Android Open Source - making-apps-beautiful Article List Fragment

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License

The source code is released under:

Apache License

Java Source Code

/*
 * Copyright 2013 The Android Open Source Project
 *//from   w ww .ja  va2 s.c om
 * 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.example.xyzreader.cp7;

import android.annotation.TargetApi;
import android.app.Activity;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.os.AsyncTask;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.app.ListFragment;
import android.support.v4.app.NotificationCompat;
import android.support.v4.util.LruCache;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;

import com.example.xyzreader.cp7.dummy.DummyContent;

import java.lang.ref.WeakReference;

/**
 * A list fragment representing a list of Articles. This fragment also supports tablet devices by
 * allowing list items to be given an 'activated' state upon selection. This helps indicate which
 * item is currently being viewed in a {@link ArticleDetailFragment}. <p> Activities containing this
 * fragment MUST implement the {@link Callbacks} interface.
 */
public class ArticleListFragment extends ListFragment {

    /**
     * The serialization (saved instance state) Bundle key representing the activated item position.
     * Only used on tablets.
     */
    private static final String STATE_ACTIVATED_POSITION = "activated_position";

    /**
     * The fragment's current callback object, which is notified of list item clicks.
     */
    private Callbacks mCallbacks = sDummyCallbacks;

    /**
     * The current activated item position. Only used on tablets.
     */
    private int mActivatedPosition = ListView.INVALID_POSITION;

    /**
     * A place holder bitmap before the true bitmap is loaded
     */
    private Bitmap mPlaceHolderBitmap;

    /**
     * The memory cache for bitmap images
     */
    private LruCache<String, Bitmap> mMemoryCache;


    /**
     * A callback interface that all activities containing this fragment must implement. This
     * mechanism allows activities to be notified of item selections.
     */
    public interface Callbacks {
        /**
         * Callback for when an item has been selected.
         */
        public void onItemSelected(String id);
    }

    /**
     * A dummy implementation of the {@link Callbacks} interface that does nothing. Used only when
     * this fragment is not attached to an activity.
     */
    private static Callbacks sDummyCallbacks = new Callbacks() {
        @Override
        public void onItemSelected(String id) {
        }
    };

    /**
     * Mandatory empty constructor for the fragment manager to instantiate the fragment (e.g. upon
     * screen orientation changes).
     */
    public ArticleListFragment() {
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Get max available VM memory, exceeding this amount will throw an
        // OutOfMemory exception. Stored in kilobytes as LruCache takes an
        // int in its constructor.
        final int maxMemory = (int) (Runtime.getRuntime().maxMemory() / 1024);

        // Use 1/8th of the available memory for this memory cache.
        final int cacheSize = maxMemory / 8;

        mMemoryCache = new LruCache<String, Bitmap>(cacheSize) {
            @TargetApi(Build.VERSION_CODES.HONEYCOMB_MR1)
            @Override
            protected int sizeOf(String key, Bitmap bitmap) {
                // The cache size will be measured in kilobytes rather than
                // number of items.
                if (Build.VERSION.SDK_INT > Build.VERSION_CODES.HONEYCOMB_MR1) {
                    return bitmap.getByteCount() / 1024;
                } else {
                    return bitmap.getRowBytes() * bitmap.getHeight() / 1024;
                }
            }
        };

        setListAdapter(new MyAdapter());
        setHasOptionsMenu(true);
    }

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        // Restore the previously serialized activated item position.
        if (savedInstanceState != null
                && savedInstanceState.containsKey(STATE_ACTIVATED_POSITION)) {
            setActivatedPosition(savedInstanceState
                    .getInt(STATE_ACTIVATED_POSITION));
        }
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);

        // Activities containing this fragment must implement its callbacks.
        if (!(activity instanceof Callbacks)) {
            throw new IllegalStateException(
                    "Activity must implement fragment's callbacks.");
        }

        mCallbacks = (Callbacks) activity;
        mPlaceHolderBitmap = decodeSampledBitmapFromResource(getResources(), R.drawable.stat_icon, 20, 20);
    }

    @Override
    public void onDetach() {
        super.onDetach();

        // Reset the active callbacks interface to the dummy implementation.
        mCallbacks = sDummyCallbacks;
    }

    @Override
    public void onListItemClick(ListView listView, View view, int position,
                                long id) {
        super.onListItemClick(listView, view, position, id);

        // Notify the active callbacks interface (the activity, if the
        // fragment is attached to one) that an item has been selected.
        mCallbacks.onItemSelected(DummyContent.ITEMS.get(position).id);
    }

    @Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        if (mActivatedPosition != ListView.INVALID_POSITION) {
            // Serialize and persist the activated item position.
            outState.putInt(STATE_ACTIVATED_POSITION, mActivatedPosition);
        }
    }

    /**
     * Turns on activate-on-click mode. When this mode is on, list items will be given the
     * 'activated' state when touched.
     */
    public void setActivateOnItemClick(boolean activateOnItemClick) {
        // When setting CHOICE_MODE_SINGLE, ListView will automatically
        // give items the 'activated' state when touched.
        getListView().setChoiceMode(
                activateOnItemClick ? ListView.CHOICE_MODE_SINGLE
                        : ListView.CHOICE_MODE_NONE);
    }

    private void setActivatedPosition(int position) {
        if (position == ListView.INVALID_POSITION) {
            getListView().setItemChecked(mActivatedPosition, false);
        } else {
            getListView().setItemChecked(position, true);
        }

        mActivatedPosition = position;
    }

    @Override
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
        inflater.inflate(R.menu.main, menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if (item.getItemId() == R.id.refresh) {
            DummyContent.DummyItem dummy = DummyContent.ITEMS.get(0);

            BitmapFactory.Options options = new BitmapFactory.Options();
            options.inSampleSize = 16;
            Bitmap photo = BitmapFactory.decodeResource(getResources(), dummy.photoResId);

            Notification n = new NotificationCompat.Builder(getActivity())
                    .setContentTitle("Article published")
                    .setSmallIcon(R.drawable.stat_icon)
                    .setDefaults(Notification.DEFAULT_SOUND)
                    .setLargeIcon(photo)
                    .setStyle(new NotificationCompat.BigPictureStyle()
                            .bigPicture(photo)
                            .setSummaryText(dummy.title))
                    .setContentText(dummy.title)
                    .setContentIntent(PendingIntent.getActivity(getActivity(), 0,
                            new Intent(getActivity(), getActivity().getClass()),
                            PendingIntent.FLAG_UPDATE_CURRENT))
                    .setAutoCancel(true)
                    .addAction(R.drawable.ic_share, "Share",
                            PendingIntent.getActivity(getActivity(), 0,
                                    new Intent(getActivity(), getActivity().getClass()),
                                    PendingIntent.FLAG_UPDATE_CURRENT))
                    .build();
            NotificationManager nm = (NotificationManager) getActivity().getSystemService(Context.NOTIFICATION_SERVICE);
            nm.notify(1, n);
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    private class MyAdapter extends BaseAdapter {
        @Override
        public int getCount() {
            return DummyContent.ITEMS.size();
        }

        @Override
        public Object getItem(int position) {
            return DummyContent.ITEMS.get(position);
        }

        @Override
        public long getItemId(int position) {
            return DummyContent.ITEMS.get(position).id.hashCode();
        }

        @Override
        public View getView(int position, View convertView, ViewGroup container) {
            if (convertView == null) {
                convertView = LayoutInflater.from(getActivity())
                        .inflate(R.layout.list_item_article, container, false);
            }

            final DummyContent.DummyItem item = (DummyContent.DummyItem) getItem(position);
            ((TextView) convertView.findViewById(R.id.article_title)).setText(item.title);
            ((TextView) convertView.findViewById(R.id.article_subtitle)).setText(
                    item.time + " by " + item.author);

            final ImageView thumbnail = (ImageView) convertView.findViewById(R.id.thumbnail);
            loadBitmap(item.photoResId, thumbnail);

            return convertView;
        }

        public void loadBitmap(int resId, ImageView imageView) {
            final String imageKey = String.valueOf(resId);
            final Bitmap bitmap = getBitmapFromMemCache(imageKey);

            if (bitmap != null) {
                imageView.setImageBitmap(bitmap);
            } else {
                if (cancelPotentialWork(resId, imageView)) {
                    final BitmapWorkerTask task = new BitmapWorkerTask(imageView);
                    final AsyncDrawable asyncDrawable =
                            new AsyncDrawable(getResources(), mPlaceHolderBitmap, task);
                    imageView.setImageDrawable(asyncDrawable);
                    task.execute(resId);
                }
            }
        }
    }

    public static Bitmap decodeSampledBitmapFromResource(Resources res, int resId,
                                                         int reqWidth, int reqHeight) {

        // First decode with inJustDecodeBounds=true to check dimensions
        final BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeResource(res, resId, options);

        // Calculate inSampleSize
        options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);

        // Decode bitmap with inSampleSize set
        options.inJustDecodeBounds = false;
        return BitmapFactory.decodeResource(res, resId, options);
    }

    public static int calculateInSampleSize(
            BitmapFactory.Options options, int reqWidth, int reqHeight) {
        // Raw height and width of image
        final int height = options.outHeight;
        final int width = options.outWidth;
        int inSampleSize = 16;

        if (reqWidth == 0 || reqHeight == 0) return inSampleSize;

        if (height > reqHeight || width > reqWidth) {

            // Calculate ratios of height and width to requested height and width
            final int heightRatio = Math.round((float) height / (float) reqHeight);
            final int widthRatio = Math.round((float) width / (float) reqWidth);

            // Choose the smallest ratio as inSampleSize value, this will guarantee
            // a final image with both dimensions larger than or equal to the
            // requested height and width.
            inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
        }

        return inSampleSize;
    }

    public static boolean cancelPotentialWork(int resId, ImageView imageView) {
        final BitmapWorkerTask bitmapWorkerTask = getBitmapWorkerTask(imageView);

        if (bitmapWorkerTask != null) {
            final int bitmapWorkerTaskResId = bitmapWorkerTask.resId;
            if (bitmapWorkerTaskResId != resId) {
                // Cancel previous task
                bitmapWorkerTask.cancel(true);
            } else {
                // The same work is already in progress
                return false;
            }
        }
        // No task associated with the ImageView, or an existing task was cancelled
        return true;
    }

    private static BitmapWorkerTask getBitmapWorkerTask(ImageView imageView) {
        if (imageView != null) {
            final Drawable drawable = imageView.getDrawable();
            if (drawable instanceof AsyncDrawable) {
                final AsyncDrawable asyncDrawable = (AsyncDrawable) drawable;
                return asyncDrawable.getBitmapWorkerTask();
            }
        }
        return null;
    }

    class BitmapWorkerTask extends AsyncTask<Integer, Void, Bitmap> {
        private final WeakReference<ImageView> imageViewReference;
        private int resId = 0;

        public BitmapWorkerTask(ImageView imageView) {
            // Use a WeakReference to ensure the ImageView can be garbage collected
            imageViewReference = new WeakReference<ImageView>(imageView);
        }

        // Decode image in background.
        @Override
        protected Bitmap doInBackground(Integer... params) {
            resId = params[0];
            ImageView thumbnail = imageViewReference.get();
            Bitmap bitmap = decodeSampledBitmapFromResource(getResources(), resId, thumbnail.getWidth(),
                    thumbnail.getHeight());
            addBitmapToMemoryCache(String.valueOf(params[0]), bitmap);
            return bitmap;
        }

        // Once complete, see if ImageView is still around and set bitmap.
        @Override
        protected void onPostExecute(Bitmap bitmap) {
            if (isCancelled()) {
                bitmap = null;
            }

            if (imageViewReference != null && bitmap != null) {
                final ImageView imageView = imageViewReference.get();
                final BitmapWorkerTask bitmapWorkerTask =
                        getBitmapWorkerTask(imageView);
                if (this == bitmapWorkerTask && imageView != null) {
                    imageView.setImageBitmap(bitmap);
                }
            }
        }
    }

    static class AsyncDrawable extends BitmapDrawable {
        private final WeakReference<BitmapWorkerTask> bitmapWorkerTaskReference;

        public AsyncDrawable(Resources res, Bitmap bitmap,
                             BitmapWorkerTask bitmapWorkerTask) {
            super(res, bitmap);
            bitmapWorkerTaskReference =
                    new WeakReference<BitmapWorkerTask>(bitmapWorkerTask);
        }

        public BitmapWorkerTask getBitmapWorkerTask() {
            return bitmapWorkerTaskReference.get();
        }
    }

    public void addBitmapToMemoryCache(String key, Bitmap bitmap) {
        if (getBitmapFromMemCache(key) == null) {
            mMemoryCache.put(key, bitmap);
        }
    }

    public Bitmap getBitmapFromMemCache(String key) {
        return mMemoryCache.get(key);
    }
}

Java Source Code List

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