For example, when the cursor is 30 pixels from the upper edge, the text scrolls down at one line per second. At 15 pixels, the text scrolls at two lines per second, and so on.

• 例如，当光标距离上边界有30个像素的距离时，滚屏速度为每秒一行；当距离为15个像素时，滚屏速度就变成了每秒两行，依此类推。