MOUSE(3) MOUSE(3)
NAME
mouse, cursor - kernel mouse interface
SYNOPSIS
bind -a #m /dev
/dev/mouse
/dev/mousein
/dev/mousectl
/dev/cursor
DESCRIPTION
The mouse device provides an interface to the mouse. There
is also a cursor associated with the screen; it is always
displayed at the current mouse position.
Reading the mouse file returns the mouse status: its posi-
tion and button state. The read blocks until the state has
changed since the last read. The read returns 49 bytes: the
letter m followed by four decimal strings, each 11 charac-
ters wide followed by a blank: x and y, coordinates of the
mouse position in the screen image; buttons, a bitmask with
the 1, 2, and 4 bits set when the mouse's left, middle, and
right buttons, respectively, are down; and msec, a time
stamp, in units of milliseconds.
Writing the mouse file, in the same format, causes the mouse
cursor to move to the position specified by the x and y
coordinates of the message. The buttons and msec fields are
ignored and may be omitted.
Writes to the mousein file are processed as if they were
generated by the mouse hardware itself, as extra mouse
events to be processed and passed back via the mouse file.
The mousein file, which is exclusive-use and may be opened
only by the host owner, is intended for controlling devices,
such as USB mice, that are managed by user-level software.
Each event should consist of the letter m followed by delta
x, delta y, and buttons as space-separated decimal numbers.
Writing to the mousectl file configures and controls the
mouse. The messages are:
serial n sets serial port n to be the mouse port.
ps2 sets the PS2 port to be the mouse port.
intellimouse uses the wheel on a Microsoft Intellimouse
as the middle button.
ps2intellimouse is equivalent to a write of ps2 followed by
a write of intellimouse.
accelerated [n] turns on mouse acceleration. N is an
Page 1 Plan 9 (printed 12/21/24)
MOUSE(3) MOUSE(3)
optional acceleration factor.
linear turns off mouse acceleration.
res n sets mouse resolution to a setting between
0 and 3 inclusive.
hwaccel on/off sets whether acceleration is done in hard-
ware or software. By default, PS2 mice use
hardware and serial mice use software.
Some laptops (notably the IBM Thinkpad T23)
don't implement hardware acceleration for
external mice.
swap swaps the left and right buttons on the
mouse.
buttonmap xyz numbers the left, middle, and right mouse
buttons x, y, and z, respectively. If xyz
is omitted, the default map, 123, is used.
Thus in the default state writing buttonmap
321 swaps left and right buttons and writ-
ing buttonmap 123 or just buttonmap
restores their usual meaning. Note that
buttonmap messages are idempotent, unlike
swap.
reset clears the mouse to its default state.
Not all mice interpret all messages; with some devices, some
of the messages may be no-ops.
Cursors are described in graphics(2). When read or written
from or to the cursor file, they are represented in a 72-
byte binary format. The first and second four bytes are
little endian 32-bit numbers specifying the x and y coordi-
nates of the cursor offset; the next 32 bytes are the clr
bitmask, and the last 32 bytes the set bitmask.
Reading from the cursor file returns the current cursor
information. Writing to the cursor file sets the current
cursor information. A write of fewer than 72 bytes sets the
cursor to the default, an arrow.
The mouse and cursor files are multiplexed by rio(1) to give
the illusion of a private mouse to each of its clients. The
semantics are otherwise the same except that notification of
a window resize is passed to the application using a mouse
message beginning with r rather than m; see rio(4) for
details.
To cope with pointing devices with only two buttons, when
the shift key is pressed, the right mouse button generates
middle-button events.
SOURCE
/sys/src/9/port/devmouse.c
Page 2 Plan 9 (printed 12/21/24)
MOUSE(3) MOUSE(3)
SEE ALSO
rio(4)
BUGS
The cursor format is big endian while the rest of the graph-
ics interface is little endian.
Page 3 Plan 9 (printed 12/21/24)