在触摸屏上设置三个按钮，表示三种画板功能：直线、圆和任意手绘线，选择一种功能 后，即可以以这种功能开始用手指在触摸屏上画图。 -Touchscreen in the installation of three button and slate of three functions : straight lines, circles and arbitrary hand-painted lines, choose a function, we can begin to function as