本文实例为大家分享了Android实现购物车添加商品动画的具体代码，供大家参考，具体内容如下
实现需求：
在商品列表页面，从列表Item 添加商品的时候，需要一个动画，仿佛是是往购物车里添加商品。
实现思路：
- 获取起始点与终点的坐标，利用PathMeasure 绘制贝塞尔曲线；
- 为点击的Item 商品View 设置属性动画；
- 监听属性动画的update，改变View 的坐标；
实现效果：
实现中会用到 PathMeasure 类：
我们主要使用它两个方法：
1、获取长度：
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/** //获取弧线的总长度（周长） * Return the total length of the current contour, or 0 if no path is * associated with this measure object. */ public float getLength() { return native_getLength(native_instance);//系统调用native 方法； } |
2、获取坐标:
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/** * Pins distance to 0 <= distance <= getLength(), and then computes the * corresponding position and tangent. Returns false if there is no path, * or a zero-length path was specified, in which case position and tangent * are unchanged. * * @param distance The distance along the current contour to sample * @param pos If not null, eturns the sampled position (x==[0], y==[1]) * @param tan If not null, returns the sampled tangent (x==[0], y==[1]) * @return false if there was no path associated with this measure object */ public boolean getPosTan(float distance, float pos[], float tan[]) { if (pos != null && pos.length < 2 || tan != null && tan.length < 2) { throw new ArrayIndexOutOfBoundsException(); } return native_getPosTan(native_instance, distance, pos, tan); } |
方法 getPosTan(float distance, float pos[],float tan[]) － path 为 null ，返回 false
distance 为一个 0 － getLength() 之间的值，根据这个值 PathMeasure 会计算出当前点的坐标封装到 pos 中。上面这句话我们可以这么来理解，不管实际 Path 多么的复杂，PathMeasure 都相当于做了一个事情，就是把 Path “拉直”，然后给了我们一个接口(getLength)告诉我们path的总长度，然后我们想要知道具体某一点的坐标，只需要用相对的distance去取即可，这样就省去了自己用函数模拟path，然后计算获取点坐标的过程。
代码如下：
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public class GoodsListActivity extends AppCompatActivity { private RelativeLayout mRootRl; private RecyclerView mGoodsRecyclerView; private ImageView mCarImageView; private TextView mCountTv; private List<Bitmap> mBitmapList = new ArrayList<>(); private PathMeasure mPathMeasure; private float[] mCurrentPosition = new float[2]; private int mCount = 0; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_goods_list); initView(); initData(); GoodsAdapter goodsAdapter = new GoodsAdapter(mBitmapList); mGoodsRecyclerView.setLayoutManager(new LinearLayoutManager(this)); mGoodsRecyclerView.setAdapter(goodsAdapter); } private void initView(){ mGoodsRecyclerView = (RecyclerView)findViewById(R.id.recyclerView); mCarImageView = (ImageView)findViewById(R.id.imageview_shop_car); mCountTv = (TextView)findViewById(R.id.tv_count); mRootRl = (RelativeLayout)findViewById(R.id.rl_root); } private void initData(){ mBitmapList.add(BitmapFactory.decodeResource(getResources(), R.drawable.car)); mBitmapList.add(BitmapFactory.decodeResource(getResources(), R.drawable.car)); mBitmapList.add(BitmapFactory.decodeResource(getResources(), R.drawable.car)); } class GoodsAdapter extends RecyclerView.Adapter<GoodsViewHolder>{ private List<Bitmap> mData; public GoodsAdapter(List<Bitmap> data) { mData = data; } @Override public GoodsViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { View itemView = LayoutInflater.from(GoodsListActivity.this) .inflate(R.layout.rv_goods_item, parent, false); return new GoodsViewHolder(itemView); } @Override public void onBindViewHolder(final GoodsViewHolder holder, int position) { holder.ivGood.setImageBitmap(mData.get(position)); holder.tvBuy.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { addGoodToCar(holder.ivGood); } }); } @Override public int getItemCount() { return mData != null ? mData.size() : 0; } } private void addGoodToCar(ImageView imageView){ final ImageView view = new ImageView(GoodsListActivity.this); view.setImageDrawable(imageView.getDrawable()); RelativeLayout.LayoutParams layoutParams = new RelativeLayout.LayoutParams(100, 100); mRootRl.addView(view, layoutParams); //二、计算动画开始/结束点的坐标的准备工作 //得到父布局的起始点坐标（用于辅助计算动画开始/结束时的点的坐标） int[] parentLoc = new int[2]; mRootRl.getLocationInWindow(parentLoc); //得到商品图片的坐标（用于计算动画开始的坐标） int startLoc[] = new int[2]; imageView.getLocationInWindow(startLoc); //得到购物车图片的坐标(用于计算动画结束后的坐标) int endLoc[] = new int[2]; mCarImageView.getLocationInWindow(endLoc); float startX = startLoc[0] - parentLoc[0] + imageView.getWidth()/2; float startY = startLoc[1] - parentLoc[1] + imageView.getHeight()/2; //商品掉落后的终点坐标：购物车起始点-父布局起始点+购物车图片的1/5 float toX = endLoc[0] - parentLoc[0] + mCarImageView.getWidth() / 5; float toY = endLoc[1] - parentLoc[1]; //开始绘制贝塞尔曲线 Path path = new Path(); path.moveTo(startX, startY); //使用二次萨贝尔曲线：注意第一个起始坐标越大，贝塞尔曲线的横向距离就会越大，一般按照下面的式子取即可 path.quadTo((startX + toX) / 2, startY, toX, toY); mPathMeasure = new PathMeasure(path, false); //属性动画 ValueAnimator valueAnimator = ValueAnimator.ofFloat(0, mPathMeasure.getLength()); valueAnimator.setDuration(1000); valueAnimator.setInterpolator(new LinearInterpolator()); valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() { @Override public void onAnimationUpdate(ValueAnimator animation) { float value = (float)animation.getAnimatedValue(); mPathMeasure.getPosTan(value, mCurrentPosition, null); view.setTranslationX(mCurrentPosition[0]); view.setTranslationY(mCurrentPosition[1]); } }); valueAnimator.addListener(new Animator.AnimatorListener() { @Override public void onAnimationStart(Animator animation) { } @Override public void onAnimationEnd(Animator animation) { // 购物车的数量加1 mCount++; mCountTv.setText(String.valueOf(mCount)); // 把移动的图片imageview从父布局里移除 mRootRl.removeView(view); //shopImg 开始一个放大动画 Animation scaleAnim = AnimationUtils.loadAnimation(GoodsListActivity.this, R.anim.shop_car_scale); mCarImageView.startAnimation(scaleAnim); } @Override public void onAnimationCancel(Animator animation) { } @Override public void onAnimationRepeat(Animator animation) { } }); valueAnimator.start(); } class GoodsViewHolder extends RecyclerView.ViewHolder{ private ImageView ivGood; private TextView tvBuy; public GoodsViewHolder(View itemView) { super(itemView); ivGood = (ImageView)itemView.findViewById(R.id.iv_goods); tvBuy = (TextView) itemView.findViewById(R.id.tv_buy); } }} |
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持服务器之家。
原文链接：https://blog.csdn.net/happy_horse/article/details/67646202
