PyQt - QBoxLayout Class

---

---

QBoxLayout class arranges the widgets horizontally or vertically. This class is derived from two different layout classes − QVBoxLayout (for arranging widgets vertically) and QHBoxLayout (for arranging widgets horizontally). On utilization of the QBoxLayout constructor, we have the direction to specify its options such as LeftToRight, RightToLeft, TopToBottom, or BottomToTop.

Sometimes, QBoxLayout doesn't manage all of the children and areas of the widget. So we must add it to the parent layout before we create anything to it. This type of layout is called parentLayout i.e. addLayout().

Margin methods in QBoxLayout

The QBoxLayout also contains two margin width −

• setContentsMargins() − This layout is used for margin to set the width of outer border.
• setSpacing() − It is used to set the property of spacing.

Following table shows the important methods of QBoxLayout class −

Margin and Spacing in QBoxLayout

QBoxLayout offers margin and spacing properties for layout customization. Margins define space outside the layout, while spacing controls the gap between widgets, enhancing visual appeal and readability.

Example

In this example, we demonstrate the margin and spacing using the QBoxLayout methods.

from PyQt6.QtWidgets import QApplication, QWidget, QVBoxLayout, QPushButton

app = QApplication([])
# Create a QWidget
widget = QWidget()
# Create a QVBoxLayout
layout = QVBoxLayout(widget)
# Create a QPushButton
button = QPushButton('Click me!')
# Set contents margins for the layout
layout.setContentsMargins(30, 30, 30, 30)
# Set spacing between widgets
layout.setSpacing(10)
# Add the button to the layout
layout.addWidget(button)
widget.show()
app.exec()

Output

The above code produces the following output −

Vertical Buttons in QBoxLayout

QBoxLayout in PyQt enables easy creation of vertical buttons. By adding QPushButton widgets vertically, it simplifies the layout of vertical button arrangements in GUI applications for enhanced user interaction.

Example

In the following example, we create two buttons that are added to the vertical box layout. A stretchable space is added between them by the addStretch() method. Therefore, if the top-level window is resized, the position of the buttons automatically gets relocated.

import sys
from PyQt6.QtWidgets import QApplication, QWidget, QPushButton, QVBoxLayout
def window():
   app = QApplication(sys.argv)
   win = QWidget()

   b1 = QPushButton("Button1")
   b2 = QPushButton("Button2")
   vbox = QVBoxLayout()
   vbox.addWidget(b1)

   vbox.addStretch()
   vbox.addWidget(b2)
   win.setLayout(vbox)

   win.setWindowTitle("PyQt")
   win.show()
   sys.exit(app.exec())

if __name__ == '__main__':
   window()

Output

On executing the code, we get two buttons in PyQt window −

Horizontal Buttons using QBoxLayout class

The class QBoxLayout makes it easy to stack buttons horizontally, arranging them from left to right for a more user-friendly interface.

Example 1

In this example, we can use the horizontal box layout where the method addStretch() inserts a stretchable or empty space between the two button objects. Hence, the window is resized and position of the button change dynamically.

import sys
from PyQt6.QtWidgets import QApplication, QWidget, QPushButton, QHBoxLayout
def window():
   app = QApplication(sys.argv)
   win = QWidget()

   b1 = QPushButton("Button1")
   b2 = QPushButton("Button2")
   # Button appear in horizonatal direction
   hbox = QHBoxLayout()

   hbox.addWidget(b1)
   hbox.addStretch()
   hbox.addWidget(b2)
   win.setLayout(hbox)
   win.setWindowTitle("PyQt")
   win.show()
   sys.exit(app.exec())

if __name__ == '__main__':
   window()

Output

On executing the code, we get the appearance of two buttons in horizontal direction −

Example 2

The following example shows how the layouts can be nested. Here, two buttons are added to vertical box layout. Then, a horizontal box layout object with two buttons and a stretchable empty space is added to it. Finally, the vertical box layout object is applied to the top level window by the setLayout() method.

import sys
from PyQt6.QtWidgets import QApplication, QWidget, QPushButton, QHBoxLayout, QVBoxLayout
def window():
   app = QApplication(sys.argv)
   win = QWidget()

   b1 = QPushButton("Button1")
   b2 = QPushButton("Button2")

   vbox = QVBoxLayout()
   vbox.addWidget(b1)
   vbox.addStretch()
   vbox.addWidget(b2)
   hbox = QHBoxLayout()

   b3 = QPushButton("Button3")
   b4 = QPushButton("Button4")
   hbox.addWidget(b3)
   hbox.addStretch()
   hbox.addWidget(b4)

   vbox.addStretch()
   vbox.addLayout(hbox)
   win.setLayout(vbox)

   win.setWindowTitle("PyQt")
   win.show()
   sys.exit(app.exec())

if __name__ == '__main__':
   window()

Output

The above code produces the following output −