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Creating a Simple PySide2 Dialog Application
*********************************************
This tutorial shows how to build a simple dialog with some
basic widgets. The idea is to let users provide their name
in a `QLineEdit`, and the dialog greets them on click of a
`QPushButton`.
Let us just start with a simple stub that creates and shows
a dialog. This stub is updated during the course of this
tutorial, but you can use this stub as is if you need to:
::
import sys
from PySide2.QtWidgets import QApplication, QDialog, QLineEdit, QPushButton
class Form(QDialog):
def __init__(self, parent=None):
super(Form, self).__init__(parent)
self.setWindowTitle("My Form")
if __name__ == '__main__':
# Create the Qt Application
app = QApplication(sys.argv)
# Create and show the form
form = Form()
form.show()
# Run the main Qt loop
sys.exit(app.exec_())
The imports aren't new to you, the same for the creation of the
`QApplication` and the execution of the Qt main loop.
The only novelty here is the **class definition**.
You can create any class that subclasses PySide2 widgets.
In this case, we are subclassing `QDialog` to define a custom
dialog, which we name as **Form**. We have also implemented the
`init()` method that calls the `QDialog`'s init method with the
parent widget, if any. Also, the new `setWindowTitle()` method
just sets the title of the dialog window. In `main()`, you can see
that we are creating a *Form object* and showing it to the world.
Create the Widgets
===================
We are going to create two widgets: a `QLineEdit` where users can
enter their name, and a `QPushButton` that prints the contents of
the `QLineEdit`.
So, let's add the following code to the `init()` method of our Form:
::
# Create widgets
self.edit = QLineEdit("Write my name here..")
self.button = QPushButton("Show Greetings")
It's obvious from the code that both widgets will show the corresponding
texts.
Create a layout to organize the Widgets
========================================
Qt comes with layout-support that helps you organize the widgets
in your application. In this case, let's use `QVBoxLayout` to lay out
the widgets vertically. Add the following code to the `init()` method,
after creating the widgets:
::
# Create layout and add widgets
layout = QVBoxLayout()
layout.addWidget(self.edit)
layout.addWidget(self.button)
# Set dialog layout
self.setLayout(layout)
So, we create the layout, add the widgets with `addWidget()`,
and finally we say that our **Form** will have our `QVBoxLayout`
as its layout.
Create the function to greet and connect the Button
====================================================
Finally, we just have to add a function to our custom **Form**
and *connect* our button to it. Our function will be a part of
the Form, so you have to add it after the `init()` function:
::
# Greets the user
def greetings(self):
print ("Hello {}".format(self.edit.text()))
Our function just prints the contents of the `QLineEdit` to the
python console. We have access to the text by means of the
`QLineEdit.text()` method.
Now that we have everything, we just need to *connect* the
`QPushButton` to the `Form.greetings()` method. To do so, add the
following line to the `init()` method:
::
# Add button signal to greetings slot
self.button.clicked.connect(self.greetings)
Once executed, you can enter your name in the `QLineEdit` and watch
the console for greetings.
Complete code
=============
Here is the complete code for this tutorial:
::
import sys
from PySide2.QtWidgets import (QLineEdit, QPushButton, QApplication,
QVBoxLayout, QDialog)
class Form(QDialog):
def __init__(self, parent=None):
super(Form, self).__init__(parent)
# Create widgets
self.edit = QLineEdit("Write my name here")
self.button = QPushButton("Show Greetings")
# Create layout and add widgets
layout = QVBoxLayout()
layout.addWidget(self.edit)
layout.addWidget(self.button)
# Set dialog layout
self.setLayout(layout)
# Add button signal to greetings slot
self.button.clicked.connect(self.greetings)
# Greets the user
def greetings(self):
print ("Hello %s" % self.edit.text())
if __name__ == '__main__':
# Create the Qt Application
app = QApplication(sys.argv)
# Create and show the form
form = Form()
form.show()
# Run the main Qt loop
sys.exit(app.exec_())
|
