**Course Title:** PySide6 Application Development **Section Title:** Working with Graphics and Animations **Topic:** Basic 2D drawing with QPainter ### Overview In this topic, we will explore the basics of 2D drawing using QPainter in PySide6. QPainter is a powerful and versatile class that allows you to perform a wide range of drawing operations, from simple shapes and lines to complex graphics and text rendering. ### QPainter Basics Before we dive into the code, let's cover some basic concepts about QPainter: * `QPainter` is a class that provides a way to perform 2D painting on a `QWidget` or other paint device. * `QPainter` uses a `QPaintDevice` to render graphics. Examples of `QPaintDevice` include `QWidget`, `QImage`, and `QPrinter`. * `QPainter` has several modes, including drawing shapes, lines, and text. ### Basic 2D Drawing To perform basic 2D drawing with QPainter, you'll need to follow these steps: 1. Create a `QPainter` object and pass a `QPaintDevice` (such as a `QWidget`) to its constructor. 2. Set the pen and brush colors using `setPen()` and `setBrush()`. 3. Use various drawing functions to draw shapes, lines, and text. Here's an example code snippet that demonstrates basic 2D drawing with QPainter: ```python import sys from PySide6.QtCore import Qt from PySide6.QtGui import QPainter, QPen, QBrush, QFont from PySide6.QtWidgets import QWidget, QApplication class DrawingWidget(QWidget): def __init__(self): super().__init__() def paintEvent(self, event): painter = QPainter(self) painter.setPen(QPen(Qt.black, 2)) painter.setBrush(QBrush(Qt.blue)) painter.drawRect(10, 10, 200, 200) painter.drawText(20, 30, "Hello, World!") if __name__ == "__main__": app = QApplication(sys.argv) widget = DrawingWidget() widget.resize(400, 300) widget.show() sys.exit(app.exec()) ``` In this example, we create a `DrawingWidget` class that inherits from `QWidget`. In the `paintEvent()` method, we create a `QPainter` object and set the pen and brush colors. We then use the `drawRect()` function to draw a rectangle and the `drawText()` function to draw text. ### Drawing Shapes QPainter provides several functions for drawing various shapes, including: * `drawRect()`: Draws a rectangle. * `drawEllipse()`: Draws an ellipse. * `drawLine()`: Draws a line. * `drawPolyline()`: Draws a polyline. * `drawPolygon()`: Draws a polygon. Here's an example code snippet that demonstrates drawing various shapes: ```python import sys from PySide6.QtCore import Qt from PySide6.QtGui import QPainter, QPen, QBrush from PySide6.QtWidgets import QWidget, QApplication class ShapeWidget(QWidget): def __init__(self): super().__init__() def paintEvent(self, event): painter = QPainter(self) painter.setPen(QPen(Qt.black, 2)) # Draw a rectangle painter.setBrush(QBrush(Qt.red)) painter.drawRect(10, 10, 100, 100) # Draw an ellipse painter.setBrush(QBrush(Qt.green)) painter.drawEllipse(150, 150, 100, 100) # Draw a line painter.setPen(QPen(Qt.blue, 5)) painter.drawLine(10, 250, 300, 250) # Draw a polyline points = [(10, 300), (50, 350), (300, 300)] painter.setPen(QPen(Qt.black, 2)) painter.drawPolyline(points) # Draw a polygon points = [(10, 400), (50, 350), (300, 300), (200, 400)] painter.setPen(QPen(Qt.black, 2)) painter.drawPolygon(points) if __name__ == "__main__": app = QApplication(sys.argv) widget = ShapeWidget() widget.resize(400, 500) widget.show() sys.exit(app.exec()) ``` In this example, we create a `ShapeWidget` class that inherits from `QWidget`. In the `paintEvent()` method, we create a `QPainter` object and draw various shapes using the corresponding functions. ### Summary In this topic, we covered the basics of 2D drawing with QPainter in PySide6. We explored the `QPainter` class and its various functions for drawing shapes, lines, and text. We also demonstrated how to use these functions in example code snippets. ### Key Takeaways * QPainter is a powerful class for performing 2D drawing operations. * Use `QPainter` with a `QPaintDevice` to render graphics. * Set pen and brush colors using `setPen()` and `setBrush()`. * Use various drawing functions to draw shapes, lines, and text. ### Additional Resources * [Qt Documentation: QPainter](https://doc.qt.io/qtforpython/PySide6/QtGui/QPainter.html) * [Qt Documentation: QPaintDevice](https://doc.qt.io/qtforpython/PySide6/QtGui/QPaintDevice.html) We hope this topic has helped you understand the basics of 2D drawing with QPainter in PySide6. If you have any questions or need further clarification, feel free to leave a comment below. In the next topic, we will cover packaging PySide6 applications for distribution using PyInstaller and fbs.