mirror of
https://github.com/dankamongmen/notcurses.git
synced 2024-11-08 01:10:23 +00:00
194 lines
8.2 KiB
Markdown
194 lines
8.2 KiB
Markdown
% notcurses_visual(3)
|
||
% nick black <nickblack@linux.com>
|
||
% v1.6.12
|
||
|
||
# NAME
|
||
notcurses_visual - notcurses multimedia
|
||
|
||
# SYNOPSIS
|
||
|
||
**#include <notcurses/notcurses.h>**
|
||
|
||
```c
|
||
typedef enum {
|
||
NCSCALE_NONE,
|
||
NCSCALE_SCALE,
|
||
NCSCALE_STRETCH,
|
||
} ncscale_e;
|
||
|
||
typedef enum {
|
||
NCBLIT_DEFAULT, // let the ncvisual pick
|
||
NCBLIT_1x1, // full block █
|
||
NCBLIT_2x1, // upper half + 1x1 ▀█
|
||
NCBLIT_1x1x4, // shaded full blocks ▓▒░█
|
||
NCBLIT_2x2, // quadrants + 2x1 ▗▐ ▖▀▟▌▙█
|
||
NCBLIT_4x1, // four vertical levels █▆▄▂
|
||
NCBLIT_BRAILLE, // 4 rows, 2 cols (braille) ⡀⡄⡆⡇⢀⣀⣄⣆⣇⢠⣠⣤⣦⣧⢰⣰⣴⣶⣷⢸⣸⣼⣾⣿
|
||
NCBLIT_8x1, // eight vertical levels █▇▆▅▄▃▂▁
|
||
NCBLIT_SIXEL, // 6 rows, 1 col (RGB), spotty support among terminals
|
||
} ncblitter_e;
|
||
|
||
#define NCVISUAL_OPTION_NODEGRADE 0x0001
|
||
#define NCVISUAL_OPTION_BLEND 0x0002
|
||
|
||
struct ncvisual_options {
|
||
struct ncplane* n;
|
||
ncscale_e scaling;
|
||
int y, x;
|
||
int begy, begx; // origin of rendered section
|
||
int leny, lenx; // size of rendered section
|
||
ncblitter_e blitter; // glyph set to use (maps input to output cells)
|
||
uint64_t flags; // bitmask over NCVISUAL_OPTION_*
|
||
};
|
||
|
||
typedef int (*streamcb)(struct notcurses*, struct ncvisual*, void*);
|
||
```
|
||
|
||
**bool notcurses_canopen_images(const struct notcurses* nc);**
|
||
|
||
**bool notcurses_canopen_videos(const struct notcurses* nc);**
|
||
|
||
**bool notcurses_cansixel(const struct notcurses* nc);**
|
||
|
||
**struct ncvisual* ncvisual_from_file(const char* file, nc_err_e* err);**
|
||
|
||
**struct ncvisual* ncvisual_from_rgba(const void* rgba, int rows, int rowstride, int cols);**
|
||
|
||
**struct ncvisual* ncvisual_from_bgra(const void* bgra, int rows, int rowstride, int cols);**
|
||
|
||
**struct ncvisual* ncvisual_from_plane(struct ncplane* n, ncblitter_e blit, int begy, int begx, int leny, int lenx);**
|
||
|
||
**int ncvisual_geom(const struct notcurses* nc, const struct ncvisual* n, const struct ncvisual_options* vopts, int* y, int* x, int* toy, int* tox);**
|
||
|
||
**void ncvisual_destroy(struct ncvisual* ncv);**
|
||
|
||
**nc_err_e ncvisual_decode(struct ncvisual* nc);**
|
||
|
||
**struct ncplane* ncvisual_render(struct notcurses* nc, struct ncvisual* ncv, const struct ncvisual_options* vopts);**
|
||
|
||
**int ncvisual_simple_streamer(struct ncplane* n, struct ncvisual* ncv, const struct timespec* disptime, void* curry);**
|
||
|
||
**int ncvisual_stream(struct notcurses* nc, struct ncvisual* ncv, nc_err_e* err, float timescale, streamcb streamer, const struct ncvisual_options* vopts, void* curry);**
|
||
|
||
**int ncvisual_rotate(struct ncvisual* n, double rads);**
|
||
|
||
**int ncvisual_resize(struct ncvisual* n, int rows, int cols);**
|
||
|
||
**int ncvisual_polyfill_yx(struct ncvisual* n, int y, int x, uint32_t rgba);**
|
||
|
||
**int ncvisual_at_yx(const struct ncvisual* n, int y, int x, uint32_t* pixel);**
|
||
|
||
**int ncvisual_set_yx(const struct ncvisual* n, int y, int x, uint32_t pixel);**
|
||
|
||
**char* ncvisual_subtitle(const struct ncvisual* ncv);**
|
||
|
||
**int notcurses_lex_scalemode(const char* op, ncscale_e* scalemode);**
|
||
|
||
**const char* notcurses_str_scalemode(ncscale_e scalemode);**
|
||
|
||
**int notcurses_lex_blitter(const char* op, ncblitter_e* blitter);**
|
||
|
||
**const char* notcurses_str_blitter(ncblitter_e blitter);**
|
||
|
||
# DESCRIPTION
|
||
|
||
An **ncvisual** is a virtual pixel framebuffer. They can be created from
|
||
RGBA/BGRA data in memory (**ncvisual_from_rgba**/**ncvisual_from_bgra**),
|
||
or from the content of a suitable **ncplane** (**ncvisual_from_ncplane**).
|
||
If Notcurses was built against a multimedia engine (FFMpeg or OpenImageIO),
|
||
image and video files can be loaded into visuals using
|
||
**ncvisual_from_file**. **ncvisual_from_file** discovers the container
|
||
and codecs, but does not verify that the entire file is well-formed.
|
||
**ncvisual_decode** ought be invoked to recover subsequent frames, once
|
||
per frame.
|
||
|
||
Once the visual is loaded, it can be transformed using **ncvisual_rotate**
|
||
and **ncvisual_resize**. These are persistent operations, unlike any scaling
|
||
that takes place at render time. If a subtitle is associated with the frame,
|
||
it can be acquired with **ncvisual_subtitle**.
|
||
|
||
**ncvisual_from_rgba** and **ncvisual_from_bgra** both require a number of
|
||
**rows**, a number of image columns **cols**, and a virtual row length of
|
||
**rowstride** / 4 columns. The input data must provide 32 bits per pixel, and
|
||
thus must be at least **rowstride** * **rows** bytes, of which a **cols** *
|
||
**rows** * 4-byte subset is used. It is not possible to **mmap(2)** an image
|
||
file and use it directly--decompressed, decoded data is necessary. The
|
||
resulting plane will be ceil(**rows**/2) rows, and **cols** columns.
|
||
**ncvisual_from_plane** requires specification of a rectangle via **begy**,
|
||
**begx**, **leny**, and **lenx**. The only valid characters within this
|
||
region are those used by the **NCBLIT_2x2** blitter, though this may change
|
||
in the future.
|
||
|
||
**ncvisual_rotate** executes a rotation of **rads** radians, in the clockwise
|
||
(positive) or counterclockwise (negative) direction.
|
||
|
||
**ncvisual_subtitle** will return a UTF-8-encoded subtitle corresponding to
|
||
the current frame if such a subtitle was decoded. Note that a subtitle might
|
||
be returned for multiple frames, or might not.
|
||
|
||
**ncvisual_render** blits the visual to an **ncplane**, based on the contents
|
||
of its **struct ncvisual_options**. If **n** is not **NULL**, it specifies the
|
||
plane on which to render, and **y**/**x** specify a location within that plane.
|
||
Otherwise, a new plane will be created, and placed at **y**/**x** relative to
|
||
the rendering area. **begy**/**begx** specify the upper left corner of a
|
||
subsection of the **ncvisual** to render, while **leny**/**lenx** specify the
|
||
geometry of same. **flags** is a bitfield over:
|
||
|
||
* **NCVISUAL_OPTION_NODEGRADE** If the specified blitter is not available, fail rather than degrading.
|
||
* **NCVISUAL_OPTION_BLEND**: Render with **CELL_ALPHA_BLEND**.
|
||
|
||
# BLITTERS
|
||
|
||
The different **ncblitter_e** values select from among available glyph sets:
|
||
|
||
* **NCBLIT_DEFAULT**: Let the **ncvisual** choose its own blitter.
|
||
* **NCBLIT_1x1**: Full block (█) or empty glyph.
|
||
* **NCBLIT_2x1**: Adds the lower half block (▄) to **NCBLIT_1x1**.
|
||
* **NCBLIT_1x1x4**: Adds three shaded full blocks (▓▒░) to **NCBLIT_1x1**.
|
||
* **NCBLIT_2x2**: Adds left and right half blocks (▌▐) and quadrants (▖▗▟▙) to **NCBLIT_2x1**.
|
||
* **NCBLIT_4x1**: Adds ¼ and ¾ blocks (▂▆) to **NCBLIT_2x1**.
|
||
* **NCBLIT_BRAILLE**: 4 rows and 2 columns of braille (⡀⡄⡆⡇⢀⣀⣄⣆⣇⢠⣠⣤⣦⣧⢰⣰⣴⣶⣷⢸⣸⣼⣾⣿).
|
||
* **NCBLIT_8x1**: Adds ⅛, ⅜, ⅝, and ⅞ blocks (▇▅▃▁) to **NCBLIT_4x1**.
|
||
* **NCBLIT_SIXEL**: Sixel, a 6-by-1 RGB pixel arrangement.
|
||
|
||
# RETURN VALUES
|
||
|
||
**notcurses_canopen_images** and **notcurses_canopen_videos** returns true if
|
||
images and videos, respecitvely, can be decoded, or false if Notcurses was
|
||
built with insufficient multimedia support.
|
||
|
||
**ncvisual_from_file** returns an **ncvisual** object on success, or **NULL**
|
||
on failure. Success indicates that the specified **file** was opened, and
|
||
enough data was read to make a firm codec identification. It does not imply
|
||
that the entire file is properly-formed. On failure, **err** will be updated.
|
||
**ncvisual_decode** returns **NCERR_SUCCESS** on success, or **NCERR_EOF** on
|
||
end of file, or some other **nc_err_e** on failure. It likewise updates **err**
|
||
in the event of an error. It is only necessary for multimedia-based visuals.
|
||
|
||
**ncvisual_from_plane** returns **NULL** if the **ncvisual** cannot be created
|
||
and bound. This is usually due to illegal content in the source **ncplane**.
|
||
|
||
**ncvisual_render** returns **NULL** on error, and otherwise the plane to
|
||
which the visual was rendered. If **opts->n** is provided, this will be
|
||
**opts->n**. Otherwise, a plane will be created, perfectly sized for the
|
||
visual and the specified blitter.
|
||
|
||
**ncvisual_geom** returns non-zero if the **blitter** is invalid.
|
||
|
||
# NOTES
|
||
|
||
Multimedia decoding requires that Notcurses be built with either FFmpeg or
|
||
OpenImageIO support. What formats can be decoded is totally dependent on the
|
||
linked library. OpenImageIO does not support subtitles.
|
||
|
||
# BUGS
|
||
|
||
**ncvisual_rotate** currently supports only **M_PI**/2 and -**M_PI**/2
|
||
radians for **rads**, but this will change soon.
|
||
|
||
# SEE ALSO
|
||
|
||
**notcurses(3)**,
|
||
**notcurses_plane(3)**,
|
||
**utf-8(7)**
|