fenrir/src/fenrir-package/screen/linux.py

#!/bin/python
# -*- coding: utf-8 -*-

import difflib
import textwrap
import time
import re

#import fenrir.utils.debug
class screen():
    def __init__(self, device='/dev/vcsa'):
        self.vcsaDevicePath = device
        self.textWrapper = textwrap.TextWrapper()
        self.textWrapper.drop_whitespace = False
    def analyzeScreen(self, environment, trigger='updateScreen'):
        newTTY = ''
        newContentBytes = b''       
        try:
            # read screen
            currTTY = open('/sys/devices/virtual/tty/tty0/active','r')
            newTTY = currTTY.read()[3:-1]
            currTTY.close() 
            vcsa = open(self.vcsaDevicePath + newTTY,'rb',0)
            newContentBytes = vcsa.read()
            vcsa.close()
            if len(newContentBytes) < 5:
                return environment
        except:
            return environment

        # set new "old" values
        environment['screenData']['oldContentBytes'] = environment['screenData']['newContentBytes']
        environment['screenData']['oldContentText'] = environment['screenData']['newContentText']
        environment['screenData']['oldContentTextAttrib'] = environment['screenData']['newContentAttrib']
        environment['screenData']['oldCursor']['x'] = environment['screenData']['newCursor']['x']
        environment['screenData']['oldCursor']['y'] = environment['screenData']['newCursor']['y']
        environment['screenData']['oldTTY'] = environment['screenData']['newTTY']
        environment['screenData']['oldDelta'] = environment['screenData']['newDelta']
                
        environment['screenData']['newTTY'] = newTTY
        environment['screenData']['newContentBytes'] = newContentBytes
        # get metadata like cursor or screensize
        environment['screenData']['lines'] = int( environment['screenData']['newContentBytes'][0])
        environment['screenData']['columns'] = int( environment['screenData']['newContentBytes'][1])
        environment['screenData']['newCursor']['x'] = int( environment['screenData']['newContentBytes'][2])
        environment['screenData']['newCursor']['y'] = int( environment['screenData']['newContentBytes'][3])
        # analyze content
        environment['screenData']['newContentText'] = str(environment['screenData']['newContentBytes'][4:][::2].decode("ascii", "replace"))
        environment['screenData']['newContentAttrib'] = environment['screenData']['newContentBytes'][5:][::2]
        environment['screenData']['newContentText'] = '\n'.join(self.textWrapper.wrap(environment['screenData']['newContentText'], ))[:-2]
        
        if environment['screenData']['newTTY'] != environment['screenData']['oldTTY']:
            self.textWrapper.width = environment['screenData']['columns']
            environment['screenData']['oldContentBytes'] = b''
            environment['screenData']['oldContentAttrib'] = b''
            environment['screenData']['oldContentText'] = ''
            environment['screenData']['oldCursor']['x'] = 0
            environment['screenData']['oldCursor']['y'] = 0
            environment['screenData']['oldDelta'] = ''
            environment['screenData']['newDelta'] = ''
        
        # changes on the screen
        if (environment['screenData']['oldContentText'] != environment['screenData']['newContentText']) and \
          (environment['screenData']['newContentText'] != '' ):
#            diff = difflib.ndiff(environment['screenData']['oldContentText'], environment['screenData']['newContentText'])
            if environment['screenData']['oldContentText'] == '' and\
              environment['screenData']['newContentText'] != '':
                environment['screenData']['newDelta'] = environment['screenData']['newContentText']  
            else:
                diffStart = 0
                lastLine = len(environment['screenData']['newContentText']) - environment['screenData']['columns']
                if environment['screenData']['newContentText'][:lastLine] == environment['screenData']['oldContentText'][:lastLine]:
                    diffStart = lastLine + 1
      
                diff = difflib.ndiff(re.sub('[ \t]+', ' ', environment['screenData']['oldContentText'][diffStart:]),\
                  re.sub('[ \t]+', ' ', environment['screenData']['newContentText'][diffStart:]))
                environment['screenData']['newDelta'] = ''.join(x[2:] for x in diff if x.startswith('+ '))

        return environment