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 com.android.gallery3d.data; 18 19 import java.util.ArrayList; 20 21 // FilterDeleteSet filters a base MediaSet to remove some deletion items (we 22 // expect the number to be small). The user can use the following methods to 23 // add/remove deletion items: 24 // 25 // void addDeletion(Path path, int index); 26 // void removeDelection(Path path); 27 // void clearDeletion(); 28 // int getNumberOfDeletions(); 29 // 30 public class FilterDeleteSet extends MediaSet implements ContentListener { 31 private static final String TAG = "FilterDeleteSet"; 32 33 private static final int REQUEST_ADD = 1; 34 private static final int REQUEST_REMOVE = 2; 35 private static final int REQUEST_CLEAR = 3; 36 37 private static class Request { 38 int type; // one of the REQUEST_* constants 39 Path path; 40 int indexHint; 41 public Request(int type, Path path, int indexHint) { 42 this.type = type; 43 this.path = path; 44 this.indexHint = indexHint; 45 } 46 } 47 48 private static class Deletion { 49 Path path; 50 int index; 51 public Deletion(Path path, int index) { 52 this.path = path; 53 this.index = index; 54 } 55 } 56 57 // The underlying MediaSet 58 private final MediaSet mBaseSet; 59 60 // Pending Requests 61 private ArrayList<Request> mRequests = new ArrayList<Request>(); 62 63 // Deletions currently in effect, ordered by index 64 private ArrayList<Deletion> mCurrent = new ArrayList<Deletion>(); 65 private int mMediaItemCount; 66 67 public FilterDeleteSet(Path path, MediaSet baseSet) { 68 super(path, INVALID_DATA_VERSION); 69 mBaseSet = baseSet; 70 mBaseSet.addContentListener(this); 71 } 72 73 @Override 74 public String getName() { 75 return mBaseSet.getName(); 76 } 77 78 @Override 79 public int getMediaItemCount() { 80 return mMediaItemCount; 81 } 82 83 // Gets the MediaItems whose (post-deletion) index are in the range [start, 84 // start + count). Because we remove some of the MediaItems, the index need 85 // to be adjusted. 86 // 87 // For example, if there are 12 items in total. The deleted items are 3, 5, 88 // 10, and the the requested range is [3, 7]: 89 // 90 // The original index: 0 1 2 3 4 5 6 7 8 9 A B C 91 // The deleted items: X X X 92 // The new index: 0 1 2 3 4 5 6 7 8 9 93 // Requested: * * * * * 94 // 95 // We need to figure out the [3, 7] actually maps to the original index 4, 96 // 6, 7, 8, 9. 97 // 98 // We can break the MediaItems into segments, each segment other than the 99 // last one ends in a deleted item. The difference between the new index and 100 // the original index increases with each segment: 101 // 102 // 0 1 2 X (new index = old index) 103 // 4 X (new index = old index - 1) 104 // 6 7 8 9 X (new index = old index - 2) 105 // B C (new index = old index - 3) 106 // 107 @Override 108 public ArrayList<MediaItem> getMediaItem(int start, int count) { 109 if (count <= 0) return new ArrayList<MediaItem>(); 110 111 int end = start + count - 1; 112 int n = mCurrent.size(); 113 // Find the segment that "start" falls into. Count the number of items 114 // not yet deleted until it reaches "start". 115 int i = 0; 116 for (i = 0; i < n; i++) { 117 Deletion d = mCurrent.get(i); 118 if (d.index - i > start) break; 119 } 120 // Find the segment that "end" falls into. 121 int j = i; 122 for (; j < n; j++) { 123 Deletion d = mCurrent.get(j); 124 if (d.index - j > end) break; 125 } 126 127 // Now get enough to cover deleted items in [start, end] 128 ArrayList<MediaItem> base = mBaseSet.getMediaItem(start + i, count + (j - i)); 129 130 // Remove the deleted items. 131 for (int m = j - 1; m >= i; m--) { 132 Deletion d = mCurrent.get(m); 133 int k = d.index - (start + i); 134 base.remove(k); 135 } 136 return base; 137 } 138 139 // We apply the pending requests in the mRequests to construct mCurrent in reload(). 140 @Override 141 public long reload() { 142 boolean newData = mBaseSet.reload() > mDataVersion; 143 synchronized (mRequests) { 144 if (!newData && mRequests.isEmpty()) { 145 return mDataVersion; 146 } 147 for (int i = 0; i < mRequests.size(); i++) { 148 Request r = mRequests.get(i); 149 switch (r.type) { 150 case REQUEST_ADD: { 151 // Add the path into mCurrent if there is no duplicate. 152 int n = mCurrent.size(); 153 int j; 154 for (j = 0; j < n; j++) { 155 if (mCurrent.get(j).path == r.path) break; 156 } 157 if (j == n) { 158 mCurrent.add(new Deletion(r.path, r.indexHint)); 159 } 160 break; 161 } 162 case REQUEST_REMOVE: { 163 // Remove the path from mCurrent. 164 int n = mCurrent.size(); 165 for (int j = 0; j < n; j++) { 166 if (mCurrent.get(j).path == r.path) { 167 mCurrent.remove(j); 168 break; 169 } 170 } 171 break; 172 } 173 case REQUEST_CLEAR: { 174 mCurrent.clear(); 175 break; 176 } 177 } 178 } 179 mRequests.clear(); 180 } 181 182 if (!mCurrent.isEmpty()) { 183 // See if the elements in mCurrent can be found in the MediaSet. We 184 // don't want to search the whole mBaseSet, so we just search a 185 // small window that contains the index hints (plus some margin). 186 int minIndex = mCurrent.get(0).index; 187 int maxIndex = minIndex; 188 for (int i = 1; i < mCurrent.size(); i++) { 189 Deletion d = mCurrent.get(i); 190 minIndex = Math.min(d.index, minIndex); 191 maxIndex = Math.max(d.index, maxIndex); 192 } 193 194 int n = mBaseSet.getMediaItemCount(); 195 int from = Math.max(minIndex - 5, 0); 196 int to = Math.min(maxIndex + 5, n); 197 ArrayList<MediaItem> items = mBaseSet.getMediaItem(from, to - from); 198 ArrayList<Deletion> result = new ArrayList<Deletion>(); 199 for (int i = 0; i < items.size(); i++) { 200 MediaItem item = items.get(i); 201 if (item == null) continue; 202 Path p = item.getPath(); 203 // Find the matching path in mCurrent, if found move it to result 204 for (int j = 0; j < mCurrent.size(); j++) { 205 Deletion d = mCurrent.get(j); 206 if (d.path == p) { 207 d.index = from + i; 208 result.add(d); 209 mCurrent.remove(j); 210 break; 211 } 212 } 213 } 214 mCurrent = result; 215 } 216 217 mMediaItemCount = mBaseSet.getMediaItemCount() - mCurrent.size(); 218 mDataVersion = nextVersionNumber(); 219 return mDataVersion; 220 } 221 222 private void sendRequest(int type, Path path, int indexHint) { 223 Request r = new Request(type, path, indexHint); 224 synchronized (mRequests) { 225 mRequests.add(r); 226 } 227 notifyContentChanged(); 228 } 229 230 @Override 231 public void onContentDirty() { 232 notifyContentChanged(); 233 } 234 235 public void addDeletion(Path path, int indexHint) { 236 sendRequest(REQUEST_ADD, path, indexHint); 237 } 238 239 public void removeDeletion(Path path) { 240 sendRequest(REQUEST_REMOVE, path, 0 /* unused */); 241 } 242 243 public void clearDeletion() { 244 sendRequest(REQUEST_CLEAR, null /* unused */ , 0 /* unused */); 245 } 246 247 // Returns number of deletions _in effect_ (the number will only gets 248 // updated after a reload()). 249 public int getNumberOfDeletions() { 250 return mCurrent.size(); 251 } 252 } 253
