Layout management in PySide
last modified October 18, 2023
Important thing in GUI programming is the layout management. Layout management is the way how we place the widgets on the window. The management can be done in two ways. We can use absolute positioning or layout classes.
Absolute positioning
The programmer specifies the position and the size of each widget in pixels. When you use absolute positioning, you have to understand several things.
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the size and the position of a widget do not change if we resize a window
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applications might look different on various platforms
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changing fonts in our application might spoil the layout
if we decide to change our layout, we must completely redo our layout, which is tedious and time consuming
#!/usr/bin/python
""" ZetCode PySide tutorial
This example shows three labels on a window using absolute positioning.
author: Jan Bodnar website: zetcode.com """
import sys from PySide import QtGui
class Example(QtGui.QWidget):
def __init__(self):
super(Example, self).__init__()
self.initUI()
def initUI(self):
label1 = QtGui.QLabel('Zetcode', self)
label1.move(15, 10)
label2 = QtGui.QLabel('tutorials', self)
label2.move(35, 40)
label3 = QtGui.QLabel('for programmers', self)
label3.move(55, 70)
self.setGeometry(300, 300, 250, 150)
self.setWindowTitle('Absolute')
self.show()
def main():
app = QtGui.QApplication(sys.argv)
ex = Example()
sys.exit(app.exec_())
if name == ‘main’: main()
We simply call the move method to position our widgets. In our case these widgets are labels. We position them by providing the x and the y coordinates. The beginning of the coordinate system is at the left top corner. The x values grow from left to right. The y values grow from top to bottom.
Figure: Absolute positioning
Box Layout
Layout management with layout classes is much more flexible and practical. It is the preferred way to place widgets on a window. The basic layout classes are QtGui.QHBoxLayout and QtGui.QVBoxLayout. They line up widgets horizontally and vertically.
Imagine that we wanted to place two buttons in the right bottom corner. To create such a layout, we use one horizontal and one vertical box. To create the necessary space, we add a stretch factor.
#!/usr/bin/python
""" ZetCode PySide tutorial
In this example, we position two push buttons in the bottom-right corner of the window.
author: Jan Bodnar website: zetcode.com """
import sys from PySide import QtGui
class Example(QtGui.QWidget):
def __init__(self):
super(Example, self).__init__()
self.initUI()
def initUI(self):
okButton = QtGui.QPushButton("OK")
cancelButton = QtGui.QPushButton("Cancel")
hbox = QtGui.QHBoxLayout()
hbox.addStretch(1)
hbox.addWidget(okButton)
hbox.addWidget(cancelButton)
vbox = QtGui.QVBoxLayout()
vbox.addStretch(1)
vbox.addLayout(hbox)
self.setLayout(vbox)
self.setGeometry(300, 300, 300, 150)
self.setWindowTitle('Buttons')
self.show()
def main():
app = QtGui.QApplication(sys.argv)
ex = Example()
sys.exit(app.exec_())
if name == ‘main’: main()
The example places two buttons in the bottom-right corner of the window. They stay there when we resize the application window. We use both QtGui.HBoxLayout and QtGui.QVBoxLayout.
okButton = QtGui.QPushButton(“OK”) cancelButton = QtGui.QPushButton(“Cancel”)
Here we create two push buttons.
hbox = QtGui.QHBoxLayout() hbox.addStretch(1) hbox.addWidget(okButton) hbox.addWidget(cancelButton)
We create a horizontal box layout. Add a stretch factor and both buttons. The stretch adds a stretchable space before the two buttons. This will push them to the right of the window.
vbox = QtGui.QVBoxLayout() vbox.addStretch(1) vbox.addLayout(hbox)
To create the necessary layout, we put a horizontal layout into a vertical one. The stretch factor in the vertical box will push the horizontal box with the buttons to the bottom of the window.
self.setLayout(vbox)
Finally, we set the base layout of the window. It is the vertical box.
Figure: Buttons example
Grid layout
The most universal layout class in PySide is the grid layout. This layout divides the space into rows and columns. To create a grid layout, we use the QtGui.QGridLayout class.
#!/usr/bin/python
""" ZetCode PySide tutorial
In this example, we create a skeleton of a calculator using a QGridLayout.
author: Jan Bodnar website: zetcode.com """
import sys from PySide import QtGui
class Example(QtGui.QWidget):
def __init__(self):
super(Example, self).__init__()
self.initUI()
def initUI(self):
names = ['Cls', 'Bck', '', 'Close', '7', '8', '9', '/',
'4', '5', '6', '*', '1', '2', '3', '-',
'0', '.', '=', '+']
grid = QtGui.QGridLayout()
j = 0
pos = [(0, 0), (0, 1), (0, 2), (0, 3),
(1, 0), (1, 1), (1, 2), (1, 3),
(2, 0), (2, 1), (2, 2), (2, 3),
(3, 0), (3, 1), (3, 2), (3, 3 ),
(4, 0), (4, 1), (4, 2), (4, 3)]
for i in names:
button = QtGui.QPushButton(i)
if j == 2:
grid.addWidget(QtGui.QLabel(''), 0, 2)
else: grid.addWidget(button, pos[j][0], pos[j][1])
j = j + 1
self.setLayout(grid)
self.move(300, 150)
self.setWindowTitle('Calculator')
self.show()
def main():
app = QtGui.QApplication(sys.argv)
ex = Example()
sys.exit(app.exec_())
if name == ‘main’: main()
In our example, we create a grid of buttons. To fill one gap, we also add one QtGui.QLabel widget.
grid = QtGui.QGridLayout()
Here we create a grid layout.
if j == 2: grid.addWidget(QtGui.QLabel(’’), 0, 2) else: grid.addWidget(button, pos[j][0], pos[j][1])
To add a widget to a grid, we call the addWidget method. The arguments are the widget, the row and the column number.
Figure: Calculator skeleton
Review example
Widgets can span multiple columns or rows in a grid. In the next example we illustrate this.
#!/usr/bin/python
""" ZetCode PySide tutorial
In this example, we create a bit more complicated window layout using the QGridLayout manager.
author: Jan Bodnar website: zetcode.com """
import sys from PySide import QtGui
class Example(QtGui.QWidget):
def __init__(self):
super(Example, self).__init__()
self.initUI()
def initUI(self):
title = QtGui.QLabel('Title')
author = QtGui.QLabel('Author')
review = QtGui.QLabel('Review')
titleEdit = QtGui.QLineEdit()
authorEdit = QtGui.QLineEdit()
reviewEdit = QtGui.QTextEdit()
grid = QtGui.QGridLayout()
grid.setSpacing(10)
grid.addWidget(title, 1, 0)
grid.addWidget(titleEdit, 1, 1)
grid.addWidget(author, 2, 0)
grid.addWidget(authorEdit, 2, 1)
grid.addWidget(review, 3, 0)
grid.addWidget(reviewEdit, 3, 1, 5, 1)
self.setLayout(grid)
self.setGeometry(300, 300, 350, 300)
self.setWindowTitle('Review')
self.show()
def main():
app = QtGui.QApplication(sys.argv)
ex = Example()
sys.exit(app.exec_())
if name == ‘main’: main()
We create a window in which we have three labels, two line edits and one text edit widget. The layout is done with the QtGui.QGridLayout.
grid = QtGui.QGridLayout() grid.setSpacing(10)
We create a grid layout and set spacing between widgets.
grid.addWidget(reviewEdit, 3, 1, 5, 1)
If we add a widget to a grid, we can provide row span and column span of the widget. In our case, we make the reviewEdit widget span 5 rows.
Figure: Review example
This part of the PySide tutorial was dedicated to layout management.
