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      1 /*
      2  * Copyright (C) 2009 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 com.android.quicksearchbox;
     18 
     19 import com.android.quicksearchbox.util.CachedLater;
     20 import com.android.quicksearchbox.util.Consumer;
     21 import com.android.quicksearchbox.util.Now;
     22 import com.android.quicksearchbox.util.NowOrLater;
     23 import com.android.quicksearchbox.util.NowOrLaterWrapper;
     24 
     25 import android.graphics.drawable.Drawable;
     26 import android.net.Uri;
     27 import android.text.TextUtils;
     28 import android.util.Log;
     29 
     30 import java.util.WeakHashMap;
     31 
     32 /**
     33  * Icon loader that caches the results of another icon loader.
     34  *
     35  */
     36 public class CachingIconLoader implements IconLoader {
     37 
     38     private static final boolean DBG = false;
     39     private static final String TAG = "QSB.CachingIconLoader";
     40 
     41     private final IconLoader mWrapped;
     42 
     43     private final WeakHashMap<String, Entry> mIconCache;
     44 
     45     /**
     46      * Creates a new caching icon loader.
     47      *
     48      * @param wrapped IconLoader whose results will be cached.
     49      */
     50     public CachingIconLoader(IconLoader wrapped) {
     51         mWrapped = wrapped;
     52         mIconCache = new WeakHashMap<String, Entry>();
     53     }
     54 
     55     public NowOrLater<Drawable> getIcon(String drawableId) {
     56         if (DBG) Log.d(TAG, "getIcon(" + drawableId + ")");
     57         if (TextUtils.isEmpty(drawableId) || "0".equals(drawableId)) {
     58             return new Now<Drawable>(null);
     59         }
     60         Entry newEntry = null;
     61         NowOrLater<Drawable.ConstantState> drawableState;
     62         synchronized (this) {
     63             drawableState = queryCache(drawableId);
     64             if (drawableState == null) {
     65                 newEntry = new Entry();
     66                 storeInIconCache(drawableId, newEntry);
     67             }
     68         }
     69         if (drawableState != null) {
     70             return new NowOrLaterWrapper<Drawable.ConstantState, Drawable>(drawableState){
     71                 @Override
     72                 public Drawable get(Drawable.ConstantState value) {
     73                     return value == null ? null : value.newDrawable();
     74                 }};
     75         }
     76         NowOrLater<Drawable> drawable = mWrapped.getIcon(drawableId);
     77         newEntry.set(drawable);
     78         storeInIconCache(drawableId, newEntry);
     79         return drawable;
     80     }
     81 
     82     public Uri getIconUri(String drawableId) {
     83         return mWrapped.getIconUri(drawableId);
     84     }
     85 
     86     private synchronized NowOrLater<Drawable.ConstantState> queryCache(String drawableId) {
     87         NowOrLater<Drawable.ConstantState> cached = mIconCache.get(drawableId);
     88         if (DBG) {
     89             if (cached != null) Log.d(TAG, "Found icon in cache: " + drawableId);
     90         }
     91         return cached;
     92     }
     93 
     94     private synchronized void storeInIconCache(String resourceUri, Entry drawable) {
     95         if (drawable != null) {
     96             mIconCache.put(resourceUri, drawable);
     97         }
     98     }
     99 
    100     private static class Entry extends CachedLater<Drawable.ConstantState>
    101             implements Consumer<Drawable>{
    102         private NowOrLater<Drawable> mDrawable;
    103         private boolean mGotDrawable;
    104         private boolean mCreateRequested;
    105 
    106         public Entry() {
    107         }
    108 
    109         public synchronized void set(NowOrLater<Drawable> drawable) {
    110             if (mGotDrawable) throw new IllegalStateException("set() may only be called once.");
    111             mGotDrawable = true;
    112             mDrawable = drawable;
    113             if (mCreateRequested) {
    114                 getLater();
    115             }
    116         }
    117 
    118         @Override
    119         protected synchronized void create() {
    120             if (!mCreateRequested) {
    121                 mCreateRequested = true;
    122                 if (mGotDrawable) {
    123                     getLater();
    124                 }
    125             }
    126         }
    127 
    128         private void getLater() {
    129             NowOrLater<Drawable> drawable = mDrawable;
    130             mDrawable = null;
    131             drawable.getLater(this);
    132         }
    133 
    134         public boolean consume(Drawable value) {
    135             store(value == null ? null : value.getConstantState());
    136             return true;
    137         }
    138     }
    139 
    140 }
    141