src/com/android/browser/TabControl.java - platform/packages/apps/Browser - Git at Google

 /*
  * Copyright (C) 2007 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.os.Bundle;
 import android.util.Log;
 import android.webkit.WebView;

 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Vector;

 class TabControl {
     // Log Tag
     private static final String LOGTAG = "TabControl";

     // next Tab ID, starting at 1
     private static long sNextId = 1;

     private static final String POSITIONS = "positions";
     private static final String CURRENT = "current";

     public static interface OnThumbnailUpdatedListener {
         void onThumbnailUpdated(Tab t);
     }

     // Maximum number of tabs.
     private int mMaxTabs;
     // Private array of WebViews that are used as tabs.
     private ArrayList<Tab> mTabs;
     // Queue of most recently viewed tabs.
     private ArrayList<Tab> mTabQueue;
     // Current position in mTabs.
     private int mCurrentTab = -1;
     // the main browser controller
     private final Controller mController;

     private OnThumbnailUpdatedListener mOnThumbnailUpdatedListener;

     /**
      * Construct a new TabControl object
      */
     TabControl(Controller controller) {
         mController = controller;
         mMaxTabs = mController.getMaxTabs();
         mTabs = new ArrayList<Tab>(mMaxTabs);
         mTabQueue = new ArrayList<Tab>(mMaxTabs);
     }

     synchronized static long getNextId() {
         return sNextId++;
     }

     /**
      * Return the current tab's main WebView. This will always return the main
      * WebView for a given tab and not a subwindow.
      * @return The current tab's WebView.
      */
     WebView getCurrentWebView() {
         Tab t = getTab(mCurrentTab);
         if (t == null) {
             return null;
         }
         return t.getWebView();
     }

     /**
      * Return the current tab's top-level WebView. This can return a subwindow
      * if one exists.
      * @return The top-level WebView of the current tab.
      */
     WebView getCurrentTopWebView() {
         Tab t = getTab(mCurrentTab);
         if (t == null) {
             return null;
         }
         return t.getTopWindow();
     }

     /**
      * Return the current tab's subwindow if it exists.
      * @return The subwindow of the current tab or null if it doesn't exist.
      */
     WebView getCurrentSubWindow() {
         Tab t = getTab(mCurrentTab);
         if (t == null) {
             return null;
         }
         return t.getSubWebView();
     }

     /**
      * return the list of tabs
      */
     List<Tab> getTabs() {
         return mTabs;
     }

     /**
      * Return the tab at the specified position.
      * @return The Tab for the specified position or null if the tab does not
      *         exist.
      */
     Tab getTab(int position) {
         if (position >= 0 && position < mTabs.size()) {
             return mTabs.get(position);
         }
         return null;
     }

     /**
      * Return the current tab.
      * @return The current tab.
      */
     Tab getCurrentTab() {
         return getTab(mCurrentTab);
     }

     /**
      * Return the current tab position.
      * @return The current tab position
      */
     int getCurrentPosition() {
         return mCurrentTab;
     }

     /**
      * Given a Tab, find it's position
      * @param Tab to find
      * @return position of Tab or -1 if not found
      */
     int getTabPosition(Tab tab) {
         if (tab == null) {
             return -1;
         }
         return mTabs.indexOf(tab);
     }

     boolean canCreateNewTab() {
         return mMaxTabs > mTabs.size();
     }

     /**
      * Returns true if there are any incognito tabs open.
      * @return True when any incognito tabs are open, false otherwise.
      */
     boolean hasAnyOpenIncognitoTabs() {
         for (Tab tab : mTabs) {
             if (tab.getWebView() != null
                     && tab.getWebView().isPrivateBrowsingEnabled()) {
                 return true;
             }
         }
         return false;
     }

     void addPreloadedTab(Tab tab) {
         for (Tab current : mTabs) {
             if (current != null && current.getId() == tab.getId()) {
                 throw new IllegalStateException("Tab with id " + tab.getId() + " already exists: "
                         + current.toString());
             }
         }
         mTabs.add(tab);
         tab.setController(mController);
         mController.onSetWebView(tab, tab.getWebView());
         tab.putInBackground();
     }

     /**
      * Create a new tab.
      * @return The newly createTab or null if we have reached the maximum
      *         number of open tabs.
      */
     Tab createNewTab(boolean privateBrowsing) {
         return createNewTab(null, privateBrowsing);
     }

     Tab createNewTab(Bundle state, boolean privateBrowsing) {
         int size = mTabs.size();
         // Return false if we have maxed out on tabs
         if (!canCreateNewTab()) {
             return null;
         }

         final WebView w = createNewWebView(privateBrowsing);

         // Create a new tab and add it to the tab list
         Tab t = new Tab(mController, w, state);
         mTabs.add(t);
         // Initially put the tab in the background.
         t.putInBackground();
         return t;
     }

     /**
      * Create a new tab with default values for closeOnExit(false),
      * appId(null), url(null), and privateBrowsing(false).
      */
     Tab createNewTab() {
         return createNewTab(false);
     }

     SnapshotTab createSnapshotTab(long snapshotId) {
         SnapshotTab t = new SnapshotTab(mController, snapshotId);
         mTabs.add(t);
         return t;
     }

     /**
      * Remove the parent child relationships from all tabs.
      */
     void removeParentChildRelationShips() {
         for (Tab tab : mTabs) {
             tab.removeFromTree();
         }
     }

     /**
      * Remove the tab from the list. If the tab is the current tab shown, the
      * last created tab will be shown.
      * @param t The tab to be removed.
      */
     boolean removeTab(Tab t) {
         if (t == null) {
             return false;
         }

         // Grab the current tab before modifying the list.
         Tab current = getCurrentTab();

         // Remove t from our list of tabs.
         mTabs.remove(t);

         // Put the tab in the background only if it is the current one.
         if (current == t) {
             t.putInBackground();
             mCurrentTab = -1;
         } else {
             // If a tab that is earlier in the list gets removed, the current
             // index no longer points to the correct tab.
             mCurrentTab = getTabPosition(current);
         }

         // destroy the tab
         t.destroy();
         // clear it's references to parent and children
         t.removeFromTree();

         // Remove it from the queue of viewed tabs.
         mTabQueue.remove(t);
         return true;
     }

     /**
      * Destroy all the tabs and subwindows
      */
     void destroy() {
         for (Tab t : mTabs) {
             t.destroy();
         }
         mTabs.clear();
         mTabQueue.clear();
     }

     /**
      * Returns the number of tabs created.
      * @return The number of tabs created.
      */
     int getTabCount() {
         return mTabs.size();
     }

     /**
      * save the tab state:
      * current position
      * position sorted array of tab ids
      * for each tab id, save the tab state
      * @param outState
      * @param saveImages
      */
     void saveState(Bundle outState) {
         final int numTabs = getTabCount();
         if (numTabs == 0) {
             return;
         }
         long[] ids = new long[numTabs];
         int i = 0;
         for (Tab tab : mTabs) {
             Bundle tabState = tab.saveState();
             if (tabState != null) {
                 ids[i++] = tab.getId();
                 String key = Long.toString(tab.getId());
                 if (outState.containsKey(key)) {
                     // Dump the tab state for debugging purposes
                     for (Tab dt : mTabs) {
                         Log.e(LOGTAG, dt.toString());
                     }
                     throw new IllegalStateException(
                             "Error saving state, duplicate tab ids!");
                 }
                 outState.putBundle(key, tabState);
             } else {
                 ids[i++] = -1;
                 // Since we won't be restoring the thumbnail, delete it
                 tab.deleteThumbnail();
             }
         }
         if (!outState.isEmpty()) {
             outState.putLongArray(POSITIONS, ids);
             Tab current = getCurrentTab();
             long cid = -1;
             if (current != null) {
                 cid = current.getId();
             }
             outState.putLong(CURRENT, cid);
         }
     }

     /**
      * Check if the state can be restored.  If the state can be restored, the
      * current tab id is returned.  This can be passed to restoreState below
      * in order to restore the correct tab.  Otherwise, -1 is returned and the
      * state cannot be restored.
      */
     long canRestoreState(Bundle inState, boolean restoreIncognitoTabs) {
         final long[] ids = (inState == null) ? null : inState.getLongArray(POSITIONS);
         if (ids == null) {
             return -1;
         }
         final long oldcurrent = inState.getLong(CURRENT);
         long current = -1;
         if (restoreIncognitoTabs || (hasState(oldcurrent, inState) && !isIncognito(oldcurrent, inState))) {
             current = oldcurrent;
         } else {
             // pick first non incognito tab
             for (long id : ids) {
                 if (hasState(id, inState) && !isIncognito(id, inState)) {
                     current = id;
                     break;
                 }
             }
         }
         return current;
     }

     private boolean hasState(long id, Bundle state) {
         if (id == -1) return false;
         Bundle tab = state.getBundle(Long.toString(id));
         return ((tab != null) && !tab.isEmpty());
     }

     private boolean isIncognito(long id, Bundle state) {
         Bundle tabstate = state.getBundle(Long.toString(id));
         if ((tabstate != null) && !tabstate.isEmpty()) {
             return tabstate.getBoolean(Tab.INCOGNITO);
         }
         return false;
     }

     /**
      * Restore the state of all the tabs.
      * @param currentId The tab id to restore.
      * @param inState The saved state of all the tabs.
      * @param restoreIncognitoTabs Restoring private browsing tabs
      * @param restoreAll All webviews get restored, not just the current tab
      *        (this does not override handling of incognito tabs)
      */
     void restoreState(Bundle inState, long currentId,
             boolean restoreIncognitoTabs, boolean restoreAll) {
         if (currentId == -1) {
             return;
         }
         long[] ids = inState.getLongArray(POSITIONS);
         long maxId = -Long.MAX_VALUE;
         HashMap<Long, Tab> tabMap = new HashMap<Long, Tab>();
         for (long id : ids) {
             if (id > maxId) {
                 maxId = id;
             }
             final String idkey = Long.toString(id);
             Bundle state = inState.getBundle(idkey);
             if (state == null || state.isEmpty()) {
                 // Skip tab
                 continue;
             } else if (!restoreIncognitoTabs
                     && state.getBoolean(Tab.INCOGNITO)) {
                 // ignore tab
             } else if (id == currentId || restoreAll) {
                 Tab t = createNewTab(state, false);
                 if (t == null) {
                     // We could "break" at this point, but we want
                     // sNextId to be set correctly.
                     continue;
                 }
                 tabMap.put(id, t);
                 // Me must set the current tab before restoring the state
                 // so that all the client classes are set.
                 if (id == currentId) {
                     setCurrentTab(t);
                 }
             } else {
                 // Create a new tab and don't restore the state yet, add it
                 // to the tab list
                 Tab t = new Tab(mController, state);
                 tabMap.put(id, t);
                 mTabs.add(t);
                 // added the tab to the front as they are not current
                 mTabQueue.add(0, t);
             }
         }

         // make sure that there is no id overlap between the restored
         // and new tabs
         sNextId = maxId + 1;

         if (mCurrentTab == -1) {
             if (getTabCount() > 0) {
                 setCurrentTab(getTab(0));
             }
         }
         // restore parent/child relationships
         for (long id : ids) {
             final Tab tab = tabMap.get(id);
             final Bundle b = inState.getBundle(Long.toString(id));
             if ((b != null) && (tab != null)) {
                 final long parentId = b.getLong(Tab.PARENTTAB, -1);
                 if (parentId != -1) {
                     final Tab parent = tabMap.get(parentId);
                     if (parent != null) {
                         parent.addChildTab(tab);
                     }
                 }
             }
         }
     }

     /**
      * Free the memory in this order, 1) free the background tabs; 2) free the
      * WebView cache;
      */
     void freeMemory() {
         if (getTabCount() == 0) return;

         // free the least frequently used background tabs
         Vector<Tab> tabs = getHalfLeastUsedTabs(getCurrentTab());
         if (tabs.size() > 0) {
             Log.w(LOGTAG, "Free " + tabs.size() + " tabs in the browser");
             for (Tab t : tabs) {
                 // store the WebView's state.
                 t.saveState();
                 // destroy the tab
                 t.destroy();
             }
             return;
         }

         // free the WebView's unused memory (this includes the cache)
         Log.w(LOGTAG, "Free WebView's unused memory and cache");
         WebView view = getCurrentWebView();
         if (view != null) {
             view.freeMemory();
         }
     }

     private Vector<Tab> getHalfLeastUsedTabs(Tab current) {
         Vector<Tab> tabsToGo = new Vector<Tab>();

         // Don't do anything if we only have 1 tab or if the current tab is
         // null.
         if (getTabCount() == 1 || current == null) {
             return tabsToGo;
         }

         if (mTabQueue.size() == 0) {
             return tabsToGo;
         }

         // Rip through the queue starting at the beginning and tear down half of
         // available tabs which are not the current tab or the parent of the
         // current tab.
         int openTabCount = 0;
         for (Tab t : mTabQueue) {
             if (t != null && t.getWebView() != null) {
                 openTabCount++;
                 if (t != current && t != current.getParent()) {
                     tabsToGo.add(t);
                 }
             }
         }

         openTabCount /= 2;
         if (tabsToGo.size() > openTabCount) {
             tabsToGo.setSize(openTabCount);
         }

         return tabsToGo;
     }

     Tab getLeastUsedTab(Tab current) {
         if (getTabCount() == 1 || current == null) {
             return null;
         }
         if (mTabQueue.size() == 0) {
             return null;
         }
         // find a tab which is not the current tab or the parent of the
         // current tab
         for (Tab t : mTabQueue) {
             if (t != null && t.getWebView() != null) {
                 if (t != current && t != current.getParent()) {
                     return t;
                 }
             }
         }
         return null;
     }

     /**
      * Show the tab that contains the given WebView.
      * @param view The WebView used to find the tab.
      */
     Tab getTabFromView(WebView view) {
         for (Tab t : mTabs) {
             if (t.getSubWebView() == view || t.getWebView() == view) {
                 return t;
             }
         }
         return null;
     }

     /**
      * Return the tab with the matching application id.
      * @param id The application identifier.
      */
     Tab getTabFromAppId(String id) {
         if (id == null) {
             return null;
         }
         for (Tab t : mTabs) {
             if (id.equals(t.getAppId())) {
                 return t;
             }
         }
         return null;
     }

     /**
      * Stop loading in all opened WebView including subWindows.
      */
     void stopAllLoading() {
         for (Tab t : mTabs) {
             final WebView webview = t.getWebView();
             if (webview != null) {
                 webview.stopLoading();
             }
             final WebView subview = t.getSubWebView();
             if (subview != null) {
                 subview.stopLoading();
             }
         }
     }

     // This method checks if a tab matches the given url.
     private boolean tabMatchesUrl(Tab t, String url) {
         return url.equals(t.getUrl()) || url.equals(t.getOriginalUrl());
     }

     /**
      * Return the tab that matches the given url.
      * @param url The url to search for.
      */
     Tab findTabWithUrl(String url) {
         if (url == null) {
             return null;
         }
         // Check the current tab first.
         Tab currentTab = getCurrentTab();
         if (currentTab != null && tabMatchesUrl(currentTab, url)) {
             return currentTab;
         }
         // Now check all the rest.
         for (Tab tab : mTabs) {
             if (tabMatchesUrl(tab, url)) {
                 return tab;
             }
         }
         return null;
     }

     /**
      * Recreate the main WebView of the given tab.
      */
     void recreateWebView(Tab t) {
         final WebView w = t.getWebView();
         if (w != null) {
             t.destroy();
         }
         // Create a new WebView. If this tab is the current tab, we need to put
         // back all the clients so force it to be the current tab.
         t.setWebView(createNewWebView(), false);
         if (getCurrentTab() == t) {
             setCurrentTab(t, true);
         }
     }

     /**
      * Creates a new WebView and registers it with the global settings.
      */
     private WebView createNewWebView() {
         return createNewWebView(false);
     }

     /**
      * Creates a new WebView and registers it with the global settings.
      * @param privateBrowsing When true, enables private browsing in the new
      *        WebView.
      */
     private WebView createNewWebView(boolean privateBrowsing) {
         return mController.getWebViewFactory().createWebView(privateBrowsing);
     }

     /**
      * Put the current tab in the background and set newTab as the current tab.
      * @param newTab The new tab. If newTab is null, the current tab is not
      *               set.
      */
     boolean setCurrentTab(Tab newTab) {
         return setCurrentTab(newTab, false);
     }

     /**
      * If force is true, this method skips the check for newTab == current.
      */
     private boolean setCurrentTab(Tab newTab, boolean force) {
         Tab current = getTab(mCurrentTab);
         if (current == newTab && !force) {
             return true;
         }
         if (current != null) {
             current.putInBackground();
             mCurrentTab = -1;
         }
         if (newTab == null) {
             return false;
         }

         // Move the newTab to the end of the queue
         int index = mTabQueue.indexOf(newTab);
         if (index != -1) {
             mTabQueue.remove(index);
         }
         mTabQueue.add(newTab);

         // Display the new current tab
         mCurrentTab = mTabs.indexOf(newTab);
         WebView mainView = newTab.getWebView();
         boolean needRestore = !newTab.isSnapshot() && (mainView == null);
         if (needRestore) {
             // Same work as in createNewTab() except don't do new Tab()
             mainView = createNewWebView();
             newTab.setWebView(mainView);
         }
         newTab.putInForeground();
         return true;
     }

     public void setOnThumbnailUpdatedListener(OnThumbnailUpdatedListener listener) {
         mOnThumbnailUpdatedListener = listener;
         for (Tab t : mTabs) {
             WebView web = t.getWebView();
             if (web != null) {
                 web.setPictureListener(listener != null ? t : null);
             }
         }
     }

     public OnThumbnailUpdatedListener getOnThumbnailUpdatedListener() {
         return mOnThumbnailUpdatedListener;
     }

 }
	/*
	* Copyright (C) 2007 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.os.Bundle;
	import android.util.Log;
	import android.webkit.WebView;

	import java.util.ArrayList;
	import java.util.HashMap;
	import java.util.List;
	import java.util.Vector;

	class TabControl {
	// Log Tag
	private static final String LOGTAG = "TabControl";

	// next Tab ID, starting at 1
	private static long sNextId = 1;

	private static final String POSITIONS = "positions";
	private static final String CURRENT = "current";

	public static interface OnThumbnailUpdatedListener {
	void onThumbnailUpdated(Tab t);
	}

	// Maximum number of tabs.
	private int mMaxTabs;
	// Private array of WebViews that are used as tabs.
	private ArrayList<Tab> mTabs;
	// Queue of most recently viewed tabs.
	private ArrayList<Tab> mTabQueue;
	// Current position in mTabs.
	private int mCurrentTab = -1;
	// the main browser controller
	private final Controller mController;

	private OnThumbnailUpdatedListener mOnThumbnailUpdatedListener;

	/**
	* Construct a new TabControl object
	*/
	TabControl(Controller controller) {
	mController = controller;
	mMaxTabs = mController.getMaxTabs();
	mTabs = new ArrayList<Tab>(mMaxTabs);
	mTabQueue = new ArrayList<Tab>(mMaxTabs);
	}

	synchronized static long getNextId() {
	return sNextId++;
	}

	/**
	* Return the current tab's main WebView. This will always return the main
	* WebView for a given tab and not a subwindow.
	* @return The current tab's WebView.
	*/
	WebView getCurrentWebView() {
	Tab t = getTab(mCurrentTab);
	if (t == null) {
	return null;
	}
	return t.getWebView();
	}

	/**
	* Return the current tab's top-level WebView. This can return a subwindow
	* if one exists.
	* @return The top-level WebView of the current tab.
	*/
	WebView getCurrentTopWebView() {
	Tab t = getTab(mCurrentTab);
	if (t == null) {
	return null;
	}
	return t.getTopWindow();
	}

	/**
	* Return the current tab's subwindow if it exists.
	* @return The subwindow of the current tab or null if it doesn't exist.
	*/
	WebView getCurrentSubWindow() {
	Tab t = getTab(mCurrentTab);
	if (t == null) {
	return null;
	}
	return t.getSubWebView();
	}

	/**
	* return the list of tabs
	*/
	List<Tab> getTabs() {
	return mTabs;
	}

	/**
	* Return the tab at the specified position.
	* @return The Tab for the specified position or null if the tab does not
	* exist.
	*/
	Tab getTab(int position) {
	if (position >= 0 && position < mTabs.size()) {
	return mTabs.get(position);
	}
	return null;
	}

	/**
	* Return the current tab.
	* @return The current tab.
	*/
	Tab getCurrentTab() {
	return getTab(mCurrentTab);
	}

	/**
	* Return the current tab position.
	* @return The current tab position
	*/
	int getCurrentPosition() {
	return mCurrentTab;
	}

	/**
	* Given a Tab, find it's position
	* @param Tab to find
	* @return position of Tab or -1 if not found
	*/
	int getTabPosition(Tab tab) {
	if (tab == null) {
	return -1;
	}
	return mTabs.indexOf(tab);
	}

	boolean canCreateNewTab() {
	return mMaxTabs > mTabs.size();
	}

	/**
	* Returns true if there are any incognito tabs open.
	* @return True when any incognito tabs are open, false otherwise.
	*/
	boolean hasAnyOpenIncognitoTabs() {
	for (Tab tab : mTabs) {
	if (tab.getWebView() != null
	&& tab.getWebView().isPrivateBrowsingEnabled()) {
	return true;
	}
	}
	return false;
	}

	void addPreloadedTab(Tab tab) {
	for (Tab current : mTabs) {
	if (current != null && current.getId() == tab.getId()) {
	throw new IllegalStateException("Tab with id " + tab.getId() + " already exists: "
	+ current.toString());
	}
	}
	mTabs.add(tab);
	tab.setController(mController);
	mController.onSetWebView(tab, tab.getWebView());
	tab.putInBackground();
	}

	/**
	* Create a new tab.
	* @return The newly createTab or null if we have reached the maximum
	* number of open tabs.
	*/
	Tab createNewTab(boolean privateBrowsing) {
	return createNewTab(null, privateBrowsing);
	}

	Tab createNewTab(Bundle state, boolean privateBrowsing) {
	int size = mTabs.size();
	// Return false if we have maxed out on tabs
	if (!canCreateNewTab()) {
	return null;
	}

	final WebView w = createNewWebView(privateBrowsing);

	// Create a new tab and add it to the tab list
	Tab t = new Tab(mController, w, state);
	mTabs.add(t);
	// Initially put the tab in the background.
	t.putInBackground();
	return t;
	}

	/**
	* Create a new tab with default values for closeOnExit(false),
	* appId(null), url(null), and privateBrowsing(false).
	*/
	Tab createNewTab() {
	return createNewTab(false);
	}

	SnapshotTab createSnapshotTab(long snapshotId) {
	SnapshotTab t = new SnapshotTab(mController, snapshotId);
	mTabs.add(t);
	return t;
	}

	/**
	* Remove the parent child relationships from all tabs.
	*/
	void removeParentChildRelationShips() {
	for (Tab tab : mTabs) {
	tab.removeFromTree();
	}
	}

	/**
	* Remove the tab from the list. If the tab is the current tab shown, the
	* last created tab will be shown.
	* @param t The tab to be removed.
	*/
	boolean removeTab(Tab t) {
	if (t == null) {
	return false;
	}

	// Grab the current tab before modifying the list.
	Tab current = getCurrentTab();

	// Remove t from our list of tabs.
	mTabs.remove(t);

	// Put the tab in the background only if it is the current one.
	if (current == t) {
	t.putInBackground();
	mCurrentTab = -1;
	} else {
	// If a tab that is earlier in the list gets removed, the current
	// index no longer points to the correct tab.
	mCurrentTab = getTabPosition(current);
	}

	// destroy the tab
	t.destroy();
	// clear it's references to parent and children
	t.removeFromTree();

	// Remove it from the queue of viewed tabs.
	mTabQueue.remove(t);
	return true;
	}

	/**
	* Destroy all the tabs and subwindows
	*/
	void destroy() {
	for (Tab t : mTabs) {
	t.destroy();
	}
	mTabs.clear();
	mTabQueue.clear();
	}

	/**
	* Returns the number of tabs created.
	* @return The number of tabs created.
	*/
	int getTabCount() {
	return mTabs.size();
	}

	/**
	* save the tab state:
	* current position
	* position sorted array of tab ids
	* for each tab id, save the tab state
	* @param outState
	* @param saveImages
	*/
	void saveState(Bundle outState) {
	final int numTabs = getTabCount();
	if (numTabs == 0) {
	return;
	}
	long[] ids = new long[numTabs];
	int i = 0;
	for (Tab tab : mTabs) {
	Bundle tabState = tab.saveState();
	if (tabState != null) {
	ids[i++] = tab.getId();
	String key = Long.toString(tab.getId());
	if (outState.containsKey(key)) {
	// Dump the tab state for debugging purposes
	for (Tab dt : mTabs) {
	Log.e(LOGTAG, dt.toString());
	}
	throw new IllegalStateException(
	"Error saving state, duplicate tab ids!");
	}
	outState.putBundle(key, tabState);
	} else {
	ids[i++] = -1;
	// Since we won't be restoring the thumbnail, delete it
	tab.deleteThumbnail();
	}
	}
	if (!outState.isEmpty()) {
	outState.putLongArray(POSITIONS, ids);
	Tab current = getCurrentTab();
	long cid = -1;
	if (current != null) {
	cid = current.getId();
	}
	outState.putLong(CURRENT, cid);
	}
	}

	/**
	* Check if the state can be restored. If the state can be restored, the
	* current tab id is returned. This can be passed to restoreState below
	* in order to restore the correct tab. Otherwise, -1 is returned and the
	* state cannot be restored.
	*/
	long canRestoreState(Bundle inState, boolean restoreIncognitoTabs) {
	final long[] ids = (inState == null) ? null : inState.getLongArray(POSITIONS);
	if (ids == null) {
	return -1;
	}
	final long oldcurrent = inState.getLong(CURRENT);
	long current = -1;
	if (restoreIncognitoTabs \|\| (hasState(oldcurrent, inState) && !isIncognito(oldcurrent, inState))) {
	current = oldcurrent;
	} else {
	// pick first non incognito tab
	for (long id : ids) {
	if (hasState(id, inState) && !isIncognito(id, inState)) {
	current = id;
	break;
	}
	}
	}
	return current;
	}

	private boolean hasState(long id, Bundle state) {
	if (id == -1) return false;
	Bundle tab = state.getBundle(Long.toString(id));
	return ((tab != null) && !tab.isEmpty());
	}

	private boolean isIncognito(long id, Bundle state) {
	Bundle tabstate = state.getBundle(Long.toString(id));
	if ((tabstate != null) && !tabstate.isEmpty()) {
	return tabstate.getBoolean(Tab.INCOGNITO);
	}
	return false;
	}

	/**
	* Restore the state of all the tabs.
	* @param currentId The tab id to restore.
	* @param inState The saved state of all the tabs.
	* @param restoreIncognitoTabs Restoring private browsing tabs
	* @param restoreAll All webviews get restored, not just the current tab
	* (this does not override handling of incognito tabs)
	*/
	void restoreState(Bundle inState, long currentId,
	boolean restoreIncognitoTabs, boolean restoreAll) {
	if (currentId == -1) {
	return;
	}
	long[] ids = inState.getLongArray(POSITIONS);
	long maxId = -Long.MAX_VALUE;
	HashMap<Long, Tab> tabMap = new HashMap<Long, Tab>();
	for (long id : ids) {
	if (id > maxId) {
	maxId = id;
	}
	final String idkey = Long.toString(id);
	Bundle state = inState.getBundle(idkey);
	if (state == null \|\| state.isEmpty()) {
	// Skip tab
	continue;
	} else if (!restoreIncognitoTabs
	&& state.getBoolean(Tab.INCOGNITO)) {
	// ignore tab
	} else if (id == currentId \|\| restoreAll) {
	Tab t = createNewTab(state, false);
	if (t == null) {
	// We could "break" at this point, but we want
	// sNextId to be set correctly.
	continue;
	}
	tabMap.put(id, t);
	// Me must set the current tab before restoring the state
	// so that all the client classes are set.
	if (id == currentId) {
	setCurrentTab(t);
	}
	} else {
	// Create a new tab and don't restore the state yet, add it
	// to the tab list
	Tab t = new Tab(mController, state);
	tabMap.put(id, t);
	mTabs.add(t);
	// added the tab to the front as they are not current
	mTabQueue.add(0, t);
	}
	}

	// make sure that there is no id overlap between the restored
	// and new tabs
	sNextId = maxId + 1;

	if (mCurrentTab == -1) {
	if (getTabCount() > 0) {
	setCurrentTab(getTab(0));
	}
	}
	// restore parent/child relationships
	for (long id : ids) {
	final Tab tab = tabMap.get(id);
	final Bundle b = inState.getBundle(Long.toString(id));
	if ((b != null) && (tab != null)) {
	final long parentId = b.getLong(Tab.PARENTTAB, -1);
	if (parentId != -1) {
	final Tab parent = tabMap.get(parentId);
	if (parent != null) {
	parent.addChildTab(tab);
	}
	}
	}
	}
	}

	/**
	* Free the memory in this order, 1) free the background tabs; 2) free the
	* WebView cache;
	*/
	void freeMemory() {
	if (getTabCount() == 0) return;

	// free the least frequently used background tabs
	Vector<Tab> tabs = getHalfLeastUsedTabs(getCurrentTab());
	if (tabs.size() > 0) {
	Log.w(LOGTAG, "Free " + tabs.size() + " tabs in the browser");
	for (Tab t : tabs) {
	// store the WebView's state.
	t.saveState();
	// destroy the tab
	t.destroy();
	}
	return;
	}

	// free the WebView's unused memory (this includes the cache)
	Log.w(LOGTAG, "Free WebView's unused memory and cache");
	WebView view = getCurrentWebView();
	if (view != null) {
	view.freeMemory();
	}
	}

	private Vector<Tab> getHalfLeastUsedTabs(Tab current) {
	Vector<Tab> tabsToGo = new Vector<Tab>();

	// Don't do anything if we only have 1 tab or if the current tab is
	// null.
	if (getTabCount() == 1 \|\| current == null) {
	return tabsToGo;
	}

	if (mTabQueue.size() == 0) {
	return tabsToGo;
	}

	// Rip through the queue starting at the beginning and tear down half of
	// available tabs which are not the current tab or the parent of the
	// current tab.
	int openTabCount = 0;
	for (Tab t : mTabQueue) {
	if (t != null && t.getWebView() != null) {
	openTabCount++;
	if (t != current && t != current.getParent()) {
	tabsToGo.add(t);
	}
	}
	}

	openTabCount /= 2;
	if (tabsToGo.size() > openTabCount) {
	tabsToGo.setSize(openTabCount);
	}

	return tabsToGo;
	}

	Tab getLeastUsedTab(Tab current) {
	if (getTabCount() == 1 \|\| current == null) {
	return null;
	}
	if (mTabQueue.size() == 0) {
	return null;
	}
	// find a tab which is not the current tab or the parent of the
	// current tab
	for (Tab t : mTabQueue) {
	if (t != null && t.getWebView() != null) {
	if (t != current && t != current.getParent()) {
	return t;
	}
	}
	}
	return null;
	}

	/**
	* Show the tab that contains the given WebView.
	* @param view The WebView used to find the tab.
	*/
	Tab getTabFromView(WebView view) {
	for (Tab t : mTabs) {
	if (t.getSubWebView() == view \|\| t.getWebView() == view) {
	return t;
	}
	}
	return null;
	}

	/**
	* Return the tab with the matching application id.
	* @param id The application identifier.
	*/
	Tab getTabFromAppId(String id) {
	if (id == null) {
	return null;
	}
	for (Tab t : mTabs) {
	if (id.equals(t.getAppId())) {
	return t;
	}
	}
	return null;
	}

	/**
	* Stop loading in all opened WebView including subWindows.
	*/
	void stopAllLoading() {
	for (Tab t : mTabs) {
	final WebView webview = t.getWebView();
	if (webview != null) {
	webview.stopLoading();
	}
	final WebView subview = t.getSubWebView();
	if (subview != null) {
	subview.stopLoading();
	}
	}
	}

	// This method checks if a tab matches the given url.
	private boolean tabMatchesUrl(Tab t, String url) {
	return url.equals(t.getUrl()) \|\| url.equals(t.getOriginalUrl());
	}

	/**
	* Return the tab that matches the given url.
	* @param url The url to search for.
	*/
	Tab findTabWithUrl(String url) {
	if (url == null) {
	return null;
	}
	// Check the current tab first.
	Tab currentTab = getCurrentTab();
	if (currentTab != null && tabMatchesUrl(currentTab, url)) {
	return currentTab;
	}
	// Now check all the rest.
	for (Tab tab : mTabs) {
	if (tabMatchesUrl(tab, url)) {
	return tab;
	}
	}
	return null;
	}

	/**
	* Recreate the main WebView of the given tab.
	*/
	void recreateWebView(Tab t) {
	final WebView w = t.getWebView();
	if (w != null) {
	t.destroy();
	}
	// Create a new WebView. If this tab is the current tab, we need to put
	// back all the clients so force it to be the current tab.
	t.setWebView(createNewWebView(), false);
	if (getCurrentTab() == t) {
	setCurrentTab(t, true);
	}
	}

	/**
	* Creates a new WebView and registers it with the global settings.
	*/
	private WebView createNewWebView() {
	return createNewWebView(false);
	}

	/**
	* Creates a new WebView and registers it with the global settings.
	* @param privateBrowsing When true, enables private browsing in the new
	* WebView.
	*/
	private WebView createNewWebView(boolean privateBrowsing) {
	return mController.getWebViewFactory().createWebView(privateBrowsing);
	}

	/**
	* Put the current tab in the background and set newTab as the current tab.
	* @param newTab The new tab. If newTab is null, the current tab is not
	* set.
	*/
	boolean setCurrentTab(Tab newTab) {
	return setCurrentTab(newTab, false);
	}

	/**
	* If force is true, this method skips the check for newTab == current.
	*/
	private boolean setCurrentTab(Tab newTab, boolean force) {
	Tab current = getTab(mCurrentTab);
	if (current == newTab && !force) {
	return true;
	}
	if (current != null) {
	current.putInBackground();
	mCurrentTab = -1;
	}
	if (newTab == null) {
	return false;
	}

	// Move the newTab to the end of the queue
	int index = mTabQueue.indexOf(newTab);
	if (index != -1) {
	mTabQueue.remove(index);
	}
	mTabQueue.add(newTab);

	// Display the new current tab
	mCurrentTab = mTabs.indexOf(newTab);
	WebView mainView = newTab.getWebView();
	boolean needRestore = !newTab.isSnapshot() && (mainView == null);
	if (needRestore) {
	// Same work as in createNewTab() except don't do new Tab()
	mainView = createNewWebView();
	newTab.setWebView(mainView);
	}
	newTab.putInForeground();
	return true;
	}

	public void setOnThumbnailUpdatedListener(OnThumbnailUpdatedListener listener) {
	mOnThumbnailUpdatedListener = listener;
	for (Tab t : mTabs) {
	WebView web = t.getWebView();
	if (web != null) {
	web.setPictureListener(listener != null ? t : null);
	}
	}
	}

	public OnThumbnailUpdatedListener getOnThumbnailUpdatedListener() {
	return mOnThumbnailUpdatedListener;
	}

	}