使用 PyQt5 的计时器应用程序

在本文中，我们将了解如何在 PyQt5 中创建计时器应用程序。计时器是一种专门用于测量特定时间间隔的时钟，对于给定的时间，我们必须减少时间，直到时间变为零，即向下计数。

GUI Implementation steps :

1. Create a push button to open pop up for getting time and set its geometry
2. Create label to show time and complete status
3. Set label geometry, font size and align its text to center
4. Create three push button for starting the timer, pausing the timer and for resetting the timer
5. Set the geometry of each button

Back-end Implementation steps :

1. Create count variable and flag to know if counter is stopped or running
2. Add action to each button
3. Inside the get second button action get the value of second using input dialog box and make the flag false
4. Inside the start action make flag true but if count is zero make if false
5. Inside pause action make flag false
6. Inside the reset action make flag false, set count value to zero and set text to the label
7. Make a timer object which calls its method after every 100 milliseconds
8. Inside the timer action check for the flag then decrement the value of count and set text to the label

下面是实现

# importing libraries
from PyQt5.QtWidgets import * 
from PyQt5 import QtCore, QtGui
from PyQt5.QtGui import * 
from PyQt5.QtCore import * 
import sys
  
  
class Window(QMainWindow):
  
    def __init__(self):
        super().__init__()
  
        # setting title
        self.setWindowTitle("Python ")
  
        # setting geometry
        self.setGeometry(100, 100, 400, 600)
  
        # calling method
        self.UiComponents()
  
        # showing all the widgets
        self.show()
  
    # method for widgets
    def UiComponents(self):
  
        # variables
        # count variable
        self.count = 0
  
        # start flag
        self.start = False
  
        # creating push button to get time in seconds
        button = QPushButton("Set time(s)", self)
  
        # setting geometry to the push button
        button.setGeometry(125, 100, 150, 50)
  
        # adding action to the button
        button.clicked.connect(self.get_seconds)
  
        # creating label to show the seconds
        self.label = QLabel("//TIMER//", self)
  
        # setting geometry of label
        self.label.setGeometry(100, 200, 200, 50)
  
        # setting border to the label
        self.label.setStyleSheet("border : 3px solid black")
  
        # setting font to the label
        self.label.setFont(QFont('Times', 15))
  
        # setting alignment ot the label
        self.label.setAlignment(Qt.AlignCenter)
  
        # creating start button
        start_button = QPushButton("Start", self)
  
        # setting geometry to the button
        start_button.setGeometry(125, 350, 150, 40)
  
        # adding action to the button
        start_button.clicked.connect(self.start_action)
  
        # creating pause button
        pause_button = QPushButton("Pause", self)
  
        # setting geometry to the button
        pause_button.setGeometry(125, 400, 150, 40)
  
        # adding action to the button
        pause_button.clicked.connect(self.pause_action)
  
        # creating reset  button
        reset_button = QPushButton("Reset", self)
  
        # setting geometry to the button
        reset_button.setGeometry(125, 450, 150, 40)
  
        # adding action to the button
        reset_button.clicked.connect(self.reset_action)
  
        # creating a timer object
        timer = QTimer(self)
  
        # adding action to timer
        timer.timeout.connect(self.showTime)
  
        # update the timer every tenth second
        timer.start(100)
  
    # method called by timer
    def showTime(self):
  
        # checking if flag is true
        if self.start:
            # incrementing the counter
            self.count -= 1
  
            # timer is completed
            if self.count == 0:
  
                # making flag false
                self.start = False
  
                # setting text to the label
                self.label.setText("Completed !!!! ")
  
        if self.start:
            # getting text from count
            text = str(self.count / 10) + " s"
  
            # showing text
            self.label.setText(text)
  
  
    # method called by the push button
    def get_seconds(self):
  
        # making flag false
        self.start = False
  
        # getting seconds and flag
        second, done = QInputDialog.getInt(self, 'Seconds', 'Enter Seconds:')
  
        # if flag is true
        if done:
            # changing the value of count
            self.count = second * 10
  
            # setting text to the label
            self.label.setText(str(second))
  
    def start_action(self):
        # making flag true
        self.start = True
  
        # count = 0
        if self.count == 0:
            self.start = False
  
    def pause_action(self):
  
        # making flag false
        self.start = False
  
    def reset_action(self):
  
        # making flag false
        self.start = False
  
        # setting count value to 0
        self.count = 0
  
        # setting label text
        self.label.setText("//TIMER//")
  
  
  
# create pyqt5 app
App = QApplication(sys.argv)
  
# create the instance of our Window
window = Window()
  
# start the app
sys.exit(App.exec())

输出 ：