I am displaying a sensor device's measurement values using the Tkinter GUI application. The sensor sends new data every second. I started a new thread and put the result in a Queue and process the queue to display the values on GUI. Now I am facing another problem. The sensor has two modes of operations. For simplicity, I have used a random generator in the program. Users should be able to switch the modes using two buttons. Button-1 for Mode-1, Button-2 for Mode-2. (say the mode-1 operation is random.randrange(0,10) and mode-2 operation is random.randrange(100, 200). How do I control these two operations through Threading? if a user started a mode-1 operation, when he presses the Button-2, the mode-1 operation should stop (thread-1) and mode-2 operation (thread-2) should start. Does it mean do I need to kill thread-1? Or is there any way to control two modes in same thread? I am totally new into threading. Any suggestions, please.
import tkinter
import threading
import queue
import time
import random
class GuiGenerator:
def __init__(self, master, queue):
self.queue = queue
# Set up the GUI
master.geometry('800x480')
self.output = tkinter.StringVar()
output_label = tkinter.Label(master, textvariable= self.output)
output_label.place(x=300, y=200)
#I haven't shown command parts in following buttons. No idea how to use it to witch modes?
mode_1_Button = tkinter.Button(master, text = "Mode-1")
mode_1_Button.place(x=600, y=300)
mode_2_Button = tkinter.Button(master, text = "Mode-2")
mode_2_Button.place(x=600, y=400)
def processQueue(self):
while self.queue.qsize():
try:
sensorOutput = self.queue.get() #Q value
self.output.set(sensorOutput) #Display Q value on GUI
except queue.Empty:
pass
class ClientClass:
def __init__(self, master):
self.master = master
# Create the queue
self.queue = queue.Queue()
# Set up the GUI part
self.myGui = GuiGenerator(master, self.queue)
#How do I switch the modes of operations? do I need some flags setting through button press?
# Set up the thread to do asynchronous I/O
self.thread1_mode1 = threading.Thread(target=self.firstModeOperation)
self.thread1_mode1.start()
# Start the periodic call in the GUI to check if the queue contains
# anything new
self.periodicCall()
def periodicCall(self):
# Check every 1000 ms if there is something new in the queue.
self.myGui.processQueue()
self.master.after(1000, self.periodicCall)
def firstModeOperation(self):
while True: #??? how do i control here through mode selection
time.sleep(1.0)
msg_mode_1= random.randrange(0,10)
self.queue.put(msg_mode_1)
def secondModeOperation(self):
while True: #??? how do i control here through mode selection
time.sleep(1.0)
msg_mode_2= random.randrange(100,200)
self.queue.put(msg_mode_2)
#Operation part
root = tkinter.Tk()
client = ClientClass(root)
root.mainloop()
Related
I can use QStatusBar to display a message by feeding it a single string, e.g.:
self.statusBar().showMessage("My message here, also show it for 1 sec", 1000)
In my event-loop, the above message will be shown on the status-bar for exactly 1000 ms. But say that instead of a string "My message here", I have a list of strings I want to display one at the time. I can do that via a loop by giving it a delay via time.sleep(1) - but that would unfortunately block the gui until the loop is over, and I don't want that. Can I separate the processes of main event loop and status bar updating, and if so, how?
The example code below has a button, which when pressed, generates three different messages stored in a list. They are then shown in the status-bar, one at a time, and the button cannot be pressed until the loop ends. The behaviour that I want is that the button is clickable (gui isn't blocked), and if it's clicked while the previous messages are showing, the showing is interrupted and new messages are shown.
---Example code below---
import sys
import time
from PyQt5 import QtWidgets
class Window(QtWidgets.QMainWindow):
"""Main Window."""
MSG_ID = 1
def __init__(self, parent=None):
"""Initializer."""
super().__init__(parent)
#stuff
self.messages = []
self.setWindowTitle('Main Window')
self.setStatusBar(QtWidgets.QStatusBar())
self.statusBar().showMessage("My message first time")
self.button = QtWidgets.QPushButton("Test",self)
self.button.clicked.connect(self.handleButton)
def handleButton(self):
self.messages = [f"message_num {msg_id}" for msg_id in range(Window.MSG_ID,Window.MSG_ID+3)]
Window.MSG_ID+=3
self.updateStatus()
print(self.messages)
def updateStatus(self):
self.statusBar().clearMessage()
for item in self.messages:
self.statusBar().showMessage(item,1000)
time.sleep(1.2)
if __name__ == '__main__':
app = QtWidgets.QApplication(sys.argv)
win = Window()
win.show()
sys.exit(app.exec_())
The above code creates a list of messages
There is no need to use timers or sleep for this, because the status-bar sends a messageChanged signal every time a temporary message changes (including when it's removed). This can be used to create a simple call-back loop that does what you want:
class Window(QtWidgets.QMainWindow):
...
def __init__(self, parent=None):
...
self.statusBar().messageChanged.connect(self.updateStatus)
def handleButton(self):
self.messages = [f"message_num {msg_id}" for msg_id in range(Window.MSG_ID,Window.MSG_ID+3)]
Window.MSG_ID+=3
self.updateStatus()
def updateStatus(self, message=None):
print('update-status:', (message, self.messages))
if not message and self.messages:
self.statusBar().showMessage(self.messages.pop(0), 1000)
This does not block the gui and allows the message sequence to be re-started at any time by clicking the button.
1) What is my goal:
I’m creating an application that should read data every 60s from ModBusServer, append those data to Graphs and then when the app is closed save the data to excel file.
Site note:
The process of reading data from ModBusServer and appending them to graphs should start after a start button is pressed.
And end after stop button is pressed OR when ModBusServer sends a request to stop.
2) What I have so far:
I created the GUI without any major problems as a class “GUI_komora”.
Everything there works just fine.
3) What is the problem:
But now I’m lost on how to approach the “read data every 60 seconds”, and overall how to control the application.
I did some research on threading but still I’m confused how to implement this to my application.
I learned how to make functions run simultaneously in this tutorial.
And also how to call a function every few seconds using this question.
But none of them helped me to learn how to control the overall flow of the application.
If you could redirect me somewhere or tell me about a better approach I would be really glad.
Some of my code:
from tkinter import *
from GUI_komora import GUI
root = Tk()
my_gui = GUI(root) #my GUI class instance
#main loop
root.mainloop()
"""
How do I achieve something like this???
whenToEnd = False
while whenToEnd:
if step == "Inicialzation":
#inicializace the app
if step == "ReadData":
#read data every 60 seconds and append them to graphs
if step == "EndApp"
#save data to excel file and exit app
whenToEnd = True
"""
Here is an example of a loop that takes a decision (every 60 sec in your case) and pushes the outcome of the decision to tkinter GUI: https://github.com/shorisrip/PixelescoPy/blob/master/base.py
Parts:
main thread - starts tkinter window
control thread - reads some data and decides what to show in GUI
GUI class - has a method "add_image" which takes input an image and displays on GUI.(add_data_to_graph maybe in your case). This method is called everytime by the control thread.
Snippets:
def worker(guiObj, thread_dict):
# read some data and make decision here
time.sleep(60)
data_to_show = <outcome of the decision>
while some_logic:
pictureObj = Picture(chosen, timer)
pictureObj.set_control_thread_obj(thread_dict["control_thread"])
guiObj.set_picture_obj(pictureObj)
pictureObj.display(guiObj)
# do post display tasks
guiObj.quit_window()
# Keep GUI on main thread and everything else on thread
guiObj = GuiWindow()
thread_list = []
thread_dict = {}
thread_for_image_control = threading.Thread(target=worker, args=(guiObj,
thread_dict))
thread_dict["control_thread"] = thread_for_image_control
thread_list.append(thread_for_image_control)
thread_for_image_control.start()
guiObj.run_window_on_loop()
# thread_for_image_control.join()
Code for Picture class:
class Picture:
def __init__(self, path, timer):
self.path = path
self.timer = timer
self.control_thread_obj = None
def set_control_thread_obj(self, thread_obj):
self.control_thread_obj = thread_obj
def display(self, guiObj):
image_path = self.path
guiObj.add_image(image_path)
time.sleep(self.timer)
Code for GUI class
class GuiWindow():
def __init__(self):
self.picture_obj = None
self.root = Tk()
self.image_label = None
self.image = None
self.folder_path = None
self.timer = None
self.root.protocol("WM_DELETE_WINDOW", self.exit_button)
def add_image(self, image_path):
resized_img = self.resize(image_path)
image_obj = ImageTk.PhotoImage(resized_img)
image_label = Label(self.root, image=image_obj,
height=resized_img.height,
width=resized_img.width)
self.image = image_obj # DO NOT REMOVE - Garbage collector error
if self.image_label is not None:
self.remove_image()
image_label.grid(row=0, column=0, columnspan=3)
self.image_label = image_label
Here based on my control loop thread I am changing image (in your case graph data) of the tkinter GUI.
Does this help?
i'm trying to manage two MainWindow (MainWindow & AccessWindow) with PyQt for my RFID ACCESS CONTROL Project.
I want to show the first MainWindow all time (Endless Loop).
Then, i want to hide it and show the second MainWindow when the RFID Reader (who's working on "auto-reading mode") read an RFID Tag.
so in the main python program i have a pseudo "do while" loop (while True: and break with a condition) to read on serial port the data provided by the reader. Then i check a DB.. It's not important. So the trigger event is "when the reader read something).
I got some help from another forum and now i have this:
# -*- coding: utf-8 -*-
from PyQt4 import QtCore, QtGui
import sys, pyodbc, serial
import os
import time
#Variables
Code_Zone = "d"
class MainWindow(QtGui.QWidget):
def __init__(self, main):
super(MainWindow, self).__init__()
self.main = main
self.grid = QtGui.QGridLayout(self)
self.welcome = QtGui.QLabel("WELCOME", self)
self.grid.addWidget(self.welcome, 2, 2, 1, 5)
class AccessWindow(QtGui.QWidget):
def __init__(self):
super(AccessWindow, self).__init__()
self.setMinimumSize(150, 50)
self.grid = QtGui.QGridLayout(self)
self.label = QtGui.QLabel(self)
self.grid.addWidget(self.label, 1, 1, 1, 1)
class Main(object):
def __init__(self):
self.accueil = MainWindow(self)
self.accueil.show()
self.access = AccessWindow()
def wait(self):
# RFID READER ENDLESS LOOP
while 1:
global EPC_Code
ser = serial.Serial(port='COM6', baudrate=115200)
a = ser.read(19).encode('hex')
if (len(a)==38):
EPC_Code = a[14:]
print ('EPC is : ' + EPC_Code)
break
else:
continue
ser.close()
self.on_event(EPC_Code)
def on_event(self, data):
def refresh():
self.toggle_widget(False)
self.wait()
# vérification des données
EPC_Code = data
sql_command = "[Get_Access_RFID] #Code_RFID = '"+EPC_Code+"', #Code_Zone = '"+Code_Zone+"'" # STORED PROCEDURE
db_cursor.execute(sql_command)
rows = db_cursor.fetchone()
result= str(rows[0])
print ("result = " + str(result))
if result == "True":
# si OK
self.access.label.setText('ACCESS GRANTED')
else:
# si pas OK
self.access.label.setText('ACCESS DENIED')
self.toggle_widget(True)
QtCore.QTimer.singleShot(2000, refresh)
def toggle_widget(self, b):
self.accueil.setVisible(not b)
self.access.setVisible(b)
if __name__=='__main__':
cnxn = """DRIVER={SQL Server};SERVER=***;PORT=***;UID=***;PWD=***;DATABASE=***"""
db_connection = pyodbc.connect(cnxn)
db_cursor = db_connection.cursor()
print ('Connected TO DB & READY')
app = QtGui.QApplication(sys.argv)
main = Main()
main.wait()
sys.exit(app.exec_())
and now my problem is that the text of the first window doesn't appear when i run the program but the text of the second window appear when i keep my badge near the RFID Reader.
Instead of two MainWindow, create one. As content, create two classes which extend QtGui.QWidget called MainView and AccessView. Instead of replacing the window, just put the correct view into the window. That way, you can swap views without opening/closing windows.
If you use a layout, then the window will resize to fit the view.
The next problem is that you block the UI thread which means Qt can't handle events (like the "paint UI" event). To fix this, you must move the RFID handling code in a background thread. You can emit signals from this background thread to update the UI.
Note: You must not call UI code from a thread!! Just emit signals. PyQt's main loop will see them and process them.
Related:
https://joplaete.wordpress.com/2010/07/21/threading-with-pyqt4/
Updating GUI elements in MultiThreaded PyQT, especially the second example using signals. The first example is broken (calling addItem() from a thread) is not allowed)
I have created a program to generate data points of functions that I later plot. The program takes a class which defines the function, creates a data outputting object which when called generates the data to a text file. To make the whole process faster I put the jobs in threads, however when I do, the data generated is not always correct. I have attached a picture to show what I mean:
Here are some of the relevant bits of code:
from queue import Queue
import threading
import time
queueLock = threading.Lock()
workQueue = Queue(10)
def process_data(threadName, q, queue_window, done):
while not done.get():
queueLock.acquire() # check whether or not the queue is locked
if not workQueue.empty():
data = q.get()
# data is the Plot object to be run
queueLock.release()
data.parent_window = queue_window
data.process()
else:
queueLock.release()
time.sleep(1)
class WorkThread(threading.Thread):
def __init__(self, threadID, q, done):
threading.Thread.__init__(self)
self.ID = threadID
self.q = q
self.done = done
def get_qw(self, queue_window):
# gets the queue_window object
self.queue_window = queue_window
def run(self):
# this is called when thread.start() is called
print("Thread {0} started.".format(self.ID))
process_data(self.ID, self.q, self.queue_window, self.done)
print("Thread {0} finished.".format(self.ID))
class Application(Frame):
def __init__(self, etc):
self.threads = []
# does some things
def makeThreads(self):
for i in range(1, int(self.threadNum.get()) +1):
thread = WorkThread(i, workQueue, self.calcsDone)
self.threads.append(thread)
# more code which just processes the function etc, sorts out the gui stuff.
And in a separate class (as I'm using tkinter, so the actual code to get the threads to run is called in a different window) (self.parent is the Application class):
def run_jobs(self):
if self.running == False:
# threads are only initiated when jobs are to be run
self.running = True
self.parent.calcsDone.set(False)
self.parent.threads = [] # just to make sure that it is initially empty, we want new threads each time
self.parent.makeThreads()
self.threads = self.parent.threads
for thread in self.threads:
thread.get_qw(self)
thread.start()
# put the jobs in the workQueue
queueLock.acquire()
for job in self.job_queue:
workQueue.put(job)
queueLock.release()
else:
messagebox.showerror("Error", "Jobs already running")
This is all the code which relates to the threads.
I don't know why when I run the program with multiple threads some data points are incorrect, whilst running it with just 1 single thread the data is all perfect. I tried looking up "threadsafe" processes, but couldn't find anything.
Thanks in advance!
I've written a GUI program which do a lot of calculation in the back, at the same time, display a progress bar. After it was done, a new screen will show the result.
Then I want to make another interface before the calculation to let the user select if they want to use the last calculation result, thus skipping the calculation.
I made a screen with a button which connected to the calculation, and a combo box to select last calculation result file.
However, when I clicked the button, it did nothing. And after around 10 secs( the duration for the calculation ), the result screen pop open. Thus, it skipped the progress bar screen. Why?
This it part of the original program:
import sys
import configparser
import getpass
import telnetlib
import time
import subprocess
from datetime import *
from log_tracker import *
from PyQt4.QtCore import *
from PyQt4.QtGui import *
from PyQt4 import QtCore
from PyQt4 import QtGui
class Task_Checker(QMainWindow):
def __init__(self):
super(Task_Checker, self).__init__()
config = configparser.RawConfigParser()
config.read('profile.cfg')
self.log_path = config.get('Config', 'log_path')
self.log_prefix = config.get('Config', 'log_prefix')
self.log_suffix = config.get('Config', 'log_suffix')
self.initUI()
def check_production(self):
self.log_tracker = Log_Tracker(self)
self.log_tracker.tick.connect(self.pbar.setValue)
self.log_tracker.parseConfig()
self.log_tracker.connectDb()
self.log_tracker.trackLog()
def initUI(self):
self.resize(1400, 768)
self.center()
self.statusBar().showMessage('Checking Production Programs')
self.wait_message = QLabel('Checking Production Programs')
self.wait_message.setAlignment(Qt.Alignment(Qt.AlignHCenter))
self.pbar = QProgressBar(self)
self.pbar.setMinimum(0)
self.pbar.setMaximum(100)
vbox = QVBoxLayout()
vbox.addWidget(self.wait_message)
vbox.addWidget(self.pbar)
tmpWidget2 = QWidget()
tmpWidget2.setLayout(vbox)
self.setCentralWidget(tmpWidget2)
self.show()
self.check_production()
self.pbar.hide()
self.statusBar().showMessage('Processing Information')
self.tabs = QTabWidget()
mua_table = self.processInfo('MUA')
bps_table = self.processInfo('BPS')
obdua_table = self.processInfo('OBDUA')
sua_table = self.processInfo('SUA')
ngr_ftp_table = self.processInfo('NGR_FTP')
bpspdfbill_table = self.processInfo('BpsPdfBill')
disk_space_table = self.processInfo('Disk_Space')
self.tabs.addTab(mua_table, 'MUA')
self.tabs.addTab(bps_table, 'BPS')
self.tabs.addTab(obdua_table, 'ODBUA')
self.tabs.addTab(sua_table, 'SUA')
self.tabs.addTab(ngr_ftp_table, 'NGR_FTP')
self.tabs.addTab(bpspdfbill_table, 'BpsPdfBill')
self.tabs.addTab(disk_space_table, 'Disk_Space')
self.setCentralWidget(self.tabs)
self.statusBar().showMessage('Ready')
self.setWindowTitle('Task Checker')
self.show()
def center(self):
qr = self.frameGeometry()
cp = QDesktopWidget().availableGeometry().center()
qr.moveCenter(cp)
self.move(qr.topLeft())
def processInfo(self, project_name):
...the processing...
In order to add a new screen before the progress bar ( originally it loads the calculation right away ), I made a fews changes to initUI() and move the calculation part to a new sub routine checkProd(), then connect it with a button:
import sys
import configparser
import getpass
import telnetlib
import time
import subprocess
from datetime import *
from log_tracker import *
from PyQt4.QtCore import *
from PyQt4.QtGui import *
from PyQt4 import QtCore
from PyQt4 import QtGui
class Task_Checker(QMainWindow):
def __init__(self):
super(Task_Checker, self).__init__()
config = configparser.RawConfigParser()
config.read('profile.cfg')
self.log_path = config.get('Config', 'log_path')
self.log_prefix = config.get('Config', 'log_prefix')
self.log_suffix = config.get('Config', 'log_suffix')
self.initUI()
def check_production(self):
self.log_tracker = Log_Tracker(self)
self.log_tracker.tick.connect(self.pbar.setValue)
self.log_tracker.parseConfig()
self.log_tracker.connectDb()
self.log_tracker.trackLog()
def initUI(self):
self.resize(1400, 768)
self.center()
btn_check = QPushButton('Check Lastest Status', self)
btn_check.setToolTip('Click this if you want to check the lastest status in production')
combo = QComboBox()
dirlist = os.listdir(self.log_path)
for f in dirlist:
combo.addItem(f)
QtCore.QObject.connect(btn_check, QtCore.SIGNAL('clicked()'), self.checkProd)
hbox = QHBoxLayout()
hbox.addWidget(btn_check)
hbox.addWidget(combo)
tmpWidget = QWidget()
tmpWidget.setLayout(hbox)
self.setCentralWidget(tmpWidget)
self.show()
def checkProd(self):
self.statusBar().showMessage('Checking Production Programs')
self.wait_message = QLabel('Checking Production Programs')
self.wait_message.setAlignment(Qt.Alignment(Qt.AlignHCenter))
self.pbar = QProgressBar(self)
self.pbar.setMinimum(0)
self.pbar.setMaximum(100)
vbox = QVBoxLayout()
vbox.addWidget(self.wait_message)
vbox.addWidget(self.pbar)
tmpWidget2 = QWidget()
tmpWidget2.setLayout(vbox)
self.setCentralWidget(tmpWidget2)
self.show()
self.check_production()
self.pbar.hide()
self.statusBar().showMessage('Processing Information')
self.tabs = QTabWidget()
mua_table = self.processInfo('MUA')
bps_table = self.processInfo('BPS')
obdua_table = self.processInfo('OBDUA')
sua_table = self.processInfo('SUA')
ngr_ftp_table = self.processInfo('NGR_FTP')
bpspdfbill_table = self.processInfo('BpsPdfBill')
disk_space_table = self.processInfo('Disk_Space')
self.tabs.addTab(mua_table, 'MUA')
self.tabs.addTab(bps_table, 'BPS')
self.tabs.addTab(obdua_table, 'ODBUA')
self.tabs.addTab(sua_table, 'SUA')
self.tabs.addTab(ngr_ftp_table, 'NGR_FTP')
self.tabs.addTab(bpspdfbill_table, 'BpsPdfBill')
self.tabs.addTab(disk_space_table, 'Disk_Space')
self.setCentralWidget(self.tabs)
self.statusBar().showMessage('Ready')
self.setWindowTitle('Task Checker')
self.show()
def center(self):
qr = self.frameGeometry()
cp = QDesktopWidget().availableGeometry().center()
qr.moveCenter(cp)
self.move(qr.topLeft())
def processInfo(self, project_name):
...the processing...
This is a lot of unnecessary code to read, but what I have managed to parse out of it, is that you are doing heavy calculations in the main thread, while expecting another widget in the main thread to also maintain responsiveness.
This is a common pitfall when working with PyQt4 (and probably most GUI frameworks that use a main thread event loop). The issue is that when you start your app, the main event loop constantly polls for new events to process from your GUI. Its expecting that every operation should either take a very short time to complete, or, periodically relinquish control back to the eventloop. Right now, your calculation is hogging up all the availability of the main thread, and anything that your progress window is trying to do is just backing up into a queue waiting for a chance for the event loop to pick it up.
The simple answer to this is: Do any heavy calculations in a separate QThread, and communicate back to your main thread via signals. This will require a little bit of retooling on you part. You should not put anything heavy into an init of any class. But you have managed to address this in your second example by attaching the computation to a button. Good start. The button should actually start the calc in another thread, thus not blocking up the main thread.
Qt4.7 Threading Basics
GUI Thread and Worker Thread
As mentioned, each program has one thread
when it is started. This thread is called the "main thread" (also
known as the "GUI thread" in Qt applications). The Qt GUI must run in
this thread. All widgets and several related classes, for example
QPixmap, don't work in secondary threads. A secondary thread is
commonly referred to as a "worker thread" because it is used to
offload processing work from the main thread.
...
Using Threads
There are basically two use cases for threads:
1. Make
processing faster by making use of multicore processors.
2. Keep the GUI
thread or other time critical threads responsive by offloading long
lasting processing or blocking calls to other threads.
As a quick fix if you just want to see some results, you can periodically call QtGui.QApplication.processEvents() from your calculation method. This will every so often allow the event loop to flush out pending operations. Doing so will let something like your progress widget actually function. Essentially what you are doing is manually "pumping" the event loop. This isn't the best approach though. Usually its reserved for lighter weight one off stuff. If you want the best performance, move it to a thread.