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158 lines
5.3 KiB
Markdown
158 lines
5.3 KiB
Markdown
% notcurses_cell(3)
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% nick black <nickblack@linux.com>
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% v1.6.18.3
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# NAME
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notcurses_cell - operations on notcurses cells
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# SYNOPSIS
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**#include <notcurses/notcurses.h>**
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```c
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// See DESCRIPTION below for information on EGC encoding
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typedef struct cell {
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uint32_t gcluster; // 4B → 4B
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uint8_t gcluster_backstop; // 1B → 5B (8 bits of zero)
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uint8_t reserved; // 1B → 6B (8 reserved bits, ought be zero)
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uint16_t stylemask; // 2B → 8B (16 bits of NCSTYLE_* attributes)
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uint64_t channels;
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} cell;
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#define CELL_TRIVIAL_INITIALIZER \
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{ .gcluster = '\0', .stylemask = 0, .channels = 0, }
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#define CELL_SIMPLE_INITIALIZER(c) \
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{ .gcluster = (c), .stylemask = 0, .channels = 0, }
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#define CELL_INITIALIZER(c, s, chan) \
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{ .gcluster = (c), .stylemask = (s), .channels = (chan), }
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#define CELL_WIDEASIAN_MASK 0x8000000080000000ull
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#define CELL_BGDEFAULT_MASK 0x0000000040000000ull
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#define CELL_FGDEFAULT_MASK (CELL_BGDEFAULT_MASK << 32u)
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#define CELL_BG_RGB_MASK 0x0000000000ffffffull
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#define CELL_FG_RGB_MASK (CELL_BG_MASK << 32u)
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#define CELL_BG_PALETTE 0x0000000008000000ull
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#define CELL_FG_PALETTE (CELL_BG_PALETTE << 32u)
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#define CHANNEL_ALPHA_MASK 0x30000000ull
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#define CELL_ALPHA_HIGHCONTRAST 0x30000000ull
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#define CELL_ALPHA_TRANSPARENT 0x20000000ull
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#define CELL_ALPHA_BLEND 0x10000000ull
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#define CELL_ALPHA_OPAQUE 0x00000000ull
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```
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**void cell_init(cell* c);**
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**int cell_load(struct ncplane* n, cell* c, const char* gcluster);**
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**int cell_prime(struct ncplane* n, cell* c, const char* gcluster,
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uint32_t stylemask, uint64_t channels);**
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**int cell_duplicate(struct ncplane* n, cell* targ, const cell* c);**
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**void cell_release(struct ncplane* n, cell* c);**
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**void cell_styles_set(cell* c, unsigned stylebits);**
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**unsigned cell_styles(const cell* c);**
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**void cell_styles_on(cell* c, unsigned stylebits);**
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**void cell_styles_off(cell* c, unsigned stylebits);**
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**void cell_set_fg_default(cell* c);**
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**void cell_set_bg_default(cell* c);**
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**int cell_set_fg_alpha(cell* c, unsigned alpha);**
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**int cell_set_bg_alpha(cell* c, unsigned alpha);**
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**bool cell_double_wide_p(const cell* c);**
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**const char* cell_extended_gcluster(const struct ncplane* n, const cell* c);**
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**char* cell_strdup(const struct ncplane* n, const cell* c);**
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**int cell_load_simple(struct ncplane* n, cell* c, char ch);**
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**char* cell_extract(const struct ncplane* n, const cell* c, uint16_t* stylemask, uint64_t* channels);**
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**uint32_t cell_bchannel(const cell* cl);**
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**uint32_t cell_fchannel(const cell* cl);**
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**uint64_t cell_set_bchannel(cell* cl, uint32_t channel);**
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**uint64_t cell_set_fchannel(cell* cl, uint32_t channel);**
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**uint32_t cell_fg(const cell* cl);**
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**uint32_t cell_bg(const cell* cl);**
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**unsigned cell_fg_alpha(const cell* cl);**
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**unsigned cell_bg_alpha(const cell* cl);**
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**unsigned cell_fg_rgb(const cell* cl, unsigned* r, unsigned* g, unsigned* b);**
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**unsigned cell_bg_rgb(const cell* cl, unsigned* r, unsigned* g, unsigned* b);**
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**int cell_set_fg_rgb(cell* cl, int r, int g, int b);**
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**int cell_set_bg_rgb(cell* cl, int r, int g, int b);**
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**void cell_set_fg_rgb_clipped(cell* cl, int r, int g, int b);**
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**void cell_set_bg_rgb_clipped(cell* cl, int r, int g, int b);**
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**int cell_set_fg(cell* c, uint32_t channel);**
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**int cell_set_bg(cell* c, uint32_t channel);**
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**bool cell_fg_default_p(const cell* cl);**
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**bool cell_bg_default_p(const cell* cl);**
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# DESCRIPTION
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Cells make up the framebuffer associated with each plane, with one cell per
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addressable coordinate. You should not usually need to interact directly
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with cells.
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Each **cell** contains exactly one extended grapheme cluster. If the EGC
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is encoded in UTF-8 with four or fewer bytes (all Unicode codepoints as of
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Unicode 13 can be encoded in no more than four UTF-8 bytes), it is encoded
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directly into the **cell**'s **gcluster** field, and no additional storage
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is necessary. Otherwise, the EGC is stored as a nul-terminated UTF-8 string in
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some backing egcpool. Egcpools are associated with **ncplane**s, so **cell**s
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must be considered associated with **ncplane**s. Indeed, **ncplane_erase()**
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destroys the backing storage for all a plane's cells, invalidating them. This
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association is formed at the time of **cell_load()**, **cell_prime()**, or
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**cell_duplicate()**. All of these functions first call **cell_release()**, as
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does **cell_load_simple()**. When done using a **cell** entirely, call
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**cell_release()**. **ncplane_destroy()** will free up the memory used by the
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**cell**, but the backing egcpool has a maximum size of 16MiB, and failure to
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release **cell**s can eventually block new output.
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**cell_extended_gcluster** provides a nul-terminated handle to the EGC. This
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ought be considered invalidated by changes to the **cell** or **egcpool**.
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The handle is **not** heap-allocated; do **not** attempt to **free(3)** it.
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A heap-allocated copy can be acquired with **cell_strdup**.
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# RETURN VALUES
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**cell_load()** and similar functions return the number of bytes loaded from the
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EGC, or -1 on failure. They can fail due to either an invalid UTF-8 input, or the
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backing egcpool reaching its maximum size.
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**cell_set_fg_rgb()** and similar functions will return -1 if provided invalid
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inputs, and 0 otherwise.
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# SEE ALSO
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**notcurses(3)**,
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**notcurses_channels(3)**,
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**notcurses_plane(3)**,
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**notcurses_output(3)**
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