1、前言
今天项目要用到一个类似微信发送么么哒，那种屏幕飘表情的功能，所以分析研究了一下，用到的技术应该是路径动画，不知道这样就正不正确，反正就是画一个路径线，然后对象根据这个路径去运动。所以就叫他路径动画了。
路径动画要首先要解决的问题就是怎么画这个路径？然后路径画出来后怎么取路径上的所有点的坐标值？
这里解决这两个问题就看一个类PathMeasure 这个类接收一个path对象，然后可以根据pathMeasure.getPosTan（）可以得到长度比例的坐标值。这两个问题就直接搞定了。用path画一个路径然后取点，动态移动对象，就变成了路径动画了。是不是很简单。
2、看效果
3、核心代码
/** * 撒花 * * @author yd * 用到的知识点： 1、android属性动画 2、Path路径绘制 3、贝塞尔曲线 * * * * * * * * */public class FllowerAnimation extends View implements AnimatorUpdateListener { /** * 动画改变的属性值 */ private float phase1 = 0f; private float phase2 = 0f; private float phase3 = 0f; /** * 小球集合 */ private List<Fllower> fllowers1 = new ArrayList<Fllower>(); private List<Fllower> fllowers2 = new ArrayList<Fllower>(); private List<Fllower> fllowers3 = new ArrayList<Fllower>(); /** * 动画播放的时间 */ private int time = 4000; /** * 动画间隔 */ private int delay = 500; /** * 资源ID */// private int resId = R.drawable.fllower_love; public FllowerAnimation(Context context) { super(context); init(context);// this.resId = resId; } @SuppressWarnings("deprecation") private void init(Context context) { WindowManager wm = (WindowManager) context .getSystemService(Context.WINDOW_SERVICE); width = wm.getDefaultDisplay().getWidth(); height = (int) (wm.getDefaultDisplay().getHeight() * 3 / 2f); mPaint = new Paint(); mPaint.setAntiAlias(true); mPaint.setStrokeWidth(2); mPaint.setColor(Color.BLUE); mPaint.setStyle(Style.STROKE); pathMeasure = new PathMeasure(); builderFollower(fllowerCount, fllowers1); builderFollower(fllowerCount , fllowers2); builderFollower(fllowerCount , fllowers3); } /** * 宽度 */ private int width = 0; /** * 高度 */ private int height = 0; /** * 曲线高度个数分割 */ private int quadCount = 10; /** * 曲度 */ private float intensity = 0.2f; /** * 第一批个数 */ private int fllowerCount = 4; /** * 创建花 */ private void builderFollower(int count, List<Fllower> fllowers) { int max = (int) (width * 3 / 4f); int min = (int) (width / 4f); Random random = new Random(); for (int i = 0; i < count; i++) { int s = random.nextInt(max) % (max - min + 1) + min; Path path = new Path(); CPoint CPoint = new CPoint(s, 0); List<CPoint> points = builderPath(CPoint); drawFllowerPath(path, points); Fllower fllower = new Fllower(); fllower.setPath(path); fllowers.add(fllower); } } /** * 画曲线 * @param path * @param points */ private void drawFllowerPath(Path path, List<CPoint> points) { if (points.size() > 1) { for (int j = 0; j < points.size(); j++) { CPoint point = points.get(j); if (j == 0) { CPoint next = points.get(j + 1); point.dx = ((next.x - point.x) * intensity); point.dy = ((next.y - point.y) * intensity); } else if (j == points.size() - 1) { CPoint prev = points.get(j - 1); point.dx = ((point.x - prev.x) * intensity); point.dy = ((point.y - prev.y) * intensity); } else { CPoint next = points.get(j + 1); CPoint prev = points.get(j - 1); point.dx = ((next.x - prev.x) * intensity); point.dy = ((next.y - prev.y) * intensity); } // create the cubic-spline path if (j == 0) { path.moveTo(point.x, point.y); } else { CPoint prev = points.get(j - 1); path.cubicTo(prev.x + prev.dx, (prev.y + prev.dy), point.x - point.dx, (point.y - point.dy), point.x, point.y); } } } } /** * 曲线摇摆的幅度 */ private int range = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 70, getResources().getDisplayMetrics()); /** * 画路径 * * @param point * @return */ private List<CPoint> builderPath(CPoint point) { List<CPoint> points = new ArrayList<CPoint>(); Random random = new Random(); for (int i = 0; i < quadCount; i++) { if (i == 0) { points.add(point); } else { CPoint tmp = new CPoint(0, 0); if (random.nextInt(100) % 2 == 0) { tmp.x = point.x + random.nextInt(range); } else { tmp.x = point.x - random.nextInt(range); } tmp.y = (int) (height / (float) quadCount * i); points.add(tmp); } } return points; } /** * 画笔 */ private Paint mPaint; /** * 测量路径的坐标位置 */ private PathMeasure pathMeasure = null; @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); drawFllower(canvas, fllowers1); drawFllower(canvas, fllowers2); drawFllower(canvas, fllowers3); } /** * 高度往上偏移量,把开始点移出屏幕顶部 */ private float dy = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,40, getResources().getDisplayMetrics()); /** * * @param canvas * @param fllowers */ private void drawFllower(Canvas canvas, List<Fllower> fllowers) { for (Fllower fllower : fllowers) { float[] pos = new float[2]; canvas.drawPath(fllower.getPath(),mPaint); pathMeasure.setPath(fllower.getPath(), false); pathMeasure.getPosTan(height * fllower.getValue(), pos, null); canvas.drawCircle(pos[0], pos[1], 10, mPaint);// Bitmap bitmap = BitmapFactory.decodeResource(getResources(), resId);// canvas.drawBitmap(bitmap, pos[0], pos[1] - dy, null);// bitmap.recycle(); } } public void startAnimation() { ObjectAnimator mAnimator1 = ObjectAnimator.ofFloat(this, "phase1", 0f, 1f); mAnimator1.setDuration(time); mAnimator1.addUpdateListener(this); mAnimator1.start(); mAnimator1.setInterpolator(new AccelerateInterpolator(1f)); ObjectAnimator mAnimator2 = ObjectAnimator.ofFloat(this, "phase2", 0f, 1f); mAnimator2.setDuration(time); mAnimator2.addUpdateListener(this); mAnimator2.start(); mAnimator2.setInterpolator(new AccelerateInterpolator(1f)); mAnimator2.setStartDelay(delay); ObjectAnimator mAnimator3 = ObjectAnimator.ofFloat(this, "phase3", 0f, 1f); mAnimator3.setDuration(time); mAnimator3.addUpdateListener(this); mAnimator3.start(); mAnimator3.setInterpolator(new AccelerateInterpolator(1f)); mAnimator3.setStartDelay(delay * 2); } /** * 跟新小球的位置 * * @param value * @param fllowers */ private void updateValue(float value, List<Fllower> fllowers) { for (Fllower fllower : fllowers) { fllower.setValue(value); } } /** * 动画改变回调 */ @Override public void onAnimationUpdate(ValueAnimator arg0) { updateValue(getPhase1(), fllowers1); updateValue(getPhase2(), fllowers2); updateValue(getPhase3(), fllowers3); Log.i(tag, getPhase1() + ""); invalidate(); } public float getPhase1() { return phase1; } public void setPhase1(float phase1) { this.phase1 = phase1; } public float getPhase2() { return phase2; } public void setPhase2(float phase2) { this.phase2 = phase2; } public float getPhase3() { return phase3; } public void setPhase3(float phase3) { this.phase3 = phase3; } private String tag = this.getClass().getSimpleName(); private class CPoint { public float x = 0f; public float y = 0f; /** x-axis distance */ public float dx = 0f; /** y-axis distance */ public float dy = 0f; public CPoint(float x, float y) { this.x = x; this.y = y; } }}4、项目地址
http://download.csdn.net/detail/hxc2008q/8473053