最简单的部件，以最大化和最小化屏幕亮度：只有一个按钮
The simplest widget to maximize and minimize screen brightness: only one button that
- if brightness is currently at maximum, minimizes it,
- if brightness is not at maximum, maximizes it.
No more, no less.
No settings, no choices, only one small button on your home screen to have the control always ready at hand.
It is a widget, so you install it on the home screen following the usual procedure for Android widget.