**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.

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())

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())