Android開發中RecyclerView模仿探探左右滑動布局功能

我在此基礎上優化了部分代碼, 添加了滑動回調, 可自定義性更強. 並且添加了點擊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, 首先需要自己管理布局

繼承 RecyclerView.LayoutManager , 顯示自己管理布局, 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的布局操作.此方法會被調用多次.
  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的緩存機制中拿到一個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進行布局 
   //我們在布局時，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, 那麼下面的代碼可以注釋掉...
   //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:布局好了之後, 就需要監聽鼠標事件了

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, 都在回調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() {
  //第一個參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
  //第二個參數決定可以支持滑動的方向,這裡設置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阈值
 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，這裡參照源碼寫死0.5f
  return recyclerView.getWidth() * /*getSwipeThreshold(viewHolder)*/ 0.5f;
 }
 @Override
 public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
  //由於不支持滑動排序, 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,會回調此方法
  //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, 此方法一直會被回調, 就跟onTouch事件一樣...
  //先根據滑動的dx dy 算出現在動畫的比例系數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);
    }
   }
  }
 }
 //擴展實現:點擊按鈕實現左滑效果
 public void toLeft(RecyclerView recyclerView) {
  if (check(recyclerView)) {
   animTo(recyclerView, false);
  }
 }
 //擴展實現:點擊按鈕實現右滑效果
 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滑動時回調.
   *
   * @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.

開源地址: https://github.com/angcyo/RecyclerLayoutManager

好了，以上所示是小編給大家分享的Android開發中RecyclerView模仿探探左右滑動布局功能，希望對大家有所幫助，如果大家有任何疑問歡迎給我留言。