% notcurses_input(3) % nick black % v2.4.7 # NAME notcurses_input - input via notcurses # SYNOPSIS **#include ** ```c struct timespec; struct notcurses; typedef struct ncinput { uint32_t id; // Unicode codepoint int y; // Y cell coordinate of event, -1 for undefined int x; // X cell coordinate of event, -1 for undefined bool alt; // Was Alt held during the event? bool shift; // Was Shift held during the event? bool ctrl; // Was Ctrl held during the event? enum { EVTYPE_UNKNOWN, EVTYPE_PRESS, EVTYPE_REPEAT, EVTYPE_RELEASE, } evtype; } ncinput; ``` **bool nckey_mouse_p(uint32_t ***r***);** **bool ncinput_nomod_p(const ncinput* ***ni***);** **uint32_t notcurses_get(struct notcurses* ***n***, const struct timespec* ***ts***, ncinput* ***ni***);** **int notcurses_getvec(struct notcurses* ***n***, const struct timespec* ***ts***, ncinput* ***ni***, int vcount);** **uint32_t notcurses_getc_nblock(struct notcurses* ***n***, ncinput* ***ni***);** **uint32_t notcurses_getc_blocking(struct notcurses* ***n***, ncinput* ***ni***);** **int notcurses_mouse_enable(struct notcurses* ***n***);** **int notcurses_mouse_disable(struct notcurses* ***n***);** **int notcurses_inputready_fd(struct notcurses* ***n***);** **static inline bool ncinput_equal_p(const ncinput* ***n1***, const ncinput* ***n2***);** **int notcurses_linesigs_disable(struct notcurses* ***n***);** **int notcurses_linesigs_enable(struct notcurses* ***n***);** # DESCRIPTION notcurses supports input from keyboards and mice, and any device that looks like them. Mouse support requires a broker such as GPM, Wayland, or Xorg, and must be explicitly enabled via **notcurses_mouse_enable**. The full 32-bit range of Unicode is supported (see **unicode(7)**), with synthesized events mapped into the [Supplementary Private Use Area-B](https://unicode.org/charts/PDF/U1.0.10.pdf). Unicode characters are returned directly as UCS-32, one codepoint at a time. notcurses takes its keyboard input from **stdin**, which will be placed into non-blocking mode for the duration of operation. The terminal is put into non-canonical mode (see **termios(3)**), and thus keys are received without line-buffering. notcurses maintains its own buffer of input characters, which it will attempt to fill whenever it reads. **notcurses_get** allows a **struct timespec** to be specified as a timeout. If **ts** is **NULL**, **notcurses_get** will block until it reads input, or is interrupted by a signal. If its values are zeroes, there will be no blocking. Otherwise, **ts** specifies an absolute deadline (using the same source and timezone as **gettimeofday(2)**). On timeout, 0 is returned. Event details will be reported in **ni**, unless **ni** is NULL. **notcurses_inputready_fd** provides a file descriptor suitable for use with I/O multiplexors such as **poll(2)**. This file descriptor might or might not be the actual input file descriptor. If it readable, **notcurses_get** can be called without the possibility of blocking. **ncinput_equal_p** compares two **ncinput** structs for data equality (i.e. not considering padding), returning **true** if they represent the same input (though not necessarily the same input event). **notcurses_linesigs_disable** disables conversion of inputs **INTR**, **QUIT**, **SUSP**, and **DSUSP** into **SIGINT**, **SIGQUIT**, and **SIGTSTP**. These conversions are enabled by default. **notcurses_linesigs_enable** undoes this action, but signals in the interim are permanently lost. ## Mice For mouse events, the additional fields **y** and **x** are set. These fields are not meaningful for keypress events. Mouse events can be distinguished using the **nckey_mouse_p** predicate. Once enabled, mouse button presses and releases are detected, as are mouse motions made while a button is held down. If no button is depressed, mouse movement _does not result in events_. This is known as "button-event tracking" mode in the nomenclature of [Xterm Control Sequences](https://www.xfree86.org/current/ctlseqs.html). ## Synthesized keypresses Many keys do not have a Unicode representation, let alone ASCII. Examples include the modifier keys (Alt, Meta, etc.), the "function" keys, and the arrow keys on the numeric keypad. The special keys available to the terminal are defined in the **terminfo(5)** entry, which notcurses loads on startup. Upon receiving an escape code matching a terminfo input capability, notcurses synthesizes a special value. An escape sequence must arrive in its entirety to notcurses; running out of input in the middle of an escape sequence will see it rejected. Likewise, any error while handling an escape sequence will see the lex aborted, and the sequence thus far played back as independent literal keystrokes. The full list of synthesized keys (there are well over one hundred) can be found in ****. For more details, consult **terminfo(5)**. ## **NCKEY_RESIZE** Unless the **SIGWINCH** handler has been inhibited (see **notcurses_init**), notcurses will automatically catch screen resizes, and synthesize an **NCKEY_RESIZE** event. Upon receiving this event, the user may call **notcurses_refresh** to force an immediate reflow, or just wait until the next call to **notcurses_render**, when notcurses will pick up the resize itself. If the **SIGWINCH** handler is inhibited, **NCKEY_RESIZE** is never generated. ## **NCKEY_EOF** Upon reaching the end of input, **NCKEY_EOF** will be returned. At this point, any further calls will immediately return **NCKEY_EOF**. Note that this does not necessarily result from pressing e.g. Ctrl+D. # RETURN VALUES On error, the **get** family of functions return **(uint32_t)-1**. The cause of the error may be determined using **errno(3)**. Unless the error was a temporary one (especially e.g. **EINTR**), **notcurses_get** probably cannot be usefully called forthwith. On a timeout, 0 is returned. Otherwise, the UCS-32 value of a Unicode codepoint, or a synthesized event, is returned. If an error is encountered before **notcurses_getvec** has read any input, it will return -1. If it times out before reading any input, it will return 0. Otherwise, it returns the number of **ncinput** objects written back. **notcurses_mouse_enable** returns 0 on success, and non-zero on failure, as does **notcurses_mouse_disable**. **ncinput_equal_p** returns **true** if the two **ncinput** structs represent the same input (though not necessarily the same input event), and **false** otherwise. # NOTES Like any other notcurses function, it is an error to call **notcurses_get** during or after a call to **notcurses_stop**. If a thread is always sitting on blocking input, it can be tricky to guarantee that this doesn't happen. Only one thread may call into the input stack at once, but unlike almost every other function in notcurses, **notcurses_get** and friends can be called concurrently with **notcurses_render**. Do not simply **poll** the file descriptor associated with **stdin** to test for input readiness. Instead, use the file descriptor returned by **notcurses_inputready_fd** to ensure compatibility with future versions of Notcurses (it is possible that future versions will process input in their own contexts). When support is detected, the Kitty keyboard disambiguation protocol will be requested. This eliminates most of the **BUGS** mentioned below. # BUGS Failed escape sequences are not yet played back in their entirety; only an ESC (ASCII 0x1b) will be seen by the application. The Shift key is only indicated in conjunction with mouse button presses. If e.g. Shift is used to generate a capital letter 'A', **id** will equal 'A', and **shift** will be **false**. This should be fixed in the future. When Ctrl is pressed along with a letter, the letter will currently always be reported in its uppercase form. E.g., if Shift, Ctrl, and 'a' are all pressed, this is indistinguishable from Ctrl and 'a' without Shift. This should be fixed in the future. Ctrl pressed along with 'J' or 'M', whether Shift is pressed or not, currently registers as **NCKEY_ENTER**. This will likely change in the future. When the Kitty keyboard disambiguation protocol is used, most of these issues are resolved. Mouse events in the top and left margins will never be delivered to the application (as is intended), but mouse events in the bottom and right margins sometimes can be if the event occurs prior to a window resize. # SEE ALSO **gettimeofday(2)**, **poll(2)**, **notcurses(3)**, **notcurses_refresh(3)**, **notcurses_render(3)**, **termios(3)**, **terminfo(5)**, **ascii(7)**, **signal(7)**, **unicode(7)**