QGraphicsSceneMouseEvent::button() buttons() 有什么区别

button():Returns the mouse button (if any) that caused the event

导致该事件的，mousebutton.

Returns the combination of mouse buttons that were pressed at the time the event was sent.

事件发生时，正在按下着的 键，

例
如果此时按下/抬起的是鼠标左键,

函数		返回值
mousePressEvent()/mouseReleaseEvent()	button()	Qt::LeftButton
mousePressEvent()/mouseReleaseEvent()	button()	buttons()
mouseMoveEvent()	button()	Qt::NoButton
mouseMoveEvent()	buttons()	Qt::LeftButton