Ubuntu Manpage: notcurses_input - input via notcurses

Provided by: libnotcurses-core-dev_3.0.7+dfsg.1-1ubuntu1_amd64

NAME

       notcurses_input - input via notcurses

SYNOPSIS

       #include <notcurses/notcurses.h>

              struct timespec;
              struct notcurses;

              typedef enum {
                NCTYPE_UNKNOWN,
                NCTYPE_PRESS,
                NCTYPE_REPEAT,
                NCTYPE_RELEASE,
              } ncintype_e;

              // An input event. Cell coordinates are currently defined only for mouse
              // events. It is not guaranteed that we can set the modifiers for a given
              // ncinput. We encompass single Unicode codepoints, not complete EGCs.
              // FIXME for abi4, combine the bools into |modifiers|
              typedef struct ncinput {
                uint32_t id;       // Unicode codepoint or synthesized NCKEY event
                int y, x;          // y/x cell coordinate of event, -1 for undefined
                char utf8[5];      // utf8 representation, if one exists
                // DEPRECATED do not use! going away in 4.0
                bool alt;          // was alt held?
                bool shift;        // was shift held?
                bool ctrl;         // was ctrl held?
                // END DEPRECATION
                ncintype_e evtype;
                unsigned modifiers;// bitmask over NCKEY_MOD_*
                int ypx, xpx;      // pixel offsets within cell, -1 for undefined
              } ncinput;

              #define NCMICE_NO_EVENTS     0
              #define NCMICE_MOVE_EVENT    0x1
              #define NCMICE_BUTTON_EVENT  0x2
              #define NCMICE_DRAG_EVENT    0x4
              #define NCMICE_ALL_EVENTS    0x7

       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_get_nblock(struct notcurses* n, ncinput* ni);

       uint32_t notcurses_get_blocking(struct notcurses* n, ncinput* ni);

       int notcurses_mice_enable(struct notcurses* n, unsigned eventmask);

       int notcurses_mice_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);

       bool ncinput_shift_p(const struct ncinput* n);

       bool ncinput_ctrl_p(const struct ncinput* n);

       bool ncinput_alt_p(const struct ncinput* n);

       bool ncinput_meta_p(const struct ncinput* n);

       bool ncinput_super_p(const struct ncinput* n);

       bool ncinput_hyper_p(const struct ncinput* 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_mice_enable. The full 32-bit range of Unicode is supported (see
unicode(7)), with synthesized events mapped above the 1,114,112 codepoints of Unicode
14.0's seventeen Planes. Unicode characters are returned directly as UCS-32, one
codepoint at a time. When the input has a UTF8 representation, it is written to utf8;
this field is always NUL-terminated.

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 (taken against CLOCK_MONOTONIC; see clock_gettime(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). Note that NCTYPE_UNKNOWN and NCTYPE_PRESS are considered equivalent for the
purposes of ncinput_equal_p.

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.

ncinput_shift_p, ncinput_ctrl_p, ncinput_alt_p, and ncinput_meta_p test n to see if the
relevant modifier is set. This is preferably to directly accessing the struct members.

Mice
For mouse events, the additional fields y, x, ypx, and xpx are set. These fields are not
meaningful for keypress events. Mouse events can be distinguished using the nckey_mouse_p
predicate. NCMICE_MOVE_EVENT requests events whenever the mouse moves when no buttons are
held down. NCMICE_DRAG_EVENT requests events when the mouse is moving with buttons held
down. NCMICE_BUTTON_EVENT requests events then the button state changes.
NCMICE_ALL_EVENTS is provided for convenience and future-proofing against API (though not
ABI) changes.

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
<notcurses/notcurses.h>. 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_SIGNAL
Unless the SIGWINCH handler has been inhibited (see notcurses_init), Notcurses will catch
SIGCONT, and synthesize an NCKEY_SIGNAL event. This typically indicates that the program
has been restarted after being paused or placed in the background. The next rasterization
will be a full rebuild of the screen, as if notcurses_refresh had been called; the user
might wish to immediately call notcurses_refresh themselves.

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_mice_enable  returns  0  on  success,  and  non-zero   on   failure,   as   does
       notcurses_mice_disable.   Success  does not necessarily mean that a mouse is available nor
       that all requested events will be generated.

       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).

       The full list of synthesized events is available in <notcurses/nckeys.h>.

       In API4, the various bool modifier fields will go away, and these statuses will be  merged
       into  the  modifiers  bitmask.   You  are encouraged to use ncinput_shift_p and friends to
       future-proof your code.

BUGS

Notcurses attempts to use the XTMODKEYS and Kitty keyboard disambiguation protocols. When
supported, they eliminate most of these issues.

The Shift key is traditionally not indicated in conjunction with typical Unicode text. If
e.g. Shift is used to generate a capital letter 'A', id will equal 'A', and shift will be
false. Similarly, 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'.

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. You can determine whether the protocol is in use by examining the output of
notcurses-info(1). If the kbd property is indicated, you're using the Kitty protocol.

Mouse events in the 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.

The ypx and xpx fields are never currently valid (i.e. they are always -1). This ought
be fixed in the future using the SGR PixelMode mouse protocol.

On some operating systems, CLOCK_REALTIME is used as the basis for timeouts instead of
CLOCK_MONOTONIC. This ought be fixed.

AUTHORS

       nick black <nickblack@linux.com>.

                                              v3.0.7                           notcurses_input(3)