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121 lines
5.1 KiB
Markdown
121 lines
5.1 KiB
Markdown
% notcurses_input(3)
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% nick black <nickblack@linux.com>
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% v1.0.0
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# NAME
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notcurses_input - input via notcurses
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# SYNOPSIS
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#include <notcurses.h>**
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```c
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typedef struct ncinput {
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char32_t id; // Unicode codepoint
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int y; // Y cell coordinate of event, -1 for undefined
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int x; // X cell coordinate of event, -1 for undefined
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bool alt; // Was Alt held during the event?
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bool shift; // Was Shift held during the event?
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bool ctrl; // Was Ctrl held during the event?
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} ncinput;
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```
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**bool nckey_mouse_p(char32_t r);**
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**char32_t notcurses_getc(struct notcurses* n, const struct timespec* ts, sigset_t* sigmask, ncinput* ni);**
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**char32_t notcurses_getc_nblock(struct notcurses* n, ncinput* ni);**
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**char32_t notcurses_getc_blocking(struct notcurses* n, ncinput* ni);**
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**int notcurses_mouse_enable(struct notcurses* n);**
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**int notcurses_mouse_disable(struct notcurses* n);**
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# DESCRIPTION
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notcurses supports input from keyboards and mice, and any device that looks
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like them. Mouse support requires a broker such as GPM, Wayland, or Xorg, and
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must be explicitly enabled via **notcurses_mouse_enable(3)**. The full 32-bit
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range of Unicode is supported (see **unicode(7)**), with synthesized events
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mapped into the [Supplementary Private Use Area-B](https://unicode.org/charts/PDF/U100000.pdf).
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Unicode characters are returned directly as UCS-32, one codepoint at a time.
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notcurses takes its keyboard input from **stdin**, which will be placed into
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non-blocking mode for the duration of operation. The terminal is put into raw
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mode (see **cfmakeraw(3)**), and thus keys are received without line-buffering.
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notcurses maintains its own buffer of input characters, which it will attempt
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to fill whenever it reads.
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**notcurses_getc(3)** allows a **struct timespec** to be specified as a timeout.
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If **ts** is **NULL**, **notcurses_getc(3)** will block until it reads input, or
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is interrupted by a signal. If its values are zeroes, there will be no blocking.
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Otherwise, **ts** specifies a minimum time to wait for input before giving up.
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On timeout, 0 is returned. Signals in **sigmask** will be masked and blocked in
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the same manner as a call to **ppoll(2)**. **sigmask** may be **NULL**. Event
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details will be reported in **ni**, unless **ni** is NULL.
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## Mice
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For mouse events, the additional fields **y** and **x** are set. These fields
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are not meaningful for keypress events. Mouse events can be distinguished using
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the **nckey_mouse_p(3)** predicate. Once enabled, mouse button presses are
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detected, as are mouse motions made while a button is held down. If no button
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is depressed, mouse movement _does not result in events_. This is known as
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"button-event tracking" mode in the nomenclature of [Xterm Control
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Sequences](https://www.xfree86.org/current/ctlseqs.html).
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## Synthesized keypresses
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Many keys do not have a Unicode representation, let alone ASCII. Examples
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include the modifier keys (Alt, Meta, etc.), the "function" keys, and the arrow
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keys on the numeric keypad. The special keys available to the terminal are
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defined in the **terminfo(5)** entry, which notcurses loads on startup. Upon
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receiving an escape code matching a terminfo input capability, notcurses
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synthesizes a special value. An escape sequence must arrive in its entirety to
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notcurses; running out of input in the middle of an escape sequence will see it
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rejected. Likewise, any error while handling an escape sequence will see the
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lex aborted, and the sequence thus far played back as independent literal
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keystrokes.
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The full list of synthesized keys (there are well over one hundred) can be
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found in **<notcurses.h>**. For more details, consult **terminfo(5)**.
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## **NCKEY_RESIZE**
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Unless the **SIGWINCH** handler has been inhibited (see **notcurses_init(3)**),
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notcurses will automatically catch screen resizes, and synthesize an
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**NCKEY_RESIZE** event. Upon receiving this event, the user may call
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**notcurses_resize(3)** to force an immediate reflow, or just wait until the
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next call to **notcurses_render(3)**, when notcurses will pick up the resize
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itself. If the **SIGWINCH** handler is inhibited, **NCKEY_RESIZE** is never
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generated.
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# RETURN VALUES
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On error, the **_getc** family of functions returns **(char32_t)-1**. The cause of the error may be determined
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using **errno(3)**. Unless the error was a temporary one (especially e.g. **EINTR**),
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**notcurses_getc(3)** probably cannot be usefully called forthwith. On a
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timeout, 0 is returned. Otherwise, the UCS-32 value of a Unicode codepoint, or
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a synthesized event, is returned.
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**notcurses_mouse_enable(3)** returns 0 on success, and non-zero on failure, as
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does **notcurses_mouse_disable(3)**.
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# NOTES
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Like any other notcurses function, it is an error to call **notcurses_getc(3)**
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during or after a call to **notcurses_stop(3)**. If a thread is always sitting
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on blocking input, it can be tricky to guarantee that this doesn't happen.
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# BUGS
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Failed escape sequences are not yet played back in their entirety; only an
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ESC (ASCII 0x1b) will be seen by the application.
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# SEE ALSO
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**notcurses(3)**, **poll(2)**, **unicode(7)**, **cfmakeraw(3)**, **terminfo(5)**,
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**ascii(7)**, **signal(7)**, **termios(3)**
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