画图程序，能化三角函数，直线，圆，矩形，改变画笔和背景颜色-Drawing process of trigonometric functions can be linear, circular, rectangular, and the background to change the brush color

这是JAVA写的画图板，建立输入输出流、按钮数组，存放以下名称的功能按钮、创建基本操作按钮，定义铅笔画，也就是用鼠标拖动着随意绘图、绘制以指定颜色填充的实心矩形、实心椭圆、指定颜色填充的实心圆角矩形、橡皮擦-This is written in JAVA drawing board, the input and output streams, button array storage following the name of the function button to create a ba