Semi-resizable widgets in PyQt

Question

I try to create a gui with two main widgets. The window should be resizable. When resized horizontally only one of them widgets should expand. When resized vertically both should expand. Furthermore it should be possible readjust the resize this split horizontally. I illustrated this to make it more clear:

With tkinter this was easily achievable with the properties expand and fill. In Qt I could use the resize event but I hope that I don't have to do this manually, since this should after all be a common task. I tried toying around with QHBoxLayout but without success unfortunately.

Any help is greatly appreciated. Thanks.

Answer 1

You need to use the setStretchFactor method on your QSplitter.

An example (modified from the QSplitter example here):

import sys
from PyQt4 import QtGui, QtCore

class Example(QtGui.QWidget):
    def __init__(self):
        super(Example, self).__init__()
        self.initUI()

    def initUI(self):     
        hbox = QtGui.QHBoxLayout(self)
        left = QtGui.QFrame(self)       
        left.setFrameShape(QtGui.QFrame.StyledPanel)
        right = QtGui.QFrame(self)
        right.setFrameShape(QtGui.QFrame.StyledPanel)
        splitter = QtGui.QSplitter(QtCore.Qt.Horizontal)
        splitter.addWidget(left)
        splitter.addWidget(right)
        splitter.setStretchFactor(1, 1)
        splitter.setSizes([125, 150])
        hbox.addWidget(splitter)
        self.setLayout(hbox)
        QtGui.QApplication.setStyle(QtGui.QStyleFactory.create('Cleanlooks'))
        self.setGeometry(300, 300, 300, 200)
        self.setWindowTitle('QtGui.QSplitter')
        self.show()

def main():
    app = QtGui.QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec_())

if __name__ == '__main__':
    main()  

This produces an initial UI that looks like this:

When the image is expanded horizontally, you can see that the left widget stays the same size:

When expanded vertically, both widgets expand:

Finally, the splitter is resizeable:

If you adjust the window size after adjusting the splitter, the left widget will retain it's size and the right will expand/collapse to fill the remainder of the window.

Answer 2

The Andy's post is not editable, so I add another answer. Updated for PyQt5/PyQt6.

import sys
from PyQt6.QtCore import Qt
from PyQt6.QtWidgets import QWidget, QHBoxLayout, QFrame, QSplitter, QApplication, QStyleFactory

class Example(QWidget):
    def __init__(self):
        super(Example, self).__init__()
        self.initUI()

    def initUI(self):
        hbox = QHBoxLayout(self)
        left = QFrame(self)
        left.setFrameShape(QFrame.Shape.StyledPanel)
        right = QFrame(self)
        right.setFrameShape(QFrame.Shape.StyledPanel)
        splitter = QSplitter(Qt.Orientation.Horizontal)
        splitter.addWidget(left)
        splitter.addWidget(right)
        splitter.setStretchFactor(1, 1)
        splitter.setSizes([125, 150])
        hbox.addWidget(splitter)
        self.setLayout(hbox)
        QApplication.setStyle(QStyleFactory.create('Cleanlooks'))
        self.setGeometry(300, 300, 300, 200)
        self.setWindowTitle('QtGui.QSplitter')
        self.show()

def main():
    app = QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec())

if __name__ == '__main__':
    main()