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-rw-r--r--src/com/android/gallery3d/data/FilterDeleteSet.java256
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diff --git a/src/com/android/gallery3d/data/FilterDeleteSet.java b/src/com/android/gallery3d/data/FilterDeleteSet.java
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+/*
+ * Copyright (C) 2012 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 java.util.ArrayList;
+
+// FilterDeleteSet filters a base MediaSet to remove some deletion items (we
+// expect the number to be small). The user can use the following methods to
+// add/remove deletion items:
+//
+// void addDeletion(Path path, int index);
+// void removeDelection(Path path);
+// void clearDeletion();
+// int getNumberOfDeletions();
+//
+public class FilterDeleteSet extends MediaSet implements ContentListener {
+ @SuppressWarnings("unused")
+ private static final String TAG = "FilterDeleteSet";
+
+ private static final int REQUEST_ADD = 1;
+ private static final int REQUEST_REMOVE = 2;
+ private static final int REQUEST_CLEAR = 3;
+
+ private static class Request {
+ int type; // one of the REQUEST_* constants
+ Path path;
+ int indexHint;
+ public Request(int type, Path path, int indexHint) {
+ this.type = type;
+ this.path = path;
+ this.indexHint = indexHint;
+ }
+ }
+
+ private static class Deletion {
+ Path path;
+ int index;
+ public Deletion(Path path, int index) {
+ this.path = path;
+ this.index = index;
+ }
+ }
+
+ // The underlying MediaSet
+ private final MediaSet mBaseSet;
+
+ // Pending Requests
+ private ArrayList<Request> mRequests = new ArrayList<Request>();
+
+ // Deletions currently in effect, ordered by index
+ private ArrayList<Deletion> mCurrent = new ArrayList<Deletion>();
+
+ public FilterDeleteSet(Path path, MediaSet baseSet) {
+ super(path, INVALID_DATA_VERSION);
+ mBaseSet = baseSet;
+ mBaseSet.addContentListener(this);
+ }
+
+ @Override
+ public boolean isCameraRoll() {
+ return mBaseSet.isCameraRoll();
+ }
+
+ @Override
+ public String getName() {
+ return mBaseSet.getName();
+ }
+
+ @Override
+ public int getMediaItemCount() {
+ return mBaseSet.getMediaItemCount() - mCurrent.size();
+ }
+
+ // Gets the MediaItems whose (post-deletion) index are in the range [start,
+ // start + count). Because we remove some of the MediaItems, the index need
+ // to be adjusted.
+ //
+ // For example, if there are 12 items in total. The deleted items are 3, 5,
+ // 10, and the the requested range is [3, 7]:
+ //
+ // The original index: 0 1 2 3 4 5 6 7 8 9 A B C
+ // The deleted items: X X X
+ // The new index: 0 1 2 3 4 5 6 7 8 9
+ // Requested: * * * * *
+ //
+ // We need to figure out the [3, 7] actually maps to the original index 4,
+ // 6, 7, 8, 9.
+ //
+ // We can break the MediaItems into segments, each segment other than the
+ // last one ends in a deleted item. The difference between the new index and
+ // the original index increases with each segment:
+ //
+ // 0 1 2 X (new index = old index)
+ // 4 X (new index = old index - 1)
+ // 6 7 8 9 X (new index = old index - 2)
+ // B C (new index = old index - 3)
+ //
+ @Override
+ public ArrayList<MediaItem> getMediaItem(int start, int count) {
+ if (count <= 0) return new ArrayList<MediaItem>();
+
+ int end = start + count - 1;
+ int n = mCurrent.size();
+ // Find the segment that "start" falls into. Count the number of items
+ // not yet deleted until it reaches "start".
+ int i = 0;
+ for (i = 0; i < n; i++) {
+ Deletion d = mCurrent.get(i);
+ if (d.index - i > start) break;
+ }
+ // Find the segment that "end" falls into.
+ int j = i;
+ for (; j < n; j++) {
+ Deletion d = mCurrent.get(j);
+ if (d.index - j > end) break;
+ }
+
+ // Now get enough to cover deleted items in [start, end]
+ ArrayList<MediaItem> base = mBaseSet.getMediaItem(start + i, count + (j - i));
+
+ // Remove the deleted items.
+ for (int m = j - 1; m >= i; m--) {
+ Deletion d = mCurrent.get(m);
+ int k = d.index - (start + i);
+ base.remove(k);
+ }
+ return base;
+ }
+
+ // We apply the pending requests in the mRequests to construct mCurrent in reload().
+ @Override
+ public long reload() {
+ boolean newData = mBaseSet.reload() > mDataVersion;
+ synchronized (mRequests) {
+ if (!newData && mRequests.isEmpty()) {
+ return mDataVersion;
+ }
+ for (int i = 0; i < mRequests.size(); i++) {
+ Request r = mRequests.get(i);
+ switch (r.type) {
+ case REQUEST_ADD: {
+ // Add the path into mCurrent if there is no duplicate.
+ int n = mCurrent.size();
+ int j;
+ for (j = 0; j < n; j++) {
+ if (mCurrent.get(j).path == r.path) break;
+ }
+ if (j == n) {
+ mCurrent.add(new Deletion(r.path, r.indexHint));
+ }
+ break;
+ }
+ case REQUEST_REMOVE: {
+ // Remove the path from mCurrent.
+ int n = mCurrent.size();
+ for (int j = 0; j < n; j++) {
+ if (mCurrent.get(j).path == r.path) {
+ mCurrent.remove(j);
+ break;
+ }
+ }
+ break;
+ }
+ case REQUEST_CLEAR: {
+ mCurrent.clear();
+ break;
+ }
+ }
+ }
+ mRequests.clear();
+ }
+
+ if (!mCurrent.isEmpty()) {
+ // See if the elements in mCurrent can be found in the MediaSet. We
+ // don't want to search the whole mBaseSet, so we just search a
+ // small window that contains the index hints (plus some margin).
+ int minIndex = mCurrent.get(0).index;
+ int maxIndex = minIndex;
+ for (int i = 1; i < mCurrent.size(); i++) {
+ Deletion d = mCurrent.get(i);
+ minIndex = Math.min(d.index, minIndex);
+ maxIndex = Math.max(d.index, maxIndex);
+ }
+
+ int n = mBaseSet.getMediaItemCount();
+ int from = Math.max(minIndex - 5, 0);
+ int to = Math.min(maxIndex + 5, n);
+ ArrayList<MediaItem> items = mBaseSet.getMediaItem(from, to - from);
+ ArrayList<Deletion> result = new ArrayList<Deletion>();
+ for (int i = 0; i < items.size(); i++) {
+ MediaItem item = items.get(i);
+ if (item == null) continue;
+ Path p = item.getPath();
+ // Find the matching path in mCurrent, if found move it to result
+ for (int j = 0; j < mCurrent.size(); j++) {
+ Deletion d = mCurrent.get(j);
+ if (d.path == p) {
+ d.index = from + i;
+ result.add(d);
+ mCurrent.remove(j);
+ break;
+ }
+ }
+ }
+ mCurrent = result;
+ }
+
+ mDataVersion = nextVersionNumber();
+ return mDataVersion;
+ }
+
+ private void sendRequest(int type, Path path, int indexHint) {
+ Request r = new Request(type, path, indexHint);
+ synchronized (mRequests) {
+ mRequests.add(r);
+ }
+ notifyContentChanged();
+ }
+
+ @Override
+ public void onContentDirty() {
+ notifyContentChanged();
+ }
+
+ public void addDeletion(Path path, int indexHint) {
+ sendRequest(REQUEST_ADD, path, indexHint);
+ }
+
+ public void removeDeletion(Path path) {
+ sendRequest(REQUEST_REMOVE, path, 0 /* unused */);
+ }
+
+ public void clearDeletion() {
+ sendRequest(REQUEST_CLEAR, null /* unused */ , 0 /* unused */);
+ }
+
+ // Returns number of deletions _in effect_ (the number will only gets
+ // updated after a reload()).
+ public int getNumberOfDeletions() {
+ return mCurrent.size();
+ }
+}
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