com.android.fastexample.adapter.FragmentViewPagerAdapter.java Source code

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Here is the source code for com.android.fastexample.adapter.FragmentViewPagerAdapter.java

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/*
 * Copyright (C) 2014 loQua.Xee <loquaciouser@gmail.com>
 *
 * 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.fastexample.adapter;

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.View;
import android.view.ViewGroup;

import java.util.List;

/**
 * ViewPagerFragment?fragmentsviewpager
 * <p/>
 * Created with IntelliJ IDEA.
 * Author: wangjie  email:tiantian.china.2@gmail.com
 * Date: 13-10-11
 * Time: ?3:03
 */
public class FragmentViewPagerAdapter extends PagerAdapter implements ViewPager.OnPageChangeListener {
    private List<Fragment> fragments; // ?FragmentPage
    private FragmentManager fragmentManager;
    private ViewPager viewPager; // viewPager
    private int currentPageIndex = 0; // ?page??

    private OnExtraPageChangeListener onExtraPageChangeListener; // ViewPager????

    public FragmentViewPagerAdapter(FragmentManager fragmentManager, ViewPager viewPager,
            List<Fragment> fragments) {
        this.fragments = fragments;
        this.fragmentManager = fragmentManager;
        this.viewPager = viewPager;
        this.viewPager.setAdapter(this);
        this.viewPager.setOnPageChangeListener(this);
    }

    @Override
    public int getCount() {
        return fragments.size();
    }

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

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        container.removeView(fragments.get(position).getView()); // viewpagerpage
    }

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        Fragment fragment = fragments.get(position);
        if (!fragment.isAdded()) { // fragmentadded
            FragmentTransaction ft = fragmentManager.beginTransaction();
            ft.add(fragment, fragment.getClass().getSimpleName());
            ft.commit();
            /**
             * FragmentTransaction.commit()??FragmentTransaction?
             * ??
             * ?????
             * ?????
             */
            fragmentManager.executePendingTransactions();
        }

        if (fragment.getView().getParent() == null) {
            container.addView(fragment.getView()); // viewpager
        }

        return fragment.getView();
    }

    /**
     * ?page??
     *
     * @return
     */
    public int getCurrentPageIndex() {
        return currentPageIndex;
    }

    public OnExtraPageChangeListener getOnExtraPageChangeListener() {
        return onExtraPageChangeListener;
    }

    /**
     * ????
     *
     * @param onExtraPageChangeListener
     */
    public void setOnExtraPageChangeListener(OnExtraPageChangeListener onExtraPageChangeListener) {
        this.onExtraPageChangeListener = onExtraPageChangeListener;
    }

    @Override
    public void onPageScrolled(int i, float v, int i2) {
        if (null != onExtraPageChangeListener) { // ??
            onExtraPageChangeListener.onExtraPageScrolled(i, v, i2);
        }
    }

    @Override
    public void onPageSelected(int i) {
        fragments.get(currentPageIndex).onPause(); // ??FargmentonPause()
        //        fragments.get(currentPageIndex).onStop(); // ??FargmentonStop()
        if (fragments.get(i).isAdded()) {
            //            fragments.get(i).onStart(); // ??FargmentonStart()
            fragments.get(i).onResume(); // ??FargmentonResume()
        }
        currentPageIndex = i;

        if (null != onExtraPageChangeListener) { // ??
            onExtraPageChangeListener.onExtraPageSelected(i);
        }

    }

    @Override
    public void onPageScrollStateChanged(int i) {
        if (null != onExtraPageChangeListener) { // ??
            onExtraPageChangeListener.onExtraPageScrollStateChanged(i);
        }
    }

    /**
     * page???
     */
    public static class OnExtraPageChangeListener {
        public void onExtraPageScrolled(int i, float v, int i2) {
        }

        public void onExtraPageSelected(int i) {
        }

        public void onExtraPageScrollStateChanged(int i) {
        }
    }

}