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
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 Mouse Mouse;|
int buttons; /* bit array: LMR=124 */|
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
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
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
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 Mousectl Mousectl;|
Channel *c; /* chan(Mouse) */
Channel *resizec; /* chan(int) */
int mfd; /* to mouse file */
int cfd; /* to cursor file */
int pid; /* of slave proc */
Image* image; /* of associated window/display */
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.
typedef struct Menu Menu;|