access to mouseXY in ROS on raspberry-pi-2 w/ Ubuntu14.04

edit

Hi,

I found a working solution - must have been error on my end.

Attached code will broadcast the XY mouse position and speed as JSON on topic 'chatter':

{"dt": 0.25, "dx": 2, "dy": 10, "mouse": 1, "xpos": 391, "ypos": -103}

When invoking the mouseMsg.py you can select which mouse # you want to read and what is the readout frequency.

Thanks

Jan

#!/usr/bin/env python
''' 
Software License Agreement (BSD License)
Author: Jan Balewski, December 2016

Talker broadcasts mouse relative position, 
published as JSON using std_msgs/Strings message
to the 'chatter' topic
'''

import sys,os
import json
import subprocess
import rospy
from std_msgs.msg import String

#----------------------
def onFailedStart(myNo):
    print 
    print('Mouse %d data access failed. Few tips:'%myNo)
    task = subprocess.Popen("cat /proc/bus/input/devices", shell=True, stdout=subprocess.PIPE)
    data = task.stdout.read()
    assert task.wait() == 0
    m=0
    for line in data.decode('utf-8').split("\n"):
        #    print line
        if "H: Handlers=mouse" in line:
            #print line
            lL=line.split()
            #print lL[1]
            msNo=int(lL[1][-1])
            devName='/dev/input/mouse%d'%msNo
            stats = os.stat(devName)

            print 'see: ',devName, ' access=',oct(stats.st_mode& 0777)

    print ' try:   sudo chmod a+r ',devName 
    print 
    print 'use:  mouseMsg.py [mouseNo] [rate/Hz]'

#----------------------
def mouseState(myNo):
    global fm,readRate,xpos,ypos
    # read from the file. ord() converts char to integer
    state = ord(fm.read(1))
    dx = ord(fm.read(1))
    dy = ord(fm.read(1))

    #convert bits in 'state' in to an array 'mouse_state'
    mouse_state = [(state & (1 << i)) >> i for i in xrange(8)]

    # if mouse moving to the left. dx must be a negative value
    if mouse_state[4] == 1:
        dx = dx - 256    # convert 2's complement negative value

    # if mouse moving down
    if mouse_state[5] == 1:
        dy = dy - 256

    if (mouse_state[6] == 1) or (mouse_state[7]==1):
        print "Overflow!"

    # update the position
    xpos += dx
    ypos += dy

    out={"mouse":myNo,'dx':dx,'dy':dy,'xpos':xpos,'ypos':ypos}

    return out

#----------------------
def mouseMsg(myNo):
    global fm,readRate
    myName='devMouse%d'%myNo
    pub = rospy.Publisher('chatter', String, queue_size=10)
    rospy.init_node(myName, anonymous=True)
    rateHn = rospy.Rate(readRate) 
    dt=1/float(readRate)

    rospy.loginfo(myName+' found, move it , ctrl\ to abort.')
    k=0
    while not rospy.is_shutdown():
        k+=1
        outD=mouseState(myNo)
        outD['dt']=dt
        outStr=json.dumps(outD,sort_keys=True)
        if k%50==0:
            rospy.loginfo(outStr+' k=%d'%k)
        pub.publish(outStr)
        rateHn.sleep()

if __name__ == '__main__':
    global fm,readRate,xpos,ypos
    myNo=0
    readRate=10  # Hz
    (xpos,ypos)=(0,0)

    if len(sys.argv)>=2:
        myNo=int(sys.argv[1])
    if len(sys.argv)==3:
        readRate=int(sys.argv[2])
        assert(readRate>0)
        assert(readRate<20)

    devName='/dev/input/mouse%d'%myNo


    try:
        fm = open(devName, 'rb')
    except:
        onFailedStart(myNo)
        exit(1)

    try:
        mouseMsg(myNo)
    except rospy.ROSInterruptException:
        pass