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+/*
+ * Copyright (C) 2010 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.gallery3d.data;
+
+import com.android.gallery3d.util.Future;
+
+import java.util.ArrayList;
+import java.util.WeakHashMap;
+
+// MediaSet is a directory-like data structure.
+// It contains MediaItems and sub-MediaSets.
+//
+// The primary interface are:
+// getMediaItemCount(), getMediaItem() and
+// getSubMediaSetCount(), getSubMediaSet().
+//
+// getTotalMediaItemCount() returns the number of all MediaItems, including
+// those in sub-MediaSets.
+public abstract class MediaSet extends MediaObject {
+ public static final int MEDIAITEM_BATCH_FETCH_COUNT = 500;
+ public static final int INDEX_NOT_FOUND = -1;
+
+ public MediaSet(Path path, long version) {
+ super(path, version);
+ }
+
+ public int getMediaItemCount() {
+ return 0;
+ }
+
+ // Returns the media items in the range [start, start + count).
+ //
+ // The number of media items returned may be less than the specified count
+ // if there are not enough media items available. The number of
+ // media items available may not be consistent with the return value of
+ // getMediaItemCount() because the contents of database may have already
+ // changed.
+ public ArrayList<MediaItem> getMediaItem(int start, int count) {
+ return new ArrayList<MediaItem>();
+ }
+
+ public int getSubMediaSetCount() {
+ return 0;
+ }
+
+ public MediaSet getSubMediaSet(int index) {
+ throw new IndexOutOfBoundsException();
+ }
+
+ public boolean isLeafAlbum() {
+ return false;
+ }
+
+ public int getTotalMediaItemCount() {
+ int total = getMediaItemCount();
+ for (int i = 0, n = getSubMediaSetCount(); i < n; i++) {
+ total += getSubMediaSet(i).getTotalMediaItemCount();
+ }
+ return total;
+ }
+
+ // TODO: we should have better implementation of sub classes
+ public int getIndexOfItem(Path path, int hint) {
+ // hint < 0 is handled below
+ // first, try to find it around the hint
+ int start = Math.max(0,
+ hint - MEDIAITEM_BATCH_FETCH_COUNT / 2);
+ ArrayList<MediaItem> list = getMediaItem(
+ start, MEDIAITEM_BATCH_FETCH_COUNT);
+ int index = getIndexOf(path, list);
+ if (index != INDEX_NOT_FOUND) return start + index;
+
+ // try to find it globally
+ start = start == 0 ? MEDIAITEM_BATCH_FETCH_COUNT : 0;
+ list = getMediaItem(start, MEDIAITEM_BATCH_FETCH_COUNT);
+ while (true) {
+ index = getIndexOf(path, list);
+ if (index != INDEX_NOT_FOUND) return start + index;
+ if (list.size() < MEDIAITEM_BATCH_FETCH_COUNT) return INDEX_NOT_FOUND;
+ start += MEDIAITEM_BATCH_FETCH_COUNT;
+ list = getMediaItem(start, MEDIAITEM_BATCH_FETCH_COUNT);
+ }
+ }
+
+ protected int getIndexOf(Path path, ArrayList<MediaItem> list) {
+ for (int i = 0, n = list.size(); i < n; ++i) {
+ if (list.get(i).mPath == path) return i;
+ }
+ return INDEX_NOT_FOUND;
+ }
+
+ public abstract String getName();
+
+ private WeakHashMap<ContentListener, Object> mListeners =
+ new WeakHashMap<ContentListener, Object>();
+
+ // NOTE: The MediaSet only keeps a weak reference to the listener. The
+ // listener is automatically removed when there is no other reference to
+ // the listener.
+ public void addContentListener(ContentListener listener) {
+ if (mListeners.containsKey(listener)) {
+ throw new IllegalArgumentException();
+ }
+ mListeners.put(listener, null);
+ }
+
+ public void removeContentListener(ContentListener listener) {
+ if (!mListeners.containsKey(listener)) {
+ throw new IllegalArgumentException();
+ }
+ mListeners.remove(listener);
+ }
+
+ // This should be called by subclasses when the content is changed.
+ public void notifyContentChanged() {
+ for (ContentListener listener : mListeners.keySet()) {
+ listener.onContentDirty();
+ }
+ }
+
+ // Reload the content. Return the current data version. reload() should be called
+ // in the same thread as getMediaItem(int, int) and getSubMediaSet(int).
+ public abstract long reload();
+
+ @Override
+ public MediaDetails getDetails() {
+ MediaDetails details = super.getDetails();
+ details.addDetail(MediaDetails.INDEX_TITLE, getName());
+ return details;
+ }
+
+ // Enumerate all media items in this media set (including the ones in sub
+ // media sets), in an efficient order. ItemConsumer.consumer() will be
+ // called for each media item with its index.
+ public void enumerateMediaItems(ItemConsumer consumer) {
+ enumerateMediaItems(consumer, 0);
+ }
+
+ public void enumerateTotalMediaItems(ItemConsumer consumer) {
+ enumerateTotalMediaItems(consumer, 0);
+ }
+
+ public static interface ItemConsumer {
+ void consume(int index, MediaItem item);
+ }
+
+ // The default implementation uses getMediaItem() for enumerateMediaItems().
+ // Subclasses may override this and use more efficient implementations.
+ // Returns the number of items enumerated.
+ protected int enumerateMediaItems(ItemConsumer consumer, int startIndex) {
+ int total = getMediaItemCount();
+ int start = 0;
+ while (start < total) {
+ int count = Math.min(MEDIAITEM_BATCH_FETCH_COUNT, total - start);
+ ArrayList<MediaItem> items = getMediaItem(start, count);
+ for (int i = 0, n = items.size(); i < n; i++) {
+ MediaItem item = items.get(i);
+ consumer.consume(startIndex + start + i, item);
+ }
+ start += count;
+ }
+ return total;
+ }
+
+ // Recursively enumerate all media items under this set.
+ // Returns the number of items enumerated.
+ protected int enumerateTotalMediaItems(
+ ItemConsumer consumer, int startIndex) {
+ int start = 0;
+ start += enumerateMediaItems(consumer, startIndex);
+ int m = getSubMediaSetCount();
+ for (int i = 0; i < m; i++) {
+ start += getSubMediaSet(i).enumerateTotalMediaItems(
+ consumer, startIndex + start);
+ }
+ return start;
+ }
+
+ public Future<Void> requestSync() {
+ return FUTURE_STUB;
+ }
+
+ private static final Future<Void> FUTURE_STUB = new Future<Void>() {
+ @Override
+ public void cancel() {}
+
+ @Override
+ public boolean isCancelled() {
+ return false;
+ }
+
+ @Override
+ public boolean isDone() {
+ return true;
+ }
+
+ @Override
+ public Void get() {
+ return null;
+ }
+
+ @Override
+ public void waitDone() {}
+ };
+}