com.jakewharton.utils.RecyclingPagerAdapter.java Source code

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Here is the source code for com.jakewharton.utils.RecyclingPagerAdapter.java

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/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2014-2015 Umeng, Inc
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

package com.jakewharton.utils;

import android.support.v4.view.PagerAdapter;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;

public abstract class RecyclingPagerAdapter extends PagerAdapter {
    static final int IGNORE_ITEM_VIEW_TYPE = AdapterView.ITEM_VIEW_TYPE_IGNORE;

    private final RecycleBin recycleBin;

    public RecyclingPagerAdapter() {
        this(new RecycleBin());
    }

    RecyclingPagerAdapter(RecycleBin recycleBin) {
        this.recycleBin = recycleBin;
        recycleBin.setViewTypeCount(getViewTypeCount());
    }

    @Override
    public void notifyDataSetChanged() {
        recycleBin.scrapActiveViews();
        super.notifyDataSetChanged();
    }

    @Override
    public final Object instantiateItem(ViewGroup container, int position) {
        int viewType = getItemViewType(position);
        View view = null;
        if (viewType != IGNORE_ITEM_VIEW_TYPE) {
            view = recycleBin.getScrapView(position, viewType);
        }
        view = getView(position, view, container);
        container.addView(view);
        return view;
    }

    @Override
    public final void destroyItem(ViewGroup container, int position, Object object) {
        View view = (View) object;
        container.removeView(view);
        int viewType = getItemViewType(position);
        if (viewType != IGNORE_ITEM_VIEW_TYPE) {
            recycleBin.addScrapView(view, position, viewType);
        }
    }

    @Override
    public final boolean isViewFromObject(View view, Object object) {
        return view == object;
    }

    /**
     * <p>
     * Returns the number of types of Views that will be created by
     * {@link #getView}. Each type represents a set of views that can be
     * converted in {@link #getView}. If the adapter always returns the same
     * type of View for all items, this method should return 1.
     * </p>
     * <p>
     * This method will only be called when when the adapter is set on the
     * the {@link AdapterView}.
     * </p>
     *
     * @return The number of types of Views that will be created by this adapter
     */
    public int getViewTypeCount() {
        return 1;
    }

    /**
     * Get the type of View that will be created by {@link #getView} for the specified item.
     *
     * @param position The position of the item within the adapter's data set whose view type we
     *        want.
     * @return An integer representing the type of View. Two views should share the same type if one
     *         can be converted to the other in {@link #getView}. Note: Integers must be in the
     *         range 0 to {@link #getViewTypeCount} - 1. {@link #IGNORE_ITEM_VIEW_TYPE} can
     *         also be returned.
     * @see #IGNORE_ITEM_VIEW_TYPE
     */
    @SuppressWarnings("UnusedParameters") // Argument potentially used by subclasses.
    public int getItemViewType(int position) {
        return 0;
    }

    /**
     * Get a View that displays the data at the specified position in the data set. You can either
     * create a View manually or inflate it from an XML layout file. When the View is inflated, the
     * parent View (GridView, ListView...) will apply default layout parameters unless you use
     * {@link android.view.LayoutInflater#inflate(int, android.view.ViewGroup, boolean)}
     * to specify a root view and to prevent attachment to the root.
     *
     * @param position The position of the item within the adapter's data set of the item whose view
     *        we want.
     * @param convertView The old view to reuse, if possible. Note: You should check that this view
     *        is non-null and of an appropriate type before using. If it is not possible to convert
     *        this view to display the correct data, this method can create a new view.
     *        Heterogeneous lists can specify their number of view types, so that this View is
     *        always of the right type (see {@link #getViewTypeCount()} and
     *        {@link #getItemViewType(int)}).
     * @param parent The parent that this view will eventually be attached to
     * @return A View corresponding to the data at the specified position.
     */
    public abstract View getView(int position, View convertView, ViewGroup container);
}