Each time a mouse drag event occurs, a (possibly quite short) black line is drawn between the saved point and the location of the event.

每次发生鼠标拖动事件时，在保存的点和该事件位置之间就会画出一条黑线(可能很短)。

youdao

Each time a mouse drag event occurs, a (possibly quite short) black line is drawn between the saved point and the location of the event.

每次发生鼠标拖动事件时，在保存的点和该事件位置之间就会画出一条黑线(可能很短)。

youdao