YASCREEN(3)

NAME

yascreen - Yet Another Screen Library (curses replacement for daemons and embedded apps)

SYNOPSIS

#include <yascreen.h>

DESCRIPTION

Main features

    •   small footprint

    •   does not have external dependencies

    •   allows both internal and external event loop

    •   allows stdin/stdout or external input/output (can work over socket)

    •   supports basic set of telnet sequences, making it suitable for built-in terminal interfaces for daemons

    •   supports a limited set of input keystroke sequences

    •   fully unicode compatible (parts of this depend on wcwidth in libc)

    •   supports utf8 verification of input

    •   relies only on a limited subset of ansi/xterm ESC sequences, making it compatible with mostly all modern terminals (inspired by linenoise ⟨https://github.com/antirez/linenoise⟩)

    •   there is no curses API and ancient terminal compatibility, hence less bloat

    •   there is no autoconf - there is no need to have one

    •   clean API with opaque private data, usable from C/C++

    •   easy cross compilation setup (by setting CC, AR, STRIP and RANLIB)

Current development is done on Linux, with additional testing on OpenBSD/FreeBSD; other platforms may need minimal fixes.

On *BSD a gmake is required to build.

Architecture

yascreen uses an opaque data structure, allocated by the library and dynamically resized when needed - yascreen_init(int sx, int sy) / yascreen_resize(yascreen *s, int sx, int sy). An application may specify (0,0) for both calls to let yascreen detect the size or use a fixed size.

There are two modes of operation - telnet protocol over socket or running in terminal. For sockets the event loop would typically be handled outside of the library while for terminals a built-in event loop may be used.

Modes of operation can be modified at runtime.

For terminal use signal handling (SIGWINCH) should always be handled by the application.

Example initialization for terminal and handling of SIGWINCH

    yascreen *s;
    int winch=0;
    void sigwinch(int sign) {
    	winch=1;
    }
    s=yascreen_init(0,0); // let yascreen get term size
    yascreen_term_set(s,YAS_NOBUFF|YAS_NOSIGN|YAS_NOECHO);
    signal(SIGWINCH,sigwinch);
    for (;;) { // main loop
    	if (winch) {
    		winch=0;
    		if (yascreen_resize(s,0,0))
    			// handle a fatal error - no memory
    		// get the new sizes and redraw
    		newsizex=yascreen_sx(s);
    		newsizey=yascreen_sy(s);
    	}
    	…
    	// option 1
    	// input is handled in external event loop and fed to yascreen via yascreen_feed
    	if (FD_ISSET(STDIN_FILENO,r)sizeof c==read(STDIN_FILENO,c,sizeof c))
    		yascreen_feed(s,c); // pump state machine with bytestream
    	// keys are processed only when available without delay/blocking
    	while ((ch=yascreen_getch_nowait(s))!=-1) {
    		// handle processed keys
    	}
    	…
    	// option 2
    	// input is handled by yascreen and key or -1 is returned not longer than TIMEOUT ms
    	// note: if screen update is based on this, keypresses will force it
    	while ((ch=yascreen_getch_to(s,TIMEOUT))!=-1) {
    		// handle processed keys
    	}
    	…
    	// option 3
    	// input is handled by yascreen and the following call will block until a key is pressed
    	if ((ch=yascreen_getch(s))!=-1) {
    		// handle processed key
    	}
    }

For sockets input is handled like option 1 in the example above and yascreen needs to be provided with a callback for output.

In multiprocess mode daemons where stdin/stdout are redirected to a socket the same model from the example above can be used. Obviously SIGWINCH will work only for terminals and for sockets the screen size can get to be known either via telnet or ASNI sequences.

Example initialization for socket with external event loop and telnet sequences processing

    yascreen *s;
    s=yascreen_init(80,25); // there is no guarantee that screen size detection is supported on the remote end
    yascreen_setout(s,output_cb); // set callback for output
    yascreen_set_telnet(s,1); // enable processing of telnet sequences
    yascreen_init_telnet(s); // try to negotiate telnet options (regardless if telnet processing is enabled)
    yascreen_reqsize(s); // request initial screen size
    for (;;) { // main loop
    	…
    	yascreen_feed(s,c); // feed input from the socket to yascreen
    	// keys are processed only when available without delay/blocking
    	while ((ch=yascreen_getch_nowait(s))!=-1) {
    		// handle processed keys
    		// screen size change is reported as a special keypress code:
    		if (ch==YAS_TELNET_SIZE||ch==YAS_SCREEN_SIZE) // screen size change reported via telnet or ANSI sequence
    			// redraw
    	}
    }

API Reference

Predefined constants and Helper macros

Internally style is kept into bitfields in a single integer variable - that includes foreground/background colors, style modifiers (bold, italic, underline, inverse and blink.

Style codes
Name | Function
YAS_ITALIC | italic
YAS_UNDERL | underline
YAS_STRIKE | stikeout
YAS_INVERSE | inverse
YAS_BOLD | bold
YAS_BLINK | blink

Color codes
Name | Color
YAS_BLACK | black
YAS_RED | red
YAS_GREEN | green
YAS_YELLOW | yellow
YAS_BLUE | blue
YAS_MAGENTA | magenta
YAS_CYAN | cyan
YAS_WHITE | white
YAS_FGCOLORDEF | default terminal foreground
YAS_BGCOLORDEF | default terminal background

Helper macros
Name | Description
YAS_FG(attribute) | extract foreground color
YAS_BG(attribute) | extract background color
YAS_FGCOLOR(color) | shift simple color value into foreground color
YAS_BGCOLOR(color) | shift simple color value into background color
YAS_FGXCOLOR(color) | shift 256 palette color value into foreground color
YAS_BGXCOLOR(color) | shift 256 palette color value into background color

All of the above can be or'ed into attribute, provided that the bits for foreground/background color are all zeroes.

Key codes

    •   Special, generated internally
Name | Value | Description
YAS_K_NONE | -1 | no key is available; in time limited mode means that the time limit expired
YAS_SCREEN_SIZE | 0x800 | notification for screen size change (may come because of telnet or ANSI sequence)
YAS_TELNET_SIZE | 0x801 | notification for screen size change; duplicates the above, may be used to differentiate how screen size change event was generated

    •   Normal keys
Name | Value | Description
YAS_K_NUL | 0x00 | Nul; on some terminals Ctrl-2
YAS_K_C_A | 0x01 | Ctrl-A
YAS_K_C_B | 0x02 | Ctrl-B
YAS_K_C_C | 0x03 | Ctrl-C
YAS_K_C_D | 0x04 | Ctrl-D
YAS_K_C_E | 0x05 | Ctrl-E
YAS_K_C_F | 0x06 | Ctrl-F
YAS_K_C_G | 0x07 | Ctrl-G
YAS_K_C_H | 0x08 | Ctrl-H; depends on terminal see YAS_K_BSP, YAS_K_C_8
YAS_K_C_I | 0x09 | Ctrl-I
YAS_K_TAB | 0x09 | Tab
YAS_K_C_J | 0x0a | Ctrl-J
YAS_K_C_K | 0x0b | Ctrl-K
YAS_K_C_L | 0x0c | Ctrl-L
YAS_K_C_M | 0x0d | Enter, Return, Ctrl-M; see below
YAS_K_RET | 0x0d | Enter, Return, Ctrl-M; see above
YAS_K_C_N | 0x0e | Ctrl-N
YAS_K_C_O | 0x0f | Ctrl-O
YAS_K_C_P | 0x10 | Ctrl-O
YAS_K_C_Q | 0x11 | Ctrl-Q
YAS_K_C_R | 0x12 | Ctrl-R
YAS_K_C_S | 0x13 | Ctrl-S
YAS_K_C_T | 0x14 | Ctrl-T
YAS_K_C_U | 0x15 | Ctrl-U
YAS_K_C_V | 0x16 | Ctrl-V
YAS_K_C_W | 0x17 | Ctrl-W
YAS_K_C_X | 0x18 | Ctrl-X
YAS_K_C_Y | 0x19 | Ctrl-Y
YAS_K_C_Z | 0x1a | Ctrl-Z
YAS_K_ESC | 0x1b | Esc, Ctrl-3; see below; All ANSI sequences start with Esc, this is return after a timeout or double Esc
YAS_K_C_3 | 0x1b | Esc, Ctrl-3; see above; All ANSI sequences start with Esc, this is return after a timeout or double Esc
YAS_K_C_4 | 0x1c | Ctrl-4
YAS_K_C_5 | 0x1d | Ctrl-5
YAS_K_C_6 | 0x1e | Ctrl-6
YAS_K_C_7 | 0x1f | Ctrl-7
YAS_K_SPACE | 0x20 | Space
YAS_K_EXCL | 0x21 | !
YAS_K_DQUOT | 0x22 | "
YAS_K_HASH | 0x23 | #
YAS_K_POUND | 0x24 | $
YAS_K_PERC | 0x25 | %
YAS_K_AND | 0x26 | Ampersand
YAS_K_QUOT | 0x27 | '
YAS_K_OBRA | 0x28 | (
YAS_K_CBRA | 0x29 | )
YAS_K_STAR | 0x2a | *
YAS_K_PLUS | 0x2b | +
YAS_K_COMMA | 0x2c | ,
YAS_K_MINUS | 0x2d | -
YAS_K_DOT | 0x2e | .
YAS_K_SLASH | 0x2f | /
YAS_K_0 | 0x30 | 0
YAS_K_1 | 0x31 | 1
YAS_K_2 | 0x32 | 2
YAS_K_3 | 0x33 | 3
YAS_K_4 | 0x34 | 4
YAS_K_5 | 0x35 | 5
YAS_K_6 | 0x36 | 6
YAS_K_7 | 0x37 | 7
YAS_K_8 | 0x38 | 8
YAS_K_9 | 0x39 | 9
YAS_K_COLON | 0x3a | :
YAS_K_SEMI | 0x3b | ;
YAS_K_LT | 0x3c | <
YAS_K_EQ | 0x3d |
YAS_K_GT | 0x3e | >
YAS_K_QUEST | 0x3f | ?
YAS_K_AT | 0x40 | @
YAS_K_A | 0x41 | A
YAS_K_B | 0x42 | B
YAS_K_C | 0x43 | C
YAS_K_D | 0x44 | D
YAS_K_E | 0x45 | E
YAS_K_F | 0x46 | F
YAS_K_G | 0x47 | G
YAS_K_H | 0x48 | H
YAS_K_I | 0x49 | I
YAS_K_J | 0x4a | J
YAS_K_K | 0x4b | K
YAS_K_L | 0x4c | L
YAS_K_M | 0x4d | M
YAS_K_N | 0x4e | N
YAS_K_O | 0x4f | O
YAS_K_P | 0x50 | P
YAS_K_Q | 0x51 | Q
YAS_K_R | 0x52 | R
YAS_K_S | 0x53 | S
YAS_K_T | 0x54 | T
YAS_K_U | 0x55 | U
YAS_K_V | 0x56 | V
YAS_K_W | 0x57 | W
YAS_K_X | 0x58 | X
YAS_K_Y | 0x59 | Y
YAS_K_Z | 0x5a | Z
YAS_K_OSQ | 0x5b | [
YAS_K_BSLASH | 0x5c | \
YAS_K_CSQ | 0x5d | ]
YAS_K_CARRET | 0x5e | ^
YAS_K_USCORE | 0x5f |
YAS_K_BTICK | 0x60 | `
YAS_K_a | 0x61 | a
YAS_K_b | 0x62 | b
YAS_K_c | 0x63 | c
YAS_K_d | 0x64 | d
YAS_K_e | 0x65 | e
YAS_K_f | 0x66 | f
YAS_K_g | 0x67 | g
YAS_K_h | 0x68 | h
YAS_K_i | 0x69 | i
YAS_K_j | 0x6a | j
YAS_K_k | 0x6b | k
YAS_K_l | 0x6c | l
YAS_K_m | 0x6d | m
YAS_K_n | 0x6e | n
YAS_K_o | 0x6f | o
YAS_K_p | 0x70 | p
YAS_K_q | 0x71 | q
YAS_K_r | 0x72 | r
YAS_K_s | 0x73 | s
YAS_K_t | 0x74 | t
YAS_K_u | 0x75 | u
YAS_K_v | 0x76 | v
YAS_K_w | 0x77 | w
YAS_K_x | 0x78 | x
YAS_K_y | 0x79 | y
YAS_K_z | 0x7a | z
YAS_K_OCUR | 0x7b | {
YAS_K_PIPE | 0x7c | |
YAS_K_CCUR | 0x7d | }
YAS_K_TLD | 0x7e | Tilde
YAS_K_C_8 | 0x7f | Backspace; see below; depends on terminal see YAS_K_C_H
YAS_K_BSP | 0x7f | Backspace; see below; depends on terminal see YAS_K_C_H

    •   Extended keys, parsed from ANSI sequences
Name | Value | Description
YAS_K_F1 | 0x100 | F1
YAS_K_F2 | 0x101 | F2
YAS_K_F3 | 0x102 | F3
YAS_K_F4 | 0x103 | F4
YAS_K_F5 | 0x104 | F5
YAS_K_F6 | 0x105 | F6
YAS_K_F7 | 0x106 | F7
YAS_K_F8 | 0x107 | F8
YAS_K_F9 | 0x108 | F9
YAS_K_F10 | 0x109 | F10
YAS_K_F11 | 0x10a | F11
YAS_K_F12 | 0x10b | F12
YAS_K_S_F1 | 0x10c | Shift-F1
YAS_K_S_F2 | 0x10d | Shift-F2
YAS_K_S_F3 | 0x10e | Shift-F3
YAS_K_S_F4 | 0x10f | Shift-F4
YAS_K_S_F5 | 0x110 | Shift-F5
YAS_K_S_F6 | 0x111 | Shift-F6
YAS_K_S_F7 | 0x112 | Shift-F7
YAS_K_S_F8 | 0x113 | Shift-F8
YAS_K_S_F9 | 0x114 | Shift-F9
YAS_K_S_F10 | 0x115 | Shift-F10
YAS_K_S_F11 | 0x116 | Shift-F11
YAS_K_S_F12 | 0x117 | Shift-F12
YAS_K_C_F1 | 0x118 | Ctrl-F1
YAS_K_C_F2 | 0x119 | Ctrl-F2
YAS_K_C_F3 | 0x11a | Ctrl-F3
YAS_K_C_F4 | 0x11b | Ctrl-F4
YAS_K_C_F5 | 0x11c | Ctrl-F5
YAS_K_C_F6 | 0x11d | Ctrl-F6
YAS_K_C_F7 | 0x11e | Ctrl-F7
YAS_K_C_F8 | 0x11f | Ctrl-F8
YAS_K_C_F9 | 0x120 | Ctrl-F9
YAS_K_C_F10 | 0x121 | Ctrl-F10
YAS_K_C_F11 | 0x122 | Ctrl-F11
YAS_K_C_F12 | 0x123 | Ctrl-F12
YAS_K_A_F1 | 0x124 | Alt-F1
YAS_K_A_F2 | 0x125 | Alt-F2
YAS_K_A_F3 | 0x126 | Alt-F3
YAS_K_A_F4 | 0x127 | Alt-F4
YAS_K_A_F5 | 0x128 | Alt-F5
YAS_K_A_F6 | 0x129 | Alt-F6
YAS_K_A_F7 | 0x12a | Alt-F7
YAS_K_A_F8 | 0x12b | Alt-F8
YAS_K_A_F9 | 0x12c | Alt-F9
YAS_K_A_F10 | 0x12d | Alt-F10
YAS_K_A_F11 | 0x12e | Alt-F11
YAS_K_A_F12 | 0x12f | Alt-F12
YAS_K_LEFT | 0x130 | Left
YAS_K_UP | 0x131 | Up
YAS_K_DOWN | 0x132 | Down
YAS_K_RIGHT | 0x133 | Right
YAS_K_HOME | 0x134 | Home
YAS_K_END | 0x135 | End
YAS_K_PGUP | 0x136 | PageUp
YAS_K_PGDN | 0x137 | PageDown
YAS_K_INS | 0x138 | Insert
YAS_K_DEL | 0x139 | Delete
YAS_K_C_LEFT | 0x13a | Ctrl-Left
YAS_K_C_UP | 0x13b | Ctrl-Up
YAS_K_C_DOWN | 0x13c | Ctrl-Down
YAS_K_C_RIGHT | 0x13d | Ctrl-Right

    •   Alt-<letter>

These codes are generated by a helper macro - YAS_K_ALT(keycode).
Name | Description
YAS_K_A_BT | Alt-Backtick
YAS_K_A_1 | Alt-1
YAS_K_A_2 | Alt-2
YAS_K_A_3 | Alt-3
YAS_K_A_4 | Alt-4
YAS_K_A_5 | Alt-5
YAS_K_A_6 | Alt-6
YAS_K_A_7 | Alt-7
YAS_K_A_8 | Alt-8
YAS_K_A_9 | Alt-9
YAS_K_A_0 | Alt-0
YAS_K_A_MINUS | Alt-Minus
YAS_K_A_EQ | Alt-=
YAS_K_A_BSP | Alt-Backspace
YAS_K_A_TLD | Alt-Tilde
YAS_K_A_EXCL | Alt-!
YAS_K_A_AT | Alt-@
YAS_K_A_HASH | Alt-#
YAS_K_A_POUND | Alt-$
YAS_K_A_PERC | Alt-%
YAS_K_A_CARRET | Alt-^
YAS_K_A_AND | Alt-Ampersand
YAS_K_A_STAR | Alt-*
YAS_K_A_OBRA | Alt-(
YAS_K_A_CBRA | Alt-)
YAS_K_A_UND | Alt-_
YAS_K_A_PLUS | Alt-+
YAS_K_A_a | Alt-a
YAS_K_A_b | Alt-b
YAS_K_A_c | Alt-c
YAS_K_A_d | Alt-d
YAS_K_A_e | Alt-e
YAS_K_A_f | Alt-f
YAS_K_A_g | Alt-g
YAS_K_A_h | Alt-h
YAS_K_A_i | Alt-i
YAS_K_A_j | Alt-j
YAS_K_A_k | Alt-k
YAS_K_A_l | Alt-l
YAS_K_A_m | Alt-m
YAS_K_A_n | Alt-n
YAS_K_A_o | Alt-o
YAS_K_A_p | Alt-p
YAS_K_A_q | Alt-q
YAS_K_A_r | Alt-r
YAS_K_A_s | Alt-s
YAS_K_A_t | Alt-t
YAS_K_A_u | Alt-u
YAS_K_A_v | Alt-v
YAS_K_A_w | Alt-w
YAS_K_A_x | Alt-x
YAS_K_A_y | Alt-y
YAS_K_A_z | Alt-z

Functions

All functions in the API work with a pointer to an opaque yascreen structure.

The structure is allocated internally in the library by yascreen_init and it is the job of the user program to keep track of it.

The library is thread safe, as long as each struct yascreen object is accessed by a single thread.

  yascreen_init

    inline yascreen *yascreen_init(int sx,int sy);

allocate and initialize screen data output defaults to stdout in case output is a terminal and initial size is (0,0), the screen size is autodetected

in case of error, returns NULL

  yascreen_ver

    inline const char *yascreen_ver(void);

returns a string with the library version

  yascreen_setout

    inline int yascreen_setout(yascreen *s,ssize_t (*out)(yascreen *s,const void *data,size_t len));

set callback that handles output if out=NULL, the output goes to stdout

the callback may implement internal buffering, a flush is signalled by calling out with len=0

  yascreen_set_telnet

    inline void yascreen_set_telnet(yascreen *s,int on);

enable (on is non-zero) or disable (on=0) telnet sequence processing

  yascreen_init_telnet

    inline void yascreen_init_telnet(yascreen *s);

depending on telnet sequence processing, sends a set of telnet initialization sequences

  yascreen_resize

    inline int yascreen_resize(yascreen *s,int sx,int sy);

resize screen should redraw afterwards since allocation is involved, this may fail and return -1

  yascreen_free

    inline void yascreen_free(yascreen *s);

finish the lifecycle of struct yascreen - all internally allocated memory is freed

  yascreen_term_save

    inline void yascreen_term_save(yascreen *s);

save current terminal state on top of state stack

  yascreen_term_restore

    inline void yascreen_term_restore(yascreen *s);

restore previously saved terminal state from top of state stack

  yascreen_term_push

    inline void yascreen_term_push(yascreen *s);

push current terminal state to state stack

  yascreen_term_pop

    inline void yascreen_term_pop(yascreen *s);

pop and restore previously saved terminal state from state stack

  yascreen_term_set

    inline void yascreen_term_set(yascreen *s,int mode);

set terminal for proper screen operation

  mode is a bitmask, containing one of
Name | Value | Description
YAS_NOBUFF | 1 | turn off canonical mode (disable ICANON and IEXTEN)
YAS_NOSIGN | 2 | disable ISIG
YAS_NOECHO | 4 | disable local echo (ECHO)
YAS_ONLCR | 8 | ONLCR|OPOST

  yascreen_printxy

    inline int yascreen_printxy(yascreen *s,int x,int y,uint32_t attr,const char *format,...) __attribute__((format(printf,5,6)));

  yascreen_putsxy

    inline int yascreen_putsxy(yascreen *s,int x,int y,uint32_t attr,const char *str);

print at position, if data exceeds buffer, then it gets truncated

  yascreen_printxyu

    inline int yascreen_printxyu(yascreen *s,int x,int y,uint32_t attr,const char *format,...) __attribute__((format(printf,5,6)));

  yascreen_putsxyu

    inline int yascreen_putsxyu(yascreen *s,int x,int y,uint32_t attr,const char *str);

print at position, if data exceeds buffer, then it gets truncated screen is immediately updated

  yascreen_update

    inline int yascreen_update(yascreen *s);

sync memory state to screen since allocation is involved, this may fail and return -1

  yascreen_redraw

    inline void yascreen_redraw(yascreen *s);

set next update to be a full redraw

  yascreen_clear_mem

    inline void yascreen_clear_mem(yascreen *s,uint32_t attr);

clear memory buffer all cells in the screen are set to Space, using attr for colors and style

  yascreen_cursor

    inline void yascreen_cursor(yascreen *s,int on);

hide (on=0) or show (on is non-zero) cusror screen is updated immediately

  yascreen_cursor_xy

    inline void yascreen_cursor_xy(yascreen *s,int x,int y);

set cursor position screen is updated immediately

  yascreen_altbuf

    inline void yascreen_altbuf(yascreen *s,int on);

switch between regular and alternative buffer screen is updated immediately

  yascreen_clear

    inline void yascreen_clear(yascreen *s);

clear real screen, no change to memory buffers

  yascreen_clearln

    inline void yascreen_clearln(yascreen *s);

clear current line, no change to memory buffers

  yascreen_update_attr

    inline void yascreen_update_attr(yascreen *s,uint32_t oattr,uint32_t nattr);

apply difference between two attrs and output the optimized ANSI sequence to switch from oattr to nattr if oattr=0xffffffff, the full ANSI sequence will be generated no change to memory buffers

  yascreen_set_attr

    yascreen_set_attr(s,attr)

reset all attrs and set specific one (attr)

  yascreen_print

    inline int yascreen_print(yascreen *s,const char *format,...) __attribute__((format(printf,2,3)));

  yascreen_write

    inline int yascreen_write(yascreen *s,const char *str,int len);

  yascreen_puts

    inline int yascreen_puts(yascreen *s,const char *str);

  yascreen_clearln_s

    inline const char *yascreen_clearln_s(yascreen *s);

print in line mode

  yascreen_sx

    inline int yascreen_sx(yascreen *s);

get current x size

  yascreen_sy

    inline int yascreen_sy(yascreen *s);

get current y size

  yascreen_x

    inline int yascreen_x(yascreen *s);

get current x

  yascreen_y

    inline int yascreen_y(yascreen *s);

get current y

  yascreen_esc_to

    inline void yascreen_esc_to(yascreen *s,int timeout);

set timeout for single ESC key press

  yascreen_ckto

    inline void yascreen_ckto(yascreen *s);

in case of external event loop, this call will check for single ESC key should be called regularly enough so that the above specified timeout is not extended too much if not called often enough then single ESC will be yielded after longer timeout if not called at all then single ESC will be yielded with next key press

  yascreen_getch_to

    inline int yascreen_getch_to(yascreen *s,int timeout);

wait for a key, return ASCII or extended keycode, wait no more than timeout in milliseconds

  yascreen_getch

    yascreen_getch(s)

get a key without timeout this macro expands to yascreen_getch_to(s,0) zero timeout=wait forever

  yascreen_getch_nowait

    yascreen_getch_nowait(s)

get a key, if available, return immediately this macro expands to yascreen_getch_to(s,-1) negative timeout=do not wait

  yascreen_ungetch

    inline void yascreen_ungetch(yascreen *s,int key);

put back key value in key buffer the internal key buffer is dynamically allocated, hence there is no limit of how many key codes may be put back, but in case of memory allocation failure, the error will not be reported and the key will not be put into the buffer

  yascreen_pushch

    inline void yascreen_pushch(yascreen *s,int key);

push key value at end of key buffer similar to yascreen_ungetch but the key code will be returned after all other key codes currently in the buffer the internal key buffer is dynamically allocated, hence there is no limit of how many key codes may be put back, but in case of memory allocation failure, the error will not be reported and the key will not be put into the buffer

  yascreen_feed

    inline void yascreen_feed(yascreen *s,unsigned char c);

feed key sequence state machine with byte stream this is useful to implement external event loop and read key codes by yascreen_getch_nowait until it returns -1

  yascreen_peekch

    inline int yascreen_peekch(yascreen *s);

peek for key without removing it from input queue

  yascreen_getsize

    inline void yascreen_getsize(yascreen *s,int *sx,int *sy);

get last reported screen size set both to 0 if there is none this will yield valid result after YAS_SCREEN_SIZE is returned as keypress

  yascreen_reqsize

    inline void yascreen_reqsize(yascreen *s);

request terminal to report its size via ANSI sequence

  yascreen_set_hint_i

    inline void yascreen_set_hint_i(yascreen *s,int hint);

  yascreen_get_hint_i

    inline int yascreen_get_hint_i(yascreen *s);

  yascreen_set_hint_p

    inline void yascreen_set_hint_p(yascreen *s,void *hint);

  yascreen_get_hint_p

    inline void *yascreen_get_hint_p(yascreen *s);

get/set opaque hint values integer and pointer hints are stored separately and both can be used at the same time

these are useful to link the yascreen instance to user program data

for example a single output callback may output to socket or a terminal, depending on the hint values

  yascreen_line_flush

    inline void yascreen_line_flush(yascreen *s,int on);

enable/disable auto flush for line and direct screen oriented operations

yascreen versions before 1.77 didn't use buffered output and would immediately send the output to the screen

disabling internal flush can help an application optimize the number of write calls at the cost of performing explicit flush after each group of operations

explicit flush example:

    yascreen_write(s,"",0);