content: /*
   * Copyright (C) 2015 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package com.android.launcher3;
  
  import android.content.Context;
  import android.util.AttributeSet;
  import android.view.MotionEvent;
  import android.view.View;
  import android.view.ViewGroup;
  
  import com.android.launcher3.compat.AccessibilityManagerCompat;
  import com.android.launcher3.views.RecyclerViewFastScroller;
  
  import androidx.recyclerview.widget.RecyclerView;
  
  
  /**
   * A base {@link RecyclerView}, which does the following:
   * <ul>
   *   <li> NOT intercept a touch unless the scrolling velocity is below a predefined threshold.
   *   <li> Enable fast scroller.
   * </ul>
   */
  public abstract class BaseRecyclerView extends RecyclerView  {
  
      protected RecyclerViewFastScroller mScrollbar;
  
      public BaseRecyclerView(Context context) {
          this(context, null);
      }
  
      public BaseRecyclerView(Context context, AttributeSet attrs) {
          this(context, attrs, 0);
      }
  
      public BaseRecyclerView(Context context, AttributeSet attrs, int defStyleAttr) {
          super(context, attrs, defStyleAttr);
      }
  
      @Override
      protected void onAttachedToWindow() {
          super.onAttachedToWindow();
          bindFastScrollbar();
      }
  
      public void bindFastScrollbar() {
          ViewGroup parent = (ViewGroup) getParent().getParent();
          mScrollbar = parent.findViewById(R.id.fast_scroller);
          mScrollbar.setRecyclerView(this, parent.findViewById(R.id.fast_scroller_popup));
          onUpdateScrollbar(0);
      }
  
      public RecyclerViewFastScroller getScrollbar() {
          return mScrollbar;
      }
  
      public int getScrollBarTop() {
          return getPaddingTop();
      }
  
      /**
       * Returns the height of the fast scroll bar
       */
      public int getScrollbarTrackHeight() {
          return mScrollbar.getHeight() - getScrollBarTop() - getPaddingBottom();
      }
  
      /**
       * Returns the available scroll height:
       *   AvailableScrollHeight = Total height of the all items - last page height
       */
      protected abstract int getAvailableScrollHeight();
  
      /**
       * Returns the available scroll bar height:
       *   AvailableScrollBarHeight = Total height of the visible view - thumb height
       */
      protected int getAvailableScrollBarHeight() {
          int availableScrollBarHeight = getScrollbarTrackHeight() - mScrollbar.getThumbHeight();
          return availableScrollBarHeight;
      }
  
      /**
       * Updates the scrollbar thumb offset to match the visible scroll of the recycler view.  It does
       * this by mapping the available scroll area of the recycler view to the available space for the
       * scroll bar.
       *
       * @param scrollY the current scroll y
       */
      protected void synchronizeScrollBarThumbOffsetToViewScroll(int scrollY,
              int availableScrollHeight) {
          // Only show the scrollbar if there is height to be scrolled
          if (availableScrollHeight <= 0) {
              mScrollbar.setThumbOffsetY(-1);
              return;
          }
  
          // Calculate the current scroll position, the scrollY of the recycler view accounts for the
          // view padding, while the scrollBarY is drawn right up to the background padding (ignoring
          // padding)
          int scrollBarY =
                  (int) (((float) scrollY / availableScrollHeight) * getAvailableScrollBarHeight());
  
          // Calculate the position and size of the scroll bar
          mScrollbar.setThumbOffsetY(scrollBarY);
      }
  
      /**
       * Returns whether the view itself will handle the touch event or not.
       * @param ev MotionEvent in {@param eventSource}
       */
      public boolean shouldContainerScroll(MotionEvent ev, View eventSource) {
          float[] point = new float[2];
          point[0] = ev.getX();
          point[1] = ev.getY();
          Utilities.mapCoordInSelfToDescendant(mScrollbar, eventSource, point);
          // IF the MotionEvent is inside the thumb, container should not be pulled down.
          if (mScrollbar.shouldBlockIntercept((int) point[0], (int) point[1])) {
              return false;
          }
  
          // IF scroller is at the very top OR there is no scroll bar because there is probably not
          // enough items to scroll, THEN it's okay for the container to be pulled down.
          if (getCurrentScrollY() == 0) {
              return true;
          }
          return false;
      }
  
      /**
       * @return whether fast scrolling is supported in the current state.
       */
      public boolean supportsFastScrolling() {
          return true;
      }
  
      /**
       * Maps the touch (from 0..1) to the adapter position that should be visible.
       * <p>Override in each subclass of this base class.
       *
       * @return the scroll top of this recycler view.
       */
      public abstract int getCurrentScrollY();
  
      /**
       * Maps the touch (from 0..1) to the adapter position that should be visible.
       * <p>Override in each subclass of this base class.
       */
      public abstract String scrollToPositionAtProgress(float touchFraction);
  
      /**
       * Updates the bounds for the scrollbar.
       * <p>Override in each subclass of this base class.
       */
      public abstract void onUpdateScrollbar(int dy);
  
      /**
       * <p>Override in each subclass of this base class.
       */
      public void onFastScrollCompleted() {}
  
      @Override
      public void onScrollStateChanged(int state) {
          super.onScrollStateChanged(state);
  
          if (state == SCROLL_STATE_IDLE) {
              AccessibilityManagerCompat.sendScrollFinishedEventToTest(getContext());
          }
      }
  }