Android Open Source - task-timer-legacy New Fragment State Pager Adapter

From Project

License

The source code is released under:
GNU General Public License
If you think the Android project task-timer-legacy listed in this page is inappropriate, such as containing malicious code/tools or violating the copyright, please email info at java2s dot com, thanks.
Java Source Code

/*
 * Copyright (C) 2011 The Android Open Source Project
 *//  ww  w  .  ja  v  a2  s .co  m
 * 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.gawdl3y.android.tasktimer.adapters;

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.util.Log;
import android.view.View;
import android.view.ViewGroup;

import java.util.ArrayList;
import java.util.Arrays;

/**
 * Fixed version of FragmentStatePagerAdapter
 * <p>This fixes the issue of views not being recreated/reordered when data is added/removed or reordered
 * @see android.support.v4.app.FragmentStatePagerAdapter
 */
public abstract class NewFragmentStatePagerAdapter extends PagerAdapter {
    private static final String TAG = "NewFragmentStatePagerAdapter";
    private static final boolean DEBUG = false;

    private final FragmentManager mFragmentManager;
    private FragmentTransaction mCurTransaction = null;

    private int[] mItemIds = new int[]{};
    private ArrayList<Fragment.SavedState> mSavedState = new ArrayList<Fragment.SavedState>();
    private ArrayList<Fragment> mFragments = new ArrayList<Fragment>();
    private Fragment mCurrentPrimaryItem = null;

    public NewFragmentStatePagerAdapter(FragmentManager fm) {
        mFragmentManager = fm;
        mItemIds = new int[getCount()];
        for(int i = 0; i < mItemIds.length; i++) {
            mItemIds[i] = getItemId(i);
        }
    }

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

    /**
     * Return a unique identifier for the item at the given position.
     */
    public int getItemId(int position) {
        return position;
    }

    @Override
    public void notifyDataSetChanged() {
        int[] newItemIds = new int[getCount()];
        for(int i = 0; i < newItemIds.length; i++) {
            newItemIds[i] = getItemId(i);
        }

        if(!Arrays.equals(mItemIds, newItemIds)) {
            ArrayList<Fragment.SavedState> newSavedState = new ArrayList<Fragment.SavedState>();
            ArrayList<Fragment> newFragments = new ArrayList<Fragment>();

            for(int oldPosition = 0; oldPosition < mItemIds.length; oldPosition++) {
                int newPosition = POSITION_NONE;
                for(int i = 0; i < newItemIds.length; i++) {
                    if(mItemIds[oldPosition] == newItemIds[i]) {
                        newPosition = i;
                        break;
                    }
                }
                if(newPosition >= 0) {
                    if(oldPosition < mSavedState.size()) {
                        Fragment.SavedState savedState = mSavedState.get(oldPosition);
                        if(savedState != null) {
                            while(newSavedState.size() <= newPosition) {
                                newSavedState.add(null);
                            }
                            newSavedState.set(newPosition, savedState);
                        }
                    }
                    if(oldPosition < mFragments.size()) {
                        Fragment fragment = mFragments.get(oldPosition);
                        if(fragment != null) {
                            while(newFragments.size() <= newPosition) {
                                newFragments.add(null);
                            }
                            newFragments.set(newPosition, fragment);
                        }
                    }
                }
            }

            mItemIds = newItemIds;
            mSavedState = newSavedState;
            mFragments = newFragments;
        }

        super.notifyDataSetChanged();
    }

    @Override
    public void startUpdate(ViewGroup container) {
    }

    @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(DEBUG) Log.v(TAG, "Adding item #" + position + ": f=" + fragment);
        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);
        mFragments.set(position, fragment);
        mCurTransaction.add(container.getId(), fragment, "android:switcher:" + container.getId() + ":" + position);

        return fragment;
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        Fragment fragment = (Fragment) object;

        if(mCurTransaction == null) {
            mCurTransaction = mFragmentManager.beginTransaction();
        }

        position = getItemPosition(object);
        if(DEBUG) Log.v(TAG, "Removing item #" + position + ": f=" + object
                + " v=" + ((Fragment) object).getView());
        if(position >= 0) {
            while(mSavedState.size() <= position) {
                mSavedState.add(null);
            }
            mSavedState.set(position, mFragmentManager.saveFragmentInstanceState(fragment));
            try {
                mFragments.set(position, null);
            } catch(IndexOutOfBoundsException e) {
            }
        }

        mCurTransaction.remove(fragment);
    }

    @Override
    public void setPrimaryItem(ViewGroup container, int position, Object object) {
        Fragment fragment = (Fragment) object;
        if(fragment != mCurrentPrimaryItem) {
            if(mCurrentPrimaryItem != null) {
                mCurrentPrimaryItem.setMenuVisibility(false);
            }
            if(fragment != null) {
                fragment.setMenuVisibility(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 = new Bundle();
        if(mItemIds.length > 0) {
            state.putIntArray("itemids", mItemIds);
        }
        if(mSavedState.size() > 0) {
            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) {
                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);
            mItemIds = bundle.getIntArray("itemids");
            if(mItemIds == null) {
                mItemIds = new int[]{};
            }
            Parcelable[] fss = bundle.getParcelableArray("states");
            mSavedState.clear();
            mFragments.clear();
            if(fss != null) {
                for(int i = 0; i < fss.length; i++) {
                    mSavedState.add((Fragment.SavedState) fss[i]);
                }
            }
            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);
                    } else {
                        Log.w(TAG, "Bad fragment at key " + key);
                    }
                }
            }
        }
    }
}
Java Source Code List
