PyQt绘制科赫雪花

import sys
from PyQt5.QtWidgets import QApplication, QWidget
from PyQt5.QtGui import QPainter, QBrush, QPen
from PyQt5.QtCore import Qt


class KochCurveWidget(QWidget):
    def __init__(self):
        super().__init__()
        self.setGeometry(0, 0, 1108, 900)
        self.setWindowTitle('Koch Curve')

    def paintEvent(self, event):
        painter = QPainter(self)

        painter.setRenderHint(QPainter.Antialiasing)

        pen = QPen(Qt.black)
        pen.setWidth(2)
        painter.setPen(pen)

        # 抽象步骤，如果是0阶，只需前行；如果是一阶，需要前行，转向，前行，转向，前行，转向，前行，
        # 共有的是前行，阶数需要控制转向的次数，所以边界是0阶，只需前行
        def koch(length, n):
            if n == 0:
                painter.drawLine(0, 0, length, 0)
                painter.translate(length, 0)
            else:
                #
                for angle in [0, -60, 120, -60]:
                    painter.rotate(angle)
                    koch(length / 3, n - 1)

        painter.translate(250, 250)
        for i in range(3):
            koch(600, 2)
            painter.rotate(120)


app = QApplication(sys.argv)
koch_curve_widget = KochCurveWidget()
koch_curve_widget.show()
sys.exit(app.exec_())

三阶科赫雪花