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MOUSE(3)		   Library Functions Manual		      MOUSE(3)

       initmouse,   readmouse,	 closemouse,  moveto,  cursorswitch,  getrect,
       drawgetrect, menuhit, setcursor - mouse control

       #include	<u.h>
       #include	<libc.h>
       #include	<draw.h>
       #include	<thread.h>
       #include	<mouse.h>
       #include	<cursor.h>

       Mousectl	 *initmouse(char *file,	Image *i)

       int	 readmouse(Mousectl *mc)

       int	 atomouse();

       void	 closemouse(Mousectl *mc)

       void	 moveto(Mousectl *mc, Point pt)

       void	 setcursor(Mousectl *mc, Cursor	*c)

       Rectangle getrect(int but, Mousectl *mc)

       void	 drawgetrect(Rectangle r, int up)

       int	 menuhit(int but, Mousectl *mc,	Menu *menu, Screen *scr)

       These functions access and control a mouse in a multi-threaded environ-
       ment.   They  use  the message-passing Channel interface	in the threads
       library (see programs that wish a  more	event-driven,  single-threaded
       approach	should use

       The  state  of  the mouse is recorded in	a structure, Mouse, defined in

	      typedef struct Mouse Mouse;
	      struct Mouse
		    int	      buttons;	 /* bit	array: LMR=124 */
		    Point     xy;
		    ulong     msec;

       The Point xy records the	position of the	cursor,	buttons	the  state  of
       the  buttons  (three bits representing, from bit	0 up, the buttons from
       left to right, 0	if the button is released, 1 if	it  is	pressed),  and
       msec, a millisecond time	stamp.

       The  routine initmouse returns a	structure through which	one may	access
       the mouse:

	      typedef struct Mousectl Mousectl;
	      struct Mousectl
		    Mouse     m;
		    Channel   *c;	 /* chan(Mouse)[16] */
		    Channel   *resizec;	 /* chan(int)[2] */

		    char      *file;
		    int	      mfd;	 /* to mouse file */
		    int	      cfd;	 /* to cursor file */
		    int	      pid;	 /* of slave proc */
		    Image*    image;	 /* of associated window/display */

       The arguments to	initmouse are a	file naming the	device file  connected
       to  the	mouse  and  an	Image (see on which the	mouse will be visible.
       Typically the file is nil, which	requests the default  /dev/mouse;  and
       the  image  is  the window in which the program is running, held	in the
       variable	screen after a call to initdraw.

       Once the	Mousectl is set	up, mouse motion will be reported by  messages
       of  type	 Mouse	sent  on the Channel Mousectl.c.  Typically, a message
       will be sent every time a read of /dev/mouse succeeds, which  is	 every
       time the	state of the mouse changes.

       When the	window is resized, a message is	sent on	Mousectl.resizec.  The
       actual value sent may be	discarded; the receipt of  the	message	 tells
       the program that	it should call getwindow (see to reconnect to the win-

       Readmouse updates the Mouse structure m held in the Mousectl,  blocking
       if  the	state has not changed since the	last readmouse or message sent
       on the channel.	It calls  flushimage  (see  before  blocking,  so  any
       buffered	graphics requests are displayed.

       Closemouse closes the file descriptors associated with the mouse, kills
       the slave processes, and	frees the Mousectl structure.

       Moveto moves the	mouse cursor on	the display to the position  specified
       by pt.

       Setcursor sets the image	of the cursor to that specified	by c.  If c is
       nil, the	cursor is set to the default.  The format of the  cursor  data
       is spelled out in <cursor.h> and	described in

       Getrect	returns	the dimensions of a rectangle swept by the user, using
       the mouse, in the manner	or uses	to create a new	window.	 The but argu-
       ment  specifies	which  button the user must press to sweep the window;
       any other button	press cancels the action.  The returned	 rectangle  is
       all zeros if the	user cancels.

       Getrect	uses  successive calls to drawgetrect to maintain the red rec-
       tangle showing the sweep-in-progress.  The rectangle  to	 be  drawn  is
       specified  by rc	and the	up parameter says whether to draw (1) or erase
       (0) the rectangle.

       Menuhit provides	a simple menu mechanism.  It uses a Menu structure de-
       fined in	<mouse.h>:

	      typedef struct Menu Menu;
	      struct Menu
		    char      **item;
		    char      *(*gen)(int);
		    int	      lasthit;

       Menuhit behaves the same	as its namesake	emenuhit described in with two
       exceptions.  First, it uses a Mousectl to access	the mouse rather  than
       using  the  event  interface; and second, it creates the	menu as	a true
       window on the Screen scr	(see permitting	the menu to  be	 displayed  in
       parallel	with other activities on the display.  If scr is null, menuhit
       behaves like emenuhit, creating backing store for the menu, writing the
       menu  directly  on the display, and restoring the display when the menu
       is removed.




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