Android开发中RecyclerView模仿探探左右滑动布局功能

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) {  //平移时, 需要用到的参考值  TRANS_Y_GAP = (int) (20 * context.getResources().getDisplayMetrics().density); } @Override public RecyclerView.LayoutParams generateDefaultLayoutParams() {  //必须要实现的方法  return new RecyclerView.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT); } @Override public void onLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state) {  //在这个方法中进行View的布局操作.此方法会被调用多次.  detachAndScrapAttachedViews(recycler);  int itemCount = getItemCount();  if (itemCount < 1) {   return;  }  //top-3View的position  int bottomPosition;  //边界处理  if (itemCount < MAX_SHOW_COUNT) {   bottomPosition = 0;  } else {   bottomPosition = itemCount - MAX_SHOW_COUNT;  }  //从可见的最底层View开始layout，依次层叠上去  for (int position = bottomPosition; position < itemCount; position++) {   //1:重recycler的缓存机制中拿到一个View   View view = recycler.getViewForPosition(position);   //2:和自定义ViewGroup一样, 需要先addView   addView(view);   //3:和自定义ViewGroup一样, 也需要测量View的大小   measureChildWithMargins(view, 0, 0);   int widthSpace = getWidth() - getDecoratedMeasuredWidth(view);   int heightSpace = getHeight() - getDecoratedMeasuredHeight(view);   //4:和自定义ViewGroup的onLayout一样, 需要layout View.对View进行布局    //我们在布局时，将childView居中处理，这里也可以改为只水平居中   layoutDecoratedWithMargins(view, widthSpace / 2, heightSpace / 2,     widthSpace / 2 + getDecoratedMeasuredWidth(view),     heightSpace / 2 + getDecoratedMeasuredHeight(view));   /**    * TopView的Scale 为1，translationY 0    * 每一级Scale相差0.05f，translationY相差7dp左右    *    * 观察人人影视的UI，拖动时，topView被拖动，Scale不变，一直为1.    * top-1View 的Scale慢慢变化至1，translation也慢慢恢复0    * top-2View的Scale慢慢变化至 top-1View的Scale，translation 也慢慢变化只top-1View的translation    * top-3View的Scale要变化，translation岿然不动    */   //第几层,举例子，count =7， 最后一个TopView（6）是第0层，   int level = itemCount - position - 1;   //如果不需要缩放平移, 那么下面的代码可以注释掉...   //除了顶层不需要缩小和位移   if (level > 0 /*&& level < mShowCount - 1*/) {    //每一层都需要X方向的缩小    view.setScaleX(1 - SCALE_GAP * level);    //前N层，依次向下位移和Y方向的缩小    if (level < MAX_SHOW_COUNT - 1) {     view.setTranslationY(TRANS_Y_GAP * level);     view.setScaleY(1 - SCALE_GAP * level);    } else {//第N层在 向下位移和Y方向的缩小的成都与 N-1层保持一致     view.setTranslationY(TRANS_Y_GAP * (level - 1));     view.setScaleY(1 - SCALE_GAP * (level - 1));    }   }  } }}

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() {  //第一个参数决定可以拖动排序的方向, 这里由于不需要拖动排序,所以传0  //第二个参数决定可以支持滑动的方向,这里设置了上下左右都可以滑动.  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阈值 public float getThreshold(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {  //2016 12 26 考虑 探探垂直上下方向滑动，不删除卡片，这里参照源码写死0.5f  return recyclerView.getWidth() * /*getSwipeThreshold(viewHolder)*/ 0.5f; } @Override public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {  //由于不支持滑动排序, 所以不需要处理此方法  return false; } @Override public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {  //当view需要滑动的时候,会回调此方法  //但是这个方法只是告诉你View需要滑动, 并不是对View和Adapter进行额外的操作,  //所以, 如果你需要实现滑动删除, 那么需要在此方法中remove item等.  //我们这里需要对滑动过后的View,进行恢复操作.   viewHolder.itemView.setRotation(0);//恢复最后一次的旋转状态  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) {  //滑动的比例达到多少之后, 视为滑动  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);  //当你在滑动的过程中, 此方法一直会被回调, 就跟onTouch事件一样...  //先根据滑动的dx dy 算出现在动画的比例系数fraction  float swipeValue = (float) Math.sqrt(dX * dX + dY * dY);  final float threshold = getThreshold(recyclerView, viewHolder);  float fraction = swipeValue / threshold;  //边界修正 最大为1  if (fraction > 1) {   fraction = 1;  } else if (fraction < -1) {   fraction = -1;  }  //对每个ChildView进行缩放 位移  int childCount = recyclerView.getChildCount();  for (int i = 0; i < childCount; i++) {   View child = recyclerView.getChildAt(i);   //第几层,举例子，count =7， 最后一个TopView（6）是第0层，   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 {    //最上层    //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);    }   }  } } //扩展实现:点击按钮实现左滑效果 public void toLeft(RecyclerView recyclerView) {  if (check(recyclerView)) {   animTo(recyclerView, false);  } } //扩展实现:点击按钮实现右滑效果 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);  /**   * 最上层View滑动时回调.   *   * @param viewHolder 最上层的ViewHolder   * @param offset  距离原始位置的偏移量   */  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) {  } }}