To figure out how much yarn you need to cut for the first layer, just hold it on top of the circle, spread it out like a fan and see if there are any hollow areas.
算好第一层所需的毛线，将其固定在圆上，散开成扇形，并查看是否存在空白区域。
2
This time the circle slides in from the top left to the bottom right, and grows as its does so.
这一次，该圆从左上方滚向右下方，并在滚动的过程中不断变大。
3
Notice the four circle "zoom" icons at the top left of the frame: The last represents the most recently accessed activities.