您的首个 QtWidgets 应用程序 ¶

As with any other programming framework, you start with the traditional “Hello World” program.

Here is a simple example of a Hello World application in PySide2:

import sys
from PySide2.QtWidgets import QApplication, QLabel
app = QApplication(sys.argv)
label = QLabel("Hello World!")
label.show()
app.exec_()
								

For a widget application using PySide2, you must always start by importing the appropriate class from the PySide2.QtWidgets 模块。

After the imports, you create a QApplication instance. As Qt can receive arguments from command line, you may pass any argument to the QApplication object. Usually, you don’t need to pass any arguments so you can leave it as is, or use the following approach:

app = QApplication([])
								

After the creation of the application object, we have created a QLabel object. A QLabel is a widget that can present text (simple or rich, like html), and images:

# This HTML approach will be valid too!
label = QLabel("<font color=red size=40>Hello World!</font>")
								

最后，调用 app.exec_() to enter the Qt main loop and start to execute the Qt code. In reality, it is only here where the label is shown, but this can be ignored for now.