android/app/src/main/java/io/v/android/apps/reader/PdfViewerActivity.java - release.projects.reader - Git at Google

 // Copyright 2015 The Vanadium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 package io.v.android.apps.reader;

 import android.app.Activity;
 import android.content.Context;
 import android.content.Intent;
 import android.database.Cursor;
 import android.net.Uri;
 import android.os.Bundle;
 import android.provider.OpenableColumns;
 import android.util.Log;
 import android.view.View;
 import android.widget.Button;
 import android.widget.Toast;

 import com.google.common.io.ByteStreams;

 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.HashMap;
 import java.util.Map;

 import io.v.android.apps.reader.db.DB;
 import io.v.android.apps.reader.db.DB.DBList;
 import io.v.android.apps.reader.model.DeviceInfoFactory;
 import io.v.android.apps.reader.model.IdFactory;
 import io.v.android.apps.reader.model.Listener;
 import io.v.android.apps.reader.vdl.DeviceMeta;
 import io.v.android.apps.reader.vdl.DeviceSet;
 import io.v.android.apps.reader.vdl.File;

 /**
  * Activity that shows the contents of the selected pdf file.
  */
 public class PdfViewerActivity extends Activity {

     private static final String TAG = PdfViewerActivity.class.getSimpleName();

     private static final String EXTRA_DEVICE_SET_ID = "device_set_id";

     private PdfViewWrapper mPdfView;
     private Button mButtonPrev;
     private Button mButtonNext;

     private DB mDB;
     private DBList<DeviceSet> mDeviceSets;
     private DeviceSet mCurrentDS;

     /**
      * Helper methods for creating an intent to start a PdfViewerActivity.
      */
     public static Intent createIntent(Context context, String deviceSetId) {
         Intent intent = new Intent(context, PdfViewerActivity.class);
         intent.putExtra(EXTRA_DEVICE_SET_ID, deviceSetId);
         return intent;
     }

     public static Intent createIntent(Context context, Uri uri) {
         Intent intent = new Intent(context, PdfViewerActivity.class);
         intent.setData(uri);
         return intent;
     }

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

         // Initialize the DB
         mDB = DB.Singleton.get(this);
         mDB.init(this);

         setContentView(R.layout.activity_pdf_viewer);

         mPdfView = (PdfViewWrapper) findViewById(R.id.pdfview);
         mPdfView.init();

         mButtonPrev = (Button) findViewById(R.id.button_prev);
         mButtonNext = (Button) findViewById(R.id.button_next);

         mButtonPrev.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View v) {
                 prevPage();
             }
         });

         mButtonNext.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View v) {
                 nextPage();
             }
         });
     }

     @Override
     protected void onStart() {
         super.onStart();

         /**
          * Suppress the start process until the DB initialization is completed.
          * onStart() method will be called again after the user selects her blessings.
          */
         if (!mDB.isInitialized()) {
             return;
         }

         mDeviceSets = mDB.getDeviceSetList();
         mDeviceSets.setListener(new Listener() {
             @Override
             public void notifyItemChanged(int position) {
                 if (mCurrentDS == null) {
                     return;
                 }

                 DeviceSet changed = mDeviceSets.getItem(position);
                 if (!changed.getId().equals(mCurrentDS.getId())) {
                     return;
                 }

                 mCurrentDS = changed;
                 mPdfView.setPage(getDeviceMeta().getPage());
             }

             @Override
             public void notifyItemInserted(int position) {
                 // Nothing to do
             }

             @Override
             public void notifyItemRemoved(int position) {
                 // Nothing to do
             }
         });

         Intent intent = getIntent();

         if (intent.hasExtra(EXTRA_DEVICE_SET_ID)) {
             /**
              * Case #1.
              * The EXTRA_DEVICE_SET_ID value is set when this activity is started by touching one of
              * the existing device sets from the DeviceSetChooserActivity.
              */
             Log.i(TAG, "onStart: Case #1: started by selecting an existing device set.");

             // Get the device set from the DB and join it.
             DeviceSet ds = mDeviceSets.getItemById(intent.getStringExtra(EXTRA_DEVICE_SET_ID));
             joinDeviceSet(ds);
         } else if (intent.getData() != null) {
             /**
              * Case #2.
              * The intent.getData() is set as a content Uri when this activity is started by using
              * the floating action button from the DeviceSetChooserActivity and selecting one of the
              * local PDF files from the browser.
              */
             Log.i(TAG, "onStart: Case #2: started by using the floating action button.");

             Uri uri = intent.getData();
             createAndJoinDeviceSet(uri);
         } else if (intent.hasExtra(Intent.EXTRA_STREAM)) {
             /**
              * Case #3.
              * The EXTRA_STREAM value is set when this activity is started by receiving an implicit
              * intent from another app by sharing a PDF file to the reader app.
              */
             Log.i(TAG, "onStart: Case #3: started by an implicit intent from another app.");

             Uri uri = intent.getParcelableExtra(Intent.EXTRA_STREAM);
             createAndJoinDeviceSet(uri);
         }
     }

     private void createAndJoinDeviceSet(Uri fileUri) {
         // Get the file content.
         byte[] bytes = getBytesFromUri(fileUri);

         // Create a vdl File object representing this pdf file and put it in the db.
         File vFile = mDB.storeBytes(bytes, getTitleFromUri(fileUri));
         Log.i(TAG, "vFile created: " + vFile);
         if (vFile == null) {
             Log.e(TAG, "Could not store the file content of Uri: " + fileUri.toString());
         }
         mDB.addFile(vFile);

         // Create a device set object and put it in the db.
         DeviceSet ds = createDeviceSet(vFile);
         mDB.addDeviceSet(ds);

         // Join the device set.
         joinDeviceSet(ds);
     }

     @Override
     protected void onStop() {
         super.onStop();

         if (mDeviceSets != null) {
             mDeviceSets.discard();
         }

         leaveDeviceSet();
     }

     private DeviceMeta createDeviceMeta() {
         String deviceId = DeviceInfoFactory.getDeviceId(this);
         int page = 1;
         int zoom = 1;
         boolean linked = true;

         return new DeviceMeta(deviceId, page, zoom, linked);
     }

     private DeviceSet createDeviceSet(File vFile) {
         String id = IdFactory.getRandomId();
         String fileId = vFile.getId();
         Map<String, DeviceMeta> devices = new HashMap<>();

         return new DeviceSet(id, fileId, devices);
     }

     private void joinDeviceSet(DeviceSet ds) {
         // Get the file contents from the database
         // TODO(youngseokyoon): get the blob asynchronously. right now, it's blocking the UI thread.
         File file = mDB.getFileList().getItemById(ds.getFileId());
         byte[] bytes = mDB.readBytes(file);
         if (bytes == null) {
             Toast.makeText(this, "Could not load the file contents.", Toast.LENGTH_LONG).show();
             return;
         }

         // The pdf viewer widget requires the file to be an actual java.io.File object.
         // Create a temporary file and write the contents.
         java.io.File jFile = new java.io.File(getCacheDir(), ds.getFileId());
         try (FileOutputStream out = new FileOutputStream(jFile)) {
             out.write(bytes);
         } catch (IOException e) {
             handleException(e);
         }

         // Initialize the pdf viewer widget with the file content.
         Log.i(TAG, "File path: " + jFile.getPath());
         mPdfView.loadUrl("file:///android_asset/pdfjs/index.html?file=" + jFile.getPath());

         // Create a new device meta, and update the device set with it.
         Log.i(TAG, "Joining device set: " + ds.getId());
         DeviceMeta dm = createDeviceMeta();
         ds.getDevices().put(dm.getDeviceId(), dm);
         mDB.updateDeviceSet(ds);

         mCurrentDS = ds;
     }

     private void leaveDeviceSet() {
         if (mCurrentDS == null) {
             return;
         }

         Log.i(TAG, "Leaving device set: " + mCurrentDS.getId());
         Map<String, DeviceMeta> devices = mCurrentDS.getDevices();
         devices.remove(DeviceInfoFactory.getDeviceId(this));

         if (devices.isEmpty()) {
             Log.i(TAG, "Last one to leave the device set. Deleting " + mCurrentDS.getId());
             mDB.deleteDeviceSet(mCurrentDS.getId());
         } else {
             mDB.updateDeviceSet(mCurrentDS);
         }

         mCurrentDS = null;
     }

     private byte[] getBytesFromUri(Uri uri) {
         Log.i(TAG, "getBytesFromUri: " + uri.toString());

         try (InputStream in = getContentResolver().openInputStream(uri)) {
             // Get the entire file contents as a byte array.
             return ByteStreams.toByteArray(in);
         } catch (IOException e) {
             handleException(e);
         }

         return null;
     }

     private String getTitleFromUri(Uri uri) {
         try {
             Cursor cursor = getContentResolver().query(uri, null, null, null, null);

             int nameIndex = cursor.getColumnIndex(OpenableColumns.DISPLAY_NAME);
             cursor.moveToFirst();
             return cursor.getString(nameIndex);
         } catch (Exception e) {
             handleException(e);

             if (uri != null) {
                 return uri.getLastPathSegment();
             }
         }

         return null;
     }

     private DeviceMeta getDeviceMeta() {
         return getDeviceMeta(mCurrentDS);
     }

     private DeviceMeta getDeviceMeta(DeviceSet ds) {
         String deviceId = DeviceInfoFactory.getDeviceId(this);

         if (ds == null || !ds.getDevices().containsKey(deviceId)) {
             return null;
         }

         return ds.getDevices().get(deviceId);
     }

     /**
      * Move all the linked pages to their previous pages.
      */
     private void prevPage() {
         if (mCurrentDS == null) {
             return;
         }

         // First, check if this device is linked or not.
         // If not, simply move the page of the current device.
         if (!getDeviceMeta().getLinked()) {
             DeviceMeta dm = getDeviceMeta();
             if (dm.getPage() > 1) {
                 dm.setPage(dm.getPage() - 1);
             }

             return;
         }

         // Move all the linked pages
         Map<String, DeviceMeta> linkedDevices = getLinkedDevices();
         int smallestPage = getSmallestPage(linkedDevices);

         if (smallestPage > 1) {
             for (String deviceId : linkedDevices.keySet()) {
                 DeviceMeta dm = linkedDevices.get(deviceId);
                 dm.setPage(dm.getPage() - 1);
             }

             mDB.updateDeviceSet(mCurrentDS);
         }
     }

     /**
      * Move all the linked pages to their next pages.
      */
     private void nextPage() {
         if (mCurrentDS == null) {
             return;
         }

         // First, check if this device is linked or not.
         // If not, simply move the page of the current device.
         if (!getDeviceMeta().getLinked()) {
             DeviceMeta dm = getDeviceMeta();
             if (dm.getPage() < mPdfView.getPageCount()) {
                 dm.setPage(dm.getPage() + 1);
             }

             return;
         }

         // Move all the linked pages
         Map<String, DeviceMeta> linkedDevices = getLinkedDevices();
         int largestPage = getLargestPage(linkedDevices);

         if (largestPage < mPdfView.getPageCount()) {
             for (String deviceId : linkedDevices.keySet()) {
                 DeviceMeta dm = linkedDevices.get(deviceId);
                 dm.setPage(dm.getPage() + 1);
             }

             mDB.updateDeviceSet(mCurrentDS);
         }
     }

     private Map<String, DeviceMeta> getLinkedDevices() {
         if (mCurrentDS == null) {
             return null;
         }

         Map<String, DeviceMeta> devices = mCurrentDS.getDevices();
         Map<String, DeviceMeta> result = new HashMap<>();
         for (String deviceId : devices.keySet()) {
             DeviceMeta dm = devices.get(deviceId);
             if (dm.getLinked()) {
                 result.put(deviceId, dm);
             }
         }

         return result;
     }

     private int getSmallestPage(Map<String, DeviceMeta> devices) {
         int result = -1;

         for (String deviceId : devices.keySet()) {
             DeviceMeta dm = devices.get(deviceId);
             if (result == -1 || dm.getPage() < result) {
                 result = dm.getPage();
             }
         }

         return result;
     }

     private int getLargestPage(Map<String, DeviceMeta> devices) {
         int result = -1;

         for (String deviceId : devices.keySet()) {
             DeviceMeta dm = devices.get(deviceId);
             if (result == -1 || dm.getPage() > result) {
                 result = dm.getPage();
             }
         }

         return result;
     }

     private static void handleException(Exception e) {
         Log.e(TAG, e.getMessage(), e);
     }

     @Override
     protected void onActivityResult(int requestCode, int resultCode, Intent data) {
         super.onActivityResult(requestCode, resultCode, data);

         Log.i(TAG, String.format("onActivityResult(%d, %d, data) called", requestCode, resultCode));
         if (mDB.onActivityResult(requestCode, resultCode, data)) {
             return;
         }

         // Any other activity results would be handled here.
         Log.w(TAG, String.format(
                 "Unhandled activity result. (requestCode: %d, resultCode: %d)",
                 requestCode, resultCode));
     }

 }
	// Copyright 2015 The Vanadium Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	package io.v.android.apps.reader;

	import android.app.Activity;
	import android.content.Context;
	import android.content.Intent;
	import android.database.Cursor;
	import android.net.Uri;
	import android.os.Bundle;
	import android.provider.OpenableColumns;
	import android.util.Log;
	import android.view.View;
	import android.widget.Button;
	import android.widget.Toast;

	import com.google.common.io.ByteStreams;

	import java.io.FileOutputStream;
	import java.io.IOException;
	import java.io.InputStream;
	import java.util.HashMap;
	import java.util.Map;

	import io.v.android.apps.reader.db.DB;
	import io.v.android.apps.reader.db.DB.DBList;
	import io.v.android.apps.reader.model.DeviceInfoFactory;
	import io.v.android.apps.reader.model.IdFactory;
	import io.v.android.apps.reader.model.Listener;
	import io.v.android.apps.reader.vdl.DeviceMeta;
	import io.v.android.apps.reader.vdl.DeviceSet;
	import io.v.android.apps.reader.vdl.File;

	/**
	* Activity that shows the contents of the selected pdf file.
	*/
	public class PdfViewerActivity extends Activity {

	private static final String TAG = PdfViewerActivity.class.getSimpleName();

	private static final String EXTRA_DEVICE_SET_ID = "device_set_id";

	private PdfViewWrapper mPdfView;
	private Button mButtonPrev;
	private Button mButtonNext;

	private DB mDB;
	private DBList<DeviceSet> mDeviceSets;
	private DeviceSet mCurrentDS;

	/**
	* Helper methods for creating an intent to start a PdfViewerActivity.
	*/
	public static Intent createIntent(Context context, String deviceSetId) {
	Intent intent = new Intent(context, PdfViewerActivity.class);
	intent.putExtra(EXTRA_DEVICE_SET_ID, deviceSetId);
	return intent;
	}

	public static Intent createIntent(Context context, Uri uri) {
	Intent intent = new Intent(context, PdfViewerActivity.class);
	intent.setData(uri);
	return intent;
	}

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

	// Initialize the DB
	mDB = DB.Singleton.get(this);
	mDB.init(this);

	setContentView(R.layout.activity_pdf_viewer);

	mPdfView = (PdfViewWrapper) findViewById(R.id.pdfview);
	mPdfView.init();

	mButtonPrev = (Button) findViewById(R.id.button_prev);
	mButtonNext = (Button) findViewById(R.id.button_next);

	mButtonPrev.setOnClickListener(new View.OnClickListener() {
	@Override
	public void onClick(View v) {
	prevPage();
	}
	});

	mButtonNext.setOnClickListener(new View.OnClickListener() {
	@Override
	public void onClick(View v) {
	nextPage();
	}
	});
	}

	@Override
	protected void onStart() {
	super.onStart();

	/**
	* Suppress the start process until the DB initialization is completed.
	* onStart() method will be called again after the user selects her blessings.
	*/
	if (!mDB.isInitialized()) {
	return;
	}

	mDeviceSets = mDB.getDeviceSetList();
	mDeviceSets.setListener(new Listener() {
	@Override
	public void notifyItemChanged(int position) {
	if (mCurrentDS == null) {
	return;
	}

	DeviceSet changed = mDeviceSets.getItem(position);
	if (!changed.getId().equals(mCurrentDS.getId())) {
	return;
	}

	mCurrentDS = changed;
	mPdfView.setPage(getDeviceMeta().getPage());
	}

	@Override
	public void notifyItemInserted(int position) {
	// Nothing to do
	}

	@Override
	public void notifyItemRemoved(int position) {
	// Nothing to do
	}
	});

	Intent intent = getIntent();

	if (intent.hasExtra(EXTRA_DEVICE_SET_ID)) {
	/**
	* Case #1.
	* The EXTRA_DEVICE_SET_ID value is set when this activity is started by touching one of
	* the existing device sets from the DeviceSetChooserActivity.
	*/
	Log.i(TAG, "onStart: Case #1: started by selecting an existing device set.");

	// Get the device set from the DB and join it.
	DeviceSet ds = mDeviceSets.getItemById(intent.getStringExtra(EXTRA_DEVICE_SET_ID));
	joinDeviceSet(ds);
	} else if (intent.getData() != null) {
	/**
	* Case #2.
	* The intent.getData() is set as a content Uri when this activity is started by using
	* the floating action button from the DeviceSetChooserActivity and selecting one of the
	* local PDF files from the browser.
	*/
	Log.i(TAG, "onStart: Case #2: started by using the floating action button.");

	Uri uri = intent.getData();
	createAndJoinDeviceSet(uri);
	} else if (intent.hasExtra(Intent.EXTRA_STREAM)) {
	/**
	* Case #3.
	* The EXTRA_STREAM value is set when this activity is started by receiving an implicit
	* intent from another app by sharing a PDF file to the reader app.
	*/
	Log.i(TAG, "onStart: Case #3: started by an implicit intent from another app.");

	Uri uri = intent.getParcelableExtra(Intent.EXTRA_STREAM);
	createAndJoinDeviceSet(uri);
	}
	}

	private void createAndJoinDeviceSet(Uri fileUri) {
	// Get the file content.
	byte[] bytes = getBytesFromUri(fileUri);

	// Create a vdl File object representing this pdf file and put it in the db.
	File vFile = mDB.storeBytes(bytes, getTitleFromUri(fileUri));
	Log.i(TAG, "vFile created: " + vFile);
	if (vFile == null) {
	Log.e(TAG, "Could not store the file content of Uri: " + fileUri.toString());
	}
	mDB.addFile(vFile);

	// Create a device set object and put it in the db.
	DeviceSet ds = createDeviceSet(vFile);
	mDB.addDeviceSet(ds);

	// Join the device set.
	joinDeviceSet(ds);
	}

	@Override
	protected void onStop() {
	super.onStop();

	if (mDeviceSets != null) {
	mDeviceSets.discard();
	}

	leaveDeviceSet();
	}

	private DeviceMeta createDeviceMeta() {
	String deviceId = DeviceInfoFactory.getDeviceId(this);
	int page = 1;
	int zoom = 1;
	boolean linked = true;

	return new DeviceMeta(deviceId, page, zoom, linked);
	}

	private DeviceSet createDeviceSet(File vFile) {
	String id = IdFactory.getRandomId();
	String fileId = vFile.getId();
	Map<String, DeviceMeta> devices = new HashMap<>();

	return new DeviceSet(id, fileId, devices);
	}

	private void joinDeviceSet(DeviceSet ds) {
	// Get the file contents from the database
	// TODO(youngseokyoon): get the blob asynchronously. right now, it's blocking the UI thread.
	File file = mDB.getFileList().getItemById(ds.getFileId());
	byte[] bytes = mDB.readBytes(file);
	if (bytes == null) {
	Toast.makeText(this, "Could not load the file contents.", Toast.LENGTH_LONG).show();
	return;
	}

	// The pdf viewer widget requires the file to be an actual java.io.File object.
	// Create a temporary file and write the contents.
	java.io.File jFile = new java.io.File(getCacheDir(), ds.getFileId());
	try (FileOutputStream out = new FileOutputStream(jFile)) {
	out.write(bytes);
	} catch (IOException e) {
	handleException(e);
	}

	// Initialize the pdf viewer widget with the file content.
	Log.i(TAG, "File path: " + jFile.getPath());
	mPdfView.loadUrl("file:///android_asset/pdfjs/index.html?file=" + jFile.getPath());

	// Create a new device meta, and update the device set with it.
	Log.i(TAG, "Joining device set: " + ds.getId());
	DeviceMeta dm = createDeviceMeta();
	ds.getDevices().put(dm.getDeviceId(), dm);
	mDB.updateDeviceSet(ds);

	mCurrentDS = ds;
	}

	private void leaveDeviceSet() {
	if (mCurrentDS == null) {
	return;
	}

	Log.i(TAG, "Leaving device set: " + mCurrentDS.getId());
	Map<String, DeviceMeta> devices = mCurrentDS.getDevices();
	devices.remove(DeviceInfoFactory.getDeviceId(this));

	if (devices.isEmpty()) {
	Log.i(TAG, "Last one to leave the device set. Deleting " + mCurrentDS.getId());
	mDB.deleteDeviceSet(mCurrentDS.getId());
	} else {
	mDB.updateDeviceSet(mCurrentDS);
	}

	mCurrentDS = null;
	}

	private byte[] getBytesFromUri(Uri uri) {
	Log.i(TAG, "getBytesFromUri: " + uri.toString());

	try (InputStream in = getContentResolver().openInputStream(uri)) {
	// Get the entire file contents as a byte array.
	return ByteStreams.toByteArray(in);
	} catch (IOException e) {
	handleException(e);
	}

	return null;
	}

	private String getTitleFromUri(Uri uri) {
	try {
	Cursor cursor = getContentResolver().query(uri, null, null, null, null);

	int nameIndex = cursor.getColumnIndex(OpenableColumns.DISPLAY_NAME);
	cursor.moveToFirst();
	return cursor.getString(nameIndex);
	} catch (Exception e) {
	handleException(e);

	if (uri != null) {
	return uri.getLastPathSegment();
	}
	}

	return null;
	}

	private DeviceMeta getDeviceMeta() {
	return getDeviceMeta(mCurrentDS);
	}

	private DeviceMeta getDeviceMeta(DeviceSet ds) {
	String deviceId = DeviceInfoFactory.getDeviceId(this);

	if (ds == null \|\| !ds.getDevices().containsKey(deviceId)) {
	return null;
	}

	return ds.getDevices().get(deviceId);
	}

	/**
	* Move all the linked pages to their previous pages.
	*/
	private void prevPage() {
	if (mCurrentDS == null) {
	return;
	}

	// First, check if this device is linked or not.
	// If not, simply move the page of the current device.
	if (!getDeviceMeta().getLinked()) {
	DeviceMeta dm = getDeviceMeta();
	if (dm.getPage() > 1) {
	dm.setPage(dm.getPage() - 1);
	}

	return;
	}

	// Move all the linked pages
	Map<String, DeviceMeta> linkedDevices = getLinkedDevices();
	int smallestPage = getSmallestPage(linkedDevices);

	if (smallestPage > 1) {
	for (String deviceId : linkedDevices.keySet()) {
	DeviceMeta dm = linkedDevices.get(deviceId);
	dm.setPage(dm.getPage() - 1);
	}

	mDB.updateDeviceSet(mCurrentDS);
	}
	}

	/**
	* Move all the linked pages to their next pages.
	*/
	private void nextPage() {
	if (mCurrentDS == null) {
	return;
	}

	// First, check if this device is linked or not.
	// If not, simply move the page of the current device.
	if (!getDeviceMeta().getLinked()) {
	DeviceMeta dm = getDeviceMeta();
	if (dm.getPage() < mPdfView.getPageCount()) {
	dm.setPage(dm.getPage() + 1);
	}

	return;
	}

	// Move all the linked pages
	Map<String, DeviceMeta> linkedDevices = getLinkedDevices();
	int largestPage = getLargestPage(linkedDevices);

	if (largestPage < mPdfView.getPageCount()) {
	for (String deviceId : linkedDevices.keySet()) {
	DeviceMeta dm = linkedDevices.get(deviceId);
	dm.setPage(dm.getPage() + 1);
	}

	mDB.updateDeviceSet(mCurrentDS);
	}
	}

	private Map<String, DeviceMeta> getLinkedDevices() {
	if (mCurrentDS == null) {
	return null;
	}

	Map<String, DeviceMeta> devices = mCurrentDS.getDevices();
	Map<String, DeviceMeta> result = new HashMap<>();
	for (String deviceId : devices.keySet()) {
	DeviceMeta dm = devices.get(deviceId);
	if (dm.getLinked()) {
	result.put(deviceId, dm);
	}
	}

	return result;
	}

	private int getSmallestPage(Map<String, DeviceMeta> devices) {
	int result = -1;

	for (String deviceId : devices.keySet()) {
	DeviceMeta dm = devices.get(deviceId);
	if (result == -1 \|\| dm.getPage() < result) {
	result = dm.getPage();
	}
	}

	return result;
	}

	private int getLargestPage(Map<String, DeviceMeta> devices) {
	int result = -1;

	for (String deviceId : devices.keySet()) {
	DeviceMeta dm = devices.get(deviceId);
	if (result == -1 \|\| dm.getPage() > result) {
	result = dm.getPage();
	}
	}

	return result;
	}

	private static void handleException(Exception e) {
	Log.e(TAG, e.getMessage(), e);
	}

	@Override
	protected void onActivityResult(int requestCode, int resultCode, Intent data) {
	super.onActivityResult(requestCode, resultCode, data);

	Log.i(TAG, String.format("onActivityResult(%d, %d, data) called", requestCode, resultCode));
	if (mDB.onActivityResult(requestCode, resultCode, data)) {
	return;
	}

	// Any other activity results would be handled here.
	Log.w(TAG, String.format(
	"Unhandled activity result. (requestCode: %d, resultCode: %d)",
	requestCode, resultCode));
	}

	}