurses cells

SYNOPSIS

#include <notcurses/notcurses.h>

// See DESCRIPTION below for information on EGC encoding
typedef struct cell {
  uint32_t gcluster;          // 4B → 4B
  uint8_t gcluster_backstop;  // 1B → 5B (8 bits of zero)
  uint8_t reserved;           // 1B → 6B (8 reserved bits, ought be zero)
  uint16_t stylemask;         // 2B → 8B (16 bits of NCSTYLE_* attributes)
  uint64_t channels;
} cell;

#define CELL_TRIVIAL_INITIALIZER \
 { .gcluster = '\0', .stylemask = 0, .channels = 0, }
#define CELL_SIMPLE_INITIALIZER(c) \
 { .gcluster = (c), .stylemask = 0, .channels = 0, }
#define CELL_INITIALIZER(c, s, chan) \
 { .gcluster = (c), .stylemask = (s), .channels = (chan), }

#define CELL_WIDEASIAN_MASK     0x8000000080000000ull
#define CELL_BGDEFAULT_MASK     0x0000000040000000ull
#define CELL_FGDEFAULT_MASK     (CELL_BGDEFAULT_MASK << 32u)
#define CELL_BG_RGB_MASK        0x0000000000ffffffull
#define CELL_FG_RGB_MASK        (CELL_BG_MASK << 32u)
#define CELL_BG_PALETTE         0x0000000008000000ull
#define CELL_FG_PALETTE         (CELL_BG_PALETTE << 32u)
#define CHANNEL_ALPHA_MASK      0x30000000ull
#define CELL_ALPHA_HIGHCONTRAST 0x30000000ull
#define CELL_ALPHA_TRANSPARENT  0x20000000ull
#define CELL_ALPHA_BLEND        0x10000000ull
#define CELL_ALPHA_OPAQUE       0x00000000ull

void cell_init(cell c);*

int cell_load(struct ncplane n, cell c, const char* gcluster);**

int cell_prime(struct ncplane n, cell c, const char* gcluster, uint32_t stylemask, uint64_t channels);**

int cell_duplicate(struct ncplane n, cell targ, const cell* c);**

void cell_release(struct ncplane n, cell c);**

void cell_styles_set(cell c, unsigned stylebits);*

unsigned cell_styles(const cell c);*

void cell_styles_on(cell c, unsigned stylebits);*

void cell_styles_off(cell c, unsigned stylebits);*

void cell_set_fg_default(cell c);*

void cell_set_bg_default(cell c);*

int cell_set_fg_alpha(cell c, unsigned alpha);*

int cell_set_bg_alpha(cell c, unsigned alpha);*

bool cell_double_wide_p(const cell c);*

const char cell_extended_gcluster(const struct ncplane n, const cell* c);**

int cell_load_simple(struct ncplane n, cell c, char ch);**

unsigned cell_bchannel(const cell cl);*

unsigned cell_fchannel(const cell cl);*

uint64_t cell_set_bchannel(cell cl, uint32_t channel);*

uint64_t cell_set_fchannel(cell cl, uint32_t channel);*

unsigned cell_fg(const cell cl);*

unsigned cell_bg(const cell cl);*

unsigned cell_fg_alpha(const cell cl);*

unsigned cell_bg_alpha(const cell cl);*

unsigned cell_fg_rgb(const cell cl, unsigned r, unsigned* g, unsigned* b);**

unsigned cell_bg_rgb(const cell cl, unsigned r, unsigned* g, unsigned* b);**

int cell_set_fg_rgb(cell cl, int r, int g, int b);*

int cell_set_bg_rgb(cell cl, int r, int g, int b);*

void cell_set_fg_rgb_clipped(cell cl, int r, int g, int b);*

void cell_set_bg_rgb_clipped(cell cl, int r, int g, int b);*

int cell_set_fg(cell c, uint32_t channel);*

int cell_set_bg(cell c, uint32_t channel);*

bool cell_fg_default_p(const cell cl);*

bool cell_bg_default_p(const cell cl);*

DESCRIPTION

Cells make up the framebuffer associated with each plane, with one cell per addressable coordinate. You should not usually need to interact directly with cells.

Each cell contains exactly one extended grapheme cluster. If the EGC happens to be a single ASCII character, i.e. a single character with a value less than 128, it is encoded directly into the cell's gcluster field, and no additional storage is necessary. In this case, cell_simple_p() is true. Otherwise, the EGC is stored as a UTF-8 string in some backing egcpool. Egcpools are associated with ncplanes, so cells must be considered associated with ncplanes. Indeed, ncplane_erase() destroys the backing storage for all a plane's cells, invalidating them. This association is formed at the time of cell_load(), cell_prime(), or cell_duplicate(). All of these functions first call cell_release(), as does cell_load_simple(). When done using a cell entirely, call cell_release(). ncplane_destroy() will free up the memory used by the cell, but the backing egcpool has a maximum size of 32MiB, and failure to release cells can eventually block new output.

RETURN VALUES

cell_load() and similar functions return the number of bytes loaded from the EGC, or -1 on failure. They can fail due to either an invalid UTF-8 input, or the backing egcpool reaching its maximum size.

cell_set_fg_rgb() and similar functions will return -1 if provided invalid inputs, and 0 otherwise.

SEE ALSO

notcurses(3), notcurses_channels(3), notcurses_plane(3), notcurses_output(3)