canvas在path路径上绘制文字

1.代码及解释如下:

public class Main3Activity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        LinearLayout layout = new LinearLayout(this);
        setContentView(layout);
        MyPathView view = new MyPathView(this);
        view.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));
        layout.addView(view);
    }

    class MyPathView extends View {
        final String DRAW_STR = "你好啊！";
        Path[] paths = new Path[3];
        Paint paint;

        public MyPathView(Context context) {
            super(context);
            paths[0] = new Path();
            paths[0].moveTo(0, 0);
            for (int i = 1; i <= 20; i++) {
                paths[0].lineTo(i * 30, (float) (Math.random() * 30)); //随机20个点连成路径
            }
            paths[1] = new Path();
            RectF rectF = new RectF(0, 0, 600, 300);
            paths[1].addOval(rectF, Path.Direction.CCW); //在矩形范围中加一个椭圆路径
            paths[2] = new Path();
            paths[2].addArc(rectF, 60, 180); //画弧线,从60度角开始画了滑过180度
            //初始化画笔
            paint = new Paint();
            paint.setAntiAlias(true);
            paint.setColor(Color.RED);
            paint.setStrokeWidth(2);
        }

        @Override
        protected void onDraw(Canvas canvas) {
            canvas.drawColor(Color.WHITE);
            canvas.translate(40 ,40);
            paint.setTextAlign(Paint.Align.RIGHT); //设置文本在路径中是左对齐还是右对齐还是居中
            paint.setTextSize(20);

            paint.setStyle(Paint.Style.STROKE); //绘制线条还是用stroke
            canvas.drawPath(paths[0] , paint); //绘制第一个路径
            paint.setTextSize(60);
            paint.setStyle(Paint.Style.FILL); //绘制文本还是用fill
            //第3，4参数分别为文本在路径上的位置的偏移量
            //原本文本在路径的上方，然后y轴偏移了30，这样路径就穿过了文字，文字不在路径上方了。
            canvas.drawTextOnPath(DRAW_STR , paths[0] , 0 , 30 , paint); //在第一个路径上绘制文本

            canvas.translate(0,60);
            paint.setStyle(Paint.Style.STROKE);
            canvas.drawPath(paths[1] , paint); //绘制第二个路径
            paint.setStyle(Paint.Style.FILL);
            canvas.drawTextOnPath(DRAW_STR , paths[1] , 0 , 30 , paint);//在第2个路径上绘制文本

            canvas.translate(0 , 360);
            paint.setStyle(Paint.Style.STROKE);
            canvas.drawPath(paths[2] , paint); //绘制第3个路径
            paint.setStyle(Paint.Style.FILL);
            canvas.drawTextOnPath(DRAW_STR , paths[2] , 0 , 30 , paint);//在第3个路径上绘制文本

        }

    }

}

2.效果如下：