ZetCode

PyQt5 widgets II

last modified July 16, 2020

In this chapter we continue introducing PyQt5 widgets. We will cover QPixmap, QLineEdit, QSplitter, and QComboBox.

PyQt5 QPixmap

A QPixmap is one of the widgets used to work with images. It is optimized for showing images on screen. In our code example, we will use the QPixmap to display an image on the window.

pixmap.py
#!/usr/bin/python

"""
ZetCode PyQt5 tutorial

In this example, we display an image
on the window.

Author: Jan Bodnar
Website: zetcode.com
"""

from PyQt5.QtWidgets import (QWidget, QHBoxLayout,
                             QLabel, QApplication)
from PyQt5.QtGui import QPixmap
import sys


class Example(QWidget):

    def __init__(self):
        super().__init__()

        self.initUI()

    def initUI(self):
        hbox = QHBoxLayout(self)
        pixmap = QPixmap('sid.jpg')

        lbl = QLabel(self)
        lbl.setPixmap(pixmap)

        hbox.addWidget(lbl)
        self.setLayout(hbox)

        self.move(300, 200)
        self.setWindowTitle('Sid')
        self.show()


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


if __name__ == '__main__':
    main()

In our example, we display an image on the window.

pixmap = QPixmap('sid.jpg')

We create a QPixmap object. It takes the name of the file as a parameter.

lbl = QLabel(self)
lbl.setPixmap(pixmap)

We put the pixmap into the QLabel widget.

PyQt5 QLineEdit

QLineEdit is a widget that allows to enter and edit a single line of plain text. There are undo and redo, cut and paste, and drag & drop functions available for the widget.

line_edit.py
#!/usr/bin/python

"""
ZetCode PyQt5 tutorial

This example shows text which
is entered in a QLineEdit
in a QLabel widget.

Author: Jan Bodnar
Website: zetcode.com
"""

import sys
from PyQt5.QtWidgets import (QWidget, QLabel,
                             QLineEdit, QApplication)


class Example(QWidget):

    def __init__(self):
        super().__init__()

        self.initUI()

    def initUI(self):
        self.lbl = QLabel(self)
        qle = QLineEdit(self)

        qle.move(60, 100)
        self.lbl.move(60, 40)

        qle.textChanged[str].connect(self.onChanged)

        self.setGeometry(300, 300, 350, 250)
        self.setWindowTitle('QLineEdit')
        self.show()

    def onChanged(self, text):
        self.lbl.setText(text)
        self.lbl.adjustSize()


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


if __name__ == '__main__':
    main()

This example shows a line edit widget and a label. The text that we key in the line edit is displayed immediately in the label widget.

qle = QLineEdit(self)

The QLineEdit widget is created.

qle.textChanged[str].connect(self.onChanged)

If the text in the line edit widget changes, we call the onChanged method.

def onChanged(self, text):
    
    self.lbl.setText(text)
    self.lbl.adjustSize() 

Inside the onChanged method, we set the typed text to the label widget. We call the adjustSize method to adjust the size of the label to the length of the text.

QLineEdit
Figure: QLineEdit

PyQt5 QSplitter

QSplitter lets the user control the size of child widgets by dragging the boundary between its children. In our example, we show three QFrame widgets organized with two splitters.

splitter.py
#!/usr/bin/python

"""
ZetCode PyQt5 tutorial

This example shows
how to use QSplitter widget.

Author: Jan Bodnar
Website: zetcode.com
"""

import sys

from PyQt5.QtCore import Qt
from PyQt5.QtWidgets import (QWidget, QHBoxLayout, QFrame,
                             QSplitter, QApplication)


class Example(QWidget):

    def __init__(self):
        super().__init__()

        self.initUI()

    def initUI(self):

        hbox = QHBoxLayout(self)

        topleft = QFrame(self)
        topleft.setFrameShape(QFrame.StyledPanel)

        topright = QFrame(self)
        topright.setFrameShape(QFrame.StyledPanel)

        bottom = QFrame(self)
        bottom.setFrameShape(QFrame.StyledPanel)

        splitter1 = QSplitter(Qt.Horizontal)
        splitter1.addWidget(topleft)
        splitter1.addWidget(topright)

        splitter2 = QSplitter(Qt.Vertical)
        splitter2.addWidget(splitter1)
        splitter2.addWidget(bottom)

        hbox.addWidget(splitter2)
        self.setLayout(hbox)

        self.setGeometry(300, 300, 450, 400)
        self.setWindowTitle('QSplitter')
        self.show()


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


if __name__ == '__main__':
    main()

In our example, we have three frame widgets and two splitters. Note that under some themes, the splitters may not be visible very well.

topleft = QFrame(self)
topleft.setFrameShape(QFrame.StyledPanel)

We use a styled frame in order to see the boundaries between the QFrame widgets.

splitter1 = QSplitter(Qt.Horizontal)
splitter1.addWidget(topleft)
splitter1.addWidget(topright)

We create a QSplitter widget and add two frames into it.

splitter2 = QSplitter(Qt.Vertical)
splitter2.addWidget(splitter1)

We can also add a splitter to another splitter widget.

QSplitter widget
Figure: QSplitter widget

PyQt5 QComboBox

QComboBox is a widget that allows a user to choose from a list of options.

combobox.py
#!/usr/bin/python

"""
ZetCode PyQt5 tutorial

This example shows how to use
a QComboBox widget.

Author: Jan Bodnar
Website: zetcode.com
"""

import sys

from PyQt5.QtWidgets import (QWidget, QLabel,
                             QComboBox, QApplication)


class Example(QWidget):

    def __init__(self):
        super().__init__()

        self.initUI()

    def initUI(self):

        self.lbl = QLabel('Ubuntu', self)

        combo = QComboBox(self)
        combo.addItem('Ubuntu')
        combo.addItem('Mandriva')
        combo.addItem('Fedora')
        combo.addItem('Arch')
        combo.addItem('Gentoo')

        combo.move(50, 50)
        self.lbl.move(50, 150)

        combo.activated[str].connect(self.onActivated)

        self.setGeometry(300, 300, 450, 400)
        self.setWindowTitle('QComboBox')
        self.show()

    def onActivated(self, text):
        self.lbl.setText(text)
        self.lbl.adjustSize()


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


if __name__ == '__main__':
    main()

The example shows a QComboBox and a QLabel. The combo box has a list of five options. These are the names of Linux distros. The label widget displays the selected option from the combo box.

combo = QComboBox(self)
combo.addItem('Ubuntu')
combo.addItem('Mandriva')
combo.addItem('Fedora')
combo.addItem('Arch')
combo.addItem('Gentoo')

We create a QComboBox widget with five options.

combo.activated[str].connect(self.onActivated) 

Upon an item selection, we call the onActivated() method.

def onActivated(self, text):
  
    self.lbl.setText(text)
    self.lbl.adjustSize() 

Inside the method, we set the text of the chosen item to the label widget. We adjust the size of the label.

QComboBox
Figure: QComboBox

In this part of the PyQt5 tutorial, we have covered QPixmap, QLineEdit, QSplitter, and QComboBox.