src/com/android/browser/BrowserSettings.java

/*
 * Copyright (C) 2011 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 com.android.browser;

import android.app.ActivityManager;
import android.content.ContentResolver;
import android.content.Context;
import android.content.SharedPreferences;
import android.content.SharedPreferences.OnSharedPreferenceChangeListener;
import android.os.Build;
import android.os.Message;
import android.preference.PreferenceManager;
import android.provider.Browser;
import android.webkit.CookieManager;
import android.webkit.GeolocationPermissions;
import android.webkit.WebIconDatabase;
import android.webkit.WebSettings;
import android.webkit.WebSettings.AutoFillProfile;
import android.webkit.WebSettings.LayoutAlgorithm;
import android.webkit.WebSettings.PluginState;
import android.webkit.WebSettings.TextSize;
import android.webkit.WebSettings.ZoomDensity;
import android.webkit.WebStorage;
import android.webkit.WebView;
import android.webkit.WebViewDatabase;

import com.android.browser.homepages.HomeProvider;
import com.android.browser.provider.BrowserProvider;
import com.android.browser.search.SearchEngine;
import com.android.browser.search.SearchEngines;

import java.lang.ref.WeakReference;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.WeakHashMap;

/**
 * Class for managing settings
 */
public class BrowserSettings implements OnSharedPreferenceChangeListener,
        PreferenceKeys {

    // TODO: Do something with this UserAgent stuff
    private static final String DESKTOP_USERAGENT = "Mozilla/5.0 (X11; " +
        "Linux x86_64) AppleWebKit/534.24 (KHTML, like Gecko) " +
        "Chrome/11.0.696.34 Safari/534.24";

    private static final String IPHONE_USERAGENT = "Mozilla/5.0 (iPhone; U; " +
        "CPU iPhone OS 4_0 like Mac OS X; en-us) AppleWebKit/532.9 " +
        "(KHTML, like Gecko) Version/4.0.5 Mobile/8A293 Safari/6531.22.7";

    private static final String IPAD_USERAGENT = "Mozilla/5.0 (iPad; U; " +
        "CPU OS 3_2 like Mac OS X; en-us) AppleWebKit/531.21.10 " +
        "(KHTML, like Gecko) Version/4.0.4 Mobile/7B367 Safari/531.21.10";

    private static final String FROYO_USERAGENT = "Mozilla/5.0 (Linux; U; " +
        "Android 2.2; en-us; Nexus One Build/FRF91) AppleWebKit/533.1 " +
        "(KHTML, like Gecko) Version/4.0 Mobile Safari/533.1";

    private static final String HONEYCOMB_USERAGENT = "Mozilla/5.0 (Linux; U; " +
        "Android 3.1; en-us; Xoom Build/HMJ25) AppleWebKit/534.13 " +
        "(KHTML, like Gecko) Version/4.0 Safari/534.13";

    private static final String USER_AGENTS[] = { null,
            DESKTOP_USERAGENT,
            IPHONE_USERAGENT,
            IPAD_USERAGENT,
            FROYO_USERAGENT,
            HONEYCOMB_USERAGENT,
    };

    // The minimum min font size
    // Aka, the lower bounds for the min font size range
    // which is 1:5..24
    private static final int MIN_FONT_SIZE_OFFSET = 5;
    // The initial value in the text zoom range
    // This is what represents 100% in the SeekBarPreference range
    private static final int TEXT_ZOOM_START_VAL = 10;
    // The size of a single step in the text zoom range, in percent
    private static final int TEXT_ZOOM_STEP = 5;

    private static BrowserSettings sInstance;

    private Context mContext;
    private SharedPreferences mPrefs;
    private LinkedList<WeakReference<WebSettings>> mManagedSettings;
    private Controller mController;
    private WebStorageSizeManager mWebStorageSizeManager;
    private AutofillHandler mAutofillHandler;
    private WeakHashMap<WebSettings, String> mCustomUserAgents;
    private static boolean sInitialized = false;
    private boolean mNeedsSharedSync = true;

    // Cached values
    private int mPageCacheCapacity = 1;
    private String mAppCachePath;

    // Cached settings
    private SearchEngine mSearchEngine;

    private static String sFactoryResetUrl;

    public static void initialize(final Context context) {
        sInstance = new BrowserSettings(context);
    }

    public static BrowserSettings getInstance() {
        return sInstance;
    }

    private BrowserSettings(Context context) {
        mContext = context.getApplicationContext();
        mPrefs = PreferenceManager.getDefaultSharedPreferences(mContext);
        mAutofillHandler = new AutofillHandler(mContext);
        mManagedSettings = new LinkedList<WeakReference<WebSettings>>();
        mCustomUserAgents = new WeakHashMap<WebSettings, String>();
        mPrefs.registerOnSharedPreferenceChangeListener(this);
        mAutofillHandler.asyncLoadFromDb();
        BackgroundHandler.execute(mSetup);
    }

    public void setController(Controller controller) {
        mController = controller;
        if (sInitialized) {
            syncSharedSettings();
        }

        if (mController != null && (mSearchEngine instanceof InstantSearchEngine)) {
             ((InstantSearchEngine) mSearchEngine).setController(mController);
        }
    }

    public void startManagingSettings(WebSettings settings) {
        if (mNeedsSharedSync) {
            syncSharedSettings();
        }
        synchronized (mManagedSettings) {
            syncStaticSettings(settings);
            syncSetting(settings);
            mManagedSettings.add(new WeakReference<WebSettings>(settings));
        }
    }

    private Runnable mSetup = new Runnable() {

        @Override
        public void run() {
            // the cost of one cached page is ~3M (measured using nytimes.com). For
            // low end devices, we only cache one page. For high end devices, we try
            // to cache more pages, currently choose 5.
            if (ActivityManager.staticGetMemoryClass() > 16) {
                mPageCacheCapacity = 5;
            }
            mWebStorageSizeManager = new WebStorageSizeManager(mContext,
                    new WebStorageSizeManager.StatFsDiskInfo(getAppCachePath()),
                    new WebStorageSizeManager.WebKitAppCacheInfo(getAppCachePath()));
            if (Build.VERSION.CODENAME.equals("REL")) {
                // This is a release build, always startup with debug disabled
                setDebugEnabled(false);
            }
            if (mPrefs.contains(PREF_TEXT_SIZE)) {
                /*
                 * Update from TextSize enum to zoom percent
                 * SMALLEST is 50%
                 * SMALLER is 75%
                 * NORMAL is 100%
                 * LARGER is 150%
                 * LARGEST is 200%
                 */
                switch (getTextSize()) {
                case SMALLEST:
                    setTextZoom(50);
                    break;
                case SMALLER:
                    setTextZoom(75);
                    break;
                case LARGER:
                    setTextZoom(150);
                    break;
                case LARGEST:
                    setTextZoom(200);
                    break;
                }
                mPrefs.edit().remove(PREF_TEXT_SIZE).apply();
            }

            sFactoryResetUrl = mContext.getResources().getString(R.string.homepage_base);
            if (sFactoryResetUrl.indexOf("{CID}") != -1) {
                sFactoryResetUrl = sFactoryResetUrl.replace("{CID}",
                    BrowserProvider.getClientId(mContext.getContentResolver()));
            }

            synchronized (BrowserSettings.class) {
                sInitialized = true;
                BrowserSettings.class.notifyAll();
            }
        }
    };

    private static void requireInitialization() {
        synchronized (BrowserSettings.class) {
            while (!sInitialized) {
                try {
                    BrowserSettings.class.wait();
                } catch (InterruptedException e) {
                }
            }
        }
    }

    /**
     * Syncs all the settings that have a Preference UI
     */
    private void syncSetting(WebSettings settings) {
        settings.setGeolocationEnabled(enableGeolocation());
        settings.setJavaScriptEnabled(enableJavascript());
        settings.setLightTouchEnabled(enableLightTouch());
        settings.setNavDump(enableNavDump());
        settings.setHardwareAccelSkiaEnabled(isSkiaHardwareAccelerated());
        settings.setShowVisualIndicator(enableVisualIndicator());
        settings.setDefaultTextEncodingName(getDefaultTextEncoding());
        settings.setDefaultZoom(getDefaultZoom());
        settings.setMinimumFontSize(getMinimumFontSize());
        settings.setMinimumLogicalFontSize(getMinimumFontSize());
        settings.setForceUserScalable(forceEnableUserScalable());
        settings.setPluginState(getPluginState());
        settings.setTextZoom(getTextZoom());
        settings.setAutoFillEnabled(isAutofillEnabled());
        settings.setLayoutAlgorithm(getLayoutAlgorithm());
        settings.setJavaScriptCanOpenWindowsAutomatically(!blockPopupWindows());
        settings.setLoadsImagesAutomatically(loadImages());
        settings.setLoadWithOverviewMode(loadPageInOverviewMode());
        settings.setSavePassword(rememberPasswords());
        settings.setSaveFormData(saveFormdata());
        settings.setUseWideViewPort(isWideViewport());
        settings.setAutoFillProfile(getAutoFillProfile());

        String ua = mCustomUserAgents.get(settings);
        if (ua != null) {
            settings.setUserAgentString(ua);
        } else {
            settings.setUserAgentString(USER_AGENTS[getUserAgent()]);
        }

        settings.setProperty(WebViewProperties.gfxInvertedScreen,
                useInvertedRendering() ? "true" : "false");

        settings.setProperty(WebViewProperties.gfxInvertedScreenContrast,
                Float.toString(getInvertedContrast()));
    }

    /**
     * Syncs all the settings that have no UI
     * These cannot change, so we only need to set them once per WebSettings
     */
    private void syncStaticSettings(WebSettings settings) {
        settings.setDefaultFontSize(16);
        settings.setDefaultFixedFontSize(13);
        settings.setPageCacheCapacity(getPageCacheCapacity());

        // WebView inside Browser doesn't want initial focus to be set.
        settings.setNeedInitialFocus(false);
        // Browser supports multiple windows
        settings.setSupportMultipleWindows(true);
        // enable smooth transition for better performance during panning or
        // zooming
        settings.setEnableSmoothTransition(true);
        // disable content url access
        settings.setAllowContentAccess(false);

        // HTML5 API flags
        settings.setAppCacheEnabled(true);
        settings.setDatabaseEnabled(true);
        settings.setDomStorageEnabled(true);
        settings.setWorkersEnabled(true);  // This only affects V8.

        // HTML5 configuration parametersettings.
        settings.setAppCacheMaxSize(getWebStorageSizeManager().getAppCacheMaxSize());
        settings.setAppCachePath(getAppCachePath());
        settings.setDatabasePath(mContext.getDir("databases", 0).getPath());
        settings.setGeolocationDatabasePath(mContext.getDir("geolocation", 0).getPath());
    }

    private void syncSharedSettings() {
        mNeedsSharedSync = false;
        CookieManager.getInstance().setAcceptCookie(acceptCookies());
        if (mController != null) {
            mController.setShouldShowErrorConsole(enableJavascriptConsole());
        }
    }

    private void syncManagedSettings() {
        syncSharedSettings();
        synchronized (mManagedSettings) {
            Iterator<WeakReference<WebSettings>> iter = mManagedSettings.iterator();
            while (iter.hasNext()) {
                WeakReference<WebSettings> ref = iter.next();
                WebSettings settings = ref.get();
                if (settings == null) {
                    iter.remove();
                    continue;
                }
                syncSetting(settings);
            }
        }
    }

    @Override
    public void onSharedPreferenceChanged(
            SharedPreferences sharedPreferences, String key) {
        syncManagedSettings();
        if (PREF_SEARCH_ENGINE.equals(key)) {
            updateSearchEngine(false);
        }
        if (PREF_USE_INSTANT_SEARCH.equals(key)) {
            updateSearchEngine(true);
        }
        if (PREF_FULLSCREEN.equals(key)) {
            if (mController.getUi() != null) {
                mController.getUi().setFullscreen(useFullscreen());
            }
        } else if (PREF_ENABLE_QUICK_CONTROLS.equals(key)) {
            if (mController.getUi() != null) {
                mController.getUi().setUseQuickControls(sharedPreferences.getBoolean(key, false));
            }
        }
    }

    public static String getFactoryResetHomeUrl(Context context) {
        requireInitialization();
        return sFactoryResetUrl;
    }

    public LayoutAlgorithm getLayoutAlgorithm() {
        LayoutAlgorithm layoutAlgorithm = LayoutAlgorithm.NORMAL;
        if (autofitPages()) {
            layoutAlgorithm = LayoutAlgorithm.NARROW_COLUMNS;
        }
        if (isDebugEnabled()) {
            if (isSmallScreen()) {
                layoutAlgorithm = LayoutAlgorithm.SINGLE_COLUMN;
            } else {
                if (isNormalLayout()) {
                    layoutAlgorithm = LayoutAlgorithm.NORMAL;
                } else {
                    layoutAlgorithm = LayoutAlgorithm.NARROW_COLUMNS;
                }
            }
        }
        return layoutAlgorithm;
    }

    public int getPageCacheCapacity() {
        requireInitialization();
        return mPageCacheCapacity;
    }

    public WebStorageSizeManager getWebStorageSizeManager() {
        requireInitialization();
        return mWebStorageSizeManager;
    }

    private String getAppCachePath() {
        if (mAppCachePath == null) {
            mAppCachePath = mContext.getDir("appcache", 0).getPath();
        }
        return mAppCachePath;
    }

    private void updateSearchEngine(boolean force) {
        String searchEngineName = getSearchEngineName();
        if (force || mSearchEngine == null ||
                !mSearchEngine.getName().equals(searchEngineName)) {
            if (mSearchEngine != null) {
                if (mSearchEngine.supportsVoiceSearch()) {
                     // One or more tabs could have been in voice search mode.
                     // Clear it, since the new SearchEngine may not support
                     // it, or may handle it differently.
                     for (int i = 0; i < mController.getTabControl().getTabCount(); i++) {
                         mController.getTabControl().getTab(i).revertVoiceSearchMode();
                     }
                 }
                mSearchEngine.close();
             }
            mSearchEngine = SearchEngines.get(mContext, searchEngineName);

             if (mController != null && (mSearchEngine instanceof InstantSearchEngine)) {
                 ((InstantSearchEngine) mSearchEngine).setController(mController);
             }
         }
    }

    public SearchEngine getSearchEngine() {
        if (mSearchEngine == null) {
            updateSearchEngine(false);
        }
        return mSearchEngine;
    }

    public boolean isDebugEnabled() {
        requireInitialization();
        return mPrefs.getBoolean(PREF_DEBUG_MENU, false);
    }

    public void setDebugEnabled(boolean value) {
        mPrefs.edit().putBoolean(PREF_DEBUG_MENU, value).apply();
    }

    public void clearCache() {
        WebIconDatabase.getInstance().removeAllIcons();
        if (mController != null) {
            WebView current = mController.getCurrentWebView();
            if (current != null) {
                current.clearCache(true);
            }
        }
    }

    public void clearCookies() {
        CookieManager.getInstance().removeAllCookie();
    }

    public void clearHistory() {
        ContentResolver resolver = mContext.getContentResolver();
        Browser.clearHistory(resolver);
        Browser.clearSearches(resolver);
    }

    public void clearFormData() {
        WebViewDatabase.getInstance(mContext).clearFormData();
        if (mController!= null) {
            WebView currentTopView = mController.getCurrentTopWebView();
            if (currentTopView != null) {
                currentTopView.clearFormData();
            }
        }
    }

    public void clearPasswords() {
        WebViewDatabase db = WebViewDatabase.getInstance(mContext);
        db.clearUsernamePassword();
        db.clearHttpAuthUsernamePassword();
    }

    public void clearDatabases() {
        WebStorage.getInstance().deleteAllData();
    }

    public void clearLocationAccess() {
        GeolocationPermissions.getInstance().clearAll();
    }

    public void resetDefaultPreferences() {
        // Preserve autologin setting
        long gal = mPrefs.getLong(GoogleAccountLogin.PREF_AUTOLOGIN_TIME, -1);
        mPrefs.edit()
                .clear()
                .putLong(GoogleAccountLogin.PREF_AUTOLOGIN_TIME, gal)
                .apply();
        syncManagedSettings();
    }

    public AutoFillProfile getAutoFillProfile() {
        mAutofillHandler.waitForLoad();
        return mAutofillHandler.getAutoFillProfile();
    }

    public void setAutoFillProfile(AutoFillProfile profile, Message msg) {
        mAutofillHandler.waitForLoad();
        mAutofillHandler.setAutoFillProfile(profile, msg);
        // Auto-fill will reuse the same profile ID when making edits to the profile,
        // so we need to force a settings sync (otherwise the SharedPreferences
        // manager will optimise out the call to onSharedPreferenceChanged(), as
        // it thinks nothing has changed).
        syncManagedSettings();
    }

    public void toggleDebugSettings() {
        setDebugEnabled(!isDebugEnabled());
    }

    public boolean hasDesktopUseragent(WebView view) {
        return view != null && mCustomUserAgents.get(view.getSettings()) != null;
    }

    public void toggleDesktopUseragent(WebView view) {
        if (view == null) {
            return;
        }
        WebSettings settings = view.getSettings();
        if (mCustomUserAgents.get(settings) != null) {
            mCustomUserAgents.remove(settings);
            settings.setUserAgentString(USER_AGENTS[getUserAgent()]);
        } else {
            mCustomUserAgents.put(settings, DESKTOP_USERAGENT);
            settings.setUserAgentString(DESKTOP_USERAGENT);
        }
    }

    public static int getAdjustedMinimumFontSize(int rawValue) {
        rawValue++; // Preference starts at 0, min font at 1
        if (rawValue > 1) {
            rawValue += (MIN_FONT_SIZE_OFFSET - 2);
        }
        return rawValue;
    }

    public static int getAdjustedTextZoom(int rawValue) {
        rawValue = (rawValue - TEXT_ZOOM_START_VAL) * TEXT_ZOOM_STEP;
        return rawValue + 100;
    }

    static int getRawTextZoom(int percent) {
        return (percent - 100) / TEXT_ZOOM_STEP + TEXT_ZOOM_START_VAL;
    }

    public SharedPreferences getPreferences() {
        return mPrefs;
    }

    // -----------------------------
    // getter/setters for accessibility_preferences.xml
    // -----------------------------

    @Deprecated
    private TextSize getTextSize() {
        String textSize = mPrefs.getString(PREF_TEXT_SIZE, "NORMAL");
        return TextSize.valueOf(textSize);
    }

    public int getMinimumFontSize() {
        int minFont = mPrefs.getInt(PREF_MIN_FONT_SIZE, 0);
        return getAdjustedMinimumFontSize(minFont);
    }

    public boolean forceEnableUserScalable() {
        return mPrefs.getBoolean(PREF_FORCE_USERSCALABLE, false);
    }

    public int getTextZoom() {
        requireInitialization();
        int textZoom = mPrefs.getInt(PREF_TEXT_ZOOM, 10);
        return getAdjustedTextZoom(textZoom);
    }

    public void setTextZoom(int percent) {
        mPrefs.edit().putInt(PREF_TEXT_ZOOM, getRawTextZoom(percent)).apply();
    }

    // -----------------------------
    // getter/setters for advanced_preferences.xml
    // -----------------------------

    public String getSearchEngineName() {
        return mPrefs.getString(PREF_SEARCH_ENGINE, SearchEngine.GOOGLE);
    }

    public boolean openInBackground() {
        return mPrefs.getBoolean(PREF_OPEN_IN_BACKGROUND, false);
    }

    public boolean enableJavascript() {
        return mPrefs.getBoolean(PREF_ENABLE_JAVASCRIPT, true);
    }

    // TODO: Cache
    public PluginState getPluginState() {
        String state = mPrefs.getString(PREF_PLUGIN_STATE, "ON");
        return PluginState.valueOf(state);
    }

    // TODO: Cache
    public ZoomDensity getDefaultZoom() {
        String zoom = mPrefs.getString(PREF_DEFAULT_ZOOM, "MEDIUM");
        return ZoomDensity.valueOf(zoom);
    }

    public boolean loadPageInOverviewMode() {
        return mPrefs.getBoolean(PREF_LOAD_PAGE, true);
    }

    public boolean autofitPages() {
        return mPrefs.getBoolean(PREF_AUTOFIT_PAGES, true);
    }

    public boolean blockPopupWindows() {
        return mPrefs.getBoolean(PREF_BLOCK_POPUP_WINDOWS, true);
    }

    public boolean loadImages() {
        return mPrefs.getBoolean(PREF_LOAD_IMAGES, true);
    }

    public String getDefaultTextEncoding() {
        return mPrefs.getString(PREF_DEFAULT_TEXT_ENCODING, null);
    }

    // -----------------------------
    // getter/setters for general_preferences.xml
    // -----------------------------

    public String getHomePage() {
        return mPrefs.getString(PREF_HOMEPAGE, getFactoryResetHomeUrl(mContext));
    }

    public void setHomePage(String value) {
        mPrefs.edit().putString(PREF_HOMEPAGE, value).apply();
    }

    public boolean isAutofillEnabled() {
        return mPrefs.getBoolean(PREF_AUTOFILL_ENABLED, true);
    }

    public void setAutofillEnabled(boolean value) {
        mPrefs.edit().putBoolean(PREF_AUTOFILL_ENABLED, value).apply();
    }

    // -----------------------------
    // getter/setters for debug_preferences.xml
    // -----------------------------

    public boolean isHardwareAccelerated() {
        if (!isDebugEnabled()) {
            return true;
        }
        return mPrefs.getBoolean(PREF_ENABLE_HARDWARE_ACCEL, true);
    }

    public boolean isSkiaHardwareAccelerated() {
        if (!isDebugEnabled()) {
            return false;
        }
        return mPrefs.getBoolean(PREF_ENABLE_HARDWARE_ACCEL_SKIA, false);
    }

    public int getUserAgent() {
        if (!isDebugEnabled()) {
            return 0;
        }
        return Integer.parseInt(mPrefs.getString(PREF_USER_AGENT, "0"));
    }

    // -----------------------------
    // getter/setters for hidden_debug_preferences.xml
    // -----------------------------

    public boolean enableVisualIndicator() {
        if (!isDebugEnabled()) {
            return false;
        }
        return mPrefs.getBoolean(PREF_ENABLE_VISUAL_INDICATOR, false);
    }

    public boolean enableJavascriptConsole() {
        if (!isDebugEnabled()) {
            return false;
        }
        return mPrefs.getBoolean(PREF_JAVASCRIPT_CONSOLE, true);
    }

    public boolean isSmallScreen() {
        if (!isDebugEnabled()) {
            return false;
        }
        return mPrefs.getBoolean(PREF_SMALL_SCREEN, false);
    }

    public boolean isWideViewport() {
        if (!isDebugEnabled()) {
            return true;
        }
        return mPrefs.getBoolean(PREF_WIDE_VIEWPORT, true);
    }

    public boolean isNormalLayout() {
        if (!isDebugEnabled()) {
            return false;
        }
        return mPrefs.getBoolean(PREF_NORMAL_LAYOUT, false);
    }

    public boolean isTracing() {
        if (!isDebugEnabled()) {
            return false;
        }
        return mPrefs.getBoolean(PREF_ENABLE_TRACING, false);
    }

    public boolean enableLightTouch() {
        if (!isDebugEnabled()) {
            return false;
        }
        return mPrefs.getBoolean(PREF_ENABLE_LIGHT_TOUCH, false);
    }

    public boolean enableNavDump() {
        if (!isDebugEnabled()) {
            return false;
        }
        return mPrefs.getBoolean(PREF_ENABLE_NAV_DUMP, false);
    }

    public String getJsEngineFlags() {
        if (!isDebugEnabled()) {
            return "";
        }
        return mPrefs.getString(PREF_JS_ENGINE_FLAGS, "");
    }

    // -----------------------------
    // getter/setters for lab_preferences.xml
    // -----------------------------

    public boolean useQuickControls() {
        return mPrefs.getBoolean(PREF_ENABLE_QUICK_CONTROLS, false);
    }

    public boolean useMostVisitedHomepage() {
        return HomeProvider.MOST_VISITED.equals(getHomePage());
    }

    public boolean useInstantSearch() {
        return mPrefs.getBoolean(PREF_USE_INSTANT_SEARCH, false);
    }

    public boolean useFullscreen() {
        return mPrefs.getBoolean(PREF_FULLSCREEN, false);
    }

    public boolean useInvertedRendering() {
        return mPrefs.getBoolean(PREF_INVERTED, false);
    }

    public float getInvertedContrast() {
        return 1 + (mPrefs.getInt(PREF_INVERTED_CONTRAST, 0) / 10f);
    }

    // -----------------------------
    // getter/setters for privacy_security_preferences.xml
    // -----------------------------

    public boolean showSecurityWarnings() {
        return mPrefs.getBoolean(PREF_SHOW_SECURITY_WARNINGS, true);
    }

    public boolean acceptCookies() {
        return mPrefs.getBoolean(PREF_ACCEPT_COOKIES, true);
    }

    public boolean saveFormdata() {
        return mPrefs.getBoolean(PREF_SAVE_FORMDATA, true);
    }

    public boolean enableGeolocation() {
        return mPrefs.getBoolean(PREF_ENABLE_GEOLOCATION, true);
    }

    public boolean rememberPasswords() {
        return mPrefs.getBoolean(PREF_REMEMBER_PASSWORDS, true);
    }

    // -----------------------------
    // getter/setters for bandwidth_preferences.xml
    // -----------------------------

    public boolean isPreloadEnabled() {
        return mPrefs.getBoolean(PREF_DATA_PRELOAD, false);
    }
}