pyqt qt4 How to add a tiny arrow/collapse button to QSplitter

Question

You can customize the thickness and background image of the splitter handle

http://qt-project.org/doc/qt-4.8/stylesheet-examples.html#customizing-qsplitter

But is there a way to add a small graphical arrow button so when the user clicks on it, I can call splitter.setSizes([0, 1]) to collapse it.

I could use a vbox layout with a QButton but it takes up too much space and doesn't look as nice.

Answer 1

You could subclass QSplitter and reimplement its createHandle method. This would allow you to return an instance of your own QSplitterHandle class, with, say, a reimplemented paintEvent.

Alternatively, and more simply, you could add buttons directly to an existing splitter handle, by setting your own layout on it.

Here's a basic demo to get you started (probably needs some tweaking to make it prettier):

PyQt5:

from PyQt5 import QtCore, QtWidgets

class Window(QtWidgets.QWidget):
    def __init__(self):
        super().__init__()
        self.splitter = QtWidgets.QSplitter(self)
        self.splitter.addWidget(QtWidgets.QTextEdit(self))
        self.splitter.addWidget(QtWidgets.QTextEdit(self))
        layout = QtWidgets.QVBoxLayout(self)
        layout.addWidget(self.splitter)
        handle = self.splitter.handle(1)
        layout = QtWidgets.QVBoxLayout()
        layout.setContentsMargins(0, 0, 0, 0)
        button = QtWidgets.QToolButton(handle)
        button.setArrowType(QtCore.Qt.LeftArrow)
        button.clicked.connect(
            lambda: self.handleSplitterButton(True))
        layout.addWidget(button)
        button = QtWidgets.QToolButton(handle)
        button.setArrowType(QtCore.Qt.RightArrow)
        button.clicked.connect(
            lambda: self.handleSplitterButton(False))
        layout.addWidget(button)
        handle.setLayout(layout)

    def handleSplitterButton(self, left=True):
        if not all(self.splitter.sizes()):
            self.splitter.setSizes([1, 1])
        elif left:
            self.splitter.setSizes([0, 1])
        else:
            self.splitter.setSizes([1, 0])

if __name__ == '__main__':

    import sys
    app = QtWidgets.QApplication(sys.argv)
    window = Window()
    window.setGeometry(500, 300, 300, 300)
    window.show()
    sys.exit(app.exec_())

PyQt4:

from PyQt4 import QtCore, QtGui

class Window(QtGui.QWidget):
    def __init__(self):
        QtGui.QWidget.__init__(self)
        self.splitter = QtGui.QSplitter(self)
        self.splitter.addWidget(QtGui.QTextEdit(self))
        self.splitter.addWidget(QtGui.QTextEdit(self))
        layout = QtGui.QVBoxLayout(self)
        layout.addWidget(self.splitter)
        handle = self.splitter.handle(1)
        layout = QtGui.QVBoxLayout()
        layout.setContentsMargins(0, 0, 0, 0)
        button = QtGui.QToolButton(handle)
        button.setArrowType(QtCore.Qt.LeftArrow)
        button.clicked.connect(
            lambda: self.handleSplitterButton(True))
        layout.addWidget(button)
        button = QtGui.QToolButton(handle)
        button.setArrowType(QtCore.Qt.RightArrow)
        button.clicked.connect(
            lambda: self.handleSplitterButton(False))
        layout.addWidget(button)
        handle.setLayout(layout)

    def handleSplitterButton(self, left=True):
        if not all(self.splitter.sizes()):
            self.splitter.setSizes([1, 1])
        elif left:
            self.splitter.setSizes([0, 1])
        else:
            self.splitter.setSizes([1, 0])

if __name__ == '__main__':

    import sys
    app = QtGui.QApplication(sys.argv)
    window = Window()
    window.setGeometry(500, 300, 300, 300)
    window.show()
    sys.exit(app.exec_())