PyQt5点击button如何弹出新窗口？

Question

怎么通过点击button，来打开一个新的窗口？
是写在同一个脚本里，还是把新窗口的代码放在另一个脚本里，然后通过点击按钮来运行？

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

class FirstWindow(QWidget):
    def __init__(self):
        super().__init__()
        self.windowUI()

    def windowUI(self):
        self.setWindowTitle("Login")
        self.textfield()
        self.center()

    def center(self):
        qr = self.frameGeometry()
        cp = QDesktopWidget().availableGeometry().center()
        qr.moveCenter(cp)
        self.move(qr.topLeft())

    def textfield(self):
        QToolTip.setFont(QFont('SansSerif', 12))
        user = QLabel("User:")
        userEdit = QLineEdit()
        userEdit.setToolTip("请输入你的帐号")

        passWord = QLabel("PassWord:")
        passWordEdit = QLineEdit()
        passWordEdit.setToolTip("请输入你的密码")

        grid = QGridLayout()
        grid.setSpacing(0)

        grid.addWidget(user, 0, 0)
        grid.addWidget(userEdit, 1, 0)
        grid.addWidget(passWord, 2, 0)
        grid.addWidget(passWordEdit, 3, 0)
        empty = QLabel()
        grid.addWidget(empty, 4, 0)

        btn_logon = QPushButton("Log on")
        btn_quit = QPushButton("Quit")
        grid.addWidget(btn_logon, 5, 0, 1, 2)
        grid.addWidget(btn_quit, 6, 0, 1, 2)

        btn_logon.clicked.connect(self.onclick)
        btn_quit.clicked.connect(quit)

        self.setLayout(grid)

    def onclick(self):
        newWindow = SecondWindow()
        newWindow.show()
        newWindow.exec_()

class SecondWindow(QWidget):
    def __init__(self):
        super().__init__
        self.newWindowUI

    def newWindowUI(self):
        self.resize(300,300)
        self.move(200,200)

if __name__ == "__main__":
    App = QApplication(sys.argv)
    ex = FirstWindow()
    ex.show()
    sys.exit(App.exec_())

Answer 1

代码量不大的话，放一个文件就行了，要是代码比较多的话，考虑到维护的方便，还是放在2个里面比较好，这种事件的触发和界面切换一般都是用signal-slot做的，使得语义看起来非常清晰

# -*- coding: utf-8 -*-

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


class FirstWindow(QWidget):

    close_signal = pyqtSignal()
    def __init__(self, parent=None):
        # super这个用法是调用父类的构造函数
        # parent=None表示默认没有父Widget，如果指定父亲Widget，则调用之
        super(FirstWindow, self).__init__(parent)
        self.resize(100, 100)
        self.btn = QToolButton(self)
        self.btn.setText("click")

    def closeEvent(self, event):
        self.close_signal.emit()
        self.close()


class SecondWindow(QWidget):
    def __init__(self, parent=None):
        super(SecondWindow, self).__init__(parent)
        self.resize(200, 200)
        self.setStyleSheet("background: black")

    def handle_click(self):
        if not self.isVisible():
            self.show()

    def handle_close(self):
        self.close()


if __name__ == "__main__":
    App = QApplication(sys.argv)
    ex = FirstWindow()
    s = SecondWindow()
    ex.btn.clicked.connect(s.handle_click)
    ex.btn.clicked.connect(ex.hide)
    ex.close_signal.connect(ex.close)
    ex.show()
    sys.exit(App.exec_())

Answer 2

-- coding: utf-8 --

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

class FirstWindow(QWidget):

close_signal = pyqtSignal()
def __init__(self, parent=None):
    # super这个用法是调用父类的构造函数,parent=None表示默认没有父Widget,如果有则调用之
    super(FirstWindow, self).__init__(parent)
    self.resize(800, 600)
    self.setMaximumSize(QSize(800, 600))
    self.btn = QToolButton(self)
    self.btn.setText("click")
    self.two = SecondWindow()
    self.btn.clicked.connect(self.two.handle_click)
    #self.btn.clicked.connect(self.hide)
    self.close_signal.connect(self.closeSlot)
    print("FirstWindow")

def closeEvent(self, event):
    print("close signal emit by FirstWindow")
    self.close_signal.emit()
    #self.close()

def closeSlot(self):
    print("close signal slot to SecondWindow")
    self.two.close()

class SecondWindow(QWidget):

close_signal = pyqtSignal()
def __init__(self, parent=None):
    super(SecondWindow, self).__init__(parent)
    self.resize(800, 600)
    self.setMaximumSize(QSize(800, 600))
    self.setStyleSheet("background: black")
    self.close_signal.connect(self.closeSlot)
    
def handle_click(self):
    if not self.isVisible():
        self.show()
        print("SecondWindow")

def closeEvent(self, event):
    print("close signal emit by SecondWindow")
    self.close_signal.emit()
    #self.close()

def closeSlot(self):
    print("close signal slot to FirstWindow")
    one.close()

if name == "__main__":

App = QApplication(sys.argv)
one = FirstWindow()
one.show()
sys.exit(App.exec_())