貝塞爾曲線實現的購物車添加商品動畫效果

效果圖如下： 1.activity_main.xml menu_shop_car_selected.png corner_view.xml 2.adapter_shopping_cart_item.xml 3.MainActivity 4.GoodsAdapter 5.GoodsModel http ...

效果圖如下：

1.activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/rly_bezier_curve_shopping_cart"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin">

    <FrameLayout
        android:id="@+id/fly_bezier_curve_shopping_cart"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:paddingRight="30dp"
        android:layout_alignParentStart="true">
        <ImageView
            android:id="@+id/iv_bezier_curve_shopping_cart"
            android:layout_width="40dp"
            android:layout_height="40dp"
            android:layout_gravity="right"
            android:src="@drawable/menu_shop_car_selected" />
        <TextView
            android:id="@+id/tv_bezier_curve_shopping_cart_count"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textColor="@color/white"
            android:background="@drawable/corner_view"
            android:text="0"
            android:layout_gravity="right"/>
    </FrameLayout>

    <ListView
        android:id="@+id/lv_bezier_curve_shopping_cart"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_above="@+id/fly_bezier_curve_shopping_cart"/>
</RelativeLayout>

menu_shop_car_selected.png

corner_view.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <solid android:color="@color/red" />
    <corners android:radius="10dp" />
    <padding android:left="5dp" android:top="1dp"
        android:right="5dp" android:bottom="1dp" />
</shape>

2.adapter_shopping_cart_item.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_marginBottom="1dp"
    android:layout_height="wrap_content"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin">
    <ImageView
        android:id="@+id/iv_shopping_cart_item"
        android:layout_width="30dp"
        android:layout_height="30dp"
        android:layout_centerVertical="true"
        android:src="@mipmap/ic_launcher"/>
    <TextView
        android:id="@+id/tv_shopping_cart_item"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="購 買"
        android:textSize="16sp"
        android:layout_alignParentRight="true"
        android:layout_centerVertical="true"/>
</RelativeLayout>

3.MainActivity

public class MainActivity extends AppCompatActivity {
    // 購物車父佈局
    private RelativeLayout mShoppingCartRly;
    // 購物車列表顯示
    private ListView mShoppingCartLv;
    // 購物數目顯示
    private TextView mShoppingCartCountTv;
    // 購物車圖片顯示
    private ImageView mShoppingCartIv;
    // 購物車適配器
    private GoodsAdapter mGoodsAdapter;
    // 數據源（購物車商品圖片）
    private ArrayList<GoodsModel> mData;
    // 貝塞爾曲線中間過程點坐標
    private float[] mCurrentPosition = new float[2];
    // 路徑測量
    private PathMeasure mPathMeasure;
    // 購物車商品數目
    private int goodsCount = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // findView
        mShoppingCartLv = (ListView) findViewById(R.id.lv_bezier_curve_shopping_cart);
        mShoppingCartCountTv = (TextView) findViewById(R.id.tv_bezier_curve_shopping_cart_count);
        mShoppingCartRly = (RelativeLayout) findViewById(R.id.rly_bezier_curve_shopping_cart);
        mShoppingCartIv = (ImageView) findViewById(R.id.iv_bezier_curve_shopping_cart);
        // 是否顯示購物車商品數目
        isShowCartGoodsCount();
        // 添加數據源
        addData();
        // 設置適配器
        setAdapter();
    }

    private void setAdapter() {
        // 初始化適配器
        mGoodsAdapter = new GoodsAdapter(this, mData);
        // 設置適配器監聽
        mGoodsAdapter.setCallBackListener(new GoodsAdapter.CallBackListener() {
            @Override
            public void callBackImg(ImageView goodsImg) {
                // 添加商品到購物車
                addGoodsToCart(goodsImg);
            }
        });
        // 設置適配器
        mShoppingCartLv.setAdapter(mGoodsAdapter);
    }

    private void addGoodsToCart(ImageView goodsImg) {
        // 創造出執行動畫的主題goodsImg（這個圖片就是執行動畫的圖片,從開始位置出發,經過一個拋物線（貝塞爾曲線）,移動到購物車裡）
        final ImageView goods = new ImageView(this);
        goods.setImageDrawable(goodsImg.getDrawable());
        RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(100, 100);
        mShoppingCartRly.addView(goods, params);

        // 得到父佈局的起始點坐標（用於輔助計算動畫開始/結束時的點的坐標）
        int[] parentLocation = new int[2];
        mShoppingCartRly.getLocationInWindow(parentLocation);

        // 得到商品圖片的坐標（用於計算動畫開始的坐標）
        int startLoc[] = new int[2];
        goodsImg.getLocationInWindow(startLoc);

        // 得到購物車圖片的坐標(用於計算動畫結束後的坐標)
        int endLoc[] = new int[2];
        mShoppingCartIv.getLocationInWindow(endLoc);

        // 開始掉落的商品的起始點：商品起始點-父佈局起始點+該商品圖片的一半
        float startX = startLoc[0] - parentLocation[0] + goodsImg.getWidth() / 2;
        float startY = startLoc[1] - parentLocation[1] + goodsImg.getHeight() / 2;

        // 商品掉落後的終點坐標：購物車起始點-父佈局起始點+購物車圖片的1/5
        float toX = endLoc[0] - parentLocation[0] + mShoppingCartIv.getWidth() / 5;
        float toY = endLoc[1] - parentLocation[1];

        // 開始繪製貝塞爾曲線
        Path path = new Path();
        // 移動到起始點（貝塞爾曲線的起點）
        path.moveTo(startX, startY);
        // 使用二階貝塞爾曲線：註意第一個起始坐標越大，貝塞爾曲線的橫向距離就會越大，一般按照下麵的式子取即可
        path.quadTo((startX + toX) / 2, startY, toX, toY);
        // mPathMeasure用來計算貝塞爾曲線的曲線長度和貝塞爾曲線中間插值的坐標，如果是true，path會形成一個閉環
        mPathMeasure = new PathMeasure(path, false);

        // 屬性動畫實現（從0到貝塞爾曲線的長度之間進行插值計算，獲取中間過程的距離值）
        ValueAnimator valueAnimator = ValueAnimator.ofFloat(0, mPathMeasure.getLength());
        valueAnimator.setDuration(500);

        // 勻速線性插值器
        valueAnimator.setInterpolator(new LinearInterpolator());
        valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator animation) {
                // 當插值計算進行時，獲取中間的每個值，
                // 這裡這個值是中間過程中的曲線長度（下麵根據這個值來得出中間點的坐標值）
                float value = (Float) animation.getAnimatedValue();
                // 獲取當前點坐標封裝到mCurrentPosition
                // boolean getPosTan(float distance, float[] pos, float[] tan) ：
                // 傳入一個距離distance(0<=distance<=getLength())，然後會計算當前距離的坐標點和切線，pos會自動填充上坐標，這個方法很重要。
                // mCurrentPosition此時就是中間距離點的坐標值
                mPathMeasure.getPosTan(value, mCurrentPosition, null);
                // 移動的商品圖片（動畫圖片）的坐標設置為該中間點的坐標
                goods.setTranslationX(mCurrentPosition[0]);
                goods.setTranslationY(mCurrentPosition[1]);
            }
        });

        // 開始執行動畫
        valueAnimator.start();

        // 動畫結束後的處理
        valueAnimator.addListener(new Animator.AnimatorListener() {
            @Override
            public void onAnimationStart(Animator animation) {
            }

            @Override
            public void onAnimationEnd(Animator animation) {
                // 購物車商品數量加1
                goodsCount ++;
                isShowCartGoodsCount();
                mShoppingCartCountTv.setText(String.valueOf(goodsCount));
                // 把執行動畫的商品圖片從父佈局中移除
                mShoppingCartRly.removeView(goods);
            }

            @Override
            public void onAnimationCancel(Animator animation) {
            }

            @Override
            public void onAnimationRepeat(Animator animation) {
            }
        });
    }

    private void isShowCartGoodsCount(){
        if (goodsCount == 0){
            mShoppingCartCountTv.setVisibility(View.GONE);
        }else {
            mShoppingCartCountTv.setVisibility(View.VISIBLE);
        }
    }

    private void addData() {
        // 初始化數據源
        mData = new ArrayList<>();
        // 添加數據源
        GoodsModel goodsModel = new GoodsModel();
        goodsModel.setmGoodsBitmap(BitmapFactory.decodeResource(getResources(),
                R.drawable.goods_one));
        mData.add(goodsModel);

        goodsModel = new GoodsModel();
        goodsModel.setmGoodsBitmap(BitmapFactory.decodeResource(getResources(),
                R.drawable.goods_two));
        mData.add(goodsModel);

        goodsModel = new GoodsModel();
        goodsModel.setmGoodsBitmap(BitmapFactory.decodeResource(getResources(),
                R.drawable.goods_three));
        mData.add(goodsModel);
    }
}

4.GoodsAdapter

 1 public class GoodsAdapter extends BaseAdapter{
 2 
 3     // 數據源（購物車商品圖片）
 4     private ArrayList<GoodsModel> mData;
 5     // 佈局
 6     private LayoutInflater mLayoutInflater;
 7     // 回調監聽
 8     private CallBackListener mCallBackListener;
 9 
10     public GoodsAdapter(Context context, ArrayList<GoodsModel> mData){
11         mLayoutInflater = LayoutInflater.from(context);
12         this.mData = mData;
13     }
14 
15     @Override
16     public int getCount() {
17         return mData != null ? mData.size(): 0;
18     }
19 
20     @Override
21     public Object getItem(int i) {
22         return mData != null ? mData.get(i): null;
23     }
24 
25     @Override
26     public long getItemId(int i) {
27         return i;
28     }
29 
30     @Override
31     public View getView(int i, View view, ViewGroup viewGroup) {
32         ViewHolder viewHolder;
33         if (view == null){
34             view = mLayoutInflater.inflate(R.layout.adapter_shopping_cart_item, null);
35             viewHolder = new ViewHolder(view);
36             view.setTag(viewHolder);
37         }else {
38             // 復用ViewHolder
39             viewHolder = (ViewHolder) view.getTag();
40         }
41 
42         // 更新UI
43         if (i < mData.size())
44             viewHolder.updateUI(mData.get(i));
45         return view;
46     }
47 
48     class  ViewHolder{
49         // 顯示商品圖片
50         private ImageView mShoppingCartItemIv;
51 
52         public ViewHolder(View view){
53             // findView
54             mShoppingCartItemIv = (ImageView) view.findViewById(R.id.iv_shopping_cart_item);
55             // onClick
56             view.findViewById(R.id.tv_shopping_cart_item).setOnClickListener(
57                     new View.OnClickListener() {
58                 @Override
59                 public void onClick(View view) {
60                     if (mShoppingCartItemIv != null && mCallBackListener != null)
61                         mCallBackListener.callBackImg(mShoppingCartItemIv);
62                 }
63             });
64         }
65 
66         public void updateUI(GoodsModel goods){
67             if (goods != null
68                     && goods.getmGoodsBitmap() != null
69                     && mShoppingCartItemIv != null)
70                 mShoppingCartItemIv.setImageBitmap(goods.getmGoodsBitmap());
71         }
72     }
73 
74     public void setCallBackListener(CallBackListener mCallBackListener){
75         this.mCallBackListener = mCallBackListener;
76     }
77 
78     public interface CallBackListener{
79         void callBackImg(ImageView goodsImg);
80     }
81 
82 }

5.GoodsModel

public class GoodsModel {
    // 商品圖
    private Bitmap mGoodsBitmap;

    public Bitmap getmGoodsBitmap() {
        return mGoodsBitmap;
    }
    public void setmGoodsBitmap(Bitmap mGoodsBitmap) {
        this.mGoodsBitmap = mGoodsBitmap;
    }
}

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