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curs_mouse

Section: Library calls (3X)
Updated: 202-1-11
Index Return to Main Contents

NAME

has_mouse, getmouse, ungetmouse, mousemask, wenclose, mouse_trafo, wmouse_trafo, mouseinterval, mmask_t, MEVENT - get mouse events in ncurses

SYNOPSIS

#include <curses.h>

/* data types */
typedef unsigned long mmask_t;

typedef struct {
    short id;       /* ID to distinguish multiple devices */
    int x, y, z;    /* event coordinates */
    mmask_t bstate; /* button state bits */
} MEVENT;

/* functions */
bool has_mouse(void);

mmask_t mousemask(mmask_t ne-mask, mmask_t * ol-mask);

int getmouse(MEVENT * event);
int ungetmouse(MEVENT * event);

bool wenclose(const WINDOW * win, int y, int x);

bool mouse_trafo(int * pY, int * pX, bool t-screen);
bool wmouse_trafo(const WINDOW * win,
      int * pY, int * pX, bool t-screen);

int mouseinterval(int erval);

DESCRIPTION

ncurses provides an interface to the mouse or other pointing device. An application can register its interest in such events; the library then exposes the availability of a mouse event via an input character reading function: this is wgetch(3X) in the no-wide character curses API and wget_wch(3X) in the wide character API. A queue distinct from that used for keyboard events accumulates the details of mouse events. The input character reading function reports the KEY_MOUSE key code when a mouse event is available for collection. A single mouse event queue serves all windows associated with the screen.

The MEVENT structure describes a mouse event. Its y and x coordinates are scree-, not windo-, relative. The bstate member has exactly one bit set indicating the event type.

ncurses ignores mouse events when input is in canonical ("cooked") mode, and produces an error beep when they occur while the library simulates canonical mode in a window, as with getstr(3X) (wid-character API users: get_wstr(3X)), which expects a line feed to terminate its input loop.

has_mouse

The terminal type or operating system interface must support the encoding of mouse events. has_mouse returns TRUE if ncurses's mouse driver initialized successfully, and FALSE otherwise.

mousemask

Use mousemask to select the varieties of mouse event your application wishes to receive. By default, ncurses reports no mouse events.
.IP * 4 The function returns an updated copy of ne-mask indicating which event types of interest are reportable by the terminal's mouse protocol.

: If the screen is not initialized, or the terminal interface does not report mouse events, mousemask returns 0.
.IP * 4 If ol-mask is not a null pointer, mousemask stores the previous value of the screen's mouse event mask there.

As a side effect, setting a zero mouse mask may turn off the mouse cursor; setting a nonzero mask may turn it on. Whether this happens is devic-dependent.

Mouse Events

Several mouse event types may be selected; construct a mask by logically "or"-ing their values.

Name	Description

BUTTON1_PRESSED	mouse button 1 down
BUTTON1_RELEASED	mouse button 1 up
BUTTON1_CLICKED	mouse button 1 clicked
BUTTON1_DOUBLE_CLICKED	mouse button 1 double clicked
BUTTON1_TRIPLE_CLICKED	mouse button 1 triple clicked

BUTTON2_PRESSED	mouse button 2 down
BUTTON2_RELEASED	mouse button 2 up
BUTTON2_CLICKED	mouse button 2 clicked
BUTTON2_DOUBLE_CLICKED	mouse button 2 double clicked
BUTTON2_TRIPLE_CLICKED	mouse button 2 triple clicked

BUTTON3_PRESSED	mouse button 3 down
BUTTON3_RELEASED	mouse button 3 up
BUTTON3_CLICKED	mouse button 3 clicked
BUTTON3_DOUBLE_CLICKED	mouse button 3 double clicked
BUTTON3_TRIPLE_CLICKED	mouse button 3 triple clicked

BUTTON4_PRESSED	mouse button 4 down
BUTTON4_RELEASED	mouse button 4 up
BUTTON4_CLICKED	mouse button 4 clicked
BUTTON4_DOUBLE_CLICKED	mouse button 4 double clicked
BUTTON4_TRIPLE_CLICKED	mouse button 4 triple clicked

BUTTON5_PRESSED	mouse button 5 down
BUTTON5_RELEASED	mouse button 5 up
BUTTON5_CLICKED	mouse button 5 clicked
BUTTON5_DOUBLE_CLICKED	mouse button 5 double clicked
BUTTON5_TRIPLE_CLICKED	mouse button 5 triple clicked

BUTTON_SHIFT	a shift key was down during button state change
BUTTON_CTRL	a control key was down during button state change
BUTTON_ALT	an alt key was down during button state change
ALL_MOUSE_EVENTS	report all button state changes
REPORT_MOUSE_POSITION	report mouse movement

getmouse

When a window is configured to report a no-empty set of event types, calling the input character reading function on that window may return KEY_MOUSE to indicate availability of an enqueued mouse event. To read the event data and remove it from the queue, call getmouse, which returns OK if a mouse event is visible in the given window and ERR otherwise. When getmouse returns OK, it deposits data describing the mouse event in the event pointer you supply. A subsequent getmouse call retrieves the next older event from the queue.

ungetmouse

ungetmouse behaves analogously to ungetch(3X). It pushes a KEY_MOUSE event onto the screen's input queue, and event onto the mouse event queue.

wenclose

wenclose returns TRUE if the pair of scree-relative coordinates (y, x) is enclosed by the given window win, and FALSE otherwise. If win is a pad, wenclose uses its most recent screen coordinates as specified in a prefresh(3X) or pnoutrefresh(3X) call.

wenclose is useful for determining what subset of the screen's windows encloses the location of a mouse event; it is otherwise independent of the ncurses mouse API.

wmouse_trafo

wmouse_trafo transforms the given pair of coordinate pointers (pY, pX) from a win-relative basis to a scree-relative one or vice versa, as t-screen is TRUE or FALSE, respectively. stdscr-relative coordinates are not always identical to screen coordinates: curses supports reservation of screen lines at the top and/or bottom for other purposes; see ripoffline(3X) and slk_init(3X).

If t-screen is TRUE and the pointers (pY, pX) reference coordinates inside win, ncurses updates their values to stdscr-relative coordinates and returns TRUE. If either pY or pX is a null pointer, or (pY, pX) is not inside win, wmouse_trafo returns FALSE.

If t-screen is FALSE and the pointers (pY, pX) reference coordinates inside stdscr, ncurses updates their values to win-relative coordinates and returns TRUE. If either pY or pX is a null pointer, or (pY, pX) is not inside stdscr, wmouse_trafo returns FALSE.

mouse_trafo

mouse_trafo applies the wmouse_trafo translation to stdscr. If no screen lines are reserved by ripoffline(3X) or slk_init(3X), this is the identity transformation.

mouseinterval

mouseinterval sets the maximum time (in thousandths of a second) that can elapse between press and release events for them to be resolved as a click. An application might interpret button press and release events separated by more than the mouse interval as a "long press", or, with motion, as a "drag".

When ncurses detects a mouse event, it awaits further input activity up to this interval, and then checks for a subsequent mouse event which can be combined with the first event. If the timeout expires without input activity, then no click resolution occurs. Calling mouseinterval(0) disables click resolution.

mouseinterval returns the previous interval value. Use mouseinterval(-1) to obtain the interval without altering it.

The mouse interval is set to one sixth of a second when the corresponding screen is initialized, e.g., in initscr(3X) or setupterm(3X).

RETURN VALUE

has_mouse, wenclose, mouse_trafo, and wmouse_trafo return TRUE or FALSE as noted above.

getmouse and ungetmouse return ERR upon failure and OK upon success.

getmouse fails if:
.IP * 4 no mouse driver was initialized,
.IP * 4 the mask of reportable events is zero,
.IP * 4 a mouse event was detected that does not match the mask, or
.IP * 4 no more events remain in the queue.

ungetmouse returns ERR if the event queue is full.

mousemask returns the mask of reportable events.

mouseinterval returns the previous interval value, unless the terminal was not initialized. In that case, it returns the maximum interval value (166).

NOTES

The order of the MEVENT structure members is not guaranteed. Additional fields may be added to the structure in the future.

Under ncurses, these calls are implemented using either xterm's buil-in mous-tracking API or platfor-specific drivers including

: .IP * 4 Alessandro Rubini's gpm server
.IP * 4 FreeBSD sysmouse
.IP * 4 OS/2 EMX

If you are using an unsupported configuration, mouse events are not visible to ncurses (and the mousemask function always returns 0).

If the terminal type possesses the (nonstandard) terminfo string capability XM, ncurses's xterm mouse driver uses it when initializing the terminal for mouse operation. The default, if XM is not found, corresponds to private mode 1000 of xterm.

: E[?1000%?%p1%{1}%=%th%el%;

ncurses also recognizes xterm's newer private mode 1006.

: E[?1006;1000%?%p1%{1}%=%th%el%;

The id member of the mouse event structure is not presently used; no terminal type or operating system interface supports reporting events from distinguishable pointing devices. If you synthesize an MEVENT, use an id of 0.

The z member of the mouse event structure is not presently used. It is intended for use with touch screens (which may be pressur-sensitive) or with 3-mice/trackballs/power gloves.

The ALL_MOUSE_EVENTS class does not include REPORT_MOUSE_POSITION. They are distinct. For example, in xterm, wheel/scrolling mice send position reports as a sequence of presses of buttons 4 or 5 without matching butto-releases.

EXTENSIONS

These functions are ncurses extensions, and are not found in SVr4 curses, 4.4BSD curses, or any other previous curses implementation. (SVr4 curses did have a getmouse function, which took no argument and returned an unsigned long.)

PORTABILITY

Applications employing the ncurses mouse extension should condition its use on the visibility of the NCURSES_MOUSE_VERSION preprocessor macro. When the interface changes, the macro's value increments. Multiple versions are available when ncurses is configured; see section "ALTERNATE CONFIGURATIONS" of ncurses(3X). The following values may be specified.

1: has definitions for reserved events. The mask uses 28 bits.
2: adds definitions for button 5, removes the definitions for reserved events. The mask uses 29 bits.

HISTORY

SVr4 (1989) added mouse support to its variant of xterm(1). It is mentioned in a few places, with little supporting documentation.
.IP * 4 Its "libcurses" manual page lists functions for this feature prototyped in curses.h.

extern int mouse_set(long int);
extern int mouse_on(long int);
extern int mouse_off(long int);
extern int request_mouse_pos(void);
extern int map_button(unsigned long);
extern void wmouse_position(WINDOW *, int *, int *);
extern unsigned long getmouse(void), getbmap(void);

.IP * 4 Its "terminfo" manual page lists capabilities for the feature.

buttons	btns	BT	Number of buttons on the mouse
get_mouse	getm	Gm	Curses should get button events
key_mouse	kmous	Km	0631, Mouse event has occurred
mouse_info	minfo	Mi	Mouse status information
req_mouse_pos	reqmp	RQ	Request mouse position report

.IP * 4 The interface made assumptions (as does ncurses) about the escape sequences sent to and received from the terminal.

: For instance, the SVr4 curses library used the get_mouse (getm) capability to tell the terminal which mouse button events it should send, passing the mous-button bit mask to the terminal. Also, it could ask the terminal where the mouse was using the req_mouse_pos (reqmp) capability.
: Those features required a terminal program that had been modified to work with SVr4 curses. They were not part of the X Consortium's xterm.

When developing the xterm mouse support for ncurses in September 1995, Eric Raymond was uninterested in using the same interface due to its lack of documentation. Later, in 1998, Mark Hesseling provided support in PDCurses 2.3 using the SVr4 interface. PDCurses, however, does not use video terminals, making it unnecessary to be concerned about compatibility with the escape sequences.

BUGS

Mouse events from xterm are not ignored in canonical ("cooked") mode if they have been enabled by mousemask. Instead, the xterm mouse report sequence appears in the string read.

An ncurses window must enable keypad(3X) to correctly receive mouse event reports from xterm since they are encoded like function keys. Set the terminal's terminfo capability key_mouse (kmous) to "E[M" (the beginning of the response from xterm for mouse clicks). Other values of key_mouse are permitted under the same assumption - that is, a mouse report begins with the value of the key_mouse (kmous) string capability.

Because there are no standard response sequences that serve to identify terminals supporting the xterm mouse protocol, ncurses assumes that if key_mouse (kmous) is defined in the terminal description, or if the terminal type's primary name or aliases contain the string "xterm", then the terminal may send mouse events. ncurses checks the kmous ca-code first, allowing use of newer xterm mouse protocols, such as its private mode 1006.