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)

intreadmouse(Mousectl ∗mc)

intatomouse();

voidclosemouse(Mousectl ∗mc)

voidmoveto(Mousectl ∗mc, Point pt)

voidsetcursor(Mousectl ∗mc, Cursor ∗c)

Rectanglegetrect(int but, Mousectl ∗mc)

voiddrawgetrect(Rectangle r, int up)

intmenuhit(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(2)); programs that wish a more event-driven, single-threaded approach should use event(2).

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

typedef struct Mouse Mouse;
struct Mouse
{
intbuttons; /∗ bit array: LMR=124 ∗/
Pointxy;
ulongmsec;
};

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;
intmfd;/∗ to mouse file ∗/
intcfd;/∗ to cursor file ∗/
intpid;/∗ 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(2)) 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(2)) 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(2)) 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(2).

­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);
intlasthit;
};

Menuhit behaves the same as its namesake ­emenuhit described in event(2), 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(2)), 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

­/sys/src/libdraw

SEE ALSO

graphics(2), draw(2), event(2), keyboard(2), thread(2).

Plan 9  —  October 13, 2000