1 /*
2  * Copyright (C) 2014 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.example.androidx.graphics;
18 
19 import android.graphics.Bitmap;
20 import android.provider.MediaStore;
21 import android.widget.ImageView;
22 
23 import androidx.collection.LruCache;
24 import androidx.core.graphics.BitmapCompat;
25 
26 /**
27  * A very naive lazily implemented image loader. Do not use this in production code.
28  */
29 class ImageLoader {
30 
31     /**
32      * A LruCache used to store images which has a maximum size of 10% of the maximum heap size.
33      */
34     private static final long CACHE_SIZE = Runtime.getRuntime().maxMemory() / 10;
35     private static final BitmapCache CACHE = new BitmapCache(
36             CACHE_SIZE > Integer.MAX_VALUE ? Integer.MAX_VALUE : (int) CACHE_SIZE);
37 
ImageLoader()38     private ImageLoader() {
39     }
40 
41     interface Listener {
onImageLoaded(Bitmap bitmap)42         void onImageLoaded(Bitmap bitmap);
43     }
44 
45     @SuppressWarnings("deprecation") /* AsyncTask */
loadMediaStoreThumbnail(final ImageView imageView, final long id, final Listener listener)46     static void loadMediaStoreThumbnail(final ImageView imageView,
47             final long id,
48             final Listener listener) {
49 
50         final Bitmap cachedValue = CACHE.get(id);
51         if (cachedValue != null) {
52             // If the image is already in the cache, display the image,
53             // call the listener now and return
54             imageView.setImageBitmap(cachedValue);
55             if (listener != null) {
56                 listener.onImageLoaded(cachedValue);
57             }
58             return;
59         }
60 
61         new android.os.AsyncTask<Void, Void, Bitmap>() {
62             @Override
63             protected Bitmap doInBackground(Void... params) {
64                 return MediaStore.Images.Thumbnails.getThumbnail(
65                         imageView.getContext().getContentResolver(),
66                         id,
67                         MediaStore.Images.Thumbnails.MINI_KIND,
68                         null);
69             }
70 
71             @Override
72             protected void onPostExecute(Bitmap bitmap) {
73                 imageView.setImageBitmap(bitmap);
74 
75                 if (bitmap != null) {
76                     // Add the image to the memory cache first
77                     CACHE.put(id, bitmap);
78 
79                     if (listener != null) {
80                         listener.onImageLoaded(bitmap);
81                     }
82                 }
83             }
84         }.executeOnExecutor(android.os.AsyncTask.THREAD_POOL_EXECUTOR);
85     }
86 
87     /**
88      * A simple cache implementation for {@link android.graphics.Bitmap} instances which uses
89      * {@link androidx.collection.LruCache}.
90      */
91     private static class BitmapCache extends LruCache<Long, Bitmap> {
BitmapCache(int maxSize)92         BitmapCache(int maxSize) {
93             super(maxSize);
94         }
95 
96         @Override
sizeOf(Long key, Bitmap value)97         protected int sizeOf(Long key, Bitmap value) {
98             return BitmapCompat.getAllocationByteCount(value);
99         }
100     }
101 
102 }
103