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      1 /*
      2  * Copyright (C) 2012 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package android.webkit;
     18 
     19 import java.io.Serializable;
     20 import java.util.ArrayList;
     21 
     22 /* package */ class WebBackForwardListClassic extends WebBackForwardList implements Cloneable,
     23         Serializable {
     24 
     25     // Current position in the list.
     26     private int mCurrentIndex;
     27     // ArrayList of WebHistoryItems for maintaining our copy.
     28     private ArrayList<WebHistoryItemClassic> mArray;
     29     // Flag to indicate that the list is invalid
     30     private boolean mClearPending;
     31     // CallbackProxy to issue client callbacks.
     32     private final CallbackProxy mCallbackProxy;
     33 
     34     /*package*/ WebBackForwardListClassic(CallbackProxy proxy) {
     35         mCurrentIndex = -1;
     36         mArray = new ArrayList<WebHistoryItemClassic>();
     37         mCallbackProxy = proxy;
     38     }
     39 
     40     public synchronized WebHistoryItemClassic getCurrentItem() {
     41         return getItemAtIndex(mCurrentIndex);
     42     }
     43 
     44     public synchronized int getCurrentIndex() {
     45         return mCurrentIndex;
     46     }
     47 
     48     public synchronized WebHistoryItemClassic getItemAtIndex(int index) {
     49         if (index < 0 || index >= getSize()) {
     50             return null;
     51         }
     52         return mArray.get(index);
     53     }
     54 
     55     public synchronized int getSize() {
     56         return mArray.size();
     57     }
     58 
     59     /**
     60      * Mark the back/forward list as having a pending clear. This is used on the
     61      * UI side to mark the list as being invalid during the clearHistory method.
     62      */
     63     /*package*/ synchronized void setClearPending() {
     64         mClearPending = true;
     65     }
     66 
     67     /**
     68      * Return the status of the clear flag. This is used on the UI side to
     69      * determine if the list is valid for checking things like canGoBack.
     70      */
     71     /*package*/ synchronized boolean getClearPending() {
     72         return mClearPending;
     73     }
     74 
     75     /**
     76      * Add a new history item to the list. This will remove all items after the
     77      * current item and append the new item to the end of the list. Called from
     78      * the WebCore thread only. Synchronized because the UI thread may be
     79      * reading the array or the current index.
     80      * @param item A new history item.
     81      */
     82     /*package*/ synchronized void addHistoryItem(WebHistoryItem item) {
     83         // Update the current position because we are going to add the new item
     84         // in that slot.
     85         ++mCurrentIndex;
     86         // If the current position is not at the end, remove all history items
     87         // after the current item.
     88         final int size = mArray.size();
     89         final int newPos = mCurrentIndex;
     90         if (newPos != size) {
     91             for (int i = size - 1; i >= newPos; i--) {
     92                 final WebHistoryItem h = mArray.remove(i);
     93             }
     94         }
     95         // Add the item to the list.
     96         mArray.add((WebHistoryItemClassic) item);
     97         if (mCallbackProxy != null) {
     98             mCallbackProxy.onNewHistoryItem(item);
     99         }
    100     }
    101 
    102     /**
    103      * Clear the back/forward list. Called from the WebCore thread.
    104      */
    105     /*package*/ synchronized void close(int nativeFrame) {
    106         // Clear the array first because nativeClose will call addHistoryItem
    107         // with the current item.
    108         mArray.clear();
    109         mCurrentIndex = -1;
    110         nativeClose(nativeFrame);
    111         // Reset the clear flag
    112         mClearPending = false;
    113     }
    114 
    115     /* Remove the item at the given index. Called by JNI only. */
    116     private synchronized void removeHistoryItem(int index) {
    117         // XXX: This is a special case. Since the callback is only triggered
    118         // when removing the first item, we can assert that the index is 0.
    119         // This lets us change the current index without having to query the
    120         // native BackForwardList.
    121         if (DebugFlags.WEB_BACK_FORWARD_LIST && (index != 0)) {
    122             throw new AssertionError();
    123         }
    124         final WebHistoryItem h = mArray.remove(index);
    125         // XXX: If we ever add another callback for removing history items at
    126         // any index, this will no longer be valid.
    127         mCurrentIndex--;
    128     }
    129 
    130     public synchronized WebBackForwardListClassic clone() {
    131         WebBackForwardListClassic l = new WebBackForwardListClassic(null);
    132         if (mClearPending) {
    133             // If a clear is pending, return a copy with only the current item.
    134             l.addHistoryItem(getCurrentItem());
    135             return l;
    136         }
    137         l.mCurrentIndex = mCurrentIndex;
    138         int size = getSize();
    139         l.mArray = new ArrayList<WebHistoryItemClassic>(size);
    140         for (int i = 0; i < size; i++) {
    141             // Add a copy of each WebHistoryItem
    142             l.mArray.add(mArray.get(i).clone());
    143         }
    144         return l;
    145     }
    146 
    147     /**
    148      * Set the new history index.
    149      * @param newIndex The new history index.
    150      */
    151     /*package*/ synchronized void setCurrentIndex(int newIndex) {
    152         mCurrentIndex = newIndex;
    153         if (mCallbackProxy != null) {
    154             mCallbackProxy.onIndexChanged(getItemAtIndex(newIndex), newIndex);
    155         }
    156     }
    157 
    158     /**
    159      * Restore the history index.
    160      */
    161     /*package*/ static native synchronized void restoreIndex(int nativeFrame,
    162             int index);
    163 
    164     /* Close the native list. */
    165     private static native void nativeClose(int nativeFrame);
    166 }
    167