站在巨人的肩膀上,才能走得更遠.

我在此基礎上優化了部分程式碼, 添加了滑動回撥, 可自定義性更強. 並且添加了點選按鈕左右滑動的功能.

據說無圖都不敢發文章了.
看圖:

1:這種功能, 首先需要自己管理佈局

繼承 RecyclerView.LayoutManager , 顯示自己管理佈局, 比如最多顯示4個view, 並且都是居中顯示.
底部的View還需要進行縮放,平移操作.

public class OverLayCardLayoutManager extends RecyclerView.LayoutManager {
    private static
 
 final String TAG = "swipecard";
    public static int MAX_SHOW_COUNT = 4;
    public static float SCALE_GAP = 0.05f;
    public static int TRANS_Y_GAP;

    public OverLayCardLayoutManager(Context context) {
        //平移時, 需要用到的參考值
        TRANS_Y_GAP = (int) (20 * context.getResources().getDisplayMetrics().density);
    }

    @Override
 

    public RecyclerView.LayoutParams generateDefaultLayoutParams() {
        //必須要實現的方法
        return new RecyclerView.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
    }

    @Override
    public void onLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state) {
        //在這個方法中進行View的佈局操作.此方法會被呼叫多次.
 

        detachAndScrapAttachedViews(recycler);
        int itemCount = getItemCount();
        if (itemCount < 1) {
            return;
        }
        //top-3View的position
        int bottomPosition;
        //邊界處理
        if (itemCount < MAX_SHOW_COUNT) {
            bottomPosition = 0;
        } else {
            bottomPosition = itemCount - MAX_SHOW_COUNT;
        }

        //從可見的最底層View開始layout，依次層疊上去
        for (int position = bottomPosition; position < itemCount; position++) {
            //1:重recycler的快取機制中拿到一個View
            View view = recycler.getViewForPosition(position);
            //2:和自定義ViewGroup一樣, 需要先addView
            addView(view);
            //3:和自定義ViewGroup一樣, 也需要測量View的大小
            measureChildWithMargins(view, 0, 0);
            int widthSpace = getWidth() - getDecoratedMeasuredWidth(view);
            int heightSpace = getHeight() - getDecoratedMeasuredHeight(view);
            //4:和自定義ViewGroup的onLayout一樣, 需要layout View.對View進行佈局 
            //我們在佈局時，將childView居中處理，這裡也可以改為只水平居中
            layoutDecoratedWithMargins(view, widthSpace / 2, heightSpace / 2,
                    widthSpace / 2 + getDecoratedMeasuredWidth(view),
                    heightSpace / 2 + getDecoratedMeasuredHeight(view));
            /**
             * TopView的Scale 為1，translationY 0
             * 每一級Scale相差0.05f，translationY相差7dp左右
             *
             * 觀察人人影視的UI，拖動時，topView被拖動，Scale不變，一直為1.
             * top-1View 的Scale慢慢變化至1，translation也慢慢恢復0
             * top-2View的Scale慢慢變化至 top-1View的Scale，translation 也慢慢變化只top-1View的translation
             * top-3View的Scale要變化，translation巋然不動
             */

            //第幾層,舉例子，count =7， 最後一個TopView（6）是第0層，
            int level = itemCount - position - 1;

            //如果不需要縮放平移, 那麼下面的程式碼可以註釋掉...
            //除了頂層不需要縮小和位移
            if (level > 0 /*&& level < mShowCount - 1*/) {
                //每一層都需要X方向的縮小
                view.setScaleX(1 - SCALE_GAP * level);
                //前N層，依次向下位移和Y方向的縮小
                if (level < MAX_SHOW_COUNT - 1) {
                    view.setTranslationY(TRANS_Y_GAP * level);
                    view.setScaleY(1 - SCALE_GAP * level);
                } else {//第N層在 向下位移和Y方向的縮小的成都與 N-1層保持一致
                    view.setTranslationY(TRANS_Y_GAP * (level - 1));
                    view.setScaleY(1 - SCALE_GAP * (level - 1));
                }
            }
        }
    }
}

2:佈局好了之後, 就需要監聽滑鼠事件了

谷歌官方提供了一個ItemTouchHelper工具類, 對滑動進行了慘無人道的優越封裝, 傻x都能用…
使用方法: new ItemTouchHelper(callback).attachToRecyclerView(recyclerView);就這麼簡單,
接下來的操作, 都在回撥callback裡面進行.

public class RenRenCallback extends ItemTouchHelper.SimpleCallback {

    private static final String TAG = "RenRen";
    private static final int MAX_ROTATION = 15;
    OnSwipeListener mSwipeListener;
    boolean isSwipeAnim = false;

    public RenRenCallback() {
        //第一個引數決定可以拖動排序的方向, 這裡由於不需要拖動排序,所以傳0
        //第二個引數決定可以支援滑動的方向,這裡設定了上下左右都可以滑動.
        super(0, ItemTouchHelper.DOWN | ItemTouchHelper.UP | ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT);
    }

    public void setSwipeListener(OnSwipeListener swipeListener) {
        mSwipeListener = swipeListener;
    }

    //水平方向是否可以被回收掉的閾值
    public float getThreshold(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
        //2016 12 26 考慮 探探垂直上下方向滑動，不刪除卡片，這裡參照原始碼寫死0.5f
        return recyclerView.getWidth() * /*getSwipeThreshold(viewHolder)*/ 0.5f;
    }

    @Override
    public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
        //由於不支援滑動排序, 所以不需要處理此方法
        return false;
    }

    @Override
    public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
        //當view需要滑動的時候,會回撥此方法
        //但是這個方法只是告訴你View需要滑動, 並不是對View和Adapter進行額外的操作,
        //所以, 如果你需要實現滑動刪除, 那麼需要在此方法中remove item等.

        //我們這裡需要對滑動過後的View,進行恢復操作. 
        viewHolder.itemView.setRotation(0);//恢復最後一次的旋轉狀態
        if (mSwipeListener != null) {
            mSwipeListener.onSwipeTo(viewHolder, 0);
        }
        notifyListener(viewHolder.getAdapterPosition(), direction);
    }

    private void notifyListener(int position, int direction) {
        Log.w(TAG, "onSwiped: " + position + " " + direction);
        if (mSwipeListener != null) {
            mSwipeListener.onSwiped(position, direction);
        }
    }

    @Override
    public float getSwipeThreshold(RecyclerView.ViewHolder viewHolder) {
        //滑動的比例達到多少之後, 視為滑動
        return 0.3f;
    }


    @Override
    public void onChildDraw(Canvas c, RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, float dX, float dY, int actionState, boolean isCurrentlyActive) {
        super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive);
        //當你在滑動的過程中, 此方法一直會被回撥, 就跟onTouch事件一樣...
        //先根據滑動的dx dy 算出現在動畫的比例係數fraction
        float swipeValue = (float) Math.sqrt(dX * dX + dY * dY);
        final float threshold = getThreshold(recyclerView, viewHolder);
        float fraction = swipeValue / threshold;
        //邊界修正 最大為1
        if (fraction > 1) {
            fraction = 1;
        } else if (fraction < -1) {
            fraction = -1;
        }
        //對每個ChildView進行縮放 位移
        int childCount = recyclerView.getChildCount();
        for (int i = 0; i < childCount; i++) {
            View child = recyclerView.getChildAt(i);
            //第幾層,舉例子，count =7， 最後一個TopView（6）是第0層，
            int level = childCount - i - 1;
            if (level > 0) {
                child.setScaleX(1 - SCALE_GAP * level + fraction * SCALE_GAP);

                if (level < MAX_SHOW_COUNT - 1) {
                    child.setScaleY(1 - SCALE_GAP * level + fraction * SCALE_GAP);
                    child.setTranslationY(TRANS_Y_GAP * level - fraction * TRANS_Y_GAP);
                } else {
                    //child.setTranslationY((float) (mTranslationYGap * (level - 1) - fraction * mTranslationYGap));
                }
            } else {
                //最上層
                //rotate
                if (dX < -50) {
                    child.setRotation(-fraction * MAX_ROTATION);
                } else if (dX > 50) {
                    child.setRotation(fraction * MAX_ROTATION);
                } else {
                    child.setRotation(0);
                }

                if (mSwipeListener != null) {
                    RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
                    final int adapterPosition = params.getViewAdapterPosition();
                    mSwipeListener.onSwipeTo(recyclerView.findViewHolderForAdapterPosition(adapterPosition), dX);
                }
            }
        }
    }

    //擴充套件實現:點選按鈕實現左滑效果
    public void toLeft(RecyclerView recyclerView) {
        if (check(recyclerView)) {
            animTo(recyclerView, false);
        }
    }

    //擴充套件實現:點選按鈕實現右滑效果
    public void toRight(RecyclerView recyclerView) {
        if (check(recyclerView)) {
            animTo(recyclerView, true);
        }
    }

    private void animTo(final RecyclerView recyclerView, boolean right) {
        final int position = recyclerView.getAdapter().getItemCount() - 1;
        final View view = recyclerView.findViewHolderForAdapterPosition(position).itemView;

        TranslateAnimation translateAnimation = new TranslateAnimation(Animation.RELATIVE_TO_SELF, 0,
                Animation.RELATIVE_TO_SELF, right ? 1f : -1f,
                Animation.RELATIVE_TO_SELF, 0f, Animation.RELATIVE_TO_SELF, 1.3f);
        translateAnimation.setFillAfter(true);
        translateAnimation.setDuration(300);
        translateAnimation.setInterpolator(new DecelerateInterpolator());
        translateAnimation.setAnimationListener(new Animation.AnimationListener() {
            @Override
            public void onAnimationStart(Animation animation) {

            }

            @Override
            public void onAnimationEnd(Animation animation) {
                isSwipeAnim = false;
                recyclerView.removeView(view);
                notifyListener(position,
                        x > view.getMeasuredWidth() / 2
                                ?
                                ItemTouchHelper.RIGHT : ItemTouchHelper.LEFT);
            }

            @Override
            public void onAnimationRepeat(Animation animation) {

            }
        });
        view.startAnimation(translateAnimation);
    }

    private boolean check(RecyclerView recyclerView) {
        if (isSwipeAnim) {
            return false;
        }
        if (recyclerView == null || recyclerView.getAdapter() == null) {
            return false;
        }
        if (recyclerView.getAdapter().getItemCount() == 0) {
            return false;
        }
        isSwipeAnim = true;
        return true;
    }

    public interface OnSwipeListener {

        /**
         * @param direction {@link ItemTouchHelper#LEFT} / {@link ItemTouchHelper#RIGHT}
         *                  {@link ItemTouchHelper#UP} or {@link ItemTouchHelper#DOWN}).
         */
        void onSwiped(int adapterPosition, int direction);

        /**
         * 最上層View滑動時回撥.
         *
         * @param viewHolder 最上層的ViewHolder
         * @param offset     距離原始位置的偏移量
         */
        void onSwipeTo(RecyclerView.ViewHolder viewHolder, float offset);
    }

    public static class SimpleSwipeCallback implements OnSwipeListener {

        /**
         * {@inheritDoc}
         */
        @Override
        public void onSwiped(int adapterPosition, int direction) {

        }

        /**
         * {@inheritDoc}
         */
        @Override
        public void onSwipeTo(RecyclerView.ViewHolder viewHolder, float offset) {

        }
    }
}

看起來不難, 但是真正做的時候, 要處理的地方很多,

並且有些地方要思考很久, 才能實現效果.

總之,做了你才會發現1+1=2的魅力, just do it.

至此: 文章就結束了,如有疑問: QQ群 Android:274306954 Swift:399799363 歡迎您的加入.