jahirfiquitiva.iconshowcase.fragments.base.FragmentStatePagerAdapter.java Source code

Introduction

Here is the source code for jahirfiquitiva.iconshowcase.fragments.base.FragmentStatePagerAdapter.java

Source

/*
 * Copyright (c) 2016.  Jahir Fiquitiva
 *
 * Licensed under the CreativeCommons Attribution-ShareAlike
 * 4.0 International License. You may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 *    http://creativecommons.org/licenses/by-sa/4.0/legalcode
 *
 * 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.
 *
 * Big thanks to the project contributors. Check them in the repository.
 *
 */

/*
 *
 */

package jahirfiquitiva.iconshowcase.fragments.base;

import android.annotation.SuppressLint;
import android.os.Bundle;
import android.os.Parcelable;
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.view.View;
import android.view.ViewGroup;

import java.util.ArrayList;

/**
 * @author Aidan Follestad (afollestad)
 */

public abstract class FragmentStatePagerAdapter extends PagerAdapter {

    private final FragmentManager mFragmentManager;
    private FragmentTransaction mCurTransaction = null;

    private final ArrayList<Fragment.SavedState> mSavedState = new ArrayList<>();
    private final ArrayList<Fragment> mFragments = new ArrayList<>();
    private Fragment mCurrentPrimaryItem = null;

    protected FragmentStatePagerAdapter(FragmentManager fm) {
        mFragmentManager = fm;
    }

    /**
     * Return the Fragment associated with a specified position.
     */
    protected abstract Fragment getItem(int position);

    @Override
    public void startUpdate(ViewGroup container) {
    }

    @SuppressLint("CommitTransaction")
    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        // If we already have this item instantiated, there is nothing
        // to do.  This can happen when we are restoring the entire pager
        // from its saved state, where the fragment manager has already
        // taken care of restoring the fragments we previously had instantiated.
        if (mFragments.size() > position) {
            Fragment f = mFragments.get(position);
            if (f != null) {
                return f;
            }
        }
        if (mCurTransaction == null) {
            mCurTransaction = mFragmentManager.beginTransaction();
        }
        Fragment fragment = getItem(position);
        if (mSavedState.size() > position) {
            Fragment.SavedState fss = mSavedState.get(position);
            if (fss != null) {
                fragment.setInitialSavedState(fss);
            }
        }
        while (mFragments.size() <= position) {
            mFragments.add(null);
        }
        fragment.setMenuVisibility(false);
        fragment.setUserVisibleHint(false);
        mFragments.set(position, fragment);
        mCurTransaction.add(container.getId(), fragment, "page:" + position);
        return fragment;
    }

    @SuppressLint("CommitTransaction")
    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        Fragment fragment = (Fragment) object;
        if (mCurTransaction == null) {
            mCurTransaction = mFragmentManager.beginTransaction();
        }
        while (mSavedState.size() <= position) {
            mSavedState.add(null);
        }
        mSavedState.set(position, mFragmentManager.saveFragmentInstanceState(fragment));
        mFragments.set(position, null);
        mCurTransaction.remove(fragment);
    }

    @Override
    public void setPrimaryItem(ViewGroup container, int position, Object object) {
        Fragment fragment = (Fragment) object;
        if (fragment != mCurrentPrimaryItem) {
            if (mCurrentPrimaryItem != null) {
                fragment.setMenuVisibility(false);
                fragment.setUserVisibleHint(false);
            }
            fragment.setMenuVisibility(true);
            fragment.setUserVisibleHint(true);
            mCurrentPrimaryItem = fragment;
        }
    }

    @Override
    public void finishUpdate(ViewGroup container) {
        if (mCurTransaction != null) {
            mCurTransaction.commitAllowingStateLoss();
            mCurTransaction = null;
            mFragmentManager.executePendingTransactions();
        }
    }

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

    @Override
    public Parcelable saveState() {
        Bundle state = null;
        if (mSavedState.size() > 0) {
            state = new Bundle();
            Fragment.SavedState[] fss = new Fragment.SavedState[mSavedState.size()];
            mSavedState.toArray(fss);
            state.putParcelableArray("states", fss);
        }
        for (int i = 0; i < mFragments.size(); i++) {
            Fragment f = mFragments.get(i);
            if (f != null) {
                if (state == null) {
                    state = new Bundle();
                }
                String key = "f" + i;
                mFragmentManager.putFragment(state, key, f);
            }
        }
        return state;
    }

    @Override
    public void restoreState(Parcelable state, ClassLoader loader) {
        if (state != null) {
            Bundle bundle = (Bundle) state;
            bundle.setClassLoader(loader);
            Parcelable[] fss = bundle.getParcelableArray("states");
            mSavedState.clear();
            mFragments.clear();
            if (fss != null) {
                for (Parcelable fs : fss) {
                    mSavedState.add((Fragment.SavedState) fs);
                }
            }
            Iterable<String> keys = bundle.keySet();
            for (String key : keys) {
                if (key.startsWith("f")) {
                    int index = Integer.parseInt(key.substring(1));
                    Fragment f = mFragmentManager.getFragment(bundle, key);
                    if (f != null) {
                        while (mFragments.size() <= index) {
                            mFragments.add(null);
                        }
                        f.setMenuVisibility(false);
                        mFragments.set(index, f);
                    }
                }
            }
        }
    }
}