Automatically scroll to the currently playing song whenever (it changes || the window is shown) && (the user hasn't done anything for 1 minute). Fixes issue #124

src/playlistview.cpp

@@ -31,6 +31,7 @@
 
 const char* PlaylistView::kSettingsGroup = "Playlist";
 const int PlaylistView::kGlowIntensitySteps = 32;
+const int PlaylistView::kAutoscrollGraceTimeout = 60; // seconds
 
 
 PlaylistView::PlaylistView(QWidget *parent)
@@ -38,6 +39,8 @@ PlaylistView::PlaylistView(QWidget *parent)
     glow_enabled_(false),
     glow_timer_(new QTimer(this)),
     glow_intensity_step_(0),
+    inhibit_autoscroll_timer_(new QTimer(this)),
+    inhibit_autoscroll_(false),
     row_height_(-1),
     currenttrack_play_(":currenttrack_play.png"),
     currenttrack_pause_(":currenttrack_pause.png")
@@ -48,6 +51,10 @@ PlaylistView::PlaylistView(QWidget *parent)
   connect(header(), SIGNAL(sectionResized(int,int,int)), SLOT(SaveGeometry()));
   connect(header(), SIGNAL(sectionMoved(int,int,int)), SLOT(SaveGeometry()));
 
+  inhibit_autoscroll_timer_->setInterval(kAutoscrollGraceTimeout * 1000);
+  inhibit_autoscroll_timer_->setSingleShot(true);
+  connect(inhibit_autoscroll_timer_, SIGNAL(timeout()), SLOT(InhibitAutoscrollTimeout()));
+
   glow_timer_->setInterval(1500 / kGlowIntensitySteps);
   connect(glow_timer_, SIGNAL(timeout()), SLOT(GlowIntensityChanged()));
 
@@ -211,6 +218,7 @@ void PlaylistView::hideEvent(QHideEvent*) {
 void PlaylistView::showEvent(QShowEvent*) {
   if (glow_enabled_)
     glow_timer_->start();
+  MaybeAutoscroll();
 }
 
 bool CompareSelectionRanges(const QItemSelectionRange& a, const QItemSelectionRange& b) {
@@ -320,3 +328,39 @@ void PlaylistView::closeEditor(QWidget* editor, QAbstractItemDelegate::EndEditHi
     QTreeView::closeEditor(editor, hint);
   }
 }
+
+void PlaylistView::mousePressEvent(QMouseEvent *event) {
+  QTreeView::mousePressEvent(event);
+  inhibit_autoscroll_ = true;
+  inhibit_autoscroll_timer_->start();
+}
+
+void PlaylistView::scrollContentsBy(int dx, int dy) {
+  QTreeView::scrollContentsBy(dx, dy);
+  inhibit_autoscroll_ = true;
+  inhibit_autoscroll_timer_->start();
+}
+
+void PlaylistView::InhibitAutoscrollTimeout() {
+  // For 1 minute after the user clicks on or scrolls the playlist we promise
+  // not to automatically scroll the view to keep up with a track change.
+  inhibit_autoscroll_ = false;
+}
+
+void PlaylistView::dataChanged(const QModelIndex&, const QModelIndex&) {
+  MaybeAutoscroll();
+}
+
+void PlaylistView::MaybeAutoscroll() {
+  Playlist* playlist = qobject_cast<Playlist*>(model());
+  Q_ASSERT(playlist);
+
+  if (inhibit_autoscroll_)
+    return;
+
+  if (playlist->current_index() == -1)
+    return;
+
+  QModelIndex current = playlist->index(playlist->current_index(), 0);
+  scrollTo(current, QAbstractItemView::PositionAtCenter);
+}

src/playlistview.h

@@ -53,19 +53,27 @@ class PlaylistView : public QTreeView {
  protected:
   void hideEvent(QHideEvent* event);
   void showEvent(QShowEvent* event);
+  void mousePressEvent(QMouseEvent *event);
+  void scrollContentsBy(int dx, int dy);
+
+ protected slots:
+  void dataChanged(const QModelIndex &topLeft, const QModelIndex &bottomRight);
 
  private slots:
   void LoadGeometry();
   void SaveGeometry();
   void GlowIntensityChanged();
+  void InhibitAutoscrollTimeout();
 
  private:
   void ReloadBarPixmaps();
   QList<QPixmap> LoadBarPixmap(const QString& filename);
+  void MaybeAutoscroll();
 
  private:
   static const char* kSettingsGroup;
   static const int kGlowIntensitySteps;
+  static const int kAutoscrollGraceTimeout;
 
   QList<int> GetEditableColumns();
   QModelIndex NextEditableIndex(const QModelIndex& current);
@@ -77,6 +85,9 @@ class PlaylistView : public QTreeView {
   QModelIndex last_current_item_;
   QRect last_glow_rect_;
 
+  QTimer* inhibit_autoscroll_timer_;
+  bool inhibit_autoscroll_;
+
   int row_height_; // Used to invalidate the currenttrack_bar pixmaps
   QList<QPixmap> currenttrack_bar_left_;
   QList<QPixmap> currenttrack_bar_mid_;