% notcurses_cell(3) % nick black % v3.0.5 # NAME notcurses_cell - operations on nccell objects # SYNOPSIS **#include ** ```c // See DESCRIPTION below for information on EGC encoding typedef struct nccell { uint32_t gcluster; // 4B → 4B uint8_t gcluster_backstop; // 1B → 5B (8 bits of zero) uint8_t width; // 1B → 6B (8 bits of column width) uint16_t stylemask; // 2B → 8B (16 bits of NCSTYLE_* attributes) uint64_t channels; } nccell; #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 NCALPHA_HIGHCONTRAST 0x30000000ull #define NCALPHA_TRANSPARENT 0x20000000ull #define NCALPHA_BLEND 0x10000000ull #define NCALPHA_OPAQUE 0x00000000ull ``` **void nccell_init(nccell* ***c***);** **int nccell_load(struct ncplane* ***n***, nccell* ***c***, const char* ***gcluster***);** **int nccell_prime(struct ncplane* ***n***, nccell* ***c***, const char* ***gcluster***, uint32_t ***stylemask***, uint64_t ***channels***);** **int nccell_duplicate(struct ncplane* ***n***, nccell* ***targ***, const nccell* ***c***);** **void nccell_release(struct ncplane* ***n***, nccell* ***c***);** **int nccell_cols(const nccell* ***c***);** **void nccell_styles_set(nccell* ***c***, unsigned ***stylebits***);** **unsigned nccell_styles(const nccell* ***c***);** **bool nccellcmp(const struct ncplane* ***n1***, const nccell* ***c1***, const struct ncplane* ***n2***, const nccell* ***c2***);** **void nccell_on_styles(nccell* ***c***, unsigned ***stylebits***);** **void nccell_off_styles(nccell* ***c***, unsigned ***stylebits***);** **void nccell_set_fg_default(nccell* ***c***);** **void nccell_set_bg_default(nccell* ***c***);** **int nccell_set_fg_alpha(nccell* ***c***, unsigned ***alpha***);** **int nccell_set_bg_alpha(nccell* ***c***, unsigned ***alpha***);** **bool nccell_double_wide_p(const nccell* ***c***);** **const char* nccell_extended_gcluster(const struct ncplane* ***n***, const nccell* ***c***);** **char* nccell_strdup(const struct ncplane* ***n***, const nccell* ***c***);** **int nccell_load_char(struct ncplane* ***n***, nccell* ***c***, char ***ch***);** **int nccell_load_egc32(struct ncplane* ***n***, nccell* ***c***, uint32_t ***egc***);** **int nccell_load_ucs32(struct ncplane* ***n***, nccell* ***c***, uint32_t ***u***);** **char* nccell_extract(const struct ncplane* ***n***, const nccell* ***c***, uint16_t* ***stylemask***, uint64_t* ***channels***);** **uint64_t nccell_channels(const nccell* ***c***);** **uint32_t nccell_bchannel(const nccell* ***c***);** **uint32_t nccell_fchannel(const nccell* ***c***);** **uint64_t nccell_set_channels(nccell* ***c***, uint64_t ***channels***);** **uint64_t nccell_set_bchannel(nccell* ***c***, uint32_t ***channel***);** **uint64_t nccell_set_fchannel(nccell* ***c***, uint32_t ***channel***);** **uint32_t nccell_fg_rgb(const nccell* ***c***);** **uint32_t nccell_bg_rgb(const nccell* ***c***);** **unsigned nccell_fg_alpha(const nccell* ***c***);** **unsigned nccell_bg_alpha(const nccell* ***c***);** **unsigned nccell_fg_rgb8(const nccell* ***c***, unsigned* ***r***, unsigned* ***g***, unsigned* ***b***);** **unsigned nccell_bg_rgb8(const ncell* ***c***, unsigned* ***r***, unsigned* ***g***, unsigned* ***b***);** **int nccell_set_fg_rgb8(nccell* ***c***, unsigned ***r***, unsigned ***g***, unsigned ***b***);** **int nccell_set_bg_rgb8(nccell* ***c***, unsigned ***r***, unsigned ***g***, unsigned ***b***);** **void nccell_set_fg_rgb8_clipped(nccell* ***c***, int ***r***, int ***g***, int ***b***);** **void nccell_set_bg_rgb8_clipped(nccell* ***c***, int ***r***, int ***g***, int ***b***);** **int nccell_set_fg_rgb(nccell* ***c***, uint32_t ***channel***);** **int nccell_set_bg_rgb(nccell* ***c***, uint32_t ***channel***);** **bool nccell_fg_default_p(const nccell* ***c***);** **bool nccell_bg_default_p(const nccell* ***c***);** **int nccell_set_fg_palindex(nccell* ***cl***, unsigned ***idx***);** **int nccell_set_bg_palindex(nccell* ***cl***, unsigned ***idx***);** **uint32_t nccell_fg_palindex(const nccell* ***cl***);** **uint32_t nccell_bg_palindex(const nccell* ***cl***);** **bool nccell_fg_palindex_p(const nccell* ***cl***);** **bool nccell_bg_palindex_p(const nccell* ***cl***);** **int ncstrwidth(const char* ***text***)**; **int ncstrwidth_valid(const char* ***text***, int* ***validbytes***, int* ***validwidth***)**; # 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 **nccell**s. Each **nccell** contains exactly one extended grapheme cluster. If the EGC is encoded in UTF-8 with four or fewer bytes (all Unicode codepoints as of Unicode 13 can be encoded in no more than four UTF-8 bytes), it is encoded directly into the **nccell**'s **gcluster** field, and no additional storage is necessary. Otherwise, the EGC is stored as a nul-terminated UTF-8 string in some backing egcpool. Egcpools are associated with **ncplane**s, so **nccell**s must be considered associated with **ncplane**s. Indeed, **ncplane_erase** destroys the backing storage for all a plane's cells, invalidating them. This association is formed at the time of **nccell_load**, **nccell_prime**, or **nccell_duplicate**. All of these functions first call **nccell_release**, as do **nccell_load_egc32**, **nccell_load_char**, and **nccell_load_ucs32**. When done using a **nccell** entirely, call **nccell_release**. **ncplane_destroy** will free up the memory used by the **nccell**, but the backing egcpool has a maximum size of 16MiB, and failure to release **nccell**s can eventually block new output. Writing over an **ncplane**'s cells releases them automatically. **nccell_extended_gcluster** provides a nul-terminated handle to the EGC. This ought be considered invalidated by changes to the **nccell** or **egcpool**. The handle is **not** heap-allocated; do **not** attempt to **free(3)** it. A heap-allocated copy can be acquired with **nccell_strdup**. **ncstrwidth_valid** returns the number of columns occupied by a valid UTF-8 string, or -1 if an error is encountered. In either case, the number of valid bytes and columns, respectively, consumed before error into ***validbytes*** and ***validwidth*** (assuming them to not be **NULL**). **nccell_fg_palindex** extracts the palette index from a cell's foreground channel. The channel must be palette-indexed, or the return value is meaningless. Verify palette indexing with **nccell_fg_palindex_p**. A cell's foreground channel can be set to palette-indexed mode (and have the index set) with **nccell_set_fg_palindex**. The index must be less than **NCPALETTESIZE**. Replace **fg** with **bg** to operate on the background channel. # RETURN VALUES **nccell_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. **nccell_set_fg_rgb8** and similar functions will return -1 if provided invalid inputs, and 0 otherwise. **nccellcmp** returns a negative integer, 0, or a positive integer if ***c1*** is less than, equal to, or more than ***c2***, respectively. **nccell_extended_gcluster** returns **NULL** if called on a sprixel (see **notcurses_visual(3)**. **nccell_cols** returns the number of columns occupied by ***c***, according to **wcwidth(3)***. **ncstrwidth** is an equivalent for strings. **ncstrwidth_valid** returns the same value as **ncstrwidth**. # NOTES **cell** was renamed to **nccell** in Notcurses 2.2.0, so as not to bleed such a common term into the (single, global) C namespace. **cell** will be retained as an alias until Notcurses 3.0. Likewise, many functions prefixed with **cell** have been renamed to start with **nccell**. # SEE ALSO **notcurses(3)**, **notcurses_channels(3)**, **notcurses_plane(3)**, **notcurses_output(3)**, **notcurses_visual(3)**, **wcwidth(3)**, **utf8(7)**