playlist: Reimplement random and album random sequencing.

playlist.cpp

@@ -64,6 +64,7 @@
 #include <time.h>
 #include <cmath>
 #include <algorithm>
+#include <random>
 
 #include "directoryloader.h"
 #include "playlistitem.h"
@@ -122,10 +123,24 @@ Playlist::Playlist(
     : QTreeWidget(collection->playlistStack())
     , m_collection(collection)
     , m_playlistName(name)
+    , m_refillDebounce(new QTimer(this))
     , m_fetcher(new WebImageFetcher(this))
 {
     setup(extraCols);
 
+    // The timer soaks up repeated events that may cause the random play list
+    // to be regenerated repeatedly.
+    m_refillDebounce->setInterval(100);
+    m_refillDebounce->setSingleShot(true);
+    connect(m_refillDebounce, &QTimer::timeout,
+            this,             &Playlist::refillRandomList);
+
+    // Any of the random-related actions being triggered will cause the parent
+    // group to emit the triggered signal.
+    QActionGroup *randomGroup = action("disableRandomPlay")->actionGroup();
+    connect(randomGroup,      &QActionGroup::triggered,
+            m_refillDebounce, qOverload<>(&QTimer::start));
+
     // Some subclasses need to do even more handling but will remember to
     // call setupPlaylist
     if(!delaySetup) {
@@ -174,6 +189,7 @@ Playlist::~Playlist()
     // make clear that it's intentional that those subclassed versions don't
     // get called (because we can't call them)
 
+    m_randomSequence.clear();
     Playlist::clearItems(Playlist::items());
 
     if(!m_shuttingDown)
@@ -197,26 +213,82 @@ void Playlist::playFirst()
 {
     QTreeWidgetItemIterator listIt(const_cast<Playlist *>(this), QTreeWidgetItemIterator::NotHidden);
     beginPlayingItem(static_cast<PlaylistItem *>(*listIt));
+    refillRandomList();
 }
 
 void Playlist::playNextAlbum()
 {
-#if 0
-#else
-    playNext();
-#endif
+    const auto &item = playingItem();
+    if(!item || !action("albumRandomPlay")->isChecked()) {
+        playNext();
+        return;
+    }
+
+    const auto currentAlbum = item->file().tag()->album();
+    const auto nextAlbumTrack = std::find_if(m_randomSequence.begin(), m_randomSequence.end(),
+            [currentAlbum](const PlaylistItem *item) {
+                return item->file().tag()->album() != currentAlbum;
+            });
+
+    if(nextAlbumTrack == m_randomSequence.end()) {
+        // We were on the last album, playNext will handle looping if we should loop
+        m_randomSequence.clear();
+        playNext();
+    }
+    else {
+        m_randomSequence.erase(m_randomSequence.begin(), nextAlbumTrack);
+        beginPlayingItem(*nextAlbumTrack);
+    }
 }
 
 void Playlist::playNext()
 {
-    auto nowPlaying = playingItem();
-    QTreeWidgetItemIterator listIt(nowPlaying, QTreeWidgetItemIterator::NotHidden);
     PlaylistItem *next = nullptr;
-    if(*listIt) {
-        ++listIt;
+    auto nowPlaying = playingItem();
+    bool doLoop = action("loopPlaylist")->isChecked();
+
+    // Treat an item from a different playlist as if we were being asked to
+    // play from a stop
+    if(nowPlaying && nowPlaying->playlist() != this) {
+        nowPlaying = nullptr;
+    }
+
+    if(action("disableRandomPlay")->isChecked()) {
+        QTreeWidgetItemIterator listIt = nowPlaying
+            ? QTreeWidgetItemIterator(nowPlaying, QTreeWidgetItemIterator::NotHidden)
+            : QTreeWidgetItemIterator(this,       QTreeWidgetItemIterator::NotHidden);
+
+        if(*listIt && nowPlaying) {
+            ++listIt;
+        }
+
         next = static_cast<PlaylistItem *>(*listIt);
+
+        if(!next && doLoop) {
+            playFirst();
+            return;
+        }
     }
+    else {
+        // The two random play modes are identical here, the difference is in how the
+        // randomized sequence is generated by refillRandomList
+
+        if(m_randomSequence.isEmpty() && (doLoop || !nowPlaying)) {
+            refillRandomList();
+
+            // Don't play the same track twice in a row even if it can
+            // "randomly" happen
+            if(m_randomSequence.front() == nowPlaying) {
+                std::swap(m_randomSequence.front(), m_randomSequence.back());
+            }
+        }
 
+        if(!m_randomSequence.isEmpty()) {
+            next = m_randomSequence.takeFirst();
+        }
+    }
+
+    // Will stop playback if next is still null
     beginPlayingItem(next);
 }
 
@@ -298,7 +370,7 @@ void Playlist::saveAs()
 void Playlist::updateDeletedItem(PlaylistItem *item)
 {
     m_members.remove(item->file().absFilePath());
-
+    m_randomSequence.removeAll(item);
     m_history.removeAll(item);
 }
 
@@ -509,7 +581,8 @@ void Playlist::slotBeginPlayback()
     PlaylistItem *item = static_cast<PlaylistItem *>(*visible);
 
     if(item) {
-        beginPlayingItem(item);
+        refillRandomList();
+        playNext();
     }
     else {
         action("stop")->trigger();
@@ -586,7 +659,7 @@ void Playlist::slotAddCover(bool retrieveLocal)
 // Called when image fetcher has added a new cover.
 void Playlist::slotCoverChanged(int coverId)
 {
-    qCDebug(JUK_LOG) << "Refreshing information for newly changed covers.\n";
+    qCDebug(JUK_LOG) << "Refreshing information for newly changed covers.";
     refreshAlbums(selectedItems(), coverId);
 }
 
@@ -626,6 +699,36 @@ void Playlist::slotReload()
     loadFile(m_fileName, fileInfo);
 }
 
+void Playlist::refillRandomList()
+{
+    qCDebug(JUK_LOG) << "Refilling random items.";
+
+    if(action("disableRandomPlay")->isChecked()) {
+        m_randomSequence.clear();
+        return;
+    }
+
+    PlaylistItemList randomItems = visibleItems();
+
+    // See https://www.pcg-random.org/posts/cpp-seeding-surprises.html
+    std::random_device rdev;
+    uint64_t rseed = (uint64_t(rdev()) << 32) | rdev();
+    std::linear_congruential_engine<
+        uint64_t, 6364136223846793005U, 1442695040888963407U, 0U
+        > knuth_lcg(rseed);
+
+    std::shuffle(randomItems.begin(), randomItems.end(), knuth_lcg);
+
+    if(action("albumRandomPlay")->isChecked()) {
+        std::sort(randomItems.begin(), randomItems.end(),
+            [](PlaylistItem *a, PlaylistItem *b) {
+                return a->file().tag()->album() < b->file().tag()->album();
+            });
+    }
+
+    std::swap(m_randomSequence, randomItems);
+}
+
 void Playlist::slotWeightDirty(int column)
 {
     if(column < 0) {
@@ -738,6 +841,7 @@ void Playlist::removeFromDisk(const PlaylistItemList &items)
 void Playlist::synchronizeItemsTo(const PlaylistItemList &itemList)
 {
     // direct call to ::items to avoid infinite loop, bug 402355
+    m_randomSequence.clear();
     clearItems(Playlist::items());
     createItems(itemList);
 }
@@ -1667,11 +1771,12 @@ void Playlist::cleanupAfterAllFileLoadsCompleted()
     // and let user adjust from there.
     if(manualResize()) {
         auto manualResizeAction = action<KToggleAction>("resizeColumnsManually");
+        auto wasChecked = manualResizeAction->isChecked();
 
-        manualResizeAction->toggle();
+        manualResizeAction->setChecked(false);
         calculateColumnWeights();
         slotUpdateColumnWidths();
-        manualResizeAction->toggle();
+        manualResizeAction->setChecked(wasChecked);
     }
 
     playlistItemsChanged();
@@ -2089,6 +2194,7 @@ void Playlist::slotPlayCurrent()
     QTreeWidgetItemIterator it(this, QTreeWidgetItemIterator::Selected);
     PlaylistItem *next = static_cast<PlaylistItem *>(*it);
     beginPlayingItem(next);
+    refillRandomList();
 }
 
 void Playlist::slotUpdateTime()

playlist.h

@@ -34,9 +34,10 @@
 
 class KActionMenu;
 
+class QAction;
 class QFileInfo;
 class QMimeData;
-class QAction;
+class QTimer;
 
 class WebImageFetcher;
 class PlaylistItem;
@@ -405,6 +406,12 @@ public slots:
      */
     virtual void slotReload();
 
+    /**
+     * Ensures the random sequence of playlist items is built. Ignored if we're
+     * not in random playback mode so it is safe to call in any mode.
+     */
+    void refillRandomList();
+
     /**
      * Tells the listview that the next time that it paints that the weighted
      * column widths must be recalculated.  If this is called without a column
@@ -685,6 +692,10 @@ private:
     bool m_widthsDirty                 = true;
     bool m_applySharedSettings         = true;
 
+    /// Used for random play and album random play
+    PlaylistItemList m_randomSequence;
+    QTimer          *m_refillDebounce;
+
     PlaylistSearch* m_search;
     bool m_searchEnabled = true;