pyqt QGraphicsView 以鼠标为中心进行缩放功能实现

class CustomGraphicsView(QGraphicsView):
    def __init__(self, parent=None):
        super(CustomGraphicsView, self).__init__(parent)
        self.scene = QGraphicsScene()
        self.setScene(self.scene)
        self.setGeometry(0, 0, 1024, 600)
        # 以下初始化代码较为重要
        self.setMouseTracking(True)
        self.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOff)   # 按需开启
        # self.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOff)   # 按需开启     
        self.setTransformationAnchor(QGraphicsView.AnchorUnderMouse)
        self.setResizeAnchor(QGraphicsView.AnchorUnderMouse)

def wheelEvent(self, event: QWheelEvent) -> None:
        if event.modifiers() == Qt.ControlModifier:
            mouse_pos = event.pos()
            scene_pos = self.mapToScene(mouse_pos) #缩放前鼠标在scene的位置
            s = 1.2 #按需调整
            if(event.angleDelta().y() > 0):
                self.scale(s,s)
            else:
                self.scale(1/s,1/s)
            view_point = self.mapFromScene(scene_pos) #缩放后原scene进行映射新鼠标位置
            self.verticalScrollBar().setValue(int(view_point.y()-mouse_pos.y())) #通过滚动条进行移动视图
            self.horizontalScrollBar().setValue(int(view_point.x()-mouse_pos.x()))
            return 
        else:
            return super().wheelEvent(event) # 保证滚动条能滚动

def mousePressEvent(self, event: QMouseEvent) -> None:
        if event.button() == Qt.LeftButton:
            self.dragStartPos = event.pos() #用于鼠标拖拽视图
        return

def mouseReleaseEvent(self, event: QMouseEvent) -> None:
        pass
        return

def mouseMoveEvent(self, event):
        if event.buttons() and Qt.LeftButton: # 实现鼠标拖拽视图
            newpos = event.pos()
            delta = newpos - self.dragStartPos
            self.dragStartPos = newpos
            self.verticalScrollBar().setValue(self.verticalScrollBar().value() - delta.y())
            self.horizontalScrollBar().setValue(self.horizontalScrollBar().value() - delta.x())
        return