nextcloud-android/src/com/owncloud/android/ui/preview/PreviewImagePagerAdapter.java

/* ownCloud Android client application
 *   Copyright (C) 2012-2013  ownCloud Inc.
 *
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */
package com.owncloud.android.ui.preview;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.Set;
import java.util.Vector;

import android.accounts.Account;
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.FragmentStatePagerAdapter;
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 com.owncloud.android.datamodel.DataStorageManager;
import com.owncloud.android.datamodel.OCFile;

/**
 * Adapter class that provides Fragment instances  
 * 
 * @author David A. Velasco
 */
//public class PreviewImagePagerAdapter extends PagerAdapter {
public class PreviewImagePagerAdapter extends FragmentStatePagerAdapter {
    
    private static final String TAG = PreviewImagePagerAdapter.class.getSimpleName();
            
    private Vector<OCFile> mImageFiles;
    private Account mAccount;
    private Set<Object> mObsoleteFragments;
    private DataStorageManager mStorageManager;
    
    /*
    private final FragmentManager mFragmentManager;
    private FragmentTransaction mCurTransaction = null;
    private ArrayList<Fragment.SavedState> mSavedState = new ArrayList<Fragment.SavedState>();
    private ArrayList<Fragment> mFragments = new ArrayList<Fragment>();
    private Fragment mCurrentPrimaryItem = null;
    */

    /**
     * Constructor.
     * 
     * @param fragmentManager   {@link FragmentManager} instance that will handle the {@link Fragment}s provided by the adapter. 
     * @param parentFolder      Folder where images will be searched for.
     * @param storageManager    Bridge to database.
     */
    public PreviewImagePagerAdapter(FragmentManager fragmentManager, OCFile parentFolder, Account account, DataStorageManager storageManager) {
        super(fragmentManager);

        if (fragmentManager == null) {
            throw new IllegalArgumentException("NULL FragmentManager instance");
        }
        if (parentFolder == null) {
            throw new IllegalArgumentException("NULL parent folder");
        } 
        if (storageManager == null) {
            throw new IllegalArgumentException("NULL storage manager");
        }

        mAccount = account;
        mStorageManager = storageManager;
        mImageFiles = mStorageManager.getDirectoryImages(parentFolder); 
        mObsoleteFragments = new HashSet<Object>();
    }

    
    /**
     * Returns the image files handled by the adapter.
     * 
     * @return  A vector with the image files handled by the adapter.
     */
    protected OCFile getFileAt(int position) {
        return mImageFiles.get(position);
    }

    
    public Fragment getItem(int i) {
        Log.e(TAG, "GETTING PAGE " + i);
        OCFile file = mImageFiles.get(i);
        Fragment fragment = null;
        if (file.isDown()) {
            fragment = new PreviewImageFragment(file, mAccount);
        } else {
            fragment = new FileDownloadFragment(file, mAccount);
        }
        return fragment;
    }

    public int getFilePosition(OCFile file) {
        return mImageFiles.indexOf(file);
    }
    
    @Override
    public int getCount() {
        return mImageFiles.size();
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return mImageFiles.get(position).getFileName();
    }

    public void updateFile(int position, OCFile file) {
        mImageFiles.set(position, file);
        mObsoleteFragments.add(instantiateItem(null, position));
    }
    
    @Override
    public int getItemPosition(Object object) {
        Log.e(TAG, "getItemPosition ");
        if (mObsoleteFragments.contains(object)) {
            mObsoleteFragments.remove(object);
            return POSITION_NONE;
        }
        return super.getItemPosition(object);
    }


    /* *
     * Called when a change in the shown pages is going to start being made.
     * 
     * @param   container   The containing View which is displaying this adapter's page views.
     * -/
    @Override
    public void startUpdate(ViewGroup container) {
        Log.e(TAG, "** startUpdate");
    }

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        Log.e(TAG, "** instantiateItem " + position);
        
        if (mFragments.size() > position) {
            Fragment fragment = mFragments.get(position);
            if (fragment != null) {
                Log.e(TAG, "** \t returning cached item");
                return fragment;
            }
        }

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

        Fragment fragment = getItem(position);
        if (mSavedState.size() > position) {
            Fragment.SavedState savedState = mSavedState.get(position);
            if (savedState != null) {
                // TODO WATCH OUT:
                // * The Fragment must currently be attached to the FragmentManager.
                // * A new Fragment created using this saved state must be the same class type as the Fragment it was created from.
                // * The saved state can not contain dependencies on other fragments -- that is it can't use putFragment(Bundle, String, Fragment) 
                //   to store a fragment reference                 
                fragment.setInitialSavedState(savedState);
            }
        }
        while (mFragments.size() <= position) {
            mFragments.add(null);
        }
        fragment.setMenuVisibility(false);
        mFragments.set(position, fragment);
        Log.e(TAG, "** \t adding fragment at position " + position + ", containerId " + container.getId());
        mCurTransaction.add(container.getId(), fragment);

        return fragment;
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        Log.e(TAG, "** destroyItem " + position);
        Fragment fragment = (Fragment)object;
        
        if (mCurTransaction == null) {
            mCurTransaction = mFragmentManager.beginTransaction();
        }
        Log.e(TAG, "** \t removing fragment at position " + position);
        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) {
                mCurrentPrimaryItem.setMenuVisibility(false);
            }
            if (fragment != null) {
                fragment.setMenuVisibility(true);
            }
            mCurrentPrimaryItem = fragment;
        }
    }

    @Override
    public void finishUpdate(ViewGroup container) {
        Log.e(TAG, "** finishUpdate (start)");
        if (mCurTransaction != null) {
            mCurTransaction.commitAllowingStateLoss();
            mCurTransaction = null;
            mFragmentManager.executePendingTransactions();
        }
        Log.e(TAG, "** finishUpdate (end)");
    }

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

    @Override
    public void restoreState(Parcelable state, ClassLoader loader) {
        if (state != null) {
            Bundle bundle = (Bundle)state;
            bundle.setClassLoader(loader);
            Parcelable[] states = bundle.getParcelableArray("states");
            mSavedState.clear();
            mFragments.clear();
            if (states != null) {
                for (int i=0; i<states.length; i++) {
                    mSavedState.add((Fragment.SavedState)states[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);
                    }
                }
            }
        }
    } */
    
}