PYQT5中，在QGraphicsView鼠标左键点击绘制点，并且绘制的点也会在光标箭头的位置，下一个点与上一个点用一条线段连接，鼠标右键可以实现停止绘制线段和撤销绘制两个功能，鼠标滚轮可以实现QGraphicsView的放大与缩小，并且放大缩小后绘制点时位置还是在光标箭头处，请给出相关python代码

以下是实现上述功能的Python代码：

from PyQt5.QtWidgets import *
from PyQt5.QtGui import *
from PyQt5.QtCore import *

class MyView(QGraphicsView):
    def __init__(self):
        super().__init__()
        self.scene = QGraphicsScene(self)
        self.setScene(self.scene)
        self.pen = QPen(Qt.black, 2)
        self.line = None
        self.points = []
        self.is_drawing = False
        self.is_undo = False
        self.setRenderHint(QPainter.Antialiasing)
        self.setDragMode(QGraphicsView.ScrollHandDrag)
        self.setTransformationAnchor(QGraphicsView.AnchorUnderMouse)
        self.setResizeAnchor(QGraphicsView.AnchorUnderMouse)
        self.setInteractive(True)
        self.setMouseTracking(True)
        self.setRenderHint(QPainter.Antialiasing)
        self.setRenderHint(QPainter.SmoothPixmapTransform)

    def mousePressEvent(self, event):
        if event.button() == Qt.LeftButton:
            self.is_drawing = True
            self.points.append(event.pos())
            self.line = QGraphicsLineItem(QLineF(event.pos(), event.pos()))
            self.line.setPen(self.pen)
            self.scene.addItem(self.line)
        elif event.button() == Qt.RightButton:
            if self.is_drawing:
                self.is_undo = True
                self.is_drawing = False
                self.scene.removeItem(self.line)
                self.line = None
                self.points = []
        super().mousePressEvent(event)

    def mouseMoveEvent(self, event):
        if self.is_drawing:
            self.line.setLine(QLineF(self.points[-1], event.pos()))
        super().mouseMoveEvent(event)

    def mouseReleaseEvent(self, event):
        if self.is_drawing:
            self.points.append(event.pos())
            self.is_drawing = False
        super().mouseReleaseEvent(event)

    def wheelEvent(self, event):
        if event.angleDelta().y() > 0:
            self.scale(1.1, 1.1)
        else:
            self.scale(0.9, 0.9)
        super().wheelEvent(event)

    def keyPressEvent(self, event):
        if event.key() == Qt.Key_Z and event.modifiers() == Qt.ControlModifier:
            if self.is_undo:
                self.is_undo = False
                self.is_drawing = True
                self.points.pop()
                self.line = QGraphicsLineItem(QLineF(self.points[-1], self.points[-2]))
                self.line.setPen(self.pen)
                self.scene.addItem(self.line)
        super().keyPressEvent(event)

if __name__ == '__main__':
    app = QApplication([])
    view = MyView()
    view.show()
    app.exec_()

这段代码实现了在QGraphicsView中绘制线段的功能，同时支持鼠标滚轮缩放和撤销绘制。具体实现方式是在鼠标左键按下时记录鼠标位置，创建一个QGraphicsLineItem对象，并将其添加到场景中；在鼠标移动时更新线段的终点位置；在鼠标释放时记录终点位置，并停止绘制。在鼠标右键按下时，如果正在绘制，则撤销绘制；在鼠标滚轮滚动时，根据滚动方向进行缩放；在按下Ctrl+Z时，如果有绘制操作可以撤销，则撤销最后一次绘制。