QStackedWidget打开多个窗口

Question

我使用PyQt构建了一个小型应用程序，据我所知，QStackedWidget用于制作多页应用程序。问题是它正在打开多个页面，而且我也无法使用class Abc中的按钮重定向到class Abc。

main.py

from PyQt4 import QtGui, QtCore
import sys

class Window(QtGui.QMainWindow):
    def __init__(self, parent=None):
        super(Window, self).__init__(parent)

        self.stacked_widget = QtGui.QStackedWidget()

        layout = QtGui.QVBoxLayout()
        layout.setContentsMargins(0,0,0,0)
        layout.addWidget(self.stacked_widget)

        widget = QtGui.QWidget()
        widget.setLayout(layout)
        self.setCentralWidget(widget)

        widget_1 = Abc(self.stacked_widget)
        widget_2 = Xyz(self.stacked_widget)

        self.stacked_widget.addWidget(widget_1)
        self.stacked_widget.addWidget(widget_2)

        self.showMaximized()

class Abc(QtGui.QWidget):
    def __init__(self, stacked_widget, parent=None):
        super(Abc, self).__init__(parent)
        
        self.stacked_widget = stacked_widget

        self.frame = QtGui.QFrame()
        self.frame_layout = QtGui.QVBoxLayout()
        self.button = QtGui.QPushButton('Click me!')
        self.button.clicked.connect(self.click)
        self.frame_layout.addWidget(self.button)
        self.frame.setLayout(self.frame_layout)

        self.layout = QtGui.QVBoxLayout()
        self.layout.addWidget(self.frame)
        self.setLayout(self.layout)

        self.showMaximized()

    def click(self):
        print("You clicked me!")
        self.stacked_widget.setCurrentIndex(1)

class Xyz(QtGui.QWidget):
    def __init__(self, parent=None):
        super(Xyz, self).__init__(parent)

        self.frame_layout = QtGui.QStackedLayout()
        self.page1 = Page("Page 1", self.frame_layout)
        self.page2 = Page("Page 2", self.frame_layout)
        self.frame_layout.addWidget(self.page1)
        self.frame_layout.addWidget(self.page2)


class Page(QtGui.QWidget):
    def __init__(self, text, frame_layout, parent=None):
        super(Page, self).__init__(parent)

        print(self.width(), self.height())
        self.frame_layout = frame_layout

        self.frame = QtGui.QFrame()
        self.frame_layout = QtGui.QVBoxLayout()
        self.frame.setStyleSheet("background-color: rgb(191, 191, 191)")
        self.label = QtGui.QLabel()
        self.label.setText(text)
        self.frame_layout.addWidget(self.label, alignment=QtCore.Qt.AlignCenter)
        self.frame.setLayout(self.frame_layout)

        self.layout = QtGui.QVBoxLayout()
        self.layout.addWidget(self.frame)
        self.layout.setContentsMargins(0,0,0,0)
        self.setLayout(self.layout)

        self.showMaximized()
        print(self.width(), self.height())


if __name__ == "__main__":
    app = QtGui.QApplication([])
    window = Window()
    window.show()
    sys.exit(app.exec_())

Answer 1

主要问题是，您没有为QStackedLayout小部件设置Xyz，结果是所有页面实际上都将显示为顶级窗口。

当一个小部件被添加到一个布局中时，它获得了它的所有权；如果布局已经设置为一个小部件，那么添加到布局中的小部件就会被另一个小部件修复。如果之后设置布局，也会发生同样的情况。

为什么它将第一页显示为一个单独的窗口？为什么它不显示第二个呢？

当创建一个没有父级的新小部件时，它就变成了一个顶层窗口；当一个小部件被添加到一个新的堆叠布局中时，Qt会自动尝试显示它；您没有将布局设置为任何东西(这将像前面解释的那样重新创建它)，结果就是第一个页面显示为一个独立窗口。

现在，由于第一次只显示第一个“屏幕”，您可以将该小部件设置为中心小部件，然后将Xyz实例(实际上是一个QStackedWidget子类)设置为一个新的中心小部件。

注意，您不需要使用QWidget来添加一个QFrame，如果这是显示的唯一父小部件:您可以只是子类QFrame。

这是一个更简单、更简洁的代码版本：

from PyQt4 import QtGui, QtCore

class Window(QtGui.QMainWindow):
    def __init__(self, parent=None):
        super(Window, self).__init__(parent)

        self.startPage = Abc()
        self.setCentralWidget(self.startPage)

        self.startPage.startRequest.connect(self.buildPages)

    def buildPages(self):
        self.pages = Xyz()
        self.setCentralWidget(self.pages)


class Abc(QtGui.QFrame):
    startRequest = QtCore.pyqtSignal()
    def __init__(self, parent=None):
        super(Abc, self).__init__(parent)
        
        layout = QtGui.QVBoxLayout(self)

        self.button = QtGui.QPushButton('Click me!')
        self.button.clicked.connect(self.startRequest)
        layout.addWidget(self.button)


class Xyz(QtGui.QStackedWidget):
    def __init__(self, parent=None):
        super(Xyz, self).__init__(parent)

        self.page1 = Page("Page 1")
        self.page2 = Page("Page 2")
        self.addWidget(self.page1)
        self.addWidget(self.page2)

        self.page1.switchRequest.connect(lambda: self.setCurrentIndex(1))
        self.page2.switchRequest.connect(lambda: self.setCurrentIndex(0))


class Page(QtGui.QFrame):
    switchRequest = QtCore.pyqtSignal()
    def __init__(self, text, parent=None):
        super(Page, self).__init__(parent)

        layout = QtGui.QVBoxLayout(self)
        # set the background only for QFrame subclasses (which also includes 
        # QLabel), this prevents setting the background for other classes, 
        # such as the push button
        self.setStyleSheet('''
            QFrame {
                background-color: rgb(191, 191, 191)
            }
        ''')
        # when adding a widget to a layout, the layout tries to automatically 
        # make it as big as possible (based on the widget's sizeHint); so you
        # should not use the alignment argument for layout.addWidget(), but for 
        # the label instead
        self.label = QtGui.QLabel(text, alignment=QtCore.Qt.AlignCenter)
        layout.addWidget(self.label)

        self.switchButton = QtGui.QPushButton('Switch')
        layout.addWidget(self.switchButton)
        self.switchButton.clicked.connect(self.switchRequest)


if __name__ == "__main__":
    import sys
    app = QtGui.QApplication(sys.argv)
    window = Window()
    window.show()
    sys.exit(app.exec_())