getting rid of control character with ncurses and threaded class - python-3.x

Question

I'm trying to develop some kind of terminal user interface in python3
with threading and ncurse and some weird characters appear.
Based on the answer in this post:
Threading with Python Curses giving me weird characters?
which is exactly my problem, i tried to implement locking the maj() function (and also tested with rlock) in my code .
But it seams the lock does not block other thread .
Is my lock misplaced ?? or am i hitting a technical limit ?
here after is an example my code :
import threading
from time import sleep
import curses
import logging
from curses.textpad import Textbox, rectangle
from datetime import datetime
class GenericTUI(threading.Thread):
def __init__(self,textmode=False, messageBoxSize=10, logger=logging.getLogger()):
threading.Thread.__init__(self)
self.keyPressedList = list()
self.alive = True
self.myStdscr = None
self.title = ""
self.messageList = list()
self.messageBoxSize = messageBoxSize
self.subTitle = ""
self.priceInfo = ""
self.progInfo = ""
self.textMode = textmode
self.logger = logger
self.lock = threading.Lock()
def run(self):
if self.textMode :
with open('/tmp/genericTUI.command','w+') as f:
# command file in text mode
pass
while self.alive :
print("Program :"+ self.title)
print("sub"+self.subTitle)
print("Prices : "+self.priceInfo)
print("ProgInfos :"+self.progInfo)
for m in self.messageList :
print(m)
with open('/tmp/genericTUI.command','r+') as f:
c = f.read(1)
if c:
self.keyPressedList.append(c)
f.truncate(0)
sleep(5)
else :
curses.wrapper(self.main)
def maj(self):
'''
mise a jour de l ecran
au sujet du thread lock :
https://stackoverflow.com/questions/46773577/threading-with-python-curses-giving-me-weird-characters
'''
# determine la taille de l ecran
max_y, max_x = self.myStdscr.getmaxyx()
# reecriture
with self.lock :
try :
self.myStdscr.clear()
for x in range(max_x):
self.myStdscr.addch(0,x,curses.ACS_HLINE)
self.myStdscr.addstr(1, 2, "Program :"+ self.title, curses.color_pair(1) )
self.myStdscr.addstr(2, 2, self.subTitle)
for x in range(max_x):
self.myStdscr.addch(3,x,curses.ACS_HLINE)
self.myStdscr.addstr(4, 2, "Prices : "+self.priceInfo, curses.color_pair(2))
for x in range(max_x):
self.myStdscr.addch(5,x,curses.ACS_HLINE)
self.myStdscr.addstr(6, 2, "ProgInfos :"+self.progInfo, curses.color_pair(5))
for x in range(max_x):
self.myStdscr.addch(7,x,curses.ACS_HLINE)
indent =0
for m in self.messageList :
self.myStdscr.addstr(8+indent, 3,m)
indent+=1
for y in range(max_y):
self.myStdscr.addch(y,0,curses.ACS_VLINE)
self.myStdscr.refresh()
except Exception as e:
self.logger.error(repr(e))
self.myStdscr.clear()
def main(self,stdscr):
# color definition
if curses.has_colors():
curses.start_color()
curses.init_pair(1, curses.COLOR_WHITE, curses.COLOR_BLUE)
curses.init_pair(2, curses.COLOR_WHITE, curses.COLOR_RED)
curses.init_pair(3, curses.COLOR_WHITE, curses.COLOR_YELLOW)
curses.init_pair(4, curses.COLOR_BLACK, curses.COLOR_BLUE)
curses.init_pair(5, curses.COLOR_BLACK, curses.COLOR_GREEN)
## NE SURTOUT PAS METTRE keypad(false) GENERE DES CARACTERES AU HASARD .. DANGEREUX
self.myStdscr = stdscr
self.myStdscr.nodelay(True)
self.myStdscr.keypad(True)
self.myStdscr.box()
counter = 0
while self.alive:
try :
key = self.myStdscr.getkey()
self.keyPressedList.append(key)
except Exception as e:
## le nodelay rend l interface reactive mais ,le getkey genere un noinput error
## si pas de touche pressée d ou le pass
pass
sleep(0.1)
counter +=1
def getKeyPressed(self):
if self.keyPressedList :
return self.keyPressedList.pop()
else :
return None
def stop(self):
self.alive = False
def updatePriceInfo(self,priceDict,maj=False):
result = " ".join(str(key) +":"+ str(value)+"|" for key, value in priceDict.items())
self.priceInfo = result
if maj :
self.maj()
def updateTitle(self,title, maj=False):
self.title = str(title)
if maj :
self.maj()
def updateSubTitle(self,subtitleDict, maj=False):
result = " ".join(str(key) +":"+ str(value)+"|" for key, value in subtitleDict.items())
self.subTitle = str(result)
if maj :
self.maj()
def updateProgInfo(self,messDict, maj=False):
result = " ".join(str(key) +":"+ str(value)+"|" for key, value in messDict.items())
self.progInfo = result
if maj :
self.maj()
def addMessage(self,mess, maj=False):
self.messageList.append(repr(mess))
if len(self.messageList) > self.messageBoxSize : self.messageList.pop(0)
if maj :
self.maj()
def getValue(self, mess="Enter Value: (hit Ctrl-G to send)"):
self.myStdscr.addstr(0, 0, mess)
editwin = curses.newwin(1,7, 2,1)
rectangle(self.myStdscr, 1,0, 1+1+1, 1+7+1)
self.myStdscr.refresh()
box = Textbox(editwin)
box.stripspaces = True
# Let the user edit until Ctrl-G is struck.
box.edit()
# Get resulting contents
return(box.gather().strip())
if __name__ == "__main__":
## the main is used for some test when the lib is called directly
testGUI = GenericTUI()
alive = True
testGUI.logger.addHandler(logging.StreamHandler())
testGUI.logger.setLevel(logging.DEBUG)
testGUI.start()
while alive :
testGUI.updateTitle('time %s'%str(datetime.now() ))
k = testGUI.getKeyPressed()
if k is not None:
if k=='Q' :
alive = False
elif k=='M' :
mess = testGUI.getValue()
testGUI.addMessage(mess,maj=True)
else :
testGUI.addMessage('unknown key %s'%k , maj=True)
sleep(0.1)
testGUI.stop()
as you can see there is a with self.lock statement in the maj()function o the class, but
in my log i still get a lot of errors like :
alphanumeric key ? pressed
unknown key press : ?
alphanumeric key [ pressed
unknown key press : [
alphanumeric key pressed
unknown key press :
alphanumeric key ? pressed
where should i place my lock to avoid that ??

Answer 1

I answer my own question, but I think it will be hepfull for others :
The trick is in the ncurses wrapper which have is own thread . So If i want the lock to work I have to put it in the main loop .
Below is the code modified :
import threading
from time import sleep
import curses
import logging
from curses.textpad import Textbox, rectangle
from datetime import datetime
import re
class GenericTUI(threading.Thread):
def __init__(self,textmode=False, messageBoxSize=10, logger=logging.getLogger()):
threading.Thread.__init__(self)
self.keyPressedList = list()
self.alive = True
self.myStdscr = None
self.title = ""
self.messageList = list()
self.messageBoxSize = messageBoxSize
self.subTitle = ""
self.priceInfo = ""
self.progInfo = ""
self.textMode = textmode
self.logger = logger
self.lock = threading.Lock()
self.refreshFlag = True
def run(self):
if self.textMode :
with open('/tmp/genericTUI.command','w+') as f:
# command file in text mode
pass
while self.alive :
print("Program :"+ self.title)
print("sub"+self.subTitle)
print("Prices : "+self.priceInfo)
print("ProgInfos :"+self.progInfo)
for m in self.messageList :
print(m)
with open('/tmp/genericTUI.command','r+') as f:
c = f.read(1)
if c:
self.keyPressedList.append(c)
f.truncate(0)
sleep(5)
else :
curses.wrapper(self.main)
def main(self,stdscr):
# color definition
if curses.has_colors():
curses.start_color()
curses.init_pair(1, curses.COLOR_WHITE, curses.COLOR_BLUE)
curses.init_pair(2, curses.COLOR_WHITE, curses.COLOR_RED)
curses.init_pair(3, curses.COLOR_WHITE, curses.COLOR_YELLOW)
curses.init_pair(4, curses.COLOR_BLACK, curses.COLOR_BLUE)
curses.init_pair(5, curses.COLOR_BLACK, curses.COLOR_GREEN)
## NE SURTOUT PAS METTRE keypad(false) GENERE DES CARACTERES AU HASARD .. DANGEREUX
self.myStdscr = stdscr
self.myStdscr.nodelay(True)
self.myStdscr.keypad(True)
self.myStdscr.box()
counter = 0
while self.alive:
try :
key = self.myStdscr.getkey()
#workaround to avoid multi thread escape character
if re.match('[A-Z_\+\-\*/]', key) :
self.keyPressedList.append(key)
except Exception as e:
## le nodelay rend l interface reactive mais ,le getkey genere un noinput error
## si pas de touche pressée d ou le pass
pass
'''
screen update in the mail loop
to be able to thread lock :
https://stackoverflow.com/questions/46773577/threading-with-python-curses-giving-me-weird-characters
'''
# determine la taille de l ecran
max_y, max_x = self.myStdscr.getmaxyx()
# reecriture
if self.refreshFlag:
try :
with self.lock :
self.myStdscr.clear()
for x in range(max_x):
self.myStdscr.addch(0,x,curses.ACS_HLINE)
self.myStdscr.addstr(1, 2, "Program :"+ self.title, curses.color_pair(1) )
self.myStdscr.addstr(2, 2, self.subTitle)
for x in range(max_x):
self.myStdscr.addch(3,x,curses.ACS_HLINE)
self.myStdscr.addstr(4, 2, "Prices : "+self.priceInfo, curses.color_pair(2))
for x in range(max_x):
self.myStdscr.addch(5,x,curses.ACS_HLINE)
self.myStdscr.addstr(6, 2, "ProgInfos :"+self.progInfo, curses.color_pair(5))
for x in range(max_x):
self.myStdscr.addch(7,x,curses.ACS_HLINE)
indent =0
for m in self.messageList :
self.myStdscr.addstr(8+indent, 3,m)
indent+=1
for y in range(max_y):
self.myStdscr.addch(y,0,curses.ACS_VLINE)
self.myStdscr.refresh()
except Exception as e:
self.logger.error(repr(e))
self.myStdscr.clear()
finally:
self.refreshFlag = False
sleep(0.1)
counter +=1
def getKeyPressed(self):
if self.keyPressedList :
return self.keyPressedList.pop()
else :
return None
def stop(self):
self.alive = False
def updatePriceInfo(self,priceDict,maj=False):
result = " ".join(str(key) +":"+ str(value)+"|" for key, value in priceDict.items())
self.priceInfo = result
self.refreshFlag = maj
def updateTitle(self,title, maj=False):
self.title = str(title)
self.refreshFlag = maj
def updateSubTitle(self,subtitleDict, maj=False):
result = " ".join(str(key) +":"+ str(value)+"|" for key, value in subtitleDict.items())
self.subTitle = str(result)
self.refreshFlag = maj
def updateProgInfo(self,messDict, maj=False):
result = " ".join(str(key) +":"+ str(value)+"|" for key, value in messDict.items())
self.progInfo = result
self.refreshFlag = maj
def addMessage(self,mess, maj=False):
self.messageList.append(repr(mess))
if len(self.messageList) > self.messageBoxSize : self.messageList.pop(0)
self.refreshFlag = maj
def getValue(self, mess="Enter Value: (hit Ctrl-G to send)"):
with self.lock :
self.myStdscr.addstr(0, 0, mess)
editwin = curses.newwin(1,7, 2,1)
rectangle(self.myStdscr, 1,0, 1+1+1, 1+7+1)
box = Textbox(editwin)
box.stripspaces = True
self.myStdscr.refresh()
# Let the user edit until Ctrl-G is struck.
box.edit()
# Get resulting contents
return(box.gather().strip())
if __name__ == "__main__":
## the main is used for some test when the lib is called directly
testGUI = GenericTUI()
alive = True
testGUI.logger.addHandler(logging.StreamHandler())
testGUI.logger.setLevel(logging.DEBUG)
testGUI.start()
while alive :
testGUI.updateTitle('time %s'%str(datetime.now() ))
k = testGUI.getKeyPressed()
if k is not None:
if k=='Q' :
alive = False
elif k=='M' :
mess = testGUI.getValue()
testGUI.addMessage(mess,maj=True)
else :
testGUI.addMessage('unknown key %s'%k , maj=True)
sleep(0.1)
testGUI.stop()
```
you may also notice there is another lock in the getvalue function to avoid the main thread to erase the textbox .
Hope this help others.