ScreenTimeoutSettings.java

package net.bible.service.device;

import android.content.ContentResolver;
import android.content.SharedPreferences;
import android.provider.Settings;
import android.provider.Settings.SettingNotFoundException;
import android.util.Log;

import net.bible.android.BibleApplication;
import net.bible.android.activity.R;
import net.bible.android.control.event.apptobackground.AppToBackgroundEvent;
import net.bible.service.common.CommonUtils;

import org.apache.commons.lang3.StringUtils;

import de.greenrobot.event.EventBus;

/**
 * Manage local Window timeout (Sleep) time which is different to the default/system Sleep time
 * 
 * @author Martin Denham [mjdenham at gmail dot com]
 * @see gnu.lgpl.License for license details.<br>
 *      The copyright to this program is held by it's author.
 */
public class ScreenTimeoutSettings {

	public static final String SCREEN_TIMEOUT_PREF = "screen_timeout_pref";
	
	// persist the system screen timeout otherwise it could potentially be lost if not reset and app is terminated
	public static final String SYSTEM_SCREEN_TIMEOUT_KEY = "system_screen_timeout";
	
	// Offset custom timeout by 27 milliseconds to ensure custom timeouts are recognisable - all standard timeouts will be whole seconds
	// This is a safety measure to allow custom timeouts to be recognised and not permanently override system timeout
	private static final int CUSTOM_TIMEOUT_OFFSET_MARKER_MILLIS = 17;

	public static final int NOT_SET = -999;
	public static final int DEFAULT_VALUE = -998;
	
	private static final int ONE_MINUTE_MILLIS = 60*1000;
	
	private static final String TAG = "BibleApplication";

	/**
	 * Add fore/background event hook to manage screen timeout setting
	 */
	public void overrideScreenTimeout() {
		
		// listen for app to come and go to override screen timeout value
		EventBus.getDefault().register(this);
	}

	/**
	 * Set/reset app/standard screen timeout values
	 */
	public void onEvent(AppToBackgroundEvent event) {
		if (event.isMovedToBackground()) {
			try {
				restoreSystemTimeout();
			} catch (Exception e) {
				// Avoid occasional exception in setScreenTimeout when restoring system timeout:
				// java.lang.SecurityException: Permission Denial: writing com.android.providers.settings.OverlaySettingsProvider uri content://settings/system from pid=9176, uid=10076 requires android.permission.WRITE_SETTINGS
				// Bad, but cannot allow app to crash on exit - system timeout may not be set if crash occurs in above method
				// It only occurred twice among thousands of users in first few days of release
				Log.e(TAG, "Error restoring system timeout", e);
			}
		} else {
			// Now in foreground
			
			// save the, possibly changed, system timeout
			saveSystemTimeout();
			
			// set And Bible screen timeout
			setScreenTimeout();
		}
	}
	
	/**
	 * Default, 2, 10, 30 minutes
	 * @return
	 */
	public String[] getPreferenceEntries() {
        String[] entries = new String[4];
        
        entries[0] = CommonUtils.getResourceString(R.string.default_value);
        entries[1] = CommonUtils.getResourceString(R.string.x_minutes, 2);
        entries[2] = CommonUtils.getResourceString(R.string.x_minutes, 10);
        entries[3] = CommonUtils.getResourceString(R.string.x_minutes, 30);
        
        return entries;
	}

	/** Must be array of String not int[] or Integer[] because of deficiency in Android Preference handling
	 */
	public String[] getPreferenceEntryValues() {
        String[] entryValues = new String[4];
        
        entryValues[0] = Integer.toString(DEFAULT_VALUE);
        entryValues[1] = Integer.toString((2*ONE_MINUTE_MILLIS)+CUSTOM_TIMEOUT_OFFSET_MARKER_MILLIS);
        entryValues[2] = Integer.toString((10*ONE_MINUTE_MILLIS)+CUSTOM_TIMEOUT_OFFSET_MARKER_MILLIS);
        entryValues[3] = Integer.toString((30*ONE_MINUTE_MILLIS)+CUSTOM_TIMEOUT_OFFSET_MARKER_MILLIS);
        
        return entryValues;
	}
	
	public void saveSystemTimeout() {
		try {
			// save old timeout ready for restore when app goes to background
			int currentTimeoutTime = Settings.System.getInt(getContentResolver(), Settings.System.SCREEN_OFF_TIMEOUT);
			
			// must avoid saving an And Bible specific custom timeout as the systemTimeout because this would cause And Bible to overwrite the default timeout value
			// we use the OFFSET_MARKER to distinguish system and custom timeouts because all system timeouts should be a whole number of seconds
			boolean isCurrentTimeoutCustom = ((currentTimeoutTime % 1000)==CUSTOM_TIMEOUT_OFFSET_MARKER_MILLIS); 
			if (!isCurrentTimeoutCustom) {
				CommonUtils.getSharedPreferences().edit()
							.putInt(SYSTEM_SCREEN_TIMEOUT_KEY, currentTimeoutTime)
							.commit();
			}
		} catch (SettingNotFoundException snfe) {
			Log.e(TAG, "Error setting Window timeout", snfe);
		}
	}
	
	private static int getSystemTimeoutTimeMillis() {
		return CommonUtils.getSharedPreferences().getInt(SYSTEM_SCREEN_TIMEOUT_KEY, NOT_SET);
	}

	public void restoreSystemTimeout() {
		setScreenTimeout(getSystemTimeoutTimeMillis());
	}

	public void setScreenTimeout() {
		int newTimeout = getScreenTimeoutPreferenceValue();
		setScreenTimeout(newTimeout);
	}

	public static void setScreenTimeout(int newScreenTimeout) {
		// default value is whatever is set as the Android Sleep time in the main Android settings screen
		if (newScreenTimeout==DEFAULT_VALUE) {
			newScreenTimeout = getSystemTimeoutTimeMillis();
		}
		
		if (newScreenTimeout!=NOT_SET) {
			Log.d(TAG, "Set screen timeout:"+newScreenTimeout);
			//override screen timeout
			// Set screen timeout to 10 minutes...
			Settings.System.putInt(getContentResolver(), Settings.System.SCREEN_OFF_TIMEOUT, newScreenTimeout);
		}
	}

	private int getScreenTimeoutPreferenceValue() {
		int screenTimeoutPref = NOT_SET;
		try {
			SharedPreferences preferences = CommonUtils.getSharedPreferences();
			if (preferences!=null) {
				String prefString = preferences.getString(SCREEN_TIMEOUT_PREF, Integer.toString(NOT_SET));
				if (StringUtils.isNotEmpty(prefString)) {
					screenTimeoutPref = Integer.parseInt(prefString);
				}
			}
		} catch (Exception e) {
			// just allow return of NOT_SET
			Log.e(TAG, "Error getting screen timeout preference setting", e);
		}
		return screenTimeoutPref;
	}
	
	private static ContentResolver getContentResolver() {
		return BibleApplication.getApplication().getContentResolver();
	}
}