**Topic: Custom Widgets and Components - Creating a Circular Slider** In this example, we will create a custom circular slider widget using PySide6. This widget will allow users to select a value from a circular range, making it suitable for applications such as color pickers, volume controls, or angle selectors. **circular_slider.py** ```python import sys from PySide6.QtCore import Qt, QPropertyAnimation, QPoint, QRect from PySide6.QtGui import QPainter, QPen, QBrush, QColor from PySide6.QtWidgets import QWidget, QApplication class CircularSlider(QWidget): def __init__(self): super().__init__() self._angle = 0 self._minimum = 0 self._maximum = 360 self._color = QColor("blue") self._dragging = False self._last_point = QPoint() self._animation = QPropertyAnimation(self, b'angle') self._animation.setDuration(200) self._animation.setStartValue(0) @property def angle(self): return self._angle @angle.setter def angle(self, value): self._angle = value self._animation.setEndValue(value) self.update() @property def minimum(self): return self._minimum @minimum.setter def minimum(self, value): self._minimum = value self.update() @property def maximum(self): return self._maximum @maximum.setter def maximum(self, value): self._maximum = value self.update() @property def color(self): return self._color @color.setter def color(self, value): self._color = value self.update() def paintEvent(self, event): painter = QPainter(self) painter.setRenderHint(painter.Antialiasing) brush = QBrush(self._color) pen = QPen(brush, 5) painter.setPen(pen) radius = min(self.width(), self.height()) // 2 - 10 center = QPoint(self.width() // 2, self.height() // 2) start_angle = self._minimum end_angle = self._angle painter.drawPie(QRect(center.x() - radius, center.y() - radius, radius * 2, radius * 2), start_angle * 16, (end_angle - start_angle) * 16) def mousePressEvent(self, event): self._dragging = True self._last_point = event.pos() def mouseMoveEvent(self, event): if self._dragging: center = QPoint(self.width() // 2, self.height() // 2) angle = self._calculate_angle(event.pos(), center) self.angle = angle def mouseReleaseEvent(self, event): self._dragging = False def _calculate_angle(self, point, center): dx = point.x() - center.x() dy = point.y() - center.y() angle = (dy / (dx ** 2 + dy ** 2) ** 0.5) * 180 / 3.14 + 90 if dx >= 0 else (dy / (dx ** 2 + dy ** 2) ** 0.5) * 180 / 3.14 + 270 return angle if __name__ == "__main__": app = QApplication(sys.argv) slider = CircularSlider() slider.resize(200, 200) slider.angle = 120 slider.color = "red" slider.show() sys.exit(app.exec()) ``` This code creates a `CircularSlider` class that inherits from `QWidget`. It overrides the `paintEvent` method to draw the circular slider and uses the `mousePressEvent`, `mouseMoveEvent`, and `mouseReleaseEvent` methods to handle user interactions. You can use the `angle` property to set the current value of the slider, and the `minimum` and `maximum` properties to set the range of the slider. The `color` property can be used to set the color of the slider. To use this widget, simply create an instance of the `CircularSlider` class and show it. You can also use it as a custom widget in your own applications. **Example Use Case:** ```python import sys from PySide6.QtWidgets import QApplication, QVBoxLayout, QWidget from circular_slider import CircularSlider class MainWindow(QWidget): def __init__(self): super().__init__() layout = QVBoxLayout() self.setLayout(layout) self.slider = CircularSlider() self.slider.setRange(0, 360) self.slider.valueChanged.connect(self.update_label) layout.addWidget(self.slider) def update_label(self): print(f"Slider value: {self.slider.angle}") if __name__ == "__main__": app = QApplication(sys.argv) window = MainWindow() window.resize(400, 400) window.show() sys.exit(app.exec()) ``` This example creates a `MainWindow` class that uses the `CircularSlider` widget to display a circular slider. The `update_label` method is called whenever the slider value changes, and it prints the current value of the slider.