PyQt5编程入门

1  25行的弹出式闹钟

import sys
import time

from PyQt5 import QtCore
from PyQt5.QtWidgets import QLabel
from PyQt5.QtWidgets import QApplication

#先创建一个app实例
app = QApplication(sys.argv)

# handle the argv
try:
    due = QtCore.QTime.currentTime()
    message = 'Alert!'
    if len(sys.argv) < 2:
        raise ValueError
    hours, mins = sys.argv[1].split(':')
    due = QtCore.QTime(int(hours), int(mins))
    if not due.isValid():
        raise ValueError
    if len(sys.argv) > 2:
        message = ' '.join(sys.argv[2:])
        
except ValueError:
    message = 'Usage: alarm_clock.py HH:MM [optional message]'

while QtCore.QTime.currentTime() < due:
    print(QtCore.QTime.currentTime())
    time.sleep(1)

#设定标签内容，然后show这个标签
#调用一个单次触发器，6w毫秒（1min）后，触发app.quit。
label = QLabel('<font color=red size=72><b>' + message + '</b></font>')
label.show()
QtCore.QTimer.singleShot(60000, app.quit)

#执行app实例
app.exec_()

　　

 2 30行的表达式求值程序

import sys
from math import *
from PyQt5 import QtCore
from PyQt5.QtWidgets import QApplication,QDialog,QLineEdit,QTextBrowser,QVBoxLayout

#Form这个class是一个界面
class Form(QDialog):
    #使用几种方法来做用户响应
    def __init__(self,parent=None):
        super(Form, self).__init__(parent)
        self.browser = QTextBrowser()
        self.lineedit = QLineEdit('input the expression and press Enter')
        self.lineedit.selectAll()

        #设定布局
        layout = QVBoxLayout()
        layout.addWidget(self.browser)
        layout.addWidget(self.lineedit)
        self.setLayout(layout)
        self.lineedit.setFocus()
        
        #设定触发机制
        self.lineedit.returnPressed.connect(self.updateUi)
        
        #设定title
        self.setWindowTitle('Calculate')

    #具体的数学方法
    def updateUi(self):
        try:
            text = self.lineedit.text()
            result = eval(text)
            self.browser.append('%s = %s' %(text,result))
        except:
            self.browser.append('<font color=red>%s is invalid!</font>' %text)

app = QApplication(sys.argv)
form = Form()
form.show()
app.exec_()

　　

3 70行货币转换程序

import sys
from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *

class Form(QDialog):
    def __init__(self,parent=None):
        super(Form, self).__init__(parent)
        self.rates = {'CNY': 1, 'HK': 0.86, 'USD': 6.79}

        # 创建多选框，并添加多选数据
        self.fromComboBox = QComboBox()
        self.fromComboBox.addItems(self.rates)

        #创建浮点型数据微调框，并设定精度范围和初始值
        self.fromSpinBox = QDoubleSpinBox()
        self.fromSpinBox.setRange(0.01,100000.00)
        self.fromSpinBox.setValue(1.00)

        #第二个多选框，用于计算对应货币
        self.toComboBox = QComboBox()
        self.toComboBox.addItems(self.rates)

        #创建一个标签，并给定显示内容
        self.toLable = QLabel('1.00')

        #将多个界面构成一个布局
        grid = QGridLayout()
        grid.addWidget(self.fromComboBox, 1, 0)
        grid.addWidget(self.fromSpinBox,1,1)
        grid.addWidget(self.toComboBox,2,0)
        grid.addWidget(self.toLable,2,1)
        self.setLayout(grid)

        #只要任意一个变化，就触发函数，用于实时计算结果
        #多选框是index变化，浮点数字框是value变化
        self.fromComboBox.currentIndexChanged.connect(self.updateUi)
        self.toComboBox.currentIndexChanged.connect(self.updateUi)
        self.fromSpinBox.valueChanged.connect(self.updateUi)

        #设置标题
        self.setWindowTitle('Currency')

    def updateUi(self):
         #QComboBox有index和text，对应字典中的k-v。当索引变化，就触发text的计算，然后写入toLable(取两位小数点)。
         to = self.toComboBox.currentText()
         from_ = self.fromComboBox.currentText()
         amount = self.rates[from_] / self.rates[to] * self.fromSpinBox.value()
         self.toLable.setText('%.2f' %amount)

app = QApplication(sys.argv)
form = Form()
form.show()
app.exec_()