I'm currently working on an application that run in the background and sometime create an input dialog for the user to answer. If the user doesn't interact, I'd like to close the dialog after 30 seconds. I made a QThread that act like a timer and the "finished" signal should close the dialog. I unfortunately cannot find a way to close it.
At this point I'm pretty much lost. I completely new to QThread and a beginner in PyQt5
Here is a simplified version of the code (we are inside a class running a UI):
def Myfunction(self,q):
# q : [q1,q2,q3]
self.popup = counter_thread()
self.popup.start()
self.dial = QInputDialog
self.popup.finished.connect(self.dial.close)
text, ok = self.dial.getText(self, 'Time to compute !', '%s %s %s = ?'%(q[0], q[2], q[1]))
#[...]
I tried ".close()" and others but i got this error message:
TypeError: close(self): first argument of unbound method must have type 'QWidget'
I did it in a separated function but got the same problem...
You cannot close it because the self.dial you created is just an alias (another reference) to a class, not an instance.
Also, getText() is a static function that internally creates the dialog instance, and you have no access to it.
While it is possible to get that dialog through some tricks (installing an event filter on the QApplication), there's no point in complicating things: instead of using the static function, create a full instance of QInputDialog.
def Myfunction(self,q):
# q : [q1,q2,q3]
self.popup = counter_thread()
self.dial = QInputDialog(self) # <- this is an instance!
self.dial.setInputMode(QInputDialog.TextInput)
self.dial.setWindowTitle('Time to compute !')
self.dial.setLabelText('%s %s %s = ?'%(q[0], q[2], q[1]))
self.popup.finished.connect(self.dial.reject)
self.popup.start()
if self.dial.exec():
text = self.dial.textValue()
Note that I started the thread just before showing the dialog, in the rare case it may return immediately, and also because, for the same reason, the signal should be connected before starting it.
Related
I would like to know how to disable the button while another method is running by that button, and then re enable it when that method is finished. I tried with the sample code, but that logic does not work, it still clickable and only becomes disabled when the loop finishes in another method. If I click it multiple times during the while loop, then it restart it again and again.
from PyQt5.QtWidgets import QApplication, QMainWindow, QPushButton
import sys
class MainWindow(QMainWindow):
def __init__(self):
super().__init__()
self.setWindowTitle("Demo")
self.button = QPushButton("Press me!")
self.button.clicked.connect(self.the_button_was_clicked)
self.setCentralWidget(self.button)
def the_button_was_clicked(self):
self.button.setText("You already pressed it.")
self.runner()
self.setWindowTitle("Changed title")
def runner(self):
self.button.setEnabled(False)
i = 0
while i < 5000000:
i = i+1
print(i, end=" ")
self.button.setEnabled(True)
app = QApplication(sys.argv)
window = MainWindow()
window.show()
app.exec()
You have 2 problems.
Almost any UI based toolkit uses an event loop, meaning that it has a while-like loop that waits for any event in order to react; as long as you run a blocking function in the same thread of that event loop, it means that that loop is not able to process its events, which will be queued instead and lately processed as soon as control returns to it; among these events there are paint events (those responsible of painting the UI) and input events (those coming from the user interaction); your while loop blocks both of them, meaning that the button will not be displayed as disabled, and all input events will be queued and processed only after the function returns;
the Python buffer (used by print()) is somehow limited, which can block furthermore anything else;
Since Python doesn't allow direct concurrence, you only have two choices: periodically ensure that the event loop process its events (see QCoreApplication.processEvents()), or use multiprocessing capabilities (which can be very tricky if you need UI interaction).
For this simple case, the suggested solution is the former one (including skipping the buffer at all until the string is completed):
def runner(self):
self.button.setEnabled(False)
QApplication.processEvents()
i = 0
print('started')
while i < 5000000:
i = i+1
if not i % 100000:
QApplication.processEvents()
print('finished')
self.button.setEnabled(True)
Remember that processEvents() is possible and tolerated, but you should not use it without awareness: it should only be used when you really know what you are doing and any other alternative is not a viable option. If the processing does not directly deal with CPU-bound aspects (eg. IO management, like file system operation or network retrieval), you should consider threading instead, and always use QThreads and custom signals whenever any result of the processing requires interaction with UI elements, since widgets are NOT thread-safe.
I have a GtkTreeView object that uses a GtkListStore model that is constantly being updated as follows:
Get new transaction
Feed data into numpy array
Convert numbers to formatted strings, store in pandas dataframe
Add updated token info to GtkListStore via GtkListStore.set(titer, liststore_cols, liststore_data), where liststore_data is the updated info, liststore_cols is the name of the columns (both are lists).
Here's the function that updates the ListStore:
# update ListStore
titer = ls_full.get_iter(row)
liststore_data = []
[liststore_data.append(df.at[row, col])
for col in my_vars['ls_full'][3:]]
# check for NaN value, add a (space) placeholder is necessary
for i in range(3, len(liststore_data)):
if liststore_data[i] != liststore_data[i]:
liststore_data[i] = " "
liststore_cols = []
[liststore_cols.append(my_vars['ls_full'].index(col) + 1)
for col in my_vars['ls_full'][3:]]
ls_full.set(titer, liststore_cols, liststore_data)
Class that gets the messages from the websocket:
class MyWebsocketClient(cbpro.WebsocketClient):
# class exceptions to WebsocketClient
def on_open(self):
# sets up ticker Symbol, subscriptions for socket feed
self.url = "wss://ws-feed.pro.coinbase.com/"
self.channels = ['ticker']
self.products = list(cbp_symbols.keys())
def on_message(self, msg):
# gets latest message from socket, sends off to be processed
if "best_ask" and "time" in msg:
# checks to see if token price has changed before updating
update_needed = parse_data(msg)
if update_needed:
update_ListStore(msg)
else:
print(f'Bad message: {msg}')
When the program first starts, the updates are consistent. Each time a new transaction comes in, the screen reflects it, updating the proper token. However, after a random amount of time - seen it anywhere from 5 minutes to over an hour - the screen will stop updating, unless I change the focus of the window (either activate or inactive). This does not last long, though (only enough to update the screen once). No other errors are being reported, memory usage is not spiking (constant at 140 MB).
How can I troubleshoot this? I'm not even sure where to begin. The data back-ends seem to be OK (data is never corrupted nor lags behind).
As you've said in the comments that it is running in a separate thread then i'd suggest wrapping your "update liststore" function with GLib.idle_add.
from gi.repository import GLib
GLib.idle_add(update_liststore)
I've had similar issues in the past and this fixed things. Sometimes updating liststore is fine, sometimes it will randomly spew errors.
Basically only one thread should update the GUI at a time. So by wrapping in GLib.idle_add() you make sure your background thread does not intefer with the main thread updating the GUI.
Currently, I am working with a EV3 lego robot that is controlled by several neurons. Now I want to modify the code (running on
python3) in such a way that one can change certain parameter values on the run via the shell (Ubuntu) in order to manipulate the robot's dynamics at any time (and for multiple times). Here is a schema of what I have achieved so far based on a short example code:
from multiprocessing import Process
from multiprocessing import SimpleQueue
import ev3dev.ev3 as ev3
class Neuron:
(definitions of class variables and update functions)
def check_input(queue):
while (True):
try:
new_para = str(input("Type 'parameter=value': "))
float(new_para[2:0]) # checking for float in input
var = new_para[0:2]
if (var == "k="): # change parameter k
queue.put(new_para)
elif (var == "g="): # change parameter g
queue.put(new_para)
else:
print("Error". Type 'k=...' or 'g=...')
queue.put(0) # put anything in queue
except (ValueError, EOFError):
print("New value is not a number. Try again!")
(some neuron-specific initializations)
queue = SimpleQueue()
check = Process(target=check_input, args=(queue,))
check.start()
while (True):
if (not queue.empty()):
cmd = queue.get()
var = cmd[0]
val = float(cmd[2:])
if (var == "k"):
Neuron.K = val
elif (var == "g"):
Neuron.g = val
(updating procedure for neurons, writing data to file)
Since I am new to multiprocessing there are certainly some mistakes concerning taking care of locking, efficiency and so on but the robot moves and input fields occur in the shell. However, the current problem is that it's actually impossible to make an input:
> python3 controller_multiprocess.py
> Type 'parameter=value': New value is not a number. Try again!
> Type 'parameter=value': New value is not a number. Try again!
> Type 'parameter=value': New value is not a number. Try again!
> ... (and so on)
I know that this behaviour is caused by putting the exception of EOFError due to the fact that this error occurs when the exception is removed (and the process crashes). Hence, the program just rushes through the try-loop here and assumes that no input (-> empty string) was made over and over again. Why does this happen? - when not called as a threaded procedure the program patiently waits for an input as expected. And how can one fix or bypass this issue so that changing parameters gets possible as wanted?
Thanks in advance!
I have the following code
# -*- coding: utf-8 -*-
# 好
##########################################
import time
from twisted.internet import reactor, threads
from twisted.web.server import Site, NOT_DONE_YET
from twisted.web.resource import Resource
##########################################
class Website(Resource):
def getChild(self, name, request):
return self
def render(self, request):
if request.path == "/sleep":
duration = 3
if 'duration' in request.args:
duration = int(request.args['duration'][0])
message = 'no message'
if 'message' in request.args:
message = request.args['message'][0]
#-------------------------------------
def deferred_activity():
print 'starting to wait', message
time.sleep(duration)
request.setHeader('Content-Type', 'text/plain; charset=UTF-8')
request.write(message)
print 'finished', message
request.finish()
#-------------------------------------
def responseFailed(err, deferred):
pass; print err.getErrorMessage()
deferred.cancel()
#-------------------------------------
def deferredFailed(err, deferred):
pass; # print err.getErrorMessage()
#-------------------------------------
deferred = threads.deferToThread(deferred_activity)
deferred.addErrback(deferredFailed, deferred) # will get called indirectly by responseFailed
request.notifyFinish().addErrback(responseFailed, deferred) # to handle client disconnects
#-------------------------------------
return NOT_DONE_YET
else:
return 'nothing at', request.path
##########################################
reactor.listenTCP(321, Site(Website()))
print 'starting to serve'
reactor.run()
##########################################
# http://localhost:321/sleep?duration=3&message=test1
# http://localhost:321/sleep?duration=3&message=test2
##########################################
My issue is the following:
When I open two tabs in the browser, point one at http://localhost:321/sleep?duration=3&message=test1 and the other at http://localhost:321/sleep?duration=3&message=test2 (the messages differ) and reload the first tab and then ASAP the second one, then the finish almost at the same time. The first tab about 3 seconds after hitting F5, the second tab finishes about half a second after the first tab.
This is expected, as each request got deferred into a thread, and they are sleeping in parallel.
But when I now change the URL of the second tab to be the same as the one of the first tab, that is to http://localhost:321/sleep?duration=3&message=test1, then all this becomes blocking. If I press F5 on the first tab and as quickly as possible F5 on the second one, the second tab finishes about 3 seconds after the first one. They don't get executed in parallel.
As long as the entire URI is the same in both tabs, this server starts to block. This is the same in Firefox as well as in Chrome. But when I start one in Chrome and another one in Firefox at the same time, then it is non-blocking again.
So it may not neccessarily be related to Twisted, but maybe because of some connection reusage or something like that.
Anyone knows what is happening here and how I can solve this issue?
Coincidentally, someone asked a related question over at the Tornado section. As you suspected, this is not an "issue" in Twisted but rather a "feature" of web browsers :). Tornado's FAQ page has a small section dedicated to this issue. The proposed solution is appending an arbitrary query string.
Quote of the day:
One dev's bug is another dev's undocumented feature!
I am using eztext to gather input for my program, but the input window is preventing the output window from being opened(I can't see the display until the input window is closed)
Any help on the problem described above is much appreciated, after a long trawl through the internet I can't seem to find any solutions that I can modify to suit my purposes, though if anyone sees anything I've missed, I would be grateful for a link.
Thanks again in advance
A.J.P
You should try using 2 threads: one for the first window and a second for the other. Like this, both window will open.
edit:
For example, these two threads will communicate with a list. But i's better to use classes:
from time import sleep
from threading import Thread
informations = []
def funct_a (informations):
while (1):
sleep (0.5)
print informations
def funct_b (informations):
a = 0
while (1):
sleep (1)
informations.append (a)
a += 1
Thread (target = funct_a, args = (informations, )).start ()
Thread (target = funct_b, args = (informations, )).start ()