xref: /frameworks/base/core/java/android/webkit/WebView.java

/*
 * Copyright (C) 2006 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.webkit;

import android.annotation.Widget;
import android.content.Context;
import android.content.res.Configuration;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Picture;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.net.http.SslCertificate;
import android.os.Bundle;
import android.os.Looper;
import android.os.Message;
import android.os.StrictMode;
import android.util.AttributeSet;
import android.util.Log;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewGroup.LayoutParams;
import android.view.ViewTreeObserver;
import android.view.accessibility.AccessibilityEvent;
import android.view.accessibility.AccessibilityNodeInfo;
import android.view.inputmethod.EditorInfo;
import android.view.inputmethod.InputConnection;
import android.widget.AbsoluteLayout;

import java.io.File;
import java.util.Map;

/**
 * <p>A View that displays web pages. This class is the basis upon which you
 * can roll your own web browser or simply display some online content within your Activity.
 * It uses the WebKit rendering engine to display
 * web pages and includes methods to navigate forward and backward
 * through a history, zoom in and out, perform text searches and more.</p>
 * <p>To enable the built-in zoom, set
 * {@link #getSettings() WebSettings}.{@link WebSettings#setBuiltInZoomControls(boolean)}
 * (introduced in API version 3).
 * <p>Note that, in order for your Activity to access the Internet and load web pages
 * in a WebView, you must add the {@code INTERNET} permissions to your
 * Android Manifest file:</p>
 * <pre>&lt;uses-permission android:name="android.permission.INTERNET" /></pre>
 *
 * <p>This must be a child of the <a
 * href="{@docRoot}guide/topics/manifest/manifest-element.html">{@code <manifest>}</a>
 * element.</p>
 *
 * <p>See the <a href="{@docRoot}resources/tutorials/views/hello-webview.html">Web View
 * tutorial</a>.</p>
 *
 * <h3>Basic usage</h3>
 *
 * <p>By default, a WebView provides no browser-like widgets, does not
 * enable JavaScript and web page errors are ignored. If your goal is only
 * to display some HTML as a part of your UI, this is probably fine;
 * the user won't need to interact with the web page beyond reading
 * it, and the web page won't need to interact with the user. If you
 * actually want a full-blown web browser, then you probably want to
 * invoke the Browser application with a URL Intent rather than show it
 * with a WebView. For example:
 * <pre>
 * Uri uri = Uri.parse("http://www.example.com");
 * Intent intent = new Intent(Intent.ACTION_VIEW, uri);
 * startActivity(intent);
 * </pre>
 * <p>See {@link android.content.Intent} for more information.</p>
 *
 * <p>To provide a WebView in your own Activity, include a {@code <WebView>} in your layout,
 * or set the entire Activity window as a WebView during {@link
 * android.app.Activity#onCreate(Bundle) onCreate()}:</p>
 * <pre class="prettyprint">
 * WebView webview = new WebView(this);
 * setContentView(webview);
 * </pre>
 *
 * <p>Then load the desired web page:</p>
 * <pre>
 * // Simplest usage: note that an exception will NOT be thrown
 * // if there is an error loading this page (see below).
 * webview.loadUrl("http://slashdot.org/");
 *
 * // OR, you can also load from an HTML string:
 * String summary = "&lt;html>&lt;body>You scored &lt;b>192&lt;/b> points.&lt;/body>&lt;/html>";
 * webview.loadData(summary, "text/html", null);
 * // ... although note that there are restrictions on what this HTML can do.
 * // See the JavaDocs for {@link #loadData(String,String,String) loadData()} and {@link
 * #loadDataWithBaseURL(String,String,String,String,String) loadDataWithBaseURL()} for more info.
 * </pre>
 *
 * <p>A WebView has several customization points where you can add your
 * own behavior. These are:</p>
 *
 * <ul>
 *   <li>Creating and setting a {@link android.webkit.WebChromeClient} subclass.
 *       This class is called when something that might impact a
 *       browser UI happens, for instance, progress updates and
 *       JavaScript alerts are sent here (see <a
 * href="{@docRoot}guide/developing/debug-tasks.html#DebuggingWebPages">Debugging Tasks</a>).
 *   </li>
 *   <li>Creating and setting a {@link android.webkit.WebViewClient} subclass.
 *       It will be called when things happen that impact the
 *       rendering of the content, eg, errors or form submissions. You
 *       can also intercept URL loading here (via {@link
 * android.webkit.WebViewClient#shouldOverrideUrlLoading(WebView,String)
 * shouldOverrideUrlLoading()}).</li>
 *   <li>Modifying the {@link android.webkit.WebSettings}, such as
 * enabling JavaScript with {@link android.webkit.WebSettings#setJavaScriptEnabled(boolean)
 * setJavaScriptEnabled()}. </li>
 *   <li>Injecting Java objects into the WebView using the
 *       {@link android.webkit.WebView#addJavascriptInterface} method. This
 *       method allows you to inject Java objects into a page's JavaScript
 *       context, so that they can be accessed by JavaScript in the page.</li>
 * </ul>
 *
 * <p>Here's a more complicated example, showing error handling,
 *    settings, and progress notification:</p>
 *
 * <pre class="prettyprint">
 * // Let's display the progress in the activity title bar, like the
 * // browser app does.
 * getWindow().requestFeature(Window.FEATURE_PROGRESS);
 *
 * webview.getSettings().setJavaScriptEnabled(true);
 *
 * final Activity activity = this;
 * webview.setWebChromeClient(new WebChromeClient() {
 *   public void onProgressChanged(WebView view, int progress) {
 *     // Activities and WebViews measure progress with different scales.
 *     // The progress meter will automatically disappear when we reach 100%
 *     activity.setProgress(progress * 1000);
 *   }
 * });
 * webview.setWebViewClient(new WebViewClient() {
 *   public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) {
 *     Toast.makeText(activity, "Oh no! " + description, Toast.LENGTH_SHORT).show();
 *   }
 * });
 *
 * webview.loadUrl("http://slashdot.org/");
 * </pre>
 *
 * <h3>Cookie and window management</h3>
 *
 * <p>For obvious security reasons, your application has its own
 * cache, cookie store etc.&mdash;it does not share the Browser
 * application's data. Cookies are managed on a separate thread, so
 * operations like index building don't block the UI
 * thread. Follow the instructions in {@link android.webkit.CookieSyncManager}
 * if you want to use cookies in your application.
 * </p>
 *
 * <p>By default, requests by the HTML to open new windows are
 * ignored. This is true whether they be opened by JavaScript or by
 * the target attribute on a link. You can customize your
 * {@link WebChromeClient} to provide your own behaviour for opening multiple windows,
 * and render them in whatever manner you want.</p>
 *
 * <p>The standard behavior for an Activity is to be destroyed and
 * recreated when the device orientation or any other configuration changes. This will cause
 * the WebView to reload the current page. If you don't want that, you
 * can set your Activity to handle the {@code orientation} and {@code keyboardHidden}
 * changes, and then just leave the WebView alone. It'll automatically
 * re-orient itself as appropriate. Read <a
 * href="{@docRoot}guide/topics/resources/runtime-changes.html">Handling Runtime Changes</a> for
 * more information about how to handle configuration changes during runtime.</p>
 *
 *
 * <h3>Building web pages to support different screen densities</h3>
 *
 * <p>The screen density of a device is based on the screen resolution. A screen with low density
 * has fewer available pixels per inch, where a screen with high density
 * has more &mdash; sometimes significantly more &mdash; pixels per inch. The density of a
 * screen is important because, other things being equal, a UI element (such as a button) whose
 * height and width are defined in terms of screen pixels will appear larger on the lower density
 * screen and smaller on the higher density screen.
 * For simplicity, Android collapses all actual screen densities into three generalized densities:
 * high, medium, and low.</p>
 * <p>By default, WebView scales a web page so that it is drawn at a size that matches the default
 * appearance on a medium density screen. So, it applies 1.5x scaling on a high density screen
 * (because its pixels are smaller) and 0.75x scaling on a low density screen (because its pixels
 * are bigger).
 * Starting with API Level 5 (Android 2.0), WebView supports DOM, CSS, and meta tag features to help
 * you (as a web developer) target screens with different screen densities.</p>
 * <p>Here's a summary of the features you can use to handle different screen densities:</p>
 * <ul>
 * <li>The {@code window.devicePixelRatio} DOM property. The value of this property specifies the
 * default scaling factor used for the current device. For example, if the value of {@code
 * window.devicePixelRatio} is "1.0", then the device is considered a medium density (mdpi) device
 * and default scaling is not applied to the web page; if the value is "1.5", then the device is
 * considered a high density device (hdpi) and the page content is scaled 1.5x; if the
 * value is "0.75", then the device is considered a low density device (ldpi) and the content is
 * scaled 0.75x. However, if you specify the {@code "target-densitydpi"} meta property
 * (discussed below), then you can stop this default scaling behavior.</li>
 * <li>The {@code -webkit-device-pixel-ratio} CSS media query. Use this to specify the screen
 * densities for which this style sheet is to be used. The corresponding value should be either
 * "0.75", "1", or "1.5", to indicate that the styles are for devices with low density, medium
 * density, or high density screens, respectively. For example:
 * <pre>
 * &lt;link rel="stylesheet" media="screen and (-webkit-device-pixel-ratio:1.5)" href="hdpi.css" /&gt;</pre>
 * <p>The {@code hdpi.css} stylesheet is only used for devices with a screen pixel ration of 1.5,
 * which is the high density pixel ratio.</p>
 * </li>
 * <li>The {@code target-densitydpi} property for the {@code viewport} meta tag. You can use
 * this to specify the target density for which the web page is designed, using the following
 * values:
 * <ul>
 * <li>{@code device-dpi} - Use the device's native dpi as the target dpi. Default scaling never
 * occurs.</li>
 * <li>{@code high-dpi} - Use hdpi as the target dpi. Medium and low density screens scale down
 * as appropriate.</li>
 * <li>{@code medium-dpi} - Use mdpi as the target dpi. High density screens scale up and
 * low density screens scale down. This is also the default behavior.</li>
 * <li>{@code low-dpi} - Use ldpi as the target dpi. Medium and high density screens scale up
 * as appropriate.</li>
 * <li><em>{@code <value>}</em> - Specify a dpi value to use as the target dpi (accepted
 * values are 70-400).</li>
 * </ul>
 * <p>Here's an example meta tag to specify the target density:</p>
 * <pre>&lt;meta name="viewport" content="target-densitydpi=device-dpi" /&gt;</pre></li>
 * </ul>
 * <p>If you want to modify your web page for different densities, by using the {@code
 * -webkit-device-pixel-ratio} CSS media query and/or the {@code
 * window.devicePixelRatio} DOM property, then you should set the {@code target-densitydpi} meta
 * property to {@code device-dpi}. This stops Android from performing scaling in your web page and
 * allows you to make the necessary adjustments for each density via CSS and JavaScript.</p>
 *
 * <h3>HTML5 Video support</h3>
 *
 * <p>In order to support inline HTML5 video in your application, you need to have hardware
 * acceleration turned on, and set a {@link android.webkit.WebChromeClient}. For full screen support,
 * implementations of {@link WebChromeClient#onShowCustomView(View, WebChromeClient.CustomViewCallback)}
 * and {@link WebChromeClient#onHideCustomView()} are required,
 * {@link WebChromeClient#getVideoLoadingProgressView()} is optional.
 * </p>
 *
 *
 */
/*
 * Implementation notes.
 * The WebView is a thin API class that delegates its public API to a backend WebViewProvider
 * class instance. WebView extends {@link AbsoluteLayout} for backward compatibility reasons.
 * Methods are delegated to the provider implementation: all public API methods introduced in this
 * file are fully delegated, whereas public and protected methods from the View base classes are
 * only delegated where a specific need exists for them to do so.
 */
@Widget
public class WebView extends AbsoluteLayout
        implements ViewTreeObserver.OnGlobalFocusChangeListener,
        ViewGroup.OnHierarchyChangeListener {

    // Default Provider factory class name.
    private static final String DEFAULT_WEB_VIEW_FACTORY = "android.webkit.WebViewClassic$Factory";

    private static final String LOGTAG = "webview_proxy";
    // TODO: flip DEBUG to always be disabled.
    private static final boolean DEBUG = true;

    /**
     *  Transportation object for returning WebView across thread boundaries.
     */
    public class WebViewTransport {
        private WebView mWebview;

        /**
         * Set the WebView to the transportation object.
         * @param webview The WebView to transport.
         */
        public synchronized void setWebView(WebView webview) {
            mWebview = webview;
        }

        /**
         * Return the WebView object.
         * @return WebView The transported WebView object.
         */
        public synchronized WebView getWebView() {
            return mWebview;
        }
    }

    /**
     * URI scheme for telephone number
     */
    public static final String SCHEME_TEL = "tel:";
    /**
     * URI scheme for email address
     */
    public static final String SCHEME_MAILTO = "mailto:";
    /**
     * URI scheme for map address
     */
    public static final String SCHEME_GEO = "geo:0,0?q=";

    /**
     * Interface to listen for new pictures as they change.
     * @deprecated This interface is now obsolete.
     */
    @Deprecated
    public interface PictureListener {
        /**
         * Notify the listener that the picture has changed.
         * @param view The WebView that owns the picture.
         * @param picture The new picture.
         * @deprecated Due to internal changes, the picture does not include
         * composited layers such as fixed position elements or scrollable divs.
         * While the PictureListener API can still be used to detect changes in
         * the WebView content, you are advised against its usage until a replacement
         * is provided in a future Android release
         */
        @Deprecated
        public void onNewPicture(WebView view, Picture picture);
    }

    public static class HitTestResult {
        /**
         * Default HitTestResult, where the target is unknown
         */
        public static final int UNKNOWN_TYPE = 0;
        /**
         * @deprecated This type is no longer used.
         */
        @Deprecated
        public static final int ANCHOR_TYPE = 1;
        /**
         * HitTestResult for hitting a phone number
         */
        public static final int PHONE_TYPE = 2;
        /**
         * HitTestResult for hitting a map address
         */
        public static final int GEO_TYPE = 3;
        /**
         * HitTestResult for hitting an email address
         */
        public static final int EMAIL_TYPE = 4;
        /**
         * HitTestResult for hitting an HTML::img tag
         */
        public static final int IMAGE_TYPE = 5;
        /**
         * @deprecated This type is no longer used.
         */
        @Deprecated
        public static final int IMAGE_ANCHOR_TYPE = 6;
        /**
         * HitTestResult for hitting a HTML::a tag with src=http
         */
        public static final int SRC_ANCHOR_TYPE = 7;
        /**
         * HitTestResult for hitting a HTML::a tag with src=http + HTML::img
         */
        public static final int SRC_IMAGE_ANCHOR_TYPE = 8;
        /**
         * HitTestResult for hitting an edit text area
         */
        public static final int EDIT_TEXT_TYPE = 9;

        private int mType;
        private String mExtra;

        /**
         * @hide Only for use by WebViewProvider implementations
         */
        public HitTestResult() {
            mType = UNKNOWN_TYPE;
        }

        /**
         * @hide Only for use by WebViewProvider implementations
         */
        public void setType(int type) {
            mType = type;
        }

        /**
         * @hide Only for use by WebViewProvider implementations
         */
        public void setExtra(String extra) {
            mExtra = extra;
        }

        /**
         * Gets the type of the hit test result.
         * @return See the XXX_TYPE constants defined in this class.
         */
        public int getType() {
            return mType;
        }

        /**
         * Gets additional type-dependant information about the result, see
         * {@link WebView#getHitTestResult()} for details.
         * @return may either be null or contain extra information about this result.
         */
        public String getExtra() {
            return mExtra;
        }
    }

    /**
     * Construct a new WebView with a Context object.
     * @param context A Context object used to access application assets.
     */
    public WebView(Context context) {
        this(context, null);
    }

    /**
     * Construct a new WebView with layout parameters.
     * @param context A Context object used to access application assets.
     * @param attrs An AttributeSet passed to our parent.
     */
    public WebView(Context context, AttributeSet attrs) {
        this(context, attrs, com.android.internal.R.attr.webViewStyle);
    }

    /**
     * Construct a new WebView with layout parameters and a default style.
     * @param context A Context object used to access application assets.
     * @param attrs An AttributeSet passed to our parent.
     * @param defStyle The default style resource ID.
     */
    public WebView(Context context, AttributeSet attrs, int defStyle) {
        this(context, attrs, defStyle, false);
    }

    /**
     * Construct a new WebView with layout parameters and a default style.
     * @param context A Context object used to access application assets.
     * @param attrs An AttributeSet passed to our parent.
     * @param defStyle The default style resource ID.
     * @param privateBrowsing If true the web view will be initialized in private mode.
     */
    public WebView(Context context, AttributeSet attrs, int defStyle,
            boolean privateBrowsing) {
        this(context, attrs, defStyle, null, privateBrowsing);
    }

    /**
     * Construct a new WebView with layout parameters, a default style and a set
     * of custom Javscript interfaces to be added to the WebView at initialization
     * time. This guarantees that these interfaces will be available when the JS
     * context is initialized.
     * @param context A Context object used to access application assets.
     * @param attrs An AttributeSet passed to our parent.
     * @param defStyle The default style resource ID.
     * @param javaScriptInterfaces is a Map of interface names, as keys, and
     * object implementing those interfaces, as values.
     * @param privateBrowsing If true the web view will be initialized in private mode.
     * @hide This is used internally by dumprendertree, as it requires the javaScript interfaces to
     * be added synchronously, before a subsequent loadUrl call takes effect.
     */
    @SuppressWarnings("deprecation")  // for super() call into deprecated base class constructor.
    protected WebView(Context context, AttributeSet attrs, int defStyle,
            Map<String, Object> javaScriptInterfaces, boolean privateBrowsing) {
        super(context, attrs, defStyle);
        if (context == null) {
            throw new IllegalArgumentException("Invalid context argument");
        }
        checkThread();

        ensureProviderCreated();
        mProvider.init(javaScriptInterfaces, privateBrowsing);
    }

    /**
     * Specify whether the horizontal scrollbar has overlay style.
     * @param overlay TRUE if horizontal scrollbar should have overlay style.
     */
    public void setHorizontalScrollbarOverlay(boolean overlay) {
        checkThread();
        mProvider.setHorizontalScrollbarOverlay(overlay);
    }

    /**
     * Specify whether the vertical scrollbar has overlay style.
     * @param overlay TRUE if vertical scrollbar should have overlay style.
     */
    public void setVerticalScrollbarOverlay(boolean overlay) {
        checkThread();
        mProvider.setVerticalScrollbarOverlay(overlay);
    }

    /**
     * Return whether horizontal scrollbar has overlay style
     * @return TRUE if horizontal scrollbar has overlay style.
     */
    public boolean overlayHorizontalScrollbar() {
        checkThread();
        return mProvider.overlayHorizontalScrollbar();
    }

    /**
     * Return whether vertical scrollbar has overlay style
     * @return TRUE if vertical scrollbar has overlay style.
     */
    public boolean overlayVerticalScrollbar() {
        checkThread();
        return mProvider.overlayVerticalScrollbar();
    }

    /**
     * Return the visible height (in pixels) of the embedded title bar (if any).
     *
     * @deprecated This method is now obsolete.
     */
    public int getVisibleTitleHeight() {
        checkThread();
        return mProvider.getVisibleTitleHeight();
    }

    /**
     * @return The SSL certificate for the main top-level page or null if
     * there is no certificate (the site is not secure).
     */
    public SslCertificate getCertificate() {
        checkThread();
        return mProvider.getCertificate();
    }

    /**
     * Sets the SSL certificate for the main top-level page.
     */
    public void setCertificate(SslCertificate certificate) {
        checkThread();
        mProvider.setCertificate(certificate);
    }

    //-------------------------------------------------------------------------
    // Methods called by activity
    //-------------------------------------------------------------------------

    /**
     * Save the username and password for a particular host in the WebView's
     * internal database.
     * @param host The host that required the credentials.
     * @param username The username for the given host.
     * @param password The password for the given host.
     */
    public void savePassword(String host, String username, String password) {
        checkThread();
        mProvider.savePassword(host, username, password);
    }

    /**
     * Set the HTTP authentication credentials for a given host and realm.
     *
     * @param host The host for the credentials.
     * @param realm The realm for the credentials.
     * @param username The username for the password. If it is null, it means
     *                 password can't be saved.
     * @param password The password
     */
    public void setHttpAuthUsernamePassword(String host, String realm,
            String username, String password) {
        checkThread();
        mProvider.setHttpAuthUsernamePassword(host, realm, username, password);
    }

    /**
     * Retrieve the HTTP authentication username and password for a given
     * host & realm pair
     *
     * @param host The host for which the credentials apply.
     * @param realm The realm for which the credentials apply.
     * @return String[] if found, String[0] is username, which can be null and
     *         String[1] is password. Return null if it can't find anything.
     */
    public String[] getHttpAuthUsernamePassword(String host, String realm) {
        checkThread();
        return mProvider.getHttpAuthUsernamePassword(host, realm);
    }

    /**
     * Destroy the internal state of the WebView. This method should be called
     * after the WebView has been removed from the view system. No other
     * methods may be called on a WebView after destroy.
     */
    public void destroy() {
        checkThread();
        mProvider.destroy();
    }

    /**
     * Enables platform notifications of data state and proxy changes.
     * Notifications are enabled by default.
     *
     * @deprecated This method is now obsolete.
     */
    @Deprecated
    public static void enablePlatformNotifications() {
        checkThread();
        getFactory().getStatics().setPlatformNotificationsEnabled(true);
    }

    /**
     * Disables platform notifications of data state and proxy changes.
     * Notifications are enabled by default.
     *
     * @deprecated This method is now obsolete.
     */
    @Deprecated
    public static void disablePlatformNotifications() {
        checkThread();
        getFactory().getStatics().setPlatformNotificationsEnabled(false);
    }

    /**
     * Inform WebView of the network state. This is used to set
     * the JavaScript property window.navigator.isOnline and
     * generates the online/offline event as specified in HTML5, sec. 5.7.7
     * @param networkUp boolean indicating if network is available
     */
    public void setNetworkAvailable(boolean networkUp) {
        checkThread();
        mProvider.setNetworkAvailable(networkUp);
    }

    /**
     * Save the state of this WebView used in
     * {@link android.app.Activity#onSaveInstanceState}. Please note that this
     * method no longer stores the display data for this WebView. The previous
     * behavior could potentially leak files if {@link #restoreState} was never
     * called. See {@link #savePicture} and {@link #restorePicture} for saving
     * and restoring the display data.
     * @param outState The Bundle to store the WebView state.
     * @return The same copy of the back/forward list used to save the state. If
     *         saveState fails, the returned list will be null.
     * @see #savePicture
     * @see #restorePicture
     */
    public WebBackForwardList saveState(Bundle outState) {
        checkThread();
        return mProvider.saveState(outState);
    }

    /**
     * Save the current display data to the Bundle given. Used in conjunction
     * with {@link #saveState}.
     * @param b A Bundle to store the display data.
     * @param dest The file to store the serialized picture data. Will be
     *             overwritten with this WebView's picture data.
     * @return True if the picture was successfully saved.
     * @deprecated This method is now obsolete.
     */
    @Deprecated
    public boolean savePicture(Bundle b, final File dest) {
        checkThread();
        return mProvider.savePicture(b, dest);
    }

    /**
     * Restore the display data that was save in {@link #savePicture}. Used in
     * conjunction with {@link #restoreState}.
     *
     * Note that this will not work if the WebView is hardware accelerated.
     * @param b A Bundle containing the saved display data.
     * @param src The file where the picture data was stored.
     * @return True if the picture was successfully restored.
     * @deprecated This method is now obsolete.
     */
    @Deprecated
    public boolean restorePicture(Bundle b, File src) {
        checkThread();
        return mProvider.restorePicture(b, src);
    }

    /**
     * Restore the state of this WebView from the given map used in
     * {@link android.app.Activity#onRestoreInstanceState}. This method should
     * be called to restore the state of the WebView before using the object. If
     * it is called after the WebView has had a chance to build state (load
     * pages, create a back/forward list, etc.) there may be undesirable
     * side-effects. Please note that this method no longer restores the
     * display data for this WebView. See {@link #savePicture} and {@link
     * #restorePicture} for saving and restoring the display data.
     * @param inState The incoming Bundle of state.
     * @return The restored back/forward list or null if restoreState failed.
     * @see #savePicture
     * @see #restorePicture
     */
    public WebBackForwardList restoreState(Bundle inState) {
        checkThread();
        return mProvider.restoreState(inState);
    }

    /**
     * Load the given URL with the specified additional HTTP headers.
     * @param url The URL of the resource to load.
     * @param additionalHttpHeaders The additional headers to be used in the
     *            HTTP request for this URL, specified as a map from name to
     *            value. Note that if this map contains any of the headers
     *            that are set by default by the WebView, such as those
     *            controlling caching, accept types or the User-Agent, their
     *            values may be overriden by the WebView's defaults.
     */
    public void loadUrl(String url, Map<String, String> additionalHttpHeaders) {
        checkThread();
        mProvider.loadUrl(url, additionalHttpHeaders);
    }

    /**
     * Load the given URL.
     * @param url The URL of the resource to load.
     */
    public void loadUrl(String url) {
        checkThread();
        mProvider.loadUrl(url);
    }

    /**
     * Load the url with postData using "POST" method into the WebView. If url
     * is not a network url, it will be loaded with {link
     * {@link #loadUrl(String)} instead.
     *
     * @param url The url of the resource to load.
     * @param postData The data will be passed to "POST" request.
     */
    public void postUrl(String url, byte[] postData) {
        checkThread();
        mProvider.postUrl(url, postData);
    }

    /**
     * Load the given data into the WebView using a 'data' scheme URL.
     * <p>
     * Note that JavaScript's same origin policy means that script running in a
     * page loaded using this method will be unable to access content loaded
     * using any scheme other than 'data', including 'http(s)'. To avoid this
     * restriction, use {@link
     * #loadDataWithBaseURL(String,String,String,String,String)
     * loadDataWithBaseURL()} with an appropriate base URL.
     * <p>
     * If the value of the encoding parameter is 'base64', then the data must
     * be encoded as base64. Otherwise, the data must use ASCII encoding for
     * octets inside the range of safe URL characters and use the standard %xx
     * hex encoding of URLs for octets outside that range. For example,
     * '#', '%', '\', '?' should be replaced by %23, %25, %27, %3f respectively.
     * <p>
     * The 'data' scheme URL formed by this method uses the default US-ASCII
     * charset. If you need need to set a different charset, you should form a
     * 'data' scheme URL which explicitly specifies a charset parameter in the
     * mediatype portion of the URL and call {@link #loadUrl(String)} instead.
     * Note that the charset obtained from the mediatype portion of a data URL
     * always overrides that specified in the HTML or XML document itself.
     * @param data A String of data in the given encoding.
     * @param mimeType The MIME type of the data, e.g. 'text/html'.
     * @param encoding The encoding of the data.
     */
    public void loadData(String data, String mimeType, String encoding) {
        checkThread();
        mProvider.loadData(data, mimeType, encoding);
    }

    /**
     * Load the given data into the WebView, using baseUrl as the base URL for
     * the content. The base URL is used both to resolve relative URLs and when
     * applying JavaScript's same origin policy. The historyUrl is used for the
     * history entry.
     * <p>
     * Note that content specified in this way can access local device files
     * (via 'file' scheme URLs) only if baseUrl specifies a scheme other than
     * 'http', 'https', 'ftp', 'ftps', 'about' or 'javascript'.
     * <p>
     * If the base URL uses the data scheme, this method is equivalent to
     * calling {@link #loadData(String,String,String) loadData()} and the
     * historyUrl is ignored.
     * @param baseUrl URL to use as the page's base URL. If null defaults to
     *            'about:blank'
     * @param data A String of data in the given encoding.
     * @param mimeType The MIMEType of the data, e.g. 'text/html'. If null,
     *            defaults to 'text/html'.
     * @param encoding The encoding of the data.
     * @param historyUrl URL to use as the history entry, if null defaults to
     *            'about:blank'.
     */
    public void loadDataWithBaseURL(String baseUrl, String data,
            String mimeType, String encoding, String historyUrl) {
        checkThread();
        mProvider.loadDataWithBaseURL(baseUrl, data, mimeType, encoding, historyUrl);
    }

    /**
     * Saves the current view as a web archive.
     *
     * @param filename The filename where the archive should be placed.
     */
    public void saveWebArchive(String filename) {
        checkThread();
        mProvider.saveWebArchive(filename);
    }

    /**
     * Saves the current view as a web archive.
     *
     * @param basename The filename where the archive should be placed.
     * @param autoname If false, takes basename to be a file. If true, basename
     *                 is assumed to be a directory in which a filename will be
     *                 chosen according to the url of the current page.
     * @param callback Called after the web archive has been saved. The
     *                 parameter for onReceiveValue will either be the filename
     *                 under which the file was saved, or null if saving the
     *                 file failed.
     */
    public void saveWebArchive(String basename, boolean autoname, ValueCallback<String> callback) {
        checkThread();
        mProvider.saveWebArchive(basename, autoname, callback);
    }

    /**
     * Stop the current load.
     */
    public void stopLoading() {
        checkThread();
        mProvider.stopLoading();
    }

    /**
     * Reload the current url.
     */
    public void reload() {
        checkThread();
        mProvider.reload();
    }

    /**
     * Return true if this WebView has a back history item.
     * @return True iff this WebView has a back history item.
     */
    public boolean canGoBack() {
        checkThread();
        return mProvider.canGoBack();
    }

    /**
     * Go back in the history of this WebView.
     */
    public void goBack() {
        checkThread();
        mProvider.goBack();
    }

    /**
     * Return true if this WebView has a forward history item.
     * @return True iff this Webview has a forward history item.
     */
    public boolean canGoForward() {
        checkThread();
        return mProvider.canGoForward();
    }

    /**
     * Go forward in the history of this WebView.
     */
    public void goForward() {
        checkThread();
        mProvider.goForward();
    }

    /**
     * Return true if the page can go back or forward the given
     * number of steps.
     * @param steps The negative or positive number of steps to move the
     *              history.
     */
    public boolean canGoBackOrForward(int steps) {
        checkThread();
        return mProvider.canGoBackOrForward(steps);
    }

    /**
     * Go to the history item that is the number of steps away from
     * the current item. Steps is negative if backward and positive
     * if forward.
     * @param steps The number of steps to take back or forward in the back
     *              forward list.
     */
    public void goBackOrForward(int steps) {
        checkThread();
        mProvider.goBackOrForward(steps);
    }

    /**
     * Returns true if private browsing is enabled in this WebView.
     */
    public boolean isPrivateBrowsingEnabled() {
        checkThread();
        return mProvider.isPrivateBrowsingEnabled();
    }

    /**
     * Scroll the contents of the view up by half the view size
     * @param top true to jump to the top of the page
     * @return true if the page was scrolled
     */
    public boolean pageUp(boolean top) {
        checkThread();
        return mProvider.pageUp(top);
    }

    /**
     * Scroll the contents of the view down by half the page size
     * @param bottom true to jump to bottom of page
     * @return true if the page was scrolled
     */
    public boolean pageDown(boolean bottom) {
        checkThread();
        return mProvider.pageDown(bottom);
    }

    /**
     * Clear the view so that onDraw() will draw nothing but white background,
     * and onMeasure() will return 0 if MeasureSpec is not MeasureSpec.EXACTLY
     */
    public void clearView() {
        checkThread();
        mProvider.clearView();
    }

    /**
     * Return a new picture that captures the current display of the webview.
     * This is a copy of the display, and will be unaffected if the webview
     * later loads a different URL.
     *
     * @return a picture containing the current contents of the view. Note this
     *         picture is of the entire document, and is not restricted to the
     *         bounds of the view.
     */
    public Picture capturePicture() {
        checkThread();
        return mProvider.capturePicture();
    }

    /**
     * Return the current scale of the WebView
     * @return The current scale.
     */
    public float getScale() {
        checkThread();
        return mProvider.getScale();
    }

    /**
     * Set the initial scale for the WebView. 0 means default. If
     * {@link WebSettings#getUseWideViewPort()} is true, it zooms out all the
     * way. Otherwise it starts with 100%. If initial scale is greater than 0,
     * WebView starts with this value as initial scale.
     * Please note that unlike the scale properties in the viewport meta tag,
     * this method doesn't take the screen density into account.
     *
     * @param scaleInPercent The initial scale in percent.
     */
    public void setInitialScale(int scaleInPercent) {
        checkThread();
        mProvider.setInitialScale(scaleInPercent);
    }

    /**
     * Invoke the graphical zoom picker widget for this WebView. This will
     * result in the zoom widget appearing on the screen to control the zoom
     * level of this WebView.
     */
    public void invokeZoomPicker() {
        checkThread();
        mProvider.invokeZoomPicker();
    }

    /**
     * Return a HitTestResult based on the current cursor node. If a HTML::a tag
     * is found and the anchor has a non-JavaScript url, the HitTestResult type
     * is set to SRC_ANCHOR_TYPE and the url is set in the "extra" field. If the
     * anchor does not have a url or if it is a JavaScript url, the type will
     * be UNKNOWN_TYPE and the url has to be retrieved through
     * {@link #requestFocusNodeHref} asynchronously. If a HTML::img tag is
     * found, the HitTestResult type is set to IMAGE_TYPE and the url is set in
     * the "extra" field. A type of
     * SRC_IMAGE_ANCHOR_TYPE indicates an anchor with a url that has an image as
     * a child node. If a phone number is found, the HitTestResult type is set
     * to PHONE_TYPE and the phone number is set in the "extra" field of
     * HitTestResult. If a map address is found, the HitTestResult type is set
     * to GEO_TYPE and the address is set in the "extra" field of HitTestResult.
     * If an email address is found, the HitTestResult type is set to EMAIL_TYPE
     * and the email is set in the "extra" field of HitTestResult. Otherwise,
     * HitTestResult type is set to UNKNOWN_TYPE.
     */
    public HitTestResult getHitTestResult() {
        checkThread();
        return mProvider.getHitTestResult();
    }

    /**
     * Request the anchor or image element URL at the last tapped point.
     * If hrefMsg is null, this method returns immediately and does not
     * dispatch hrefMsg to its target. If the tapped point hits an image,
     * an anchor, or an image in an anchor, the message associates
     * strings in named keys in its data. The value paired with the key
     * may be an empty string.
     *
     * @param hrefMsg This message will be dispatched with the result of the
     *                request. The message data contains three keys:
     *                - "url" returns the anchor's href attribute.
     *                - "title" returns the anchor's text.
     *                - "src" returns the image's src attribute.
     */
    public void requestFocusNodeHref(Message hrefMsg) {
        checkThread();
        mProvider.requestFocusNodeHref(hrefMsg);
    }

    /**
     * Request the url of the image last touched by the user. msg will be sent
     * to its target with a String representing the url as its object.
     *
     * @param msg This message will be dispatched with the result of the request
     *            as the data member with "url" as key. The result can be null.
     */
    public void requestImageRef(Message msg) {
        checkThread();
        mProvider.requestImageRef(msg);
    }

    /**
     * Get the url for the current page. This is not always the same as the url
     * passed to WebViewClient.onPageStarted because although the load for
     * that url has begun, the current page may not have changed.
     * @return The url for the current page.
     */
    public String getUrl() {
        checkThread();
        return mProvider.getUrl();
    }

    /**
     * Get the original url for the current page. This is not always the same
     * as the url passed to WebViewClient.onPageStarted because although the
     * load for that url has begun, the current page may not have changed.
     * Also, there may have been redirects resulting in a different url to that
     * originally requested.
     * @return The url that was originally requested for the current page.
     */
    public String getOriginalUrl() {
        checkThread();
        return mProvider.getOriginalUrl();
    }

    /**
     * Get the title for the current page. This is the title of the current page
     * until WebViewClient.onReceivedTitle is called.
     * @return The title for the current page.
     */
    public String getTitle() {
        checkThread();
        return mProvider.getTitle();
    }

    /**
     * Get the favicon for the current page. This is the favicon of the current
     * page until WebViewClient.onReceivedIcon is called.
     * @return The favicon for the current page.
     */
    public Bitmap getFavicon() {
        checkThread();
        return mProvider.getFavicon();
    }

    /**
     * Get the touch icon url for the apple-touch-icon <link> element, or
     * a URL on this site's server pointing to the standard location of a
     * touch icon.
     * @hide
     */
    public String getTouchIconUrl() {
        return mProvider.getTouchIconUrl();
    }

    /**
     * Get the progress for the current page.
     * @return The progress for the current page between 0 and 100.
     */
    public int getProgress() {
        checkThread();
        return mProvider.getProgress();
    }

    /**
     * @return the height of the HTML content.
     */
    public int getContentHeight() {
        checkThread();
        return mProvider.getContentHeight();
    }

    /**
     * @return the width of the HTML content.
     * @hide
     */
    public int getContentWidth() {
        return mProvider.getContentWidth();
    }

    /**
     * Pause all layout, parsing, and JavaScript timers for all webviews. This
     * is a global requests, not restricted to just this webview. This can be
     * useful if the application has been paused.
     */
    public void pauseTimers() {
        checkThread();
        mProvider.pauseTimers();
    }

    /**
     * Resume all layout, parsing, and JavaScript timers for all webviews.
     * This will resume dispatching all timers.
     */
    public void resumeTimers() {
        checkThread();
        mProvider.resumeTimers();
    }

    /**
     * Call this to pause any extra processing associated with this WebView and
     * its associated DOM, plugins, JavaScript etc. For example, if the WebView
     * is taken offscreen, this could be called to reduce unnecessary CPU or
     * network traffic. When the WebView is again "active", call onResume().
     *
     * Note that this differs from pauseTimers(), which affects all WebViews.
     */
    public void onPause() {
        checkThread();
        mProvider.onPause();
    }

    /**
     * Call this to resume a WebView after a previous call to onPause().
     */
    public void onResume() {
        checkThread();
        mProvider.onResume();
    }

    /**
     * Returns true if the view is paused, meaning onPause() was called. Calling
     * onResume() sets the paused state back to false.
     * @hide
     */
    public boolean isPaused() {
        return mProvider.isPaused();
    }

    /**
     * Call this to inform the view that memory is low so that it can
     * free any available memory.
     */
    public void freeMemory() {
        checkThread();
        mProvider.freeMemory();
    }

    /**
     * Clear the resource cache. Note that the cache is per-application, so
     * this will clear the cache for all WebViews used.
     *
     * @param includeDiskFiles If false, only the RAM cache is cleared.
     */
    public void clearCache(boolean includeDiskFiles) {
        checkThread();
        mProvider.clearCache(includeDiskFiles);
    }

    /**
     * Make sure that clearing the form data removes the adapter from the
     * currently focused textfield if there is one.
     */
    public void clearFormData() {
        checkThread();
        mProvider.clearFormData();
    }

    /**
     * Tell the WebView to clear its internal back/forward list.
     */
    public void clearHistory() {
        checkThread();
        mProvider.clearHistory();
    }

    /**
     * Clear the SSL preferences table stored in response to proceeding with SSL
     * certificate errors.
     */
    public void clearSslPreferences() {
        checkThread();
        mProvider.clearSslPreferences();
    }

    /**
     * Return the WebBackForwardList for this WebView. This contains the
     * back/forward list for use in querying each item in the history stack.
     * This is a copy of the private WebBackForwardList so it contains only a
     * snapshot of the current state. Multiple calls to this method may return
     * different objects. The object returned from this method will not be
     * updated to reflect any new state.
     */
    public WebBackForwardList copyBackForwardList() {
        checkThread();
        return mProvider.copyBackForwardList();

    }

    /**
     * Register the interface to be used when a find-on-page result has become
     * available. This will replace the current handler.
     *
     * @param listener An implementation of FindListener
     * @hide
     */
    public void setFindListener(FindListener listener) {
        checkThread();
        mProvider.setFindListener(listener);
    }

    /**
     * Highlight and scroll to the next occurance of String in findAll.
     * Wraps the page infinitely, and scrolls.  Must be called after
     * calling findAll.
     *
     * @param forward Direction to search.
     */
    public void findNext(boolean forward) {
        checkThread();
        mProvider.findNext(forward);
    }

    /**
     * Find all instances of find on the page and highlight them.
     *
     * @param find  String to find.
     * @return int  The number of occurances of the String "find"
     *              that were found.
     */
    public int findAll(String find) {
        checkThread();
        return mProvider.findAll(find);
    }

    /**
     * Find all instances of find on the page and highlight them,
     * asynchronously.
     *
     * @param find  String to find.
     * @hide
     */
    public void findAllAsync(String find) {
        checkThread();
        mProvider.findAllAsync(find);
    }

    /**
     * Start an ActionMode for finding text in this WebView.  Only works if this
     *              WebView is attached to the view system.
     * @param text If non-null, will be the initial text to search for.
     *             Otherwise, the last String searched for in this WebView will
     *             be used to start.
     * @param showIme If true, show the IME, assuming the user will begin typing.
     *             If false and text is non-null, perform a find all.
     * @return boolean True if the find dialog is shown, false otherwise.
     */
    public boolean showFindDialog(String text, boolean showIme) {
        checkThread();
        return mProvider.showFindDialog(text, showIme);
    }

    /**
     * Return the first substring consisting of the address of a physical
     * location. Currently, only addresses in the United States are detected,
     * and consist of:
     * - a house number
     * - a street name
     * - a street type (Road, Circle, etc), either spelled out or abbreviated
     * - a city name
     * - a state or territory, either spelled out or two-letter abbr.
     * - an optional 5 digit or 9 digit zip code.
     *
     * All names must be correctly capitalized, and the zip code, if present,
     * must be valid for the state. The street type must be a standard USPS
     * spelling or abbreviation. The state or territory must also be spelled
     * or abbreviated using USPS standards. The house number may not exceed
     * five digits.
     * @param addr The string to search for addresses.
     *
     * @return the address, or if no address is found, return null.
     */
    public static String findAddress(String addr) {
        checkThread();
        return getFactory().getStatics().findAddress(addr);
    }

    /*
     * Clear the highlighting surrounding text matches created by findAll.
     */
    public void clearMatches() {
        checkThread();
        mProvider.clearMatches();
    }

    /**
     * Query the document to see if it contains any image references. The
     * message object will be dispatched with arg1 being set to 1 if images
     * were found and 0 if the document does not reference any images.
     * @param response The message that will be dispatched with the result.
     */
    public void documentHasImages(Message response) {
        checkThread();
        mProvider.documentHasImages(response);
    }

    /**
     * Set the WebViewClient that will receive various notifications and
     * requests. This will replace the current handler.
     * @param client An implementation of WebViewClient.
     */
    public void setWebViewClient(WebViewClient client) {
        checkThread();
        mProvider.setWebViewClient(client);
    }

    /**
     * Register the interface to be used when content can not be handled by
     * the rendering engine, and should be downloaded instead. This will replace
     * the current handler.
     * @param listener An implementation of DownloadListener.
     */
    public void setDownloadListener(DownloadListener listener) {
        checkThread();
        mProvider.setDownloadListener(listener);
    }

    /**
     * Set the chrome handler. This is an implementation of WebChromeClient for
     * use in handling JavaScript dialogs, favicons, titles, and the progress.
     * This will replace the current handler.
     * @param client An implementation of WebChromeClient.
     */
    public void setWebChromeClient(WebChromeClient client) {
        checkThread();
        mProvider.setWebChromeClient(client);
    }

    /**
     * Set the Picture listener. This is an interface used to receive
     * notifications of a new Picture.
     * @param listener An implementation of WebView.PictureListener.
     * @deprecated This method is now obsolete.
     */
    @Deprecated
    public void setPictureListener(PictureListener listener) {
        checkThread();
        mProvider.setPictureListener(listener);
    }

    /**
     * This method injects the supplied Java object into the WebView. The
     * object is injected into the JavaScript context of the main frame, using
     * the supplied name. This allows the Java object to be accessed from
     * JavaScript. Note that that injected objects will not appear in
     * JavaScript until the page is next (re)loaded. For example:
     * <pre> webView.addJavascriptInterface(new Object(), "injectedObject");
     * webView.loadData("<!DOCTYPE html><title></title>", "text/html", null);
     * webView.loadUrl("javascript:alert(injectedObject.toString())");</pre>
     * <p><strong>IMPORTANT:</strong>
     * <ul>
     * <li> addJavascriptInterface() can be used to allow JavaScript to control
     * the host application. This is a powerful feature, but also presents a
     * security risk. Use of this method in a WebView containing untrusted
     * content could allow an attacker to manipulate the host application in
     * unintended ways, executing Java code with the permissions of the host
     * application. Use extreme care when using this method in a WebView which
     * could contain untrusted content.
     * <li> JavaScript interacts with Java object on a private, background
     * thread of the WebView. Care is therefore required to maintain thread
     * safety.</li>
     * </ul></p>
     * @param object The Java object to inject into the WebView's JavaScript
     *               context. Null values are ignored.
     * @param name The name used to expose the instance in JavaScript.
     */
    public void addJavascriptInterface(Object object, String name) {
        checkThread();
        mProvider.addJavascriptInterface(object, name);
    }

    /**
     * Removes a previously added JavaScript interface with the given name.
     * @param interfaceName The name of the interface to remove.
     */
    public void removeJavascriptInterface(String interfaceName) {
        checkThread();
        mProvider.removeJavascriptInterface(interfaceName);
    }

    /**
     * Return the WebSettings object used to control the settings for this
     * WebView.
     * @return A WebSettings object that can be used to control this WebView's
     *         settings.
     */
    public WebSettings getSettings() {
        checkThread();
        return mProvider.getSettings();
    }

    /**
     * Return the list of currently loaded plugins.
     * @return The list of currently loaded plugins.
     *
     * @hide
     * @deprecated This was used for Gears, which has been deprecated.
     */
    @Deprecated
    public static synchronized PluginList getPluginList() {
        checkThread();
        return new PluginList();
    }

    /**
     * @hide
     * @deprecated This was used for Gears, which has been deprecated.
     */
    @Deprecated
    public void refreshPlugins(boolean reloadOpenPages) {
        checkThread();
    }

    /**
     * Use this method to put the WebView into text selection mode.
     * Do not rely on this functionality; it will be deprecated in the future.
     * @deprecated This method is now obsolete.
     */
    @Deprecated
    public void emulateShiftHeld() {
        checkThread();
        mProvider.emulateShiftHeld();
    }

    /**
     * @deprecated WebView no longer needs to implement
     * ViewGroup.OnHierarchyChangeListener.  This method does nothing now.
     */
    @Override
    // Cannot add @hide as this can always be accessed via the interface.
    @Deprecated
    public void onChildViewAdded(View parent, View child) {}

    /**
     * @deprecated WebView no longer needs to implement
     * ViewGroup.OnHierarchyChangeListener.  This method does nothing now.
     */
    @Override
    // Cannot add @hide as this can always be accessed via the interface.
    @Deprecated
    public void onChildViewRemoved(View p, View child) {}

    /**
     * @deprecated WebView should not have implemented
     * ViewTreeObserver.OnGlobalFocusChangeListener. This method does nothing now.
     */
    @Override
    // Cannot add @hide as this can always be accessed via the interface.
    @Deprecated
    public void onGlobalFocusChanged(View oldFocus, View newFocus) {
    }

    public void setMapTrackballToArrowKeys(boolean setMap) {
        checkThread();
        mProvider.setMapTrackballToArrowKeys(setMap);
    }


    public void flingScroll(int vx, int vy) {
        checkThread();
        mProvider.flingScroll(vx, vy);
    }

    /**
     * Returns a view containing zoom controls i.e. +/- buttons. The caller is
     * in charge of installing this view to the view hierarchy. This view will
     * become visible when the user starts scrolling via touch and fade away if
     * the user does not interact with it.
     * <p/>
     * API version 3 introduces a built-in zoom mechanism that is shown
     * automatically by the MapView. This is the preferred approach for
     * showing the zoom UI.
     *
     * @deprecated The built-in zoom mechanism is preferred, see
     *             {@link WebSettings#setBuiltInZoomControls(boolean)}.
     */
    @Deprecated
    public View getZoomControls() {
        checkThread();
        return mProvider.getZoomControls();
    }

    /**
     * @return TRUE if the WebView can be zoomed in.
     */
    public boolean canZoomIn() {
        checkThread();
        return mProvider.canZoomIn();
    }

    /**
     * @return TRUE if the WebView can be zoomed out.
     */
    public boolean canZoomOut() {
        checkThread();
        return mProvider.canZoomOut();
    }

    /**
     * Perform zoom in in the webview
     * @return TRUE if zoom in succeeds. FALSE if no zoom changes.
     */
    public boolean zoomIn() {
        checkThread();
        return mProvider.zoomIn();
    }

    /**
     * Perform zoom out in the webview
     * @return TRUE if zoom out succeeds. FALSE if no zoom changes.
     */
    public boolean zoomOut() {
        checkThread();
        return mProvider.zoomOut();
    }

    /**
     * @deprecated This method is now obsolete.
     */
    @Deprecated
    public void debugDump() {
        checkThread();
        mProvider.debugDump();
    }

    //-------------------------------------------------------------------------
    // Interface for WebView providers
    //-------------------------------------------------------------------------

    /**
     * Used by providers to obtain the underlying implementation, e.g. when the appliction
     * responds to WebViewClient.onCreateWindow() request.
     *
     * @hide WebViewProvider is not public API.
     */
    public WebViewProvider getWebViewProvider() {
        return mProvider;
    }

    /**
     * Callback interface, allows the provider implementation to access non-public methods
     * and fields, and make super-class calls in this WebView instance.
     * @hide Only for use by WebViewProvider implementations
     */
    public class PrivateAccess {
        // ---- Access to super-class methods ----
        public int super_getScrollBarStyle() {
            return WebView.super.getScrollBarStyle();
        }

        public void super_scrollTo(int scrollX, int scrollY) {
            WebView.super.scrollTo(scrollX, scrollY);
        }

        public void super_computeScroll() {
            WebView.super.computeScroll();
        }

        public boolean super_performLongClick() {
            return WebView.super.performLongClick();
        }

        public boolean super_setFrame(int left, int top, int right, int bottom) {
            return WebView.super.setFrame(left, top, right, bottom);
        }

        public boolean super_dispatchKeyEvent(KeyEvent event) {
            return WebView.super.dispatchKeyEvent(event);
        }

        public boolean super_onGenericMotionEvent(MotionEvent event) {
            return WebView.super.onGenericMotionEvent(event);
        }

        public boolean super_requestFocus(int direction, Rect previouslyFocusedRect) {
            return WebView.super.requestFocus(direction, previouslyFocusedRect);
        }

        public void super_setLayoutParams(ViewGroup.LayoutParams params) {
            WebView.super.setLayoutParams(params);
        }

        // ---- Access to non-public methods ----
        public void overScrollBy(int deltaX, int deltaY,
                int scrollX, int scrollY,
                int scrollRangeX, int scrollRangeY,
                int maxOverScrollX, int maxOverScrollY,
                boolean isTouchEvent) {
            WebView.this.overScrollBy(deltaX, deltaY, scrollX, scrollY, scrollRangeX, scrollRangeY,
                    maxOverScrollX, maxOverScrollY, isTouchEvent);
        }

        public void awakenScrollBars(int duration) {
            WebView.this.awakenScrollBars(duration);
        }

        public void awakenScrollBars(int duration, boolean invalidate) {
            WebView.this.awakenScrollBars(duration, invalidate);
        }

        public float getVerticalScrollFactor() {
            return WebView.this.getVerticalScrollFactor();
        }

        public float getHorizontalScrollFactor() {
            return WebView.this.getHorizontalScrollFactor();
        }

        public void setMeasuredDimension(int measuredWidth, int measuredHeight) {
            WebView.this.setMeasuredDimension(measuredWidth, measuredHeight);
        }

        public void onScrollChanged(int l, int t, int oldl, int oldt) {
            WebView.this.onScrollChanged(l, t, oldl, oldt);
        }

        public int getHorizontalScrollbarHeight() {
            return WebView.this.getHorizontalScrollbarHeight();
        }

        // ---- Access to (non-public) fields ----
        /** Raw setter for the scroll X value, without invoking onScrollChanged handlers etc. */
        public void setScrollXRaw(int scrollX) {
            WebView.this.mScrollX = scrollX;
        }

        /** Raw setter for the scroll Y value, without invoking onScrollChanged handlers etc. */
        public void setScrollYRaw(int scrollY) {
            WebView.this.mScrollY = scrollY;
        }

    }

    //-------------------------------------------------------------------------
    // Private internal stuff
    //-------------------------------------------------------------------------

    // Cache the factory both for efficiency, and ensure any one process gets all webviews from the
    // same provider.
    private static WebViewFactoryProvider sProviderFactory;

    private WebViewProvider mProvider;

    private void ensureProviderCreated() {
        checkThread();
        if (mProvider == null) {
            if (DEBUG) Log.v(LOGTAG, "instantiating webview provider instance");
            // As this can get called during the base class constructor chain, pass the minimum
            // number of dependencies here; the rest are deferred to init().
            mProvider = getFactory().createWebView(this, new PrivateAccess());
        }
    }

    private static synchronized WebViewFactoryProvider getFactory() {
        // For now the main purpose of this function (and the factory abstration) is to keep
        // us honest and minimize usage of WebViewClassic internals when binding the proxy.
        checkThread();
        if (sProviderFactory != null) return sProviderFactory;

        sProviderFactory = getFactoryByName(DEFAULT_WEB_VIEW_FACTORY);
        if (sProviderFactory == null) {
            if (DEBUG) Log.v (LOGTAG, "Falling back to explicit linkage");
            sProviderFactory = new WebViewClassic.Factory();
        }
        return sProviderFactory;
    }

    private static WebViewFactoryProvider getFactoryByName(String providerName) {
        try {
            if (DEBUG) Log.v(LOGTAG, "attempt to load class " + providerName);
            Class<?> c = Class.forName(providerName);
            if (DEBUG) Log.v(LOGTAG, "instantiating factory");
            return (WebViewFactoryProvider) c.newInstance();
        } catch (ClassNotFoundException e) {
            Log.e(LOGTAG, "error loading " + providerName, e);
        } catch (IllegalAccessException e) {
            Log.e(LOGTAG, "error loading " + providerName, e);
        } catch (InstantiationException e) {
            Log.e(LOGTAG, "error loading " + providerName, e);
        }
        return null;
    }

    private static void checkThread() {
        if (Looper.myLooper() != Looper.getMainLooper()) {
            Throwable throwable = new Throwable(
                    "Warning: A WebView method was called on thread '" +
                    Thread.currentThread().getName() + "'. " +
                    "All WebView methods must be called on the UI thread. " +
                    "Future versions of WebView may not support use on other threads.");
            Log.w(LOGTAG, Log.getStackTraceString(throwable));
            StrictMode.onWebViewMethodCalledOnWrongThread(throwable);
        }
    }

    //-------------------------------------------------------------------------
    // Override View methods
    //-------------------------------------------------------------------------

    // TODO: Add a test that enumerates all methods in ViewDelegte & ScrollDelegate, and ensures
    // there's a corresponding override (or better, caller) for each of them in here.

    @Override
    protected void onAttachedToWindow() {
        super.onAttachedToWindow();
        mProvider.getViewDelegate().onAttachedToWindow();
    }

    @Override
    protected void onDetachedFromWindow() {
        mProvider.getViewDelegate().onDetachedFromWindow();
        super.onDetachedFromWindow();
    }

    @Override
    public void setLayoutParams(ViewGroup.LayoutParams params) {
        mProvider.getViewDelegate().setLayoutParams(params);
    }

    @Override
    public void setOverScrollMode(int mode) {
        super.setOverScrollMode(mode);
        // This method may called in the constructor chain, before the WebView provider is
        // created. (Fortunately, this is the only method we override that can get called by
        // any of the base class constructors).
        ensureProviderCreated();
        mProvider.getViewDelegate().setOverScrollMode(mode);
    }

    @Override
    public void setScrollBarStyle(int style) {
        mProvider.getViewDelegate().setScrollBarStyle(style);
        super.setScrollBarStyle(style);
    }

    @Override
    protected int computeHorizontalScrollRange() {
        return mProvider.getScrollDelegate().computeHorizontalScrollRange();
    }

    @Override
    protected int computeHorizontalScrollOffset() {
        return mProvider.getScrollDelegate().computeHorizontalScrollOffset();
    }

    @Override
    protected int computeVerticalScrollRange() {
        return mProvider.getScrollDelegate().computeVerticalScrollRange();
    }

    @Override
    protected int computeVerticalScrollOffset() {
        return mProvider.getScrollDelegate().computeVerticalScrollOffset();
    }

    @Override
    protected int computeVerticalScrollExtent() {
        return mProvider.getScrollDelegate().computeVerticalScrollExtent();
    }

    @Override
    public void computeScroll() {
        mProvider.getScrollDelegate().computeScroll();
    }

    @Override
    public boolean onHoverEvent(MotionEvent event) {
        return mProvider.getViewDelegate().onHoverEvent(event);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        return mProvider.getViewDelegate().onTouchEvent(event);
    }

    @Override
    public boolean onGenericMotionEvent(MotionEvent event) {
        return mProvider.getViewDelegate().onGenericMotionEvent(event);
    }

    @Override
    public boolean onTrackballEvent(MotionEvent event) {
        return mProvider.getViewDelegate().onTrackballEvent(event);
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        return mProvider.getViewDelegate().onKeyDown(keyCode, event);
    }

    @Override
    public boolean onKeyUp(int keyCode, KeyEvent event) {
        return mProvider.getViewDelegate().onKeyUp(keyCode, event);
    }

    @Override
    public boolean onKeyMultiple(int keyCode, int repeatCount, KeyEvent event) {
        return mProvider.getViewDelegate().onKeyMultiple(keyCode, repeatCount, event);
    }

    /*
    TODO: These are not currently implemented in WebViewClassic, but it seems inconsistent not
    to be delegating them too.

    @Override
    public boolean onKeyPreIme(int keyCode, KeyEvent event) {
        return mProvider.getViewDelegate().onKeyPreIme(keyCode, event);
    }
    @Override
    public boolean onKeyLongPress(int keyCode, KeyEvent event) {
        return mProvider.getViewDelegate().onKeyLongPress(keyCode, event);
    }
    @Override
    public boolean onKeyShortcut(int keyCode, KeyEvent event) {
        return mProvider.getViewDelegate().onKeyShortcut(keyCode, event);
    }
    */

    @Deprecated
    @Override
    public boolean shouldDelayChildPressedState() {
        return mProvider.getViewDelegate().shouldDelayChildPressedState();
    }

    @Override
    public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
        super.onInitializeAccessibilityNodeInfo(info);
        mProvider.getViewDelegate().onInitializeAccessibilityNodeInfo(info);
    }

    @Override
    public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
        super.onInitializeAccessibilityEvent(event);
        mProvider.getViewDelegate().onInitializeAccessibilityEvent(event);
    }

    /** @hide */
    @Override
    protected void onDrawVerticalScrollBar(Canvas canvas, Drawable scrollBar,
            int l, int t, int r, int b) {
        mProvider.getViewDelegate().onDrawVerticalScrollBar(canvas, scrollBar, l, t, r, b);
    }

    @Override
    protected void onOverScrolled(int scrollX, int scrollY, boolean clampedX, boolean clampedY) {
        mProvider.getViewDelegate().onOverScrolled(scrollX, scrollY, clampedX, clampedY);
    }

    @Override
    protected void onWindowVisibilityChanged(int visibility) {
        super.onWindowVisibilityChanged(visibility);
        mProvider.getViewDelegate().onWindowVisibilityChanged(visibility);
    }

    @Override
    protected boolean drawChild(Canvas canvas, View child, long drawingTime) {
        // Not using short-circuit OR: provider does suppress base-class call.
        return mProvider.getViewDelegate().drawChild(canvas, child, drawingTime) |
                super.drawChild(canvas, child, drawingTime);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        mProvider.getViewDelegate().onDraw(canvas);
    }

    @Override
    public boolean performLongClick() {
        return mProvider.getViewDelegate().performLongClick();
    }

    @Override
    protected void onConfigurationChanged(Configuration newConfig) {
        mProvider.getViewDelegate().onConfigurationChanged(newConfig);
    }

    @Override
    public InputConnection onCreateInputConnection(EditorInfo outAttrs) {
        return mProvider.getViewDelegate().onCreateInputConnection(outAttrs);
    }

    @Override
    protected void onVisibilityChanged(View changedView, int visibility) {
        super.onVisibilityChanged(changedView, visibility);
        mProvider.getViewDelegate().onVisibilityChanged(changedView, visibility);
    }

    @Override
    public void onWindowFocusChanged(boolean hasWindowFocus) {
        mProvider.getViewDelegate().onWindowFocusChanged(hasWindowFocus);
        super.onWindowFocusChanged(hasWindowFocus);
    }

    @Override
    protected void onFocusChanged(boolean focused, int direction, Rect previouslyFocusedRect) {
        mProvider.getViewDelegate().onFocusChanged(focused, direction, previouslyFocusedRect);
        super.onFocusChanged(focused, direction, previouslyFocusedRect);
    }

    /** @hide */
    @Override
    protected boolean setFrame(int left, int top, int right, int bottom) {
        return mProvider.getViewDelegate().setFrame(left, top, right, bottom);
    }

    @Override
    protected void onSizeChanged(int w, int h, int ow, int oh) {
        super.onSizeChanged(w, h, ow, oh);
        mProvider.getViewDelegate().onSizeChanged(w, h, ow, oh);
    }

    @Override
    protected void onScrollChanged(int l, int t, int oldl, int oldt) {
        super.onScrollChanged(l, t, oldl, oldt);
        mProvider.getViewDelegate().onScrollChanged(l, t, oldl, oldt);
    }

    @Override
    public boolean dispatchKeyEvent(KeyEvent event) {
        return mProvider.getViewDelegate().dispatchKeyEvent(event);
    }

    @Override
    public boolean requestFocus(int direction, Rect previouslyFocusedRect) {
        return mProvider.getViewDelegate().requestFocus(direction, previouslyFocusedRect);
    }

    @Deprecated
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        mProvider.getViewDelegate().onMeasure(widthMeasureSpec, heightMeasureSpec);
    }

    @Override
    public boolean requestChildRectangleOnScreen(View child, Rect rect, boolean immediate) {
        return mProvider.getViewDelegate().requestChildRectangleOnScreen(child, rect, immediate);
    }

    @Override
    public void setBackgroundColor(int color) {
        mProvider.getViewDelegate().setBackgroundColor(color);
    }
}