diff options
Diffstat (limited to 'core/src/main')
4 files changed, 154 insertions, 1 deletions
diff --git a/core/src/main/java/de/danoeh/antennapod/core/storage/DBWriter.java b/core/src/main/java/de/danoeh/antennapod/core/storage/DBWriter.java index 75510d2f6..49de7ffe7 100644 --- a/core/src/main/java/de/danoeh/antennapod/core/storage/DBWriter.java +++ b/core/src/main/java/de/danoeh/antennapod/core/storage/DBWriter.java @@ -43,6 +43,7 @@ import de.danoeh.antennapod.core.preferences.UserPreferences; import de.danoeh.antennapod.core.service.download.DownloadStatus; import de.danoeh.antennapod.core.service.playback.PlaybackService; import de.danoeh.antennapod.core.util.LongList; +import de.danoeh.antennapod.core.util.Permutor; import de.danoeh.antennapod.core.util.flattr.FlattrStatus; import de.danoeh.antennapod.core.util.flattr.FlattrThing; import de.danoeh.antennapod.core.util.flattr.SimpleFlattrThing; @@ -992,6 +993,32 @@ public class DBWriter { } /** + * Similar to sortQueue, but allows more complex reordering by providing whole-queue context. + * @param permutor Encapsulates whole-Queue reordering logic. + * @param broadcastUpdate <code>true</code> if this operation should trigger a + * QueueUpdateBroadcast. This option should be set to <code>false</code> + * if the caller wants to avoid unexpected updates of the GUI. + */ + public static Future<?> reorderQueue(final Permutor<FeedItem> permutor, final boolean broadcastUpdate) { + return dbExec.submit(() -> { + final PodDBAdapter adapter = PodDBAdapter.getInstance(); + adapter.open(); + final List<FeedItem> queue = DBReader.getQueue(adapter); + + if (queue != null) { + permutor.reorder(queue); + adapter.setQueue(queue); + if (broadcastUpdate) { + EventBus.getDefault().post(QueueEvent.sorted(queue)); + } + } else { + Log.e(TAG, "reorderQueue: Could not load queue"); + } + adapter.close(); + }); + } + + /** * Sets the 'auto_download'-attribute of specific FeedItem. * * @param feedItem FeedItem. diff --git a/core/src/main/java/de/danoeh/antennapod/core/util/Permutor.java b/core/src/main/java/de/danoeh/antennapod/core/util/Permutor.java new file mode 100644 index 000000000..7d6e20ab1 --- /dev/null +++ b/core/src/main/java/de/danoeh/antennapod/core/util/Permutor.java @@ -0,0 +1,17 @@ +package de.danoeh.antennapod.core.util; + +import java.util.List; + +/** + * Interface for passing around list permutor method. This is used for cases where a simple comparator + * won't work (e.g. Random, Smart Shuffle, etc). + * + * @param <E> the type of elements in the list + */ +public interface Permutor<E> { + /** + * Reorders the specified list. + * @param queue A (modifiable) list of elements to be reordered + */ + void reorder(List<E> queue); +} diff --git a/core/src/main/java/de/danoeh/antennapod/core/util/QueueSorter.java b/core/src/main/java/de/danoeh/antennapod/core/util/QueueSorter.java index c3b4c0e15..5c827dfe9 100644 --- a/core/src/main/java/de/danoeh/antennapod/core/util/QueueSorter.java +++ b/core/src/main/java/de/danoeh/antennapod/core/util/QueueSorter.java @@ -2,7 +2,12 @@ package de.danoeh.antennapod.core.util; import android.content.Context; +import java.util.ArrayList; +import java.util.Collections; import java.util.Comparator; +import java.util.HashMap; +import java.util.List; +import java.util.Map; import de.danoeh.antennapod.core.feed.FeedItem; import de.danoeh.antennapod.core.feed.FeedMedia; @@ -20,11 +25,15 @@ public class QueueSorter { DURATION_ASC, DURATION_DESC, FEED_TITLE_ASC, - FEED_TITLE_DESC + FEED_TITLE_DESC, + RANDOM, + SMART_SHUFFLE_ASC, + SMART_SHUFFLE_DESC } public static void sort(final Context context, final Rule rule, final boolean broadcastUpdate) { Comparator<FeedItem> comparator = null; + Permutor<FeedItem> permutor = null; switch (rule) { case EPISODE_TITLE_ASC: @@ -68,11 +77,109 @@ public class QueueSorter { case FEED_TITLE_DESC: comparator = (f1, f2) -> f2.getFeed().getTitle().compareTo(f1.getFeed().getTitle()); break; + case RANDOM: + permutor = Collections::shuffle; + break; + case SMART_SHUFFLE_ASC: + permutor = (queue) -> smartShuffle(queue, true); + break; + case SMART_SHUFFLE_DESC: + permutor = (queue) -> smartShuffle(queue, false); + break; default: } if (comparator != null) { DBWriter.sortQueue(comparator, broadcastUpdate); + } else if (permutor != null) { + DBWriter.reorderQueue(permutor, broadcastUpdate); + } + } + + /** + * Implements a reordering by pubdate that avoids consecutive episodes from the same feed in + * the queue. + * + * A listener might want to hear episodes from any given feed in pubdate order, but would + * prefer a more balanced ordering that avoids having to listen to clusters of consecutive + * episodes from the same feed. This is what "Smart Shuffle" tries to accomplish. + * + * The Smart Shuffle algorithm involves choosing episodes (in round-robin fashion) from a + * collection of individual, pubdate-sorted lists that each contain only items from a specific + * feed. + * + * Of course, clusters of consecutive episodes <i>at the end of the queue</i> may be + * unavoidable. This seems unlikely to be an issue for most users who presumably maintain + * large queues with new episodes continuously being added. + * + * For example, given a queue containing three episodes each from three different feeds + * (A, B, and C), a simple pubdate sort might result in a queue that looks like the following: + * + * B1, B2, B3, A1, A2, C1, C2, C3, A3 + * + * (note that feed B episodes were all published before the first feed A episode, so a simple + * pubdate sort will often result in significant clustering of episodes from a single feed) + * + * Using Smart Shuffle, the resulting queue would look like the following: + * + * A1, B1, C1, A2, B2, C2, A3, B3, C3 + * + * (note that episodes above <i>aren't strictly ordered in terms of pubdate</i>, but episodes + * of each feed <b>do</b> appear in pubdate order) + * + * @param queue A (modifiable) list of FeedItem elements to be reordered. + * @param ascending {@code true} to use ascending pubdate in the reordering; + * {@code false} for descending. + */ + private static void smartShuffle(List<FeedItem> queue, boolean ascending) { + + // Divide FeedItems into lists by feed + + Map<Long, List<FeedItem>> map = new HashMap<>(); + + while (!queue.isEmpty()) { + FeedItem item = queue.remove(0); + Long id = item.getFeedId(); + if (!map.containsKey(id)) { + map.put(id, new ArrayList<>()); + } + map.get(id).add(item); + } + + // Sort each individual list by PubDate (ascending/descending) + + Comparator<FeedItem> itemComparator = ascending + ? (f1, f2) -> f1.getPubDate().compareTo(f2.getPubDate()) + : (f1, f2) -> f2.getPubDate().compareTo(f1.getPubDate()); + + for (Long id : map.keySet()) { + Collections.sort(map.get(id), itemComparator); + } + + // Create a list of the individual FeedItems lists, and sort it by feed title (ascending). + // Doing this ensures that the feed order we use is predictable/deterministic. + + List<List<FeedItem>> feeds = new ArrayList<>(map.values()); + Collections.sort(feeds, + // (we use a desc sort here, since we're iterating back-to-front below) + (f1, f2) -> f2.get(0).getFeed().getTitle().compareTo(f1.get(0).getFeed().getTitle())); + + // Cycle through the (sorted) feed lists in a round-robin fashion, removing the first item + // and adding it back into to the original queue + + while (!feeds.isEmpty()) { + // Iterate across the (sorted) list of feeds, removing the first item in each, and + // appending it to the queue. Note that we're iterating back-to-front here, since we + // will be deleting feed lists as they become empty. + for (int i = feeds.size() - 1; i >= 0; --i) { + List<FeedItem> items = feeds.get(i); + queue.add(items.remove(0)); + // Removed the last item in this particular feed? Then remove this feed from the + // list of feeds. + if (items.isEmpty()) { + feeds.remove(i); + } + } } } } diff --git a/core/src/main/res/values/strings.xml b/core/src/main/res/values/strings.xml index 2ebc2ad77..46bac68c9 100644 --- a/core/src/main/res/values/strings.xml +++ b/core/src/main/res/values/strings.xml @@ -260,6 +260,8 @@ <string name="duration">Duration</string> <string name="episode_title">Episode title</string> <string name="feed_title">Feed title</string> + <string name="random">Random</string> + <string name="smart_shuffle">Smart Shuffle</string> <string name="ascending">Ascending</string> <string name="descending">Descending</string> <string name="clear_queue_confirmation_msg">Please confirm that you want to clear the queue of ALL of the episodes in it</string> |