有没有办法在pyqt5中显示帮助选项卡？

Question

I am writing code for my collage project in pyqt5 where I need to make one help tab. I am planning to make help content-wise as most the software have as shown in the below image(the help of onlyoffice). Is there any way to write it easily?

Answer 1

The problem with that kind of interface, which shows multiple "tabs" embedded in the title bar, is that it's not easily doable with Qt, and you should implement the whole title bar by hand, which is not easy.

If you're looking for a simpler solution, I'd suggest to use a QTabWidget that doesn't show the tab bar if there's only one tab. If you're not already using a tabbed interface with closable tabs, you can set the tab widget to allow closable tabs and override the default methods in order to hide the close button if not really required.

class TabWidget(QtWidgets.QTabWidget):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.setDocumentMode(True)
        self.setTabsClosable(True)
        self.tabCloseRequested.connect(self.removeTab)
        self.tabBar().hide()

    def addTab(self, *args, **kwargs):
        self.insertTab(-1, *args, **kwargs)

    def insertTab(self, *args, **kwargs):
        super().insertTab(*args)
        closable = kwargs.get('closable', False)
        if not closable:
            index = args[0]
            if index < 0:
                index = self.count() - 1
            for side in QtWidgets.QTabBar.LeftSide, QtWidgets.QTabBar.RightSide:
                widget = self.tabBar().tabButton(index, side)
                if isinstance(widget, QtWidgets.QAbstractButton):
                    self.tabBar().setTabButton(index, side, None)
                    break
        self.tabBar().setVisible(self.count() > 1)

    def removeTab(self, index):
        super().removeTab(index)
        self.tabBar().setVisible(self.count() > 1)


class MainWindow(QtWidgets.QMainWindow):
    def __init__(self):
        super().__init__()
        self.tabWidget = TabWidget()
        self.setCentralWidget(self.tabWidget)

        self.main = QtWidgets.QWidget()
        self.tabWidget.addTab(self.main, 'My program')
        layout = QtWidgets.QGridLayout(self.main)

        someButton = QtWidgets.QPushButton('Some button')
        layout.addWidget(someButton, 0, 0)

        layout.addWidget(QtWidgets.QLabel('Some label'), 0, 1)

        helpButton = QtWidgets.QPushButton('Show help!')
        layout.addWidget(helpButton, 0, 2)

        textEdit = QtWidgets.QTextEdit()
        layout.addWidget(textEdit, 1, 0, 1, 3)

        self.helpTab = QtWidgets.QTextBrowser()
        self.helpTab.setHtml('Hello, this is <b>help</b>!')

        helpButton.clicked.connect(self.showHelp)

    def showHelp(self):
        for i in range(self.tabWidget.count()):
            if self.tabWidget.widget(i) == self.helpTab:
                break
        else:
            self.tabWidget.addTab(self.helpTab, 'Help!', closable=True)
        self.tabWidget.setCurrentWidget(self.helpTab)
        self.tabWidget.tabBar().show()

Now, since you also want some context-based help, you could hack your way through the whatsThis() feature. The "what's this" feature allows to show some context-based help in a small overlayed window when the window is in the "what's this mode" and the user clicks on a widget. We can use an event filter to detect when the user clicks on a widget and use the whatsThis() property as a context for showing the related help.

In the following example I'm using a simple dictionary that fills the QTextBrowser, but you can obviously use access to local documentation files or even the Qt Help framework .

Note that in order to use this approach, I had to install an event filter on all child widgets, and that's because Qt is able to react to "what's this" events if the widget actually has a whatsThis() property set. The trick is to set a whatsThis property for all child widgets when the window enters the what's this mode and install a specialized event filter on each of them, then uninstall the event filter as soon as the what's this mode is left.

NoWhatsThisText = '__NoWhatsThis'
NoWhatsThisValue = 'There is no help for this object'
HelpData = {
    NoWhatsThisText: NoWhatsThisValue, 
    'someButton': 'Do something with the button', 
    'helpButton': 'Click the button to show this help', 
    'textEdit': 'Type <b>some text</b> to <i>read</i> it', 
    'mainWindow': 'A main window is cool!', 
}

class WhatsThisWatcher(QtCore.QObject):
    whatsThis = QtCore.pyqtSignal(str)
    def eventFilter(self, source, event):
        if event.type() == QtCore.QEvent.WhatsThis:
            whatsThis = source.whatsThis()
            while whatsThis == NoWhatsThisText:
                if not source.parent():
                    break
                source = source.parent()
                whatsThis = source.whatsThis()
            self.whatsThis.emit(whatsThis)
            event.accept()
            return True
        return super().eventFilter(source, event)


class MainWindow(QtWidgets.QMainWindow):
    def __init__(self):
        # ...

        whatsThisAction = self.menuBar().addAction('What\'s this?')
        whatsThisAction.triggered.connect(
            QtWidgets.QWhatsThis.enterWhatsThisMode)

        self.watchedWhatsThis = []
        self.whatsThisWatcher = WhatsThisWatcher()
        self.whatsThisWatcher.whatsThis.connect(self.showHelp)
        self.installEventFilter(self.whatsThisWatcher)

        someButton.setWhatsThis('someButton')
        helpButton.setWhatsThis('helpButton')
        textEdit.setWhatsThis('textEdit')
        self.setWhatsThis('mainWindow')

    def showHelp(self, context=''):
        # ...
        if context:
            self.helpTab.setHtml(HelpData.get(context, NoWhatsThisValue))
        if QtWidgets.QWhatsThis.inWhatsThisMode():
            QtWidgets.QWhatsThis.leaveWhatsThisMode()