Android PathMeasure使用

关于Path和PathMeasure的使用   PathMeasure可以测量路径上的点  和长度 ，可做轨迹动画效果。

public class mypathmeasure extends View {

	private Path p;
	private PathMeasure pathMeasure;

	public mypathmeasure(Context context) {
		this(context, null);
		// TODO Auto-generated constructor stub
	}

	public mypathmeasure(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
		mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
		mPaint.setDither(true);
		mPaint.setColor(0xff0000ff);
		mPaint.setStyle(Paint.Style.STROKE);

	}

	private void init() {
		p = new Path();
		mPaint.setStyle(Paint.Style.STROKE);
		p.moveTo(0, getHeight() / 2);
		p.cubicTo(getWidth() / 2 - 60, getHeight() / 2 - 60,
				getWidth() / 2 + 60, getHeight() / 2 + 60, getWidth(),
				getHeight() / 2);
		pathMeasure = new PathMeasure(p, false);

	}

	@Override
	protected void onSizeChanged(int w, int h, int oldw, int oldh) {
		// TODO Auto-generated method stub
		super.onSizeChanged(w, h, oldw, oldh);
		init();
	}

	public mypathmeasure(Context context, AttributeSet attrs) {
		this(context, attrs, 0);

	}

	private Paint mPaint;
	private float[] floats = new float[2];
	private boolean first = true;

	@Override
	protected void onDraw(Canvas canvas) {

		super.onDraw(canvas);

		mPaint.setColor(0xffff0000);
		canvas.drawPath(p, mPaint);
		mPaint.setColor(0xff00ff00);
		canvas.drawCircle(floats[0], floats[1], 10, mPaint);

		if (first) {
			first = false;
			startAnimation();
		}

	}

	void startAnimation() {
		ValueAnimator animation = ValueAnimator.ofFloat(0,
				pathMeasure.getLength());
		animation.setDuration(4000);

		animation.addUpdateListener(new AnimatorUpdateListener() {

			@Override
			public void onAnimationUpdate(ValueAnimator animation) {
				float v = (Float) animation.getAnimatedValue();
				pathMeasure.getPosTan(v, floats, null);
				postInvalidate();
			}
		});

		animation.start();

	}
}