Get mouse deltas using Python! (in Linux)
Question:
I know that Linux gives out a 9-bit two’s complement data out of the /dev/input/mice. I also know that you can get that data via /dev/hidraw0 where hidraw is your USB device giving out raw data from the HID.
I know the data sent is the delta of the movement (displacement) rather than position. By the by I can also view gibberish data via the "cat /dev/input/mice".
By using the Python language, how can I read this data? I really rather get that data as in simple integers. But it has proven hard. The real problem is reading the damn data. Is there a way to read bits and do bit arithmetic? (Currently I’m not worrying over root user-related issues. Please assume the script is run as root.)
(My main reference was http://www.computer-engineering.org/ps2mouse/)
Answers:
Yes, Python can read a file in binary form. Just use a 'b' flag when you open a file, e.g. open('dev/input/mice', 'rb').
Python also supports all the typical bitwise arithmetic operations: shifts, inversions, bitwise and, or, xor, and not, etc.
You’d probably be better served by using a library to process this data, instead of doing it on your own, though.
The data from the input system comes out as structures, not simple integers. The mice device is deprecated, I believe. The preferred method is the event device interfaces, where the mouse (and other) input events can also be obtained. I wrote some code that does this, the Event.py module You can use that, or start from there.
I’m on a basic device and not having access to X or … so event.py doesn’t works.
So here’s my simpler decode code part to interpret from “deprecated” ‘/dev/input/mice’:
import struct
file = open( "/dev/input/mice", "rb" );
def getMouseEvent():
buf = file.read(3);
button = ord( buf[0] );
bLeft = button & 0x1;
bMiddle = ( button & 0x4 ) > 0;
bRight = ( button & 0x2 ) > 0;
x,y = struct.unpack( "bb", buf[1:] );
print ("L:%d, M: %d, R: %d, x: %d, y: %dn" % (bLeft,bMiddle,bRight, x, y) );
# return stuffs
while( 1 ):
getMouseEvent();
file.close();
You need to open your editor as a root to bypass the permissions-related error messages you might experience when trying to run this script.
The /dev/input/mice device is only available to root.
I know that Linux gives out a 9-bit two’s complement data out of the /dev/input/mice. I also know that you can get that data via /dev/hidraw0 where hidraw is your USB device giving out raw data from the HID.
I know the data sent is the delta of the movement (displacement) rather than position. By the by I can also view gibberish data via the "cat /dev/input/mice".
By using the Python language, how can I read this data? I really rather get that data as in simple integers. But it has proven hard. The real problem is reading the damn data. Is there a way to read bits and do bit arithmetic? (Currently I’m not worrying over root user-related issues. Please assume the script is run as root.)
(My main reference was http://www.computer-engineering.org/ps2mouse/)
Yes, Python can read a file in binary form. Just use a 'b' flag when you open a file, e.g. open('dev/input/mice', 'rb').
Python also supports all the typical bitwise arithmetic operations: shifts, inversions, bitwise and, or, xor, and not, etc.
You’d probably be better served by using a library to process this data, instead of doing it on your own, though.
The data from the input system comes out as structures, not simple integers. The mice device is deprecated, I believe. The preferred method is the event device interfaces, where the mouse (and other) input events can also be obtained. I wrote some code that does this, the Event.py module You can use that, or start from there.
I’m on a basic device and not having access to X or … so event.py doesn’t works.
So here’s my simpler decode code part to interpret from “deprecated” ‘/dev/input/mice’:
import struct
file = open( "/dev/input/mice", "rb" );
def getMouseEvent():
buf = file.read(3);
button = ord( buf[0] );
bLeft = button & 0x1;
bMiddle = ( button & 0x4 ) > 0;
bRight = ( button & 0x2 ) > 0;
x,y = struct.unpack( "bb", buf[1:] );
print ("L:%d, M: %d, R: %d, x: %d, y: %dn" % (bLeft,bMiddle,bRight, x, y) );
# return stuffs
while( 1 ):
getMouseEvent();
file.close();
You need to open your editor as a root to bypass the permissions-related error messages you might experience when trying to run this script.
The /dev/input/mice device is only available to root.