mirror of
https://github.com/dankamongmen/notcurses.git
synced 2024-11-02 09:40:15 +00:00
103 lines
5.1 KiB
Markdown
103 lines
5.1 KiB
Markdown
# Notcurses viz Curses/NCURSES
|
|
|
|
The biggest difference, of course, is that Notcurses is neither an
|
|
implementation of X/Open (aka XSI) Curses, nor part of SUS4-2018.
|
|
|
|
## Differences from Curses
|
|
|
|
The detailed differences between Notcurses and NCURSES (a high-quality, ubiquitous
|
|
implementation of Curses) probably can't be fully enumerated, and if they
|
|
could, no one would want to read them. With that said, some design decisions
|
|
might surprise NCURSES programmers:
|
|
|
|
* There is no distinct `PANEL` type. The z-buffer is a fundamental property,
|
|
and all drawable surfaces are ordered along the z axis. There is no
|
|
equivalent to `update_panels()`.
|
|
* Scrolling is disabled by default, and cannot be globally enabled (but
|
|
see Direct Mode).
|
|
* The Curses `cchar_t` has a fixed-size array of `wchar_t`. The Notcurses
|
|
`nccell` instead supports a UTF-8 encoded extended grapheme cluster of
|
|
arbitrary length. The only supported encodings are ASCII via `ANSI_X3.4-1968`
|
|
and Unicode via `UTF-8`.
|
|
* The cursor is disabled by default, when supported (`civis` capability).
|
|
* Echoing of input is disabled by default, and `cbreak` mode is used by default.
|
|
* Colors are usually specified as 24 bits in 3 components (RGB). If necessary,
|
|
these will be quantized for the actual terminal. There are no "color pairs",
|
|
but indexed palettes are supported.
|
|
* There is no distinct "pad" concept (these are NCURSES `WINDOW`s created with
|
|
the `newpad()` function). All drawable surfaces can exceed the display size.
|
|
* Multiple threads can freely call into Notcurses, so long as they're not
|
|
accessing the same data. In particular, it is always safe to concurrently
|
|
mutate different `ncplane`s in different threads.
|
|
* NCURSES has thread-ignorant and thread-semi-safe versions, trace-enabled and
|
|
traceless versions, and versions with and without support for wide characters.
|
|
Notcurses is one library: no tracing, UTF-8, thread safety.
|
|
* There is no `ESCDELAY` concept; Notcurses expects that all bytes of an
|
|
escape sequence arrive at the same time. This improves latency and simplifies
|
|
the API.
|
|
* It is an error in NCURSES to print to the bottommost, rightmost coordinate of
|
|
the screen when scrolling is disabled (because the cursor cannot be advanced).
|
|
Failure to advance the cursor does not result in an error in Notcurses (but
|
|
attempting to print at the cursor when it has been advanced off the plane *does*).
|
|
* Notcurses has no support for soft labels (`slk_init()`, etc.), subwindows
|
|
which share memory with their parents, nor the NCURSES tracing functionality
|
|
(`trace(3NCURSES)`).
|
|
* Notcurses doesn't implement any of the `curs_util(3x)` functions, including
|
|
window serialization/deserialization via `putwin()`/`getwin()`.
|
|
* Notcurses doesn't interact with `LINES` nor `COLUMNS` environment variables.
|
|
|
|
## Adapting NCURSES programs
|
|
|
|
Do you really want to do such a thing? NCURSES and the Curses API it implements
|
|
are far more portable and better-tested than Notcurses is ever likely to be.
|
|
Will your program really benefit from Notcurses's advanced features? If not,
|
|
it's probably best left as it is.
|
|
|
|
Otherwise, most NCURSES concepts have clear partners in Notcurses. Any functions
|
|
making implicit use of `stdscr` ought be replaced with their explicit
|
|
equivalents. `stdscr` ought then be replaced with the result of
|
|
`notcurses_stdplane()` (the standard plane). `PANEL`s become `ncplane`s; the
|
|
Panels API is otherwise pretty close. Anything writing a bare character will
|
|
become a simple `nccell`; multibyte or wide characters become complex `nccell`s.
|
|
Color no longer uses "color pairs". You can easily enough hack together a
|
|
simple table mapping your colors to RGB values, and color pairs to foreground
|
|
and background indices into said table. That'll work for the duration of a
|
|
porting effort, certainly.
|
|
|
|
I have adapted two large (~5k lines of C UI code each) programs from NCURSES to
|
|
Notcurses, and found it a fairly painless process. It was helpful to introduce
|
|
a shim layer, e.g. `compat_mvwprintw` for NCURSES's `mvwprintw`:
|
|
|
|
```c
|
|
static int
|
|
compat_mvwprintw(struct ncplane* nc, int y, int x, const char* fmt, ...){
|
|
va_list va;
|
|
va_start(va, fmt);
|
|
if(ncplane_vprintf_yx(nc, y, x, fmt, va) < 0){
|
|
va_end(va);
|
|
return ERR;
|
|
}
|
|
va_end(va);
|
|
return OK;
|
|
}
|
|
```
|
|
|
|
These are pretty obvious, implementation-wise.
|
|
|
|
### Some details
|
|
|
|
* `cbreak()`/`nocbreak()`/`echo()`/`noecho()`/`nl()`/`nonl()`: termios
|
|
properties are not exposed as granularly by Notcurses. Rendered mode
|
|
always enters cbreak mode. Direct mode enters cbreak mode by default,
|
|
but `NCDIRECT_OPTION_INHIBIT_CBREAK` will inhibit this.
|
|
* `raw()`/`noraw()`: The line discipline conversions (e.g. Ctrl+C) can be
|
|
disabled at any time with `notcurses_linesigs_disable()`, and turned back on
|
|
with `notcurses_linesigs_enable()`.
|
|
* `keypad()`: The keypad is always enabled, if the `smkx`
|
|
capability is advertised.
|
|
* `halfdelay()`/`nodelay()`/`timeout()`/`wtimeout()`: No such global controls
|
|
are supported. Use `notcurses_getc()` with a timeout if you want a timeout.
|
|
Use `notcurses_getc_nblock()` if you want an immediate return.
|
|
* `intrflush()`/`qiflush()`/`noqiflush()`: No such functionality is supported.
|
|
* `typeahead()`: No such functionality is supported.
|