PreferenceFragment.java

package android.support.v4.preference;

import java.lang.reflect.Constructor;
import java.lang.reflect.Method;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.preference.Preference;
import android.preference.PreferenceManager;
import android.preference.PreferenceScreen;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ListView;

/**
 * A PreferenceFragment for the support library. Based on the platform's code with some removed features and a basic ListView layout.
 * 
 * @author Christophe Beyls
 * 
 */
public abstract class PreferenceFragment extends Fragment {

	private static final int FIRST_REQUEST_CODE = 100;
	private static final int MSG_BIND_PREFERENCES = 1;
	private static final int MSG_REQUEST_FOCUS = 2;
	private static final String PREFERENCES_TAG = "android:preferences";
	private static final float HC_HORIZONTAL_PADDING = 16;

	@SuppressLint("HandlerLeak")
	private final Handler mHandler = new Handler() {
		@Override
		public void handleMessage(Message msg) {
			switch (msg.what) {
			case MSG_BIND_PREFERENCES:
				bindPreferences();
				break;
			case MSG_REQUEST_FOCUS:
				mList.focusableViewAvailable(mList);
				break;
			}
		}
	};

	private boolean mHavePrefs;
	private boolean mInitDone;
	private ListView mList;
	private PreferenceManager mPreferenceManager;

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		try {
			Constructor<PreferenceManager> c = PreferenceManager.class.getDeclaredConstructor(Activity.class, int.class);
			c.setAccessible(true);
			mPreferenceManager = c.newInstance(this.getActivity(), FIRST_REQUEST_CODE);
		} catch (Exception ignored) {
		}
	}

	@Override
	public View onCreateView(LayoutInflater layoutInflater, ViewGroup viewGroup, Bundle savedInstanceState) {
		ListView listView = new ListView(getActivity());
		listView.setId(android.R.id.list);
		if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
			final int horizontalPadding = (int) (HC_HORIZONTAL_PADDING * getResources().getDisplayMetrics().density);
			listView.setPadding(horizontalPadding, 0, horizontalPadding, 0);
		}
		return listView;
	}

	@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);
				}
			}
		}
	}

	public void onStop() {
		super.onStop();
		try {
			Method m = PreferenceManager.class.getDeclaredMethod("dispatchActivityStop");
			m.setAccessible(true);
			m.invoke(mPreferenceManager);
		} catch (Exception ignored) {
		}
	}

	public void onDestroyView() {
		mList = null;
		mHandler.removeCallbacksAndMessages(null);
		super.onDestroyView();
	}

	public void onDestroy() {
		super.onDestroy();
		try {
			Method m = PreferenceManager.class.getDeclaredMethod("dispatchActivityDestroy");
			m.setAccessible(true);
			m.invoke(mPreferenceManager);
		} catch (Exception ignored) {
		}
	}

	public void onSaveInstanceState(Bundle outState) {
		super.onSaveInstanceState(outState);
		PreferenceScreen preferenceScreen = getPreferenceScreen();
		if (preferenceScreen != null) {
			Bundle container = new Bundle();
			preferenceScreen.saveHierarchyState(container);
			outState.putBundle(PREFERENCES_TAG, container);
		}
	}

	public void onActivityResult(int requestCode, int resultCode, Intent data) {
		super.onActivityResult(requestCode, resultCode, data);
		try {
			Method m = PreferenceManager.class.getDeclaredMethod("dispatchActivityResult", int.class, int.class, Intent.class);
			m.setAccessible(true);
			m.invoke(mPreferenceManager, requestCode, resultCode, data);
		} catch (Exception ignored) {
		}
	}

	public PreferenceManager getPreferenceManager() {
		return mPreferenceManager;
	}

	public void setPreferenceScreen(PreferenceScreen screen) {
		try {
			Method m = PreferenceManager.class.getDeclaredMethod("setPreferences", PreferenceScreen.class);
			m.setAccessible(true);
			boolean result = (Boolean) m.invoke(mPreferenceManager, screen);
			if (result && (screen != null)) {
				mHavePrefs = true;
				if (mInitDone) {
					postBindPreferences();
				}
			}
		} catch (Exception ignored) {
		}
	}

	public PreferenceScreen getPreferenceScreen() {
		try {
			Method m = PreferenceManager.class.getDeclaredMethod("getPreferenceScreen");
			m.setAccessible(true);
			return (PreferenceScreen) m.invoke(mPreferenceManager);
		} catch (Exception e) {
			return null;
		}
	}

	public void addPreferencesFromIntent(Intent intent) {
		requirePreferenceManager();
		try {
			Method m = PreferenceManager.class.getDeclaredMethod("inflateFromIntent", Intent.class, PreferenceScreen.class);
			m.setAccessible(true);
			PreferenceScreen screen = (PreferenceScreen) m.invoke(mPreferenceManager, intent, getPreferenceScreen());
			setPreferenceScreen(screen);
		} catch (Exception ignored) {
		}
	}

	public void addPreferencesFromResource(int resId) {
		requirePreferenceManager();
		try {
			Method m = PreferenceManager.class.getDeclaredMethod("inflateFromResource", Context.class, int.class, PreferenceScreen.class);
			m.setAccessible(true);
			PreferenceScreen screen = (PreferenceScreen) m.invoke(mPreferenceManager, getActivity(), resId, getPreferenceScreen());
			setPreferenceScreen(screen);
		} catch (Exception ignored) {
		}
	}

	public Preference findPreference(CharSequence key) {
		if (mPreferenceManager == null) {
			return null;
		}
		return mPreferenceManager.findPreference(key);
	}

	private void requirePreferenceManager() {
		if (this.mPreferenceManager == null) {
			throw new RuntimeException("This should be called after super.onCreate.");
		}
	}

	private void postBindPreferences() {
		if (!mHandler.hasMessages(MSG_BIND_PREFERENCES)) {
			mHandler.sendEmptyMessage(MSG_BIND_PREFERENCES);
		}
	}

	private void bindPreferences() {
		final PreferenceScreen preferenceScreen = getPreferenceScreen();
		if (preferenceScreen != null) {
			preferenceScreen.bind(getListView());
		}
	}

	public ListView getListView() {
		ensureList();
		return mList;
	}

	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 == null) {
			throw new RuntimeException("Your content must have a ListView whose id attribute is '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;
		mHandler.sendEmptyMessage(MSG_REQUEST_FOCUS);
	}
}