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notcurses_cell - operations on notcurses cells


#include <notcurses/notcurses.h>

// See DESCRIPTION below for information on EGC encoding
typedef struct cell {
  uint32_t gcluster;
  uint32_t attrword;
  uint64_t channels;
} cell;

 { .gcluster = '\0', .attrword = 0, .channels = 0, }
 { .gcluster = (c), .attrword = 0, .channels = 0, }
#define CELL_INITIALIZER(c, a, chan) \
 { .gcluster = (c), .attrword = (a), .channels = (chan), }

#define CELL_WIDEASIAN_MASK     0x8000000080000000ull
#define CELL_BGDEFAULT_MASK     0x0000000040000000ull
#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 attr, 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);

bool cell_simple_p(const cell* c);

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

bool cell_noforeground_p(const cell* c);

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

uint32_t cell_egc_idx(const cell* c);

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);

uint64_t cell_blend_fchannel(cell* cl, unsigned channel, unsigned blends)

uint64_t cell_blend_bchannel(cell* cl, unsigned channel, unsigned blends)

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);


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 16MiB, and failure to release cells can eventually block new output.


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.


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