这就是所谓的一个的输入法编辑器

有大量的应用程序，如swiftkey和Swype输入这是它以这种方式工作的自定义键盘。
基本上，Android的让用户选择谁经理将他们的投入（包括键盘和触摸）。

There are plenty of apps such as swiftkey and swype which are custom keyboards which work this way. Basically, Android let's the user choose who will manager their input (both keyboard and touch).