/*
* Copyright (C) 2012 The Android Open Source Project
*
* 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 android.support.v4.app;
import android.app.Activity;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager.NameNotFoundException;
import android.os.Build;
import android.support.v4.content.IntentCompat;
import android.util.Log;
import java.util.ArrayList;
import java.util.Iterator;
/**
* Utility class for constructing synthetic back stacks for cross-task navigation
* on Android 3.0 and newer.
*
* <p>In API level 11 (Android 3.0/Honeycomb) the recommended conventions for
* app navigation using the back key changed. The back key's behavior is local
* to the current task and does not capture navigation across different tasks.
* Navigating across tasks and easily reaching the previous task is accomplished
* through the "recents" UI, accessible through the software-provided Recents key
* on the navigation or system bar. On devices with the older hardware button configuration
* the recents UI can be accessed with a long press on the Home key.</p>
*
* <p>When crossing from one task stack to another post-Android 3.0,
* the application should synthesize a back stack/history for the new task so that
* the user may navigate out of the new task and back to the Launcher by repeated
* presses of the back key. Back key presses should not navigate across task stacks.</p>
*
* <p>TaskStackBuilder provides a backward-compatible way to obey the correct conventions
* around cross-task navigation on the device's version of the platform. On devices running
* Android 3.0 or newer, calls to the {@link #startActivities()} method or sending the
* {@link PendingIntent} generated by {@link #getPendingIntent(int, int)} will construct
* the synthetic back stack as prescribed. On devices running older versions of the platform,
* these same calls will invoke the topmost activity in the supplied stack, ignoring
* the rest of the synthetic stack and allowing the back key to navigate back to the previous
* task.</p>
*
* <div class="special reference">
* <h3>About Navigation</h3>
* For more detailed information about tasks, the back stack, and navigation design guidelines,
* please read
* <a href="{@docRoot}guide/topics/fundamentals/tasks-and-back-stack.html">Tasks and Back Stack</a>
* from the developer guide and <a href="{@docRoot}design/patterns/navigation.html">Navigation</a>
* from the design guide.
* </div>
*/
public class TaskStackBuilder implements Iterable<Intent> {
private static final String TAG = "TaskStackBuilder";
interface TaskStackBuilderImpl {
PendingIntent getPendingIntent(Context context, Intent[] intents, int requestCode,
int flags);
}
static class TaskStackBuilderImplBase implements TaskStackBuilderImpl {
public PendingIntent getPendingIntent(Context context, Intent[] intents, int requestCode,
int flags) {
Intent topIntent = intents[intents.length - 1];
topIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
return PendingIntent.getActivity(context, requestCode, topIntent, flags);
}
}
static class TaskStackBuilderImplHoneycomb implements TaskStackBuilderImpl {
public PendingIntent getPendingIntent(Context context, Intent[] intents, int requestCode,
int flags) {
intents[0].addFlags(Intent.FLAG_ACTIVITY_NEW_TASK |
IntentCompat.FLAG_ACTIVITY_CLEAR_TASK);
return TaskStackBuilderHoneycomb.getActivitiesPendingIntent(context, requestCode,
intents, flags);
}
}
private static final TaskStackBuilderImpl IMPL;
static {
if (Build.VERSION.SDK_INT >= 11) {
IMPL = new TaskStackBuilderImplHoneycomb();
} else {
IMPL = new TaskStackBuilderImplBase();
}
}
private final ArrayList<Intent> mIntents = new ArrayList<Intent>();
private final Context mSourceContext;
private TaskStackBuilder(Context a) {
mSourceContext = a;
}
/**
* Return a new TaskStackBuilder for launching a fresh task stack consisting
* of a series of activities.
*
* @param context The context that will launch the new task stack or generate a PendingIntent
* @return A new TaskStackBuilder
*/
public static TaskStackBuilder from(Context context) {
return new TaskStackBuilder(context);
}
/**
* Add a new Intent to the task stack. The most recently added Intent will invoke
* the Activity at the top of the final task stack.
*
* @param nextIntent Intent for the next Activity in the synthesized task stack
* @return This TaskStackBuilder for method chaining
*/
public TaskStackBuilder addNextIntent(Intent nextIntent) {
mIntents.add(nextIntent);
return this;
}
/**
* Add the activity parent chain as specified by manifest <meta-data> elements
* to the task stack builder.
*
* @param sourceActivity All parents of this activity will be added
* @return This TaskStackBuilder for method chaining
*/
public TaskStackBuilder addParentStack(Activity sourceActivity) {
final int insertAt = mIntents.size();
Intent parent = NavUtils.getParentActivityIntent(sourceActivity);
while (parent != null) {
mIntents.add(insertAt, parent);
try {
parent = NavUtils.getParentActivityIntent(sourceActivity, parent.getComponent());
} catch (NameNotFoundException e) {
Log.e(TAG, "Bad ComponentName while traversing activity parent metadata");
throw new IllegalArgumentException(e);
}
}
return this;
}
/**
* Add the activity parent chain as specified by manifest <meta-data> elements
* to the task stack builder.
*
* @param sourceActivityClass All parents of this activity will be added
* @return This TaskStackBuilder for method chaining
*/
public TaskStackBuilder addParentStack(Class<?> sourceActivityClass) {
final int insertAt = mIntents.size();
try {
Intent parent = NavUtils.getParentActivityIntent(mSourceContext, sourceActivityClass);
while (parent != null) {
mIntents.add(insertAt, parent);
parent = NavUtils.getParentActivityIntent(mSourceContext, parent.getComponent());
}
} catch (NameNotFoundException e) {
Log.e(TAG, "Bad ComponentName while traversing activity parent metadata");
throw new IllegalArgumentException(e);
}
return this;
}
/**
* @return the number of intents added so far.
*/
public int getIntentCount() {
return mIntents.size();
}
/**
* Get the intent at the specified index.
* Useful if you need to modify the flags or extras of an intent that was previously added,
* for example with {@link #addParentStack(Activity)}.
*
* @param index Index from 0-getIntentCount()
* @return the intent at position index
*/
public Intent getIntent(int index) {
return mIntents.get(index);
}
public Iterator<Intent> iterator() {
return mIntents.iterator();
}
/**
* Start the task stack constructed by this builder. The Context used to obtain
* this builder must be an Activity.
*
* <p>On devices that do not support API level 11 or higher the topmost activity
* will be started as a new task. On devices that do support API level 11 or higher
* the new task stack will be created in its entirety.</p>
*/
public void startActivities() {
if (mIntents.isEmpty()) {
throw new IllegalStateException(
"No intents added to TaskStackBuilder; cannot startActivities");
}
Intent[] intents = mIntents.toArray(new Intent[mIntents.size()]);
intents[0].addFlags(Intent.FLAG_ACTIVITY_NEW_TASK |
IntentCompat.FLAG_ACTIVITY_CLEAR_TASK |
IntentCompat.FLAG_ACTIVITY_TASK_ON_HOME);
if (!ActivityCompat.startActivities((Activity) mSourceContext, intents)) {
Intent topIntent = intents[intents.length - 1];
topIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
mSourceContext.startActivity(topIntent);
}
}
/**
* Obtain a {@link PendingIntent} for launching the task constructed by this builder so far.
*
* @param requestCode Private request code for the sender
* @param flags May be {@link PendingIntent#FLAG_ONE_SHOT},
* {@link PendingIntent#FLAG_NO_CREATE}, {@link PendingIntent#FLAG_CANCEL_CURRENT},
* {@link PendingIntent#FLAG_UPDATE_CURRENT}, or any of the flags supported by
* {@link Intent#fillIn(Intent, int)} to control which unspecified parts of the
* intent that can be supplied when the actual send happens.
* @return The obtained PendingIntent
*/
public PendingIntent getPendingIntent(int requestCode, int flags) {
Intent[] intents = mIntents.toArray(new Intent[mIntents.size()]);
return IMPL.getPendingIntent(mSourceContext, intents, requestCode, flags);
}
}