资料来源

如何自定义一个textView

https://www.cnblogs.com/wjtaigwh/p/6593580.html

自定义控件的3种实现

https://www.cnblogs.com/jiayongji/p/5560806.html

系统自带的角标功能

https://blog.csdn.net/wang8651971/article/details/41514519

如何让文字旋转

https://blog.csdn.net/u014649598/article/details/45563723

如何给自定义控件定义自定义属性

https://blog.csdn.net/teashui/article/details/51927072

自定义控件的原理

https://www.jianshu.com/p/a3014f8442b0

自定义属性的实现batain函数

https://blog.csdn.net/zjh_1110120/article/details/50991560

activity和view如何工作的

如何自定义文字旋转

http://www.jb51.net/article/98527.htm

主要方法就是在ondraw()方法的重写中,旋转画布

canvas.rotate(mDegree, this.getWidth() / 2f, this.getHeight()/2f );

如何画一个三角形

https://blog.csdn.net/ligl0702/article/details/8576843

先定义画笔

        Paint paint = new Paint();
        paint.setColor(getResources().getColor(android.R.color.holo_red_light));
        paint.setAntiAlias(true);
        paint.setStyle(Paint.Style.FILL);

然后开始画三角形并填充

        Path path=new Path();
        path.moveTo(0,0);
        path.lineTo(z,0);
        path.lineTo(z,z);
        path.close();
        canvas.drawPath(path,paint);