[FIXED] QTimer randomly stops before the set time?

Issue

The QTimer object stops randomly near the end, it does not stop at the same point just around, I cannot see why as it stop both the custom widget and the variable itself, so it is not the widget cannot display it.

import sys
from PySide2.QtWidgets import QWidget, QSlider, QLabel, QProgressBar, QPushButton, QHBoxLayout, QVBoxLayout, QApplication
from PySide2.QtCore import QTimer,Qt
from PySide2extn.RoundProgressBar import roundProgressBar

class Timer(QWidget):
    def __init__(self):
        super().__init__()

        # Create a slider to set the timer duration
        self.slider = QSlider()
        self.slider.setOrientation(Qt.Horizontal) # vertical slider
        self.slider.setRange(1, 60)  # timer duration range: 1-60 seconds
        self.slider.setValue(10)  # default timer duration: 10 seconds
        self.slider.valueChanged.connect(self.update_label)
        self.time=0

        # Create a label to display the current timer duration
        self.label = QLabel(f'Timer duration: {self.slider.value()} seconds')

        # Create a progress bar to show the timer progress
        self.progress = roundProgressBar()
        self.progress.rpb_setRange(0, self.slider.value() * 1000)
        self.progress.rpb_setValue(0)

        # Create start, stop, and reset buttons
        self.start_button = QPushButton('Start')
        self.stop_button = QPushButton('Stop')
        self.reset_button = QPushButton('Reset')
        self.start_button.clicked.connect(self.start_timer)
        self.stop_button.clicked.connect(self.stop_timer)
        self.reset_button.clicked.connect(self.reset_timer)
        self.stop_button.setEnabled(False)
        self.reset_button.setEnabled(False)

        # Create a layout for the buttons
        button_layout = QHBoxLayout()
        button_layout.addWidget(self.start_button)
        button_layout.addWidget(self.stop_button)
        button_layout.addWidget(self.reset_button)

        # Create a layout and add the slider, label, progress bar, and buttons
        layout = QVBoxLayout()
        layout.addWidget(self.slider)
        layout.addWidget(self.label)
        layout.addWidget(self.progress)
        layout.addLayout(button_layout)
        self.setLayout(layout)

        # Create a timer and set the timeout signal
        self.timer = QTimer()
        self.timer.timeout.connect(self.timeout)
        self.progress_timer = QTimer()
        self.progress_timer.timeout.connect(self.update_progress)

    def update_label(self):
        self.label.setText(f'Timer duration: {self.slider.value()} seconds')
        self.progress.rpb_setRange(0, self.slider.value() * 1000)

    def update_progress(self):
        self.time+=100
        print(self.time)
        self.progress.rpb_setValue(self.time)

    def start_timer(self):
        # Set the timer duration in seconds
        duration = self.slider.value()
        # Start the timer and progress timer
        self.timer.start(duration * 1000)  # milliseconds
        self.progress_timer.start(100)  # 100ms interval
        # Disable the start button, enable the stop and reset buttons
        self.start_button.setEnabled(False)
        self.stop_button.setEnabled(True)
        self.reset_button.setEnabled(True)
        self.slider.setEnabled(False)

    def stop_timer(self):
        # Stop the timer and progress timer
        self.timer.stop()
        self.progress_timer.stop()
        # Disable the stop button, enable the start button
        self.stop_button.setEnabled(False)
        self.start_button.setEnabled(True)
        self.slider.setEnabled(True)

    def reset_timer(self):
        # Stop the timer and progress timer
        self.time=0
        self.timer.stop()
        self.progress_timer.stop()
        # Reset the progress bar to 0, enable the start button, disable the stop and reset buttons
        self.progress.rpb_setValue(0)
        self.start_button.setEnabled(True)
        self.stop_button.setEnabled(False)
        self.reset_button.setEnabled(False)

    def timeout(self):
         # Stop the timer and progress timer
        self.timer.stop()
        self.progress_timer.stop()
        # Disable the stop button, enable the start button and reset button
        self.stop_button.setEnabled(False)

if __name__ == '__main__':
    app = QApplication(sys.argv)
    timer = Timer()
    timer.show()
    sys.exit(app.exec_())

Thanks for any help.

DONT NOT MIX PYSIDE2 AND PYQT5. Refer to the first comment on the question as to why.

Solution

The way you're keeping time is not accurate. You can demonstrate this by making these changes:

    def update_progress(self):
        self.time += 100
        elapsed_time = self.timer.interval() - self.timer.remainingTime()
        print(self.time, elapsed_time)
        self.progress.setValue(elapsed_time)

In the print output you can see that self.time and elapsed_time are not in sync. self.time falls behind and that gives the impression that the timer stops prematurely while in fact, it does run out. Using the elapsed_time as value to set the progress bar will give the accurate progress of the timer. It will still not reach 100% though because the moment the timer times out will fall between updates. If you lower the update interval you will get closer to 100%.

Answered By - mahkitah