MOUSE(3)

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

SYNOPSIS
#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)

DESCRIPTION
These functions access and control a mouse in a multi-threaded environment. They use the message-passing Channel interface in the threads library (see thread(3)); programs that wish a more event-driven, single-threaded approach should use event(3).

The state of the mouse is recorded in a structure, Mouse, defined in <mouse.h>:

        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;
        	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 draw(3)) 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 graphics(3)) to reconnect to the window.

Readmouse updates the Mouse structure 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 graphics(3)) 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 graphics(3).

Getrect returns the dimensions of a rectangle swept by the user, using the mouse, in the manner rio(1) or sam(1) uses to create a new window. The but argument 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 rectangle 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 defined 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 event(3), 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 window(3)), 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.

SOURCE
/usr/local/plan9/src/libdraw

SEE ALSO
graphics(3), draw(3), event(3), keyboard(3), thread(3).