pyqt5中关于绘画功能的代码

以下是一个简单的PyQt5绘画应用程序的代码示例：

import sys
from PyQt5.QtWidgets import QApplication, QMainWindow, QGraphicsScene, QGraphicsView
from PyQt5.QtGui import QPainter, QPen
from PyQt5.QtCore import Qt

class MyCanvas(QGraphicsView):

    def __init__(self):
        super().__init__()
        self.scene = QGraphicsScene(self)
        self.setScene(self.scene)
        self.pen = QPen(Qt.black, 2, Qt.SolidLine)

    def mousePressEvent(self, event):
        if event.button() == Qt.LeftButton:
            self.last_point = event.pos()

    def mouseMoveEvent(self, event):
        if event.buttons() and Qt.LeftButton:
            painter = QPainter()
            painter.begin(self.scene)
            painter.setPen(self.pen)
            painter.drawLine(self.last_point, event.pos())
            painter.end()
            self.last_point = event.pos()

class MainWindow(QMainWindow):

    def __init__(self):
        super().__init__()
        self.initUI()

    def initUI(self):
        self.canvas = MyCanvas()
        self.setCentralWidget(self.canvas)

        self.setGeometry(100, 100, 640, 480)
        self.setWindowTitle('PyQt5 Canvas')
        self.show()

if __name__ == '__main__':
    app = QApplication(sys.argv)
    mainWindow = MainWindow()
    sys.exit(app.exec_())

这个应用程序创建了一个可以用鼠标绘画的画布。当鼠标左键按下时，记录下鼠标的位置。当鼠标移动时，用QPainter绘制一条线段，连接上一个点和当前点。在MainWindow中将MyCanvas设置为中央窗口，启动应用程序。