initmouse, readmouse, closemouse, moveto, getrect, drawgetrect,
menuhit, setcursor - mouse control
Mousectl *initmouse(char *file, Image *i)
int readmouse(Mousectl *mc)
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 thread(2)); programs that wish a more event-driven, sin‐
gle-threaded approach should use event(2).
The state of the mouse is recorded in a structure, Mouse, defined in
typedef struct Mouse Mouse;
int buttons; /* bit array: LMR=124 */
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
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 */
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 vis‐
ible. Typically the file is nil, which requests the default
/dev/mouse; and the image is the window in which the program is run‐
ning, 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 recon‐
nect 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 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
defined in <mouse.h>:
typedef struct Menu Menu;
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.
SEE ALSOgraphics(2), draw(2), event(2), keyboard(2), thread(2).