/*
* Copyright (C) 2010 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.Fragment;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.res.TypedArray;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.View.OnKeyListener;
import android.widget.ListView;
/**
* Shows a hierarchy of {@link Preference} objects as
* lists. 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 fragment will use, call
* {@link PreferenceManager#getDefaultSharedPreferences(android.content.Context)}
* with a context in the same package as this fragment.
* <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 fragment (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 fragment.
* <p>
* To specify an object hierarchy rooted with {@link PreferenceScreen}, use
* {@link #setPreferenceScreen(PreferenceScreen)}.
* <p>
* As a convenience, this fragment implements a click listener for any
* preference in the current hierarchy, see
* {@link #onPreferenceTreeClick(PreferenceScreen, Preference)}.
*
* <div class="special reference">
* <h3>Developer Guides</h3>
* <p>For information about using {@code PreferenceFragment},
* read the <a href="{@docRoot}guide/topics/ui/settings.html">Settings</a>
* guide.</p>
* </div>
*
* <a name="SampleCode"></a>
* <h3>Sample Code</h3>
*
* <p>The following sample code shows a simple preference fragment that is
* populated from a resource. The resource it loads is:</p>
*
* {@sample development/samples/ApiDemos/res/xml/preferences.xml preferences}
*
* <p>The fragment implementation itself simply populates the preferences
* when created. Note that the preferences framework takes care of loading
* the current values out of the app preferences and writing them when changed:</p>
*
* {@sample development/samples/ApiDemos/src/com/example/android/apis/preference/FragmentPreferences.java
* fragment}
*
* @see Preference
* @see PreferenceScreen
*/
public abstract class PreferenceFragment extends Fragment implements
PreferenceManager.OnPreferenceTreeClickListener {
private static final String PREFERENCES_TAG = "android:preferences";
private PreferenceManager mPreferenceManager;
private ListView mList;
private boolean mHavePrefs;
private boolean mInitDone;
private int mLayoutResId = com.android.internal.R.layout.preference_list_fragment;
/**
* The starting request code given out to preference framework.
*/
private static final int FIRST_REQUEST_CODE = 100;
private static final int MSG_BIND_PREFERENCES = 1;
private Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MSG_BIND_PREFERENCES:
bindPreferences();
break;
}
}
};
final private Runnable mRequestFocus = new Runnable() {
public void run() {
mList.focusableViewAvailable(mList);
}
};
/**
* Interface that PreferenceFragment's containing activity should
* implement to be able to process preference items that wish to
* switch to a new fragment.
*/
public interface OnPreferenceStartFragmentCallback {
/**
* Called when the user has clicked on a Preference that has
* a fragment class name associated with it. The implementation
* to should instantiate and switch to an instance of the given
* fragment.
*/
boolean onPreferenceStartFragment(PreferenceFragment caller, Preference pref);
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mPreferenceManager = new PreferenceManager(getActivity(), FIRST_REQUEST_CODE);
mPreferenceManager.setFragment(this);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
TypedArray a = getActivity().obtainStyledAttributes(null,
com.android.internal.R.styleable.PreferenceFragment,
com.android.internal.R.attr.preferenceFragmentStyle,
0);
mLayoutResId = a.getResourceId(com.android.internal.R.styleable.PreferenceFragment_layout,
mLayoutResId);
a.recycle();
return inflater.inflate(mLayoutResId, container, false);
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
if (mHavePrefs) {
bindPreferences();
}
mInitDone = true;
if (savedInstanceState != null) {
Bundle container = savedInstanceState.getBundle(PREFERENCES_TAG);
if (container != null) {
final PreferenceScreen preferenceScreen = getPreferenceScreen();
if (preferenceScreen != null) {
preferenceScreen.restoreHierarchyState(container);
}
}
}
}
@Override
public void onStart() {
super.onStart();
mPreferenceManager.setOnPreferenceTreeClickListener(this);
}
@Override
public void onStop() {
super.onStop();
mPreferenceManager.dispatchActivityStop();
mPreferenceManager.setOnPreferenceTreeClickListener(null);
}
@Override
public void onDestroyView() {
mList = null;
mHandler.removeCallbacks(mRequestFocus);
mHandler.removeMessages(MSG_BIND_PREFERENCES);
super.onDestroyView();
}
@Override
public void onDestroy() {
super.onDestroy();
mPreferenceManager.dispatchActivityDestroy();
}
@Override
public 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
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
mPreferenceManager.dispatchActivityResult(requestCode, resultCode, data);
}
/**
* Returns the {@link PreferenceManager} used by this fragment.
* @return The {@link PreferenceManager}.
*/
public PreferenceManager getPreferenceManager() {
return mPreferenceManager;
}
/**
* Sets the root of the preference hierarchy that this fragment is showing.
*
* @param preferenceScreen The root {@link PreferenceScreen} of the preference hierarchy.
*/
public void setPreferenceScreen(PreferenceScreen preferenceScreen) {
if (mPreferenceManager.setPreferences(preferenceScreen) && preferenceScreen != null) {
onUnbindPreferences();
mHavePrefs = true;
if (mInitDone) {
postBindPreferences();
}
}
}
/**
* Gets the root of the preference hierarchy that this fragment 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(getActivity(),
preferencesResId, getPreferenceScreen()));
}
/**
* {@inheritDoc}
*/
public boolean onPreferenceTreeClick(PreferenceScreen preferenceScreen,
Preference preference) {
if (preference.getFragment() != null &&
getActivity() instanceof OnPreferenceStartFragmentCallback) {
return ((OnPreferenceStartFragmentCallback)getActivity()).onPreferenceStartFragment(
this, 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);
}
private void requirePreferenceManager() {
if (mPreferenceManager == null) {
throw new RuntimeException("This should be called after super.onCreate.");
}
}
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());
}
onBindPreferences();
}
/** @hide */
protected void onBindPreferences() {
}
/** @hide */
protected void onUnbindPreferences() {
}
/** @hide */
public ListView getListView() {
ensureList();
return mList;
}
/** @hide */
public boolean hasListView() {
if (mList != null) {
return true;
}
View root = getView();
if (root == null) {
return false;
}
View rawListView = root.findViewById(android.R.id.list);
if (!(rawListView instanceof ListView)) {
return false;
}
mList = (ListView)rawListView;
if (mList == null) {
return false;
}
return true;
}
private void ensureList() {
if (mList != null) {
return;
}
View root = getView();
if (root == null) {
throw new IllegalStateException("Content view not yet created");
}
View rawListView = root.findViewById(android.R.id.list);
if (!(rawListView instanceof ListView)) {
throw new RuntimeException(
"Content has view with id attribute 'android.R.id.list' "
+ "that is not a ListView class");
}
mList = (ListView)rawListView;
if (mList == null) {
throw new RuntimeException(
"Your content must have a ListView whose id attribute is " +
"'android.R.id.list'");
}
mList.setOnKeyListener(mListOnKeyListener);
mHandler.post(mRequestFocus);
}
private OnKeyListener mListOnKeyListener = new OnKeyListener() {
@Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
Object selectedItem = mList.getSelectedItem();
if (selectedItem instanceof Preference) {
View selectedView = mList.getSelectedView();
return ((Preference)selectedItem).onKey(
selectedView, keyCode, event);
}
return false;
}
};
}
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