Dialogs in PyQt4
last modified October 18, 2023
Dialog windows or dialogs are an indispensable part of most modern GUI applications. A dialog is defined as a conversation between two or more persons. In a computer application a dialog is a window which is used to "talk" to the application. A dialog is used to input data, modify data, change the application settings etc.
QtGui.QInputDialog
The QtGui.QInputDialog
provides a simple convenience dialog to
get a single value from the user.
The input value can be a string, a number or an item from a list.
#!/usr/bin/python """ ZetCode PyQt4 tutorial In this example, we receive data from a QtGui.QInputDialog dialog. author: Jan Bodnar website: zetcode.com """ import sys from PyQt4 import QtGui class Example(QtGui.QWidget): def __init__(self): super(Example, self).__init__() self.initUI() def initUI(self): self.btn = QtGui.QPushButton('Dialog', self) self.btn.move(20, 20) self.btn.clicked.connect(self.showDialog) self.le = QtGui.QLineEdit(self) self.le.move(130, 22) self.setGeometry(300, 300, 290, 150) self.setWindowTitle('Input dialog') self.show() def showDialog(self): text, ok = QtGui.QInputDialog.getText(self, 'Input Dialog', 'Enter your name:') if ok: self.le.setText(str(text)) def main(): app = QtGui.QApplication(sys.argv) ex = Example() sys.exit(app.exec_()) if __name__ == '__main__': main()
The example has a button and a line edit widget. The button shows the input dialog for getting text values. The entered text will be displayed in the line edit widget.
text, ok = QtGui.QInputDialog.getText(self, 'Input Dialog', 'Enter your name:')
This line displays the input dialog. The first string is a dialog title, the second one is a message within the dialog. The dialog returns the entered text and a boolean value. If we click the Ok button, the boolean value is true.
if ok: self.le.setText(str(text))
The text that we have received from the dialog is set to the line edit widget.
QtGui.QColorDialog
The QtGui.QColorDialog
provides a dialog widget for selecting
colour values.
#!/usr/bin/python """ ZetCode PyQt4 tutorial In this example, we select a colour value from the QtGui.QColorDialog and change the background colour of a QtGui.QFrame widget. author: Jan Bodnar website: zetcode.com """ import sys from PyQt4 import QtGui class Example(QtGui.QWidget): def __init__(self): super(Example, self).__init__() self.initUI() def initUI(self): col = QtGui.QColor(0, 0, 0) self.btn = QtGui.QPushButton('Dialog', self) self.btn.move(20, 20) self.btn.clicked.connect(self.showDialog) self.frm = QtGui.QFrame(self) self.frm.setStyleSheet("QWidget { background-color: %s }" % col.name()) self.frm.setGeometry(130, 22, 100, 100) self.setGeometry(300, 300, 250, 180) self.setWindowTitle('Color dialog') self.show() def showDialog(self): col = QtGui.QColorDialog.getColor() if col.isValid(): self.frm.setStyleSheet("QWidget { background-color: %s }" % col.name()) def main(): app = QtGui.QApplication(sys.argv) ex = Example() sys.exit(app.exec_()) if __name__ == '__main__': main()
The application example shows a push button and a QtGui.QFrame
.
The widget background is set to black colour.
Using the QtGui.QColorDialog
, we can change its background.
col = QtGui.QColor(0, 0, 0)
This is an initial colour of the QtGui.QFrame
background.
col = QtGui.QColorDialog.getColor()
This line will pop up the QtGui.QColorDialog
.
if col.isValid(): self.frm.setStyleSheet("QWidget { background-color: %s }" % col.name())
We check if the colour is valid. If we click on the Cancel button, no valid colour is returned. If the colour is valid, we change the background colour using style sheets.
QtGui.QFontDialog
The QtGui.QFontDialog
is a dialog widget for selecting a font.
#!/usr/bin/python """ ZetCode PyQt4 tutorial In this example, we select a font name and change the font of a label. author: Jan Bodnar website: zetcode.com """ import sys from PyQt4 import QtGui class Example(QtGui.QWidget): def __init__(self): super(Example, self).__init__() self.initUI() def initUI(self): vbox = QtGui.QVBoxLayout() btn = QtGui.QPushButton('Dialog', self) btn.setSizePolicy(QtGui.QSizePolicy.Fixed, QtGui.QSizePolicy.Fixed) btn.move(20, 20) vbox.addWidget(btn) btn.clicked.connect(self.showDialog) self.lbl = QtGui.QLabel('Knowledge only matters', self) self.lbl.move(130, 20) vbox.addWidget(self.lbl) self.setLayout(vbox) self.setGeometry(300, 300, 250, 180) self.setWindowTitle('Font dialog') self.show() def showDialog(self): font, ok = QtGui.QFontDialog.getFont() if ok: self.lbl.setFont(font) def main(): app = QtGui.QApplication(sys.argv) ex = Example() sys.exit(app.exec_()) if __name__ == '__main__': main()
In our example, we have a button and a label. With QtGui.QFontDialog
,
we change the font of the label.
font, ok = QtGui.QFontDialog.getFont()
Here we pop up the font dialog. The getFont
method returns the
font name and the ok parameter. It is equal to True if the user clicked OK; otherwise
it is False.
if ok: self.label.setFont(font)
If we clicked ok, the font of the label would be changed.
QtGui.QFileDialog
The QtGui.QFileDialog
is a dialog that allows users to
select files or directories. The files can be selected for both
opening and saving.
#!/usr/bin/python """ ZetCode PyQt4 tutorial In this example, we select a file with a QtGui.QFileDialog and display its contents in a QtGui.QTextEdit. author: Jan Bodnar website: zetcode.com """ import sys from PyQt4 import QtGui class Example(QtGui.QMainWindow): def __init__(self): super(Example, self).__init__() self.initUI() def initUI(self): self.textEdit = QtGui.QTextEdit() self.setCentralWidget(self.textEdit) self.statusBar() openFile = QtGui.QAction(QtGui.QIcon('open.png'), 'Open', self) openFile.setShortcut('Ctrl+O') openFile.setStatusTip('Open new File') openFile.triggered.connect(self.showDialog) menubar = self.menuBar() fileMenu = menubar.addMenu('&File') fileMenu.addAction(openFile) self.setGeometry(300, 300, 350, 300) self.setWindowTitle('File dialog') self.show() def showDialog(self): fname = QtGui.QFileDialog.getOpenFileName(self, 'Open file', '/home') f = open(fname, 'r') with f: data = f.read() self.textEdit.setText(data) def main(): app = QtGui.QApplication(sys.argv) ex = Example() sys.exit(app.exec_()) if __name__ == '__main__': main()
The example shows a menubar, centrally set text edit widget and a statusbar.
The menu item shows the QtGui.QFileDialog
which is used to select a file. The contents of the file are loaded
into the text edit widget.
class Example(QtGui.QMainWindow): def __init__(self): super(Example, self).__init__()
The example is based on the QtGui.QMainWindow
widget
because we centrally set the text edit widget.
fname = QtGui.QFileDialog.getOpenFileName(self, 'Open file', '/home')
We pop up the QtGui.QFileDialog
. The first string in the
getOpenFileName
method is the caption. The second string
specifies the dialog working directory.
By default, the file filter is set to All files (*).
f = open(fname, 'r') with f: data = f.read() self.textEdit.setText(data)
The selected file name is read and the contents of the file are set to the text edit widget.
In this part of the PyQt4 tutorial, we worked with dialogs.