android自定义View贝赛尔曲线

public class BezierTestView extends View {
    private int screenWidth;
    private Paint mPaint;
    private Path mPath;
    //两个距离的差越小角的高越小
    //最大距离 距离顶端 第一个顶点y
    private int first_y=30;
    //第一个顶点x
    private int first_x=0;
    //角的大小宽
    private int horn_size=20;
    //最小距离距离顶端
    private int minimum_distance=20;

    public int getMinimum_distance() {
        return minimum_distance;
    }

    public void setMinimum_distance(int minimum_distance) {
        this.minimum_distance = minimum_distance;
    }

    public int getScreenWidth() {
        return screenWidth;
    }

    public void setScreenWidth(int screenWidth) {
        this.screenWidth = screenWidth;
    }

    public int getFirst_x() {
        return first_x;
    }

    public int getFirst_y() {
        return first_y;
    }

    public void setFirst_x(int first_x) {
        this.first_x = first_x;
    }

    public void setFirst_y(int first_y) {
        this.first_y = first_y;
    }

    public int getHorn_size() {
        return horn_size;
    }

    public void setHorn_size(int horn_size) {
        this.horn_size = horn_size;
    }

    public BezierTestView(Context context) {
        super(context);
        init();
    }

    public BezierTestView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    public BezierTestView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    private void init() {
        //画笔
        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setColor(0xFF412129);
        mPath = new Path();
        WindowManager wm = (WindowManager) getContext()
                .getSystemService(Context.WINDOW_SERVICE);
        this.screenWidth=wm.getDefaultDisplay().getWidth();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        mPath.reset();
//        mPath.moveTo(0,90);
//        //mPath.lineTo(0,0);
//        mPath.lineTo(100,50);
//        mPath.lineTo(100*2,90);
//        mPath.lineTo(100*3,50);
//        mPath.lineTo(100*4,90);
//        mPath.lineTo(100*5,50);

        mPath.moveTo(first_x,first_y);
        //mPath.lineTo(50,10);
        for (int i=1;i<=screenWidth/horn_size;i++){
            //y前一个大角后一个小
            mPath.lineTo((i*horn_size)+first_x,i%2==0?first_y:minimum_distance);
        }
        canvas.drawPath(mPath, mPaint);
    }
}

<net.sourceforge.simcpux.customviewsawtoothstyle.BezierTestView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@android:color/white"
    android:id="@+id/testview"
/>

BezierTestView testview= (BezierTestView) findViewById(R.id.testview);
//testview.setScreenWidth(500);
//testview.setFirst_x(20);