**Course Title:** PySide6 Application Development **Section Title:** Working with Graphics and Animations **Topic:** Implementing animations with QPropertyAnimation and QSequentialAnimationGroup ### Overview of Animations in PySide6 In the previous topics, we explored the basics of graphics in PySide6 using `QGraphicsView` and `QGraphicsScene`. Now, we'll delve into implementing animations using two powerful classes: `QPropertyAnimation` and `QSequentialAnimationGroup`. ### QPropertyAnimation `QPropertyAnimation` is a class that allows you to animate a property of an object over a specified period. This class is extremely versatile and can be used to animate various aspects of your graphics, such as position, scale, rotation, and more. To use `QPropertyAnimation`, you need to create an instance of the class and set the following: * **Target object**: The object whose property you want to animate. * **Property name**: The name of the property you want to animate. * **Start value**: The initial value of the property. * **End value**: The final value of the property. * **Duration**: The time over which the animation should be performed. Here's an example of animating a rectangle's scale using `QPropertyAnimation`: ```python import sys from PySide6.QtWidgets import QApplication, QGraphicsView, QGraphicsScene, QGraphicsRectItem from PySide6.QtCore import Qt, QRectF from PySide6.QtGui import QPainter, QTransform from PySide6.QtGui import QPropertyAnimation class MyRect(QGraphicsRectItem): def __init__(self): super().__init__(0, 0, 100, 100) self.setBrush(Qt.red) def scale(self): return self.boundingRect().width() def setScale(self, scale): self.setRect(0, 0, scale, scale) scaleProperty = QtCore.Property(float, scale, setScale) app = QApplication(sys.argv) scene = QGraphicsScene() view = QGraphicsView(scene) rect = MyRect() scene.addItem(rect) animation = QPropertyAnimation(rect, b"scaleProperty") animation.setDuration(2000) # 2 seconds animation.setStartValue(100) animation.setEndValue(200) animation.start() view.show() sys.exit(app.exec()) ``` In this example, we define a custom `MyRect` class that inherits from `QGraphicsRectItem`. We create a property named `scaleProperty` and override the `boundingRect()` method to return the current scale of the rectangle. We then create an instance of `MyRect` and add it to the scene. We create a `QPropertyAnimation` instance, setting the target object to `rect`, the property name to `scaleProperty`, and the start and end values to 100 and 200, respectively. Finally, we start the animation, which smoothly scales the rectangle over a period of 2 seconds. ### QSequentialAnimationGroup `QSequentialAnimationGroup` is a class that allows you to sequence multiple animations together. This class is useful when you want to create complex animations that involve multiple steps. To use `QSequentialAnimationGroup`, you need to create an instance of the class and add animations to it using the `addAnimation()` method. You can add multiple animations in sequence or parallel. Here's an example of animating a rectangle's movement and scale using `QSequentialAnimationGroup`: ```python import sys from PySide6.QtWidgets import QApplication, QGraphicsView, QGraphicsScene, QGraphicsRectItem from PySide6.QtCore import Qt, QRectF, QPointF from PySide6.QtGui import QPainter, QTransform from PySide6.QtGui import QPropertyAnimation from PySide6.QtCore import QSequentialAnimationGroup class MyRect(QGraphicsRectItem): def __init__(self): super().__init__(0, 0, 100, 100) self.setBrush(Qt.red) def pos(self): return self.boundingRect().topLeft() def setPos(self, pos): self.setPos(pos) posProperty = QtCore.Property(QPointF, pos, setPos) def scale(self): return self.boundingRect().width() def setScale(self, scale): self.setRect(0, 0, scale, scale) scaleProperty = QtCore.Property(float, scale, setScale) app = QApplication(sys.argv) scene = QGraphicsScene() view = QGraphicsView(scene) rect = MyRect() scene.addItem(rect) animation1 = QPropertyAnimation(rect, b"posProperty") animation1.setDuration(2000) # 2 seconds animation1.setStartValue(QPointF(0, 0)) animation1.setEndValue(QPointF(100, 100)) animation2 = QPropertyAnimation(rect, b"scaleProperty") animation2.setDuration(2000) # 2 seconds animation2.setStartValue(100) animation2.setEndValue(200) group = QSequentialAnimationGroup() group.addAnimation(animation1) group.addAnimation(animation2) group.start() view.show() sys.exit(app.exec()) ``` In this example, we define a custom `MyRect` class that inherits from `QGraphicsRectItem`. We create properties for the rectangle's position and scale and override the `boundingRect()` method to return the current position and scale of the rectangle. We then create an instance of `MyRect` and add it to the scene. We create two `QPropertyAnimation` instances: one for animating the rectangle's movement and the other for animating its scale. We create a `QSequentialAnimationGroup` instance and add both animations to it. Finally, we start the animation group, which first animates the rectangle's movement and then its scale. ### Conclusion In this topic, we explored the basics of animations in PySide6 using `QPropertyAnimation` and `QSequentialAnimationGroup`. We learned how to create custom properties and animate them using `QPropertyAnimation`. We also learned how to sequence multiple animations together using `QSequentialAnimationGroup`. ### Key Takeaways * Create custom properties using `QtCore.Property` to animate objects. * Use `QPropertyAnimation` to animate a property of an object over a specified period. * Use `QSequentialAnimationGroup` to sequence multiple animations together. ### What's Next? In the next topic, we'll explore **Basic 2D drawing with QPainter**. Do you have any questions about animations in PySide6? Please leave a comment or ask for help.