.TH EVENT 2.SH NAMEevent, einit, estart, estartfn, etimer, eread, emouse, ekbd, ecanread, ecanmouse, ecankbd, ereadmouse, eatomouse, eresized, egetrect, edrawgetrect, emenuhit, emoveto, esetcursor, Event, Mouse, Menu \- graphics events.SH SYNOPSIS.nf.PP.B#include	<u.h>.B#include	<libc.h>.B#include	<draw.h>.B#include	<event.h>.B#include	<cursor.h>.ta \w'\fLRectangle 'u.PP.Bvoid	einit(ulong keys).PP.Bulong	event(Event *e).PP.BMouse	emouse(void).PP.Bint	ekbd(void).PP.Bint	ecanmouse(void).PP.Bint	ecankbd(void).PP.Bint	ereadmouse(Mouse *m).PP.Bint	eatomouse(Mouse *m, char *buf, int n).PP.Bulong	estart(ulong key, int fd, int n).PP.Bulong	estartfn(int id, ulong key, int fd, int n,.B		    int (*fn)(Event*, uchar*, int)).PP.Bulong	etimer(ulong key, int n).PP.Bulong	eread(ulong keys, Event *e).PP.Bint	ecanread(ulong keys).PP.Bvoid	eresized(int new).PP.BRectangle	egetrect(int but, Mouse *m).PP.Bvoid	edrawgetrect(Rectangle r, int up).PP.Bint	emenuhit(int but, Mouse *m, Menu *menu).PP.PP.Bint	emoveto(Point p).PP.PP.Bint	esetcursor(Cursor *c).PP.Bextern Mouse    *mouse.PP.Benum{.B	Emouse = 1,.B	Ekeyboard = 2,.B};.PP.SH DESCRIPTIONThese routines provide an interface to multiple sources of input for unthreadedprograms.Threaded programs (see.IR thread (2))should instead use the threaded mouse and keyboard interface describedin.IR mouse (2)and.IR keyboard (2)..PP.I Einitmust be called first.If the argument to.I einithas the.B Emouseand.B Ekeyboardbits set,the mouse and keyboard events will be enabled;in this case,.IR initdraw(see.IR graphics (2))must have already been called.The user must provide a function called.IR eresizedto be called whenever the window in which the processis running has been resized; the argument.I newis a flag specifying whether the program must call.I getwindow(see.IR graphics (2))to re-establish a connection to its window.After resizing (and perhaps calling.IR getwindow ),the global variable.B screenwill be updated to point to the new window's.B Imagestructure..PPAs characters are typed on the keyboard, they are read by theevent mechanism and put in a queue..I Ekbdreturns the next rune from the queue, blocking until thequeue is non-empty.The characters are read in raw mode(see.IR cons (3)),so they are available as soon as a complete rune is typed..PPWhen the mouse moves or a mouse button is pressed or released,a new mouse event is queued by the event mechanism..I Emousereturns the next mouse event from the queue, blocking until thequeue is non-empty..I Emousereturns a.B Mousestructure:.IP.EX.ta 6n +\w'Point 'ustruct Mouse{	int	buttons;	Point	xy;	ulong	msec;};.EE.PP.B Buttons&1is set when the left mouse button is pressed,.B buttons&2when the middle button is pressed,and.B buttons&4when the right button is pressed.The current mouse position is always returned in.BR xy ..B Msecis a time stamp in units of milliseconds..PP.I Ecankbdand.I ecanmousereturn non-zero when there are keyboard or mouse events availableto be read..PP.I Ereadmousereads the next mouse event from the file descriptor connected to the mouse,converts the textual data into a.B Mousestructure by calling.I eatomousewith the buffer and count from the read call,and returns the number of bytes read, or \-1 for an error..PP.I Estartcan be used to register additional file descriptors to scan for input.It takes as arguments the file descriptor to register,the maximum length of an event message on that descriptor,and a key to be used in accessing the event.The key must be a power of 2 and must not conflict with any previous keys.If a zero key is given, a key will be allocated and returned..I Estartfnis similar to.IR estart ,but processes the data received by calling.I fnbefore returning the event to the user.The function.I fnis called with the.B idof the event; it should return.B idif the event is to be passed to the user,.B 0if it is to be ignored.The variable.B Event.vcan be used by.I fnto attach an arbitrary data item to the returned.B Eventstructure..BEkeyboardand.B Emouseare the keyboard and mouse event keys..PP.I Etimerstarts a repeating timer with a period of.I nmilliseconds; it returns the timer event key, or zero if it fails.Only one timer can be started.Extra timer events are not queued and the timer channel has no associated data..PP.I Ereadwaits for the next event specified by the mask.I keysof event keys submitted to.IR estart .It fills in the appropriate field of the argument.B Eventstructure, which looks like:.IP.EXstruct Event{	int	kbdc;	Mouse	mouse;	int	n;	void	*v;	uchar	data[EMAXMSG];};.EE.PP.B Datais an array which is large enough to hold a 9P message..I Ereadreturns the key for the event which was chosen.For example, if a mouse event was read,.B Emousewill be returned..PP.I Eventwaits for the next event of any kind.The return is the same as for.IR eread ..PPAs described in.IR graphics (2),the graphics functions are buffered..IR Event ,.IR eread ,.IR emouse ,and.I ekbdall cause a buffer flush unless there is an event of theappropriate type already queued..PP.I Ecanreadchecks whether a call to.B eread(keys)would block, returning 0 if it would, 1 if it would not..PP.I Getrectprompts the user to sweep a rectangle.It should be called with.I mholding the mouse event that triggered the.I egetrect(or, if none, a.B Mousewith.B buttonsset to 7).It changes to the sweep cursor,waits for the buttons all to be released,and then waits for button number.I butto be pressed, marking the initial corner.If another button is pressed instead,.I egetrectreturns a rectanglewith zero for both corners, afterwaiting for all the buttons to be released.Otherwise,.I egetrectcontinually draws the swept rectangleuntil the button is released again, and returns the swept rectangle.The mouse structure pointed to by.I mwill contain the final mouse event..PP.I Egetrectuses successive calls to.I edrawgetrectto maintain the red rectangle showing the sweep-in-progress.The rectangle to be drawn is specified by.I rcand the.I upparameter says whether to draw (1) or erase (0) the rectangle..PP.I Emenuhitdisplays a menu and returns a selected menu item number.It should be called with.I mholding the mouse event that triggered the.IR emenuhit ;it will call.I emouseto update it.A.B Menuis a structure:.IP.EXstruct Menu{	char	**item;	char	*(*gen)(int);	int	lasthit;};.EE.PPIf.B itemis nonzero, it should be a null-terminated array of the character stringsto be displayed as menu items.Otherwise,.B genshould be a function that, given an item number, returns the characterstring for that item, or zero if the number is past the end of the list.Items are numbered starting at zero..I Menuhitwaits until.I butis released, and then returns the number of the selection,or \-1 for no selection.The.I margument is filled in with the final mouse event..PP.I Emovetomoves the mouse cursor to the position.B pon the screen..PP.I Esetcursorchanges the cursor image to that described by the.B Cursor.I c(see.IR mouse (2)).If.B cis nil, it restores the image to the default arrow..SH SOURCE.B /sys/src/libdraw.SH "SEE ALSO".IR rio (1),.IR graphics (2),.IR plumb (2),.IR cons (3),.IR draw (3)