SetupWizardLibrary/library/recyclerview/src/com/android/setupwizardlib/items/RecyclerItemAdapter.java

/*
 * 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.setupwizardlib.items;

import android.content.res.TypedArray;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.LayerDrawable;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import androidx.annotation.VisibleForTesting;
import androidx.recyclerview.widget.RecyclerView;

import com.android.setupwizardlib.R;

/**
 * An adapter used with RecyclerView to display an {@link ItemHierarchy}. The item hierarchy used to
 * create this adapter can be inflated by {@link com.android.setupwizardlib.items.ItemInflater} from
 * XML.
 */
public class RecyclerItemAdapter extends RecyclerView.Adapter<ItemViewHolder>
        implements ItemHierarchy.Observer {

    private static final String TAG = "RecyclerItemAdapter";

    /**
     * A view tag set by {@link View#setTag(Object)}. If set on the root view of a layout, it will
     * not create the default background for the list item. This means the item will not have ripple
     * touch feedback by default.
     */
    public static final String TAG_NO_BACKGROUND = "noBackground";

    /**
     * Listener for item selection in this adapter.
     */
    public interface OnItemSelectedListener {

        /**
         * Called when an item in this adapter is clicked.
         *
         * @param item The Item corresponding to the position being clicked.
         */
        void onItemSelected(IItem item);
    }

    private final ItemHierarchy mItemHierarchy;
    private OnItemSelectedListener mListener;

    public RecyclerItemAdapter(ItemHierarchy hierarchy) {
        mItemHierarchy = hierarchy;
        mItemHierarchy.registerObserver(this);
    }

    /**
     * Gets the item at the given position.
     *
     * @see ItemHierarchy#getItemAt(int)
     */
    public IItem getItem(int position) {
        return mItemHierarchy.getItemAt(position);
    }

    @Override
    public long getItemId(int position) {
        IItem mItem = getItem(position);
        if (mItem instanceof AbstractItem) {
            final int id = ((AbstractItem) mItem).getId();
            return id > 0 ? id : RecyclerView.NO_ID;
        } else {
            return RecyclerView.NO_ID;
        }
    }

    @Override
    public int getItemCount() {
        return mItemHierarchy.getCount();
    }

    @Override
    public ItemViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        final LayoutInflater inflater = LayoutInflater.from(parent.getContext());
        final View view = inflater.inflate(viewType, parent, false);
        final ItemViewHolder viewHolder = new ItemViewHolder(view);

        final Object viewTag = view.getTag();
        if (!TAG_NO_BACKGROUND.equals(viewTag)) {
            final TypedArray typedArray = parent.getContext()
                    .obtainStyledAttributes(R.styleable.SuwRecyclerItemAdapter);
            Drawable selectableItemBackground = typedArray.getDrawable(
                    R.styleable.SuwRecyclerItemAdapter_android_selectableItemBackground);
            if (selectableItemBackground == null) {
                selectableItemBackground = typedArray.getDrawable(
                        R.styleable.SuwRecyclerItemAdapter_selectableItemBackground);
            }

            Drawable background = view.getBackground();
            if (background == null) {
                background = typedArray.getDrawable(
                        R.styleable.SuwRecyclerItemAdapter_android_colorBackground);
            }

            if (selectableItemBackground == null || background == null) {
                Log.e(TAG, "Cannot resolve required attributes."
                        + " selectableItemBackground=" + selectableItemBackground
                        + " background=" + background);
            } else {
                final Drawable[] layers = {background, selectableItemBackground};
                view.setBackgroundDrawable(new PatchedLayerDrawable(layers));
            }

            typedArray.recycle();
        }

        view.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                final IItem item = viewHolder.getItem();
                if (mListener != null && item != null && item.isEnabled()) {
                    mListener.onItemSelected(item);
                }
            }
        });

        return viewHolder;
    }

    @Override
    public void onBindViewHolder(ItemViewHolder holder, int position) {
        final IItem item = getItem(position);
        holder.setEnabled(item.isEnabled());
        holder.setItem(item);
        item.onBindView(holder.itemView);
    }

    @Override
    public int getItemViewType(int position) {
        // Use layout resource as item view type. RecyclerView item type does not have to be
        // contiguous.
        IItem item = getItem(position);
        return item.getLayoutResource();
    }

    @Override
    public void onChanged(ItemHierarchy hierarchy) {
        notifyDataSetChanged();
    }

    @Override
    public void onItemRangeChanged(ItemHierarchy itemHierarchy, int positionStart, int itemCount) {
        notifyItemRangeChanged(positionStart, itemCount);
    }

    @Override
    public void onItemRangeInserted(ItemHierarchy itemHierarchy, int positionStart, int itemCount) {
        notifyItemRangeInserted(positionStart, itemCount);
    }

    @Override
    public void onItemRangeMoved(ItemHierarchy itemHierarchy, int fromPosition, int toPosition,
            int itemCount) {
        // There is no notifyItemRangeMoved
        // https://code.google.com/p/android/issues/detail?id=125984
        if (itemCount == 1) {
            notifyItemMoved(fromPosition, toPosition);
        } else {
            // If more than one, degenerate into the catch-all data set changed callback, since I'm
            // not sure how recycler view handles multiple calls to notifyItemMoved (if the result
            // is committed after every notification then naively calling
            // notifyItemMoved(from + i, to + i) is wrong).
            // Logging this in case this is a more common occurrence than expected.
            Log.i(TAG, "onItemRangeMoved with more than one item");
            notifyDataSetChanged();
        }
    }

    @Override
    public void onItemRangeRemoved(ItemHierarchy itemHierarchy, int positionStart, int itemCount) {
        notifyItemRangeRemoved(positionStart, itemCount);
    }

    /**
     * Find an item hierarchy within the root hierarchy.
     *
     * @see ItemHierarchy#findItemById(int)
     */
    public ItemHierarchy findItemById(int id) {
        return mItemHierarchy.findItemById(id);
    }

    /**
     * Gets the root item hierarchy in this adapter.
     */
    public ItemHierarchy getRootItemHierarchy() {
        return mItemHierarchy;
    }

    /**
     * Sets the listener to listen for when user clicks on a item.
     *
     * @see OnItemSelectedListener
     */
    public void setOnItemSelectedListener(OnItemSelectedListener listener) {
        mListener = listener;
    }

    /**
     * Before Lollipop, LayerDrawable always return true in getPadding, even if the children layers
     * do not have any padding. Patch the implementation so that getPadding returns false if the
     * padding is empty.
     *
     * When getPadding is true, the padding of the view will be replaced by the padding of the
     * drawable when {@link View#setBackgroundDrawable(Drawable)} is called. This patched class
     * makes sure layer drawables without padding does not clear out original padding on the view.
     */
    @VisibleForTesting
    static class PatchedLayerDrawable extends LayerDrawable {

        /**
         * {@inheritDoc}
         */
        PatchedLayerDrawable(Drawable[] layers) {
            super(layers);
        }

        @Override
        public boolean getPadding(Rect padding) {
            final boolean superHasPadding = super.getPadding(padding);
            return superHasPadding
                    && !(padding.left == 0
                            && padding.top == 0
                            && padding.right == 0
                            && padding.bottom == 0);
        }
    }
}