1. 移动时图元位置和鼠标位置有偏差移动的核心代码mousePressEvent(event) QPointF m_dragItemStartPos event-scenePos(); QPointF m_itemStartPos item-pos(); mouseMoveEvent(event) QPointF delat event-pos() - m_dragItemStartPos; item-setPos(m_itemStartPos delat);2. 自由绘制前两笔异常贝塞尔首段退化问题