如何在PYQT5中使用计时器进行循环

Question

this is the first writing for asking..

I would like to make a program for currency.
everything works well without looping. I used 'while' but it frozen the GUI. so I searched for solution, and I found timer in pyqt5. but I don't know how to use. If you can help me, it is really honor to me. sorry for my bad English.

Here's the my full code

    import sys
from PyQt5.QtWidgets import *
from bs4 import BeautifulSoup
import requests
from requests.compat import urljoin
import time
from PyQt5 import QtCore
global Currency

class MyWindow(QWidget):
    def __init__(self):
        super().__init__()
        self.setupUI()
        self.Searching_Currency()
    def setupUI(self):
        self.setGeometry(800, 200, 300, 100)
        self.label1 = QLabel("Currency: ")
        self.label2 = QLabel("Searching for")
        self.label3 = QLabel("")
        self.lineEdit2 = QLineEdit()
        self.pushButton1= QPushButton("Search")
        self.pushButton2= QPushButton("to get alert")
        self.pushButton3= QPushButton("reset")
        self.pushButton4= QPushButton("quit")
        self.pushButton1.clicked.connect(self.btn1_clicked)
        self.pushButton2.clicked.connect(self.btn2_clicked)
        self.pushButton3.clicked.connect(self.btn3_clicked)
        self.pushButton4.clicked.connect(self.btn4_clicked)


        layout = QGridLayout()

        layout.addWidget(self.label1, 0, 0)
        layout.addWidget(self.label3, 0, 1)
        layout.addWidget(self.pushButton1, 0, 2)

        layout.addWidget(self.label2, 1, 0)
        layout.addWidget(self.lineEdit2, 1, 1)
        layout.addWidget(self.pushButton2, 1, 2)
        layout.addWidget(self.pushButton3, 2, 0)
        layout.addWidget(self.pushButton4, 2, 1)
        self.setLayout(layout)

    def btn1_clicked(self):
        global Currency
        self.Searching_Currency()
        self.label3.setText(str(Currency))

    def btn2_clicked(self):
        global Currency
        textboxValue = float(self.lineEdit2.text())
        if textboxValue > Currency:
            QMessageBox.question(self, 'alert', "done. it is  " + str
            (textboxValue), QMessageBox.Ok, QMessageBox.Ok)    
        #   #### I don't know how to use timer.. to check every 1mins.   
        # self.timer = QtCore.QTimer()
        # self.timer.timeout.connect(self.update)
        # self.timer.start(5000)
        QMessageBox.question(self, 'alert', "test message  " + str
            (textboxValue), QMessageBox.Ok, QMessageBox.Ok)      
         #trigger every minute    
        # while textboxValue < Currency:
        #         time.sleep(3)
        #         Currency=Currency-0.10
        #         break
        # QMessageBox.question(self, 'alert', "it is under the " + str(textboxValue), QMessageBox.Ok, QMessageBox.Ok)    


    def btn3_clicked(self):
        self.label3.clear()

    def btn4_clicked(self):
        sys.exit(0)

    def Searching_Currency(self):
        base_url = "https://www.finanzen100.de/waehrungen/euro-britisches-pfund-eur-gbp-_H1677059499_11341217/?ac=1"
        header = {'User-Agent': 'Mozilla/5.0'}
        r = requests.get(base_url,headers=header).text
        soup=BeautifulSoup(r,'html.parser')
        MyCurrency= soup.select(".quote__price__price")[0]
        MyCurrency=MyCurrency.get_text()
        MyCurrency =MyCurrency.replace(',','.')
        global Currency
        Currency = float(MyCurrency)

if __name__ == "__main__":
    app = QApplication(sys.argv)
    mywindow = MyWindow()
    mywindow.show()
    app.exec_()

1.this program check currency using Beautiful soup.

2.and compare with the value I put

3.and pop up the message,

Answer 1

The QtCore.QTimer class provides repetitive and single-shot timers. You wrote everything practical. Add the called slot (showTime).

...
def setupUI(self):
    ....
    self.timer = QtCore.QTimer(self)
    self.timer.timeout.connect(self.showTime)
    self.timer.start(1000)
    ...

def showTime(self):
    # do something
    ....        

In your example you can use next:

1. Click "Search"
2. Click "to get alert"
3. Look on the process for 1-2 minutes

import sys
import time

from bs4 import BeautifulSoup
import requests
from requests.compat import urljoin

from PyQt5.QtWidgets import *
from PyQt5 import QtCore
from PyQt5 import Qt                                            # +++

global Currency

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

        self.setupUI()
        self.Searching_Currency()

    def setupUI(self):
        self.setGeometry(800, 200, 350, 170)                    # -+
        self.label1 = QLabel("Currency: ")
        self.label2 = QLabel("Searching for")
        self.label3 = QLabel("")
        self.label4 = QLabel("")                                # +++

        self.lineEdit2 = QLineEdit()
        self.pushButton1= QPushButton("Search")
        self.pushButton2= QPushButton("to get alert")
        self.pushButton3= QPushButton("reset")
        self.pushButton4= QPushButton("quit")
        self.pushButton1.clicked.connect(self.btn1_clicked)
        self.pushButton2.clicked.connect(self.btn2_clicked)
        self.pushButton3.clicked.connect(self.btn3_clicked)
        self.pushButton4.clicked.connect(self.btn4_clicked)

        # +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
        self.lcd = Qt.QLCDNumber()                              # +++
        self.lcd.setDigitCount(7)
        self.lcdTime = Qt.QLCDNumber()  #self
        self.lcdTime.setSegmentStyle(Qt.QLCDNumber.Filled)   
        self.lcdTime.setDigitCount(8)  
        self.timer1 = Qt.QTimer(self)
        self.timer1.timeout.connect(self.showTime)
        self.timer1.start(1000)


        layout = QGridLayout()
        layout.addWidget(self.lcdTime, 0, 0, 1, 3)              # +++
        layout.addWidget(self.label1, 1, 0)
        layout.addWidget(self.label3, 1, 1)
        layout.addWidget(self.pushButton1, 1, 2)

        layout.addWidget(self.label2, 2, 0)
        layout.addWidget(self.lineEdit2, 2, 1)
        layout.addWidget(self.pushButton2, 2, 2)
        layout.addWidget(self.pushButton3, 3, 0)
        layout.addWidget(self.pushButton4, 3, 1)
        layout.addWidget(self.label4, 3, 2)                     # +++
        layout.addWidget(self.lcd, 4, 0, 1, 3)                  # +++
        self.setLayout(layout)

        self.timer = QtCore.QTimer()                            # +++
        self.timer.timeout.connect(self.show_textboxValue)      # +++

    def btn1_clicked(self):
        global Currency
        self.Searching_Currency()
        self.label3.setText(str(Currency))

    def btn2_clicked(self):
        global Currency
        try:                                                    # +++
            self.textboxValue = float(self.lineEdit2.text())
        except:
            self.textboxValue = Currency
            self.label4.setText(str(Currency))

        ##if self.textboxValue > Currency:
        ##    QMessageBox.question(self, 'alert', "done. it is  " + str
        ##    (self.textboxValue), QMessageBox.Ok, QMessageBox.Ok)    
        #   #### I don't know how to use timer.. to check every 1mins.   
        # self.timer = QtCore.QTimer()
        # self.timer.timeout.connect(self.update)

        self.num = 0                                            # +++  
        self.timer.start(1000)                                  # +++

        ##QMessageBox.question(self, 'alert', "test message  " + str
        ##    (self.textboxValue), QMessageBox.Ok, QMessageBox.Ok)      
         #trigger every minute    
        # while self.textboxValue < Currency:
        #         time.sleep(3)
        #         Currency=Currency-0.10
        #         break
        # QMessageBox.question(self, 'alert', "it is under the " + str(self.textboxValue), QMessageBox.Ok, QMessageBox.Ok)    
    def show_textboxValue(self):
        global Currency
        self.num +=  1
        self.lcd.display(str(self.num))
        if self.textboxValue < Currency:
            #Currency = round(Currency - 0.10, 4)
            QMessageBox.information(self, "QMessageBox.information",
                "textboxValue`{}` < Currency`{}`".format(str(self.textboxValue), str(Currency)))
        elif self.textboxValue > Currency:
            self.label4.setText(str(Currency))
            QMessageBox.warning(self, "QMessageBox.warning!",
                "textboxValue`{}` < Currency`{}`".format(str(self.textboxValue), str(Currency)))
        else:
            pass    
        self.textboxValue = Currency #float(self.label4.text())            

        if not self.num % 30:
            self.Searching_Currency()


    def btn3_clicked(self):
        self.label3.clear()

    def btn4_clicked(self):
        sys.exit(0)

    def Searching_Currency(self):
        base_url = "https://www.finanzen100.de/waehrungen/euro-britisches-pfund-eur-gbp-_H1677059499_11341217/?ac=1"
        header   = {'User-Agent': 'Mozilla/5.0'}
        r        = requests.get(base_url,headers=header).text
        soup     = BeautifulSoup(r,'html.parser')

        MyCurrency = soup.select(".quote__price__price")[0]
        MyCurrency = MyCurrency.get_text()
        MyCurrency = MyCurrency.replace(',','.')
        global Currency
        Currency = float(MyCurrency)

    def showTime(self):
        time = Qt.QTime.currentTime()
        text = time.toString("hh:mm:ss")           
        if ((time.second() % 2) == 0):
            text = text[0:2] + ' ' + text[3:5] + ' ' + text[6:]
        self.lcdTime.display(text)



if __name__ == "__main__":
    app = QApplication(sys.argv)
    mywindow = MyWindow()
    mywindow.show()
    app.exec_()