如何在PyQt / Python中切换布局？ （高级）

Question

更新1： 在做出以下更正之后：

from PyQt4 import QtGui, QtCore
class LoginWidget(QtGui.QWidget):
    success = QtCore.pyqtSignal() # Might be QtCore.pyqtSignal
    def __init__(self, parent=None):
        super(LoginWidget, self).__init__(parent)
        self.Username = QtGui.QLineEdit(self)  
        self.Password = QtGui.QLineEdit(self)
        self.buttonLogin = QtGui.QPushButton('Login', self)
        self.buttonLogin.clicked.connect(self.handleLogin)
        loginLayout = QtGui.QFormLayout()
        loginLayout.addRow("Username", self.Username) 
        loginLayout.addRow("Password", self.Password)
        layout = QtGui.QVBoxLayout(self)
        layout.addLayout(loginLayout)
        layout.addWidget(self.Username)
        layout.addWidget(self.Password)
        layout.addWidget(self.buttonLogin)
    def handleLogin(self):
        if (self.Username.text() == 'example' and
            self.Password.text() == 'example'):
            self.success.emit()
            # OR you know that the main window is the parent of this class
            # so you could call self.parent().P_3()
            # Signals are better though
        else:
            QtGui.QMessageBox.warning(
                self, 'Error', 'Incorrect Username/Password combination!')

class Page3(QtGui.QWidget):
    def __init__(self, parent=None):
        super(Page3, self).__init__(parent)
        layout = QtGui.QHBoxLayout()
        self.Hello = QtGui.QLabel('Hello')
        layout.addWidget(self.Hello)
        self.setLayout(layout)

class page1(QtGui.QWidget):
    def __init__(self, parent=None):
        super(page1, self).__init__(parent)
        layout = QtGui.QHBoxLayout()
        self.nextpage = QtGui.QPushButton('Page2')
        layout.addWidget(self.nextpage)
        self.setLayout(layout)

class MainWindow(QtGui.QMainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)
        self.central_widget = QtGui.QStackedWidget()
        self.setCentralWidget(self.central_widget)
        Page1 = page1(self)
        Page1.nextpage.clicked.connect(self.P_2)
        self.central_widget.addWidget(Page1)
    def P_2(self):
        page2 = LoginWidget(self)

        # Connect your signal to a method. When success is emitted it will call P_3()
        page2.success.connect(self.P_3) # Note: P_3 does not have "()" with it

        self.central_widget.addWidget(page2)
        self.central_widget.setCurrentWidget(page2)
    def P_3(self):
        print("yay")
        page3 = Page3(self)
        # self.central_widget.addWidget(Page3) # you are calling the class (lowercase)
        # self.central_widget.setCurrentWidget(Page3) # calling the class (lowercase)
        self.central_widget.addWidget(Page3)
        self.central_widget.setCurrentWidget(Page3)

if __name__ == '__main__':
    User = ''
    app = QtGui.QApplication([])
    window = MainWindow()
    window.showFullScreen()
    app.exec_()

我收到此错误：

追踪（最近一次通话）：   P_3中的文件“C：\ Users \ Hamzah \ My Documents \ Work \ A-Level \ USB Stuff \ Pie Chart 2.py”，第66行     self.central_widget.addWidget（第3页） TypeError：QStackedWidget.addWidget（QWidget）：参数1具有意外类型'PyQt4.QtCore.pyqtWrapperType

问题：

下面的代码显示了在第1页，登录页面（第2页）和第3页之间切换布局的示例。但是我似乎无法将布局从第2页切换到第3页。我可以将布局从第1页切换到第2页虽然？！顺便说一句，在运行程序时（如果你运行它），登录详细信息是'example'和'example'或者查看代码以获取详细信息：

from PyQt4 import QtCore, QtGui

class MainWindow(QtGui.QMainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)
        self.central_widget = QtGui.QStackedWidget()
        self.setCentralWidget(self.central_widget)
        Page1 = page1(self)
        Page1.nextpage.clicked.connect(self.P_2)
        self.central_widget.addWidget(Page1)
    def P_2(self):
        page2 = LoginWidget(self)
        self.central_widget.addWidget(page2)
        self.central_widget.setCurrentWidget(page2)
    def P_3(self):
        print("Why won't the page open!!!???")
        page3 = Page3(self)
        self.central_widget.addWidget(Page3)
        self.central_widget.setCurrentWidget(Page3)

class LoginWidget(QtGui.QWidget):
    def __init__(self, parent=None):
        super(LoginWidget, self).__init__(parent)
        self.Username = QtGui.QLineEdit(self)  
        self.Password = QtGui.QLineEdit(self)
        self.buttonLogin = QtGui.QPushButton('Login', self)
        self.buttonLogin.clicked.connect(self.handleLogin)
        loginLayout = QtGui.QFormLayout()
        loginLayout.addRow("Username", self.Username) 
        loginLayout.addRow("Password", self.Password)
        layout = QtGui.QVBoxLayout(self)
        layout.addLayout(loginLayout)
        layout.addWidget(self.Username)
        layout.addWidget(self.Password)
        layout.addWidget(self.buttonLogin)
    def handleLogin(self):
        if (self.Username.text() == 'example' and
            self.Password.text() == 'example'):
            MainWindow().P_3()
        else:
            QtGui.QMessageBox.warning(
                self, 'Error', 'Incorrect Username/Password combination!')

class page1(QtGui.QWidget):
    def __init__(self, parent=None):
        super(page1, self).__init__(parent)
        layout = QtGui.QHBoxLayout()
        self.nextpage = QtGui.QPushButton('Page2')
        layout.addWidget(self.nextpage)
        self.setLayout(layout)

class Page3(QtGui.QWidget):
    def __init__(self, parent=None):
        super(Page3, self).__init__(parent)
        layout = QtGui.QHBoxLayout()
        self.Hello = QtGui.QLabel('Hello')
        layout.addWidget(self.Hello)
        self.setLayout(layout)

if __name__ == '__main__':
    User = ''
    app = QtGui.QApplication([])
    window = MainWindow()
    window.showFullScreen()
    app.exec_()

Answer 1

问题出在您的LoginWidget中。 handleLogin正在创建一个新的MainWinow并尝试调用第3页。

您不想创建新的主窗口，并且您不想要登录所需的主窗口实例。

我建议使用信号

class LoginWidget(QtGui.QWidget):
    success = QtCore.Signal() # Might be QtCore.pyqtSignal

    ...
    def handleLogin(self):
        if (self.Username.text() == 'example' and
            self.Password.text() == 'example'):
            self.success.emit()
            # OR you know that the main window is the parent of this class
            # so you could call self.parent().P_3()
            # Signals are better though
        else:
            QtGui.QMessageBox.warning(
                self, 'Error', 'Incorrect Username/Password combination!')

class MainWindow(QtGui.QMainWindow):
    def P_2(self):
        page2 = LoginWidget(self)

        # Connect your signal to a method. When success is emitted it will call P_3()
        page2.success.connect(self.P_3) # Note: P_3 does not have "()" with it

        self.central_widget.addWidget(page2)
        self.central_widget.setCurrentWidget(page2)

如果需要涉及信号的参数，请使用lambda函数。

page2.success.connect(lambda arg="": method(arg))

另请注意P_3中的错误

def P_3(self):
    page3 = Page3(self)
    # self.central_widget.addWidget(Page3) # you are calling the class (lowercase)
    # self.central_widget.setCurrentWidget(Page3) # calling the class (lowercase)

    self.central_widget.addWidget(page3)
    self.central_widget.setCurrentWidget(page3)