/*
* Copyright (C) 2007 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.preference;
import android.app.Activity;
import android.app.ListActivity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.view.Window;
/**
* Shows a hierarchy of {@link Preference} objects as
* lists, possibly spanning multiple screens. These preferences will
* automatically save to {@link SharedPreferences} as the user interacts with
* them. To retrieve an instance of {@link SharedPreferences} that the
* preference hierarchy in this activity will use, call
* {@link PreferenceManager#getDefaultSharedPreferences(android.content.Context)}
* with a context in the same package as this activity.
* <p>
* Furthermore, the preferences shown will follow the visual style of system
* preferences. It is easy to create a hierarchy of preferences (that can be
* shown on multiple screens) via XML. For these reasons, it is recommended to
* use this activity (as a superclass) to deal with preferences in applications.
* <p>
* A {@link PreferenceScreen} object should be at the top of the preference
* hierarchy. Furthermore, subsequent {@link PreferenceScreen} in the hierarchy
* denote a screen break--that is the preferences contained within subsequent
* {@link PreferenceScreen} should be shown on another screen. The preference
* framework handles showing these other screens from the preference hierarchy.
* <p>
* The preference hierarchy can be formed in multiple ways:
* <li> From an XML file specifying the hierarchy
* <li> From different {@link Activity Activities} that each specify its own
* preferences in an XML file via {@link Activity} meta-data
* <li> From an object hierarchy rooted with {@link PreferenceScreen}
* <p>
* To inflate from XML, use the {@link #addPreferencesFromResource(int)}. The
* root element should be a {@link PreferenceScreen}. Subsequent elements can point
* to actual {@link Preference} subclasses. As mentioned above, subsequent
* {@link PreferenceScreen} in the hierarchy will result in the screen break.
* <p>
* To specify an {@link Intent} to query {@link Activity Activities} that each
* have preferences, use {@link #addPreferencesFromIntent}. Each
* {@link Activity} can specify meta-data in the manifest (via the key
* {@link PreferenceManager#METADATA_KEY_PREFERENCES}) that points to an XML
* resource. These XML resources will be inflated into a single preference
* hierarchy and shown by this activity.
* <p>
* To specify an object hierarchy rooted with {@link PreferenceScreen}, use
* {@link #setPreferenceScreen(PreferenceScreen)}.
* <p>
* As a convenience, this activity implements a click listener for any
* preference in the current hierarchy, see
* {@link #onPreferenceTreeClick(PreferenceScreen, Preference)}.
*
* @see Preference
* @see PreferenceScreen
*/
public abstract class PreferenceActivity extends ListActivity implements
PreferenceManager.OnPreferenceTreeClickListener {
private static final String PREFERENCES_TAG = "android:preferences";
private PreferenceManager mPreferenceManager;
/**
* The starting request code given out to preference framework.
*/
private static final int FIRST_REQUEST_CODE = 100;
private static final int MSG_BIND_PREFERENCES = 0;
private Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MSG_BIND_PREFERENCES:
bindPreferences();
break;
}
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(com.android.internal.R.layout.preference_list_content);
mPreferenceManager = onCreatePreferenceManager();
getListView().setScrollBarStyle(View.SCROLLBARS_INSIDE_OVERLAY);
}
@Override
protected void onStop() {
super.onStop();
mPreferenceManager.dispatchActivityStop();
}
@Override
protected void onDestroy() {
super.onDestroy();
mPreferenceManager.dispatchActivityDestroy();
}
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
final PreferenceScreen preferenceScreen = getPreferenceScreen();
if (preferenceScreen != null) {
Bundle container = new Bundle();
preferenceScreen.saveHierarchyState(container);
outState.putBundle(PREFERENCES_TAG, container);
}
}
@Override
protected void onRestoreInstanceState(Bundle state) {
super.onRestoreInstanceState(state);
Bundle container = state.getBundle(PREFERENCES_TAG);
if (container != null) {
final PreferenceScreen preferenceScreen = getPreferenceScreen();
if (preferenceScreen != null) {
preferenceScreen.restoreHierarchyState(container);
}
}
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
mPreferenceManager.dispatchActivityResult(requestCode, resultCode, data);
}
@Override
public void onContentChanged() {
super.onContentChanged();
postBindPreferences();
}
/**
* Posts a message to bind the preferences to the list view.
* <p>
* Binding late is preferred as any custom preference types created in
* {@link #onCreate(Bundle)} are able to have their views recycled.
*/
private void postBindPreferences() {
if (mHandler.hasMessages(MSG_BIND_PREFERENCES)) return;
mHandler.obtainMessage(MSG_BIND_PREFERENCES).sendToTarget();
}
private void bindPreferences() {
final PreferenceScreen preferenceScreen = getPreferenceScreen();
if (preferenceScreen != null) {
preferenceScreen.bind(getListView());
}
}
/**
* Creates the {@link PreferenceManager}.
*
* @return The {@link PreferenceManager} used by this activity.
*/
private PreferenceManager onCreatePreferenceManager() {
PreferenceManager preferenceManager = new PreferenceManager(this, FIRST_REQUEST_CODE);
preferenceManager.setOnPreferenceTreeClickListener(this);
return preferenceManager;
}
/**
* Returns the {@link PreferenceManager} used by this activity.
* @return The {@link PreferenceManager}.
*/
public PreferenceManager getPreferenceManager() {
return mPreferenceManager;
}
private void requirePreferenceManager() {
if (mPreferenceManager == null) {
throw new RuntimeException("This should be called after super.onCreate.");
}
}
/**
* Sets the root of the preference hierarchy that this activity is showing.
*
* @param preferenceScreen The root {@link PreferenceScreen} of the preference hierarchy.
*/
public void setPreferenceScreen(PreferenceScreen preferenceScreen) {
if (mPreferenceManager.setPreferences(preferenceScreen) && preferenceScreen != null) {
postBindPreferences();
CharSequence title = getPreferenceScreen().getTitle();
// Set the title of the activity
if (title != null) {
setTitle(title);
}
}
}
/**
* Gets the root of the preference hierarchy that this activity is showing.
*
* @return The {@link PreferenceScreen} that is the root of the preference
* hierarchy.
*/
public PreferenceScreen getPreferenceScreen() {
return mPreferenceManager.getPreferenceScreen();
}
/**
* Adds preferences from activities that match the given {@link Intent}.
*
* @param intent The {@link Intent} to query activities.
*/
public void addPreferencesFromIntent(Intent intent) {
requirePreferenceManager();
setPreferenceScreen(mPreferenceManager.inflateFromIntent(intent, getPreferenceScreen()));
}
/**
* Inflates the given XML resource and adds the preference hierarchy to the current
* preference hierarchy.
*
* @param preferencesResId The XML resource ID to inflate.
*/
public void addPreferencesFromResource(int preferencesResId) {
requirePreferenceManager();
setPreferenceScreen(mPreferenceManager.inflateFromResource(this, preferencesResId,
getPreferenceScreen()));
}
/**
* {@inheritDoc}
*/
public boolean onPreferenceTreeClick(PreferenceScreen preferenceScreen, Preference preference) {
return false;
}
/**
* Finds a {@link Preference} based on its key.
*
* @param key The key of the preference to retrieve.
* @return The {@link Preference} with the key, or null.
* @see PreferenceGroup#findPreference(CharSequence)
*/
public Preference findPreference(CharSequence key) {
if (mPreferenceManager == null) {
return null;
}
return mPreferenceManager.findPreference(key);
}
@Override
protected void onNewIntent(Intent intent) {
if (mPreferenceManager != null) {
mPreferenceManager.dispatchNewIntent(intent);
}
}
}
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