I wrote a simple Tkinter based Python application that reads text from a serial connection and adds it to the window, specifically a text widged.
After a lot of tweaks a
OK,
based on the valuable suggestions by noob oddy I was able to rewrite the example script by using the Tkinter.generate_event()
method to generate asynchronous event and a queue to pass the information.
Every time a line is read from the stream (which is simulated by a constant string and a delay), I append the line to a queue (because passing objects to the event method is not supported AFAIK) and then create a new event.
The event callback method retrieves the message from the queue and adds it to the Text widged. This works because this method is called from the Tkinter mainloop an thus it cannot interfere with the other jobs.
Here is the script:
import re,sys,time
from Tkinter import *
import Tkinter
import threading
import traceback
import Queue
class ReaderThread(threading.Thread):
def __init__(self, root, queue):
print "Thread init"
threading.Thread.__init__(self)
self.root = root
self.running = True
self.q = queue
def stop(self):
print "Stopping thread"
running = False
def run(self):
print "Thread started"
time.sleep(5)
try:
while(self.running):
# emulating delay when reading from serial interface
time.sleep(0.05)
curline = "the quick brown fox jumps over the lazy dog\n"
try:
self.q.put(curline)
self.root.event_generate('<>', when='tail')
# If it failed, the window has been destoyed: over
except TclError as e:
print e
break
except Exception as e:
traceback.print_exc(file=sys.stdout)
print "Exception in receiver thread, stopping..."
pass
print "Thread stopped"
class Transformer:
def __init__(self):
self.q = Queue.Queue()
self.lineIndex = 1
pass
def appendLine(self, event):
line = self.q.get_nowait()
if line == None:
return
i = self.lineIndex
curIndex = "1.0"
lowerEdge = 1.0
pos = 1.0
# get cur position
pos = self.scrollbar.get()[1]
# Disable scrollbar
self.text.configure(yscrollcommand=None, state=NORMAL)
# Add to text window
self.text.insert(END, str(line))
startIndex = repr(i) + ".0"
curIndex = repr(i) + ".end"
# Perform colorization
if i % 6 == 0:
self.text.tag_add("warn", startIndex, curIndex)
elif i % 6 == 1:
self.text.tag_add("debug", startIndex, curIndex)
elif i % 6 == 2:
self.text.tag_add("info", startIndex, curIndex)
elif i % 6 == 3:
self.text.tag_add("error", startIndex, curIndex)
elif i % 6 == 4:
self.text.tag_add("fatal", startIndex, curIndex)
i = i + 1
# Enable scrollbar
self.text.configure(yscrollcommand=self.scrollbar.set, state=DISABLED)
# Auto scroll down to the end if scroll bar was at the bottom before
# Otherwise allow customer scrolling
if pos == 1.0:
self.text.yview(END)
self.lineIndex = i
def start(self):
"""starts to read linewise from self.in_stream and parses the read lines"""
count = 1
self.root = Tk()
self.root.title("Tkinter Auto-Scrolling Test")#
self.root.bind('<>', self.appendLine)
self.topPane = PanedWindow(self.root, orient=HORIZONTAL)
self.topPane.pack(side=TOP, fill=X)
self.lowerPane = PanedWindow(self.root, orient=VERTICAL)
self.scrollbar = Scrollbar(self.root)
self.scrollbar.pack(side=RIGHT, fill=Y)
self.text = Text(wrap=WORD, yscrollcommand=self.scrollbar.set)
self.scrollbar.config(command=self.text.yview)
# Color definition for log levels
self.text.tag_config("debug",foreground="gray50")
self.text.tag_config("info",foreground="green")
self.text.tag_config("warn",foreground="orange")
self.text.tag_config("error",foreground="red")
self.text.tag_config("fatal",foreground="#8B008B")
# set default color
self.text.config(background="black", foreground="gray");
self.text.pack(expand=YES, fill=BOTH)
self.lowerPane.add(self.text)
self.lowerPane.pack(expand=YES, fill=BOTH)
t = ReaderThread(self.root, self.q)
print "Starting thread"
t.start()
try:
self.root.mainloop()
except Exception as e:
print "Exception in window manager: ", e
t.stop()
t.join()
if __name__ == "__main__":
try:
trans = Transformer()
trans.start()
except Exception as e:
print "Error: ", e
sys.exit(1)
Thanks again to everybody who contributed for your help!