organise: Update the song preview when the selected destination's data changes

This will cause the file exensions to change when transcode options are changed.

src/ui/organisedialog.cpp

@@ -113,6 +113,13 @@ void OrganiseDialog::SetDestinationModel(QAbstractItemModel* model,
   ui_->destination->setModel(model);
 
   ui_->eject_after->setVisible(devices);
+
+  // In case this is called more than once, disconnect old model.
+  if (model_connection_) disconnect(model_connection_);
+  // If a device changes, transcoding options may have changed.
+  model_connection_ =
+      connect(model, SIGNAL(dataChanged(QModelIndex, QModelIndex)), this,
+              SLOT(DestDataChanged(QModelIndex, QModelIndex)));
 }
 
 bool OrganiseDialog::SetSongs(const SongList& songs) {
@@ -306,6 +313,16 @@ void OrganiseDialog::UpdatePreviews() {
   }
 }
 
+void OrganiseDialog::DestDataChanged(const QModelIndex& begin,
+                                     const QModelIndex& end) {
+  const QModelIndex destination =
+      ui_->destination->model()->index(ui_->destination->currentIndex(), 0);
+  if (QItemSelection(begin, end).contains(destination)) {
+    qLog(Debug) << "Destination data changed";
+    UpdatePreviews();
+  }
+}
+
 QSize OrganiseDialog::sizeHint() const { return QSize(650, 0); }
 
 void OrganiseDialog::Reset() {

src/ui/organisedialog.h

@@ -64,7 +64,7 @@ class OrganiseDialog : public QDialog {
 
   void SetCopy(bool copy);
 
-signals:
+ signals:
   void FileCopied(int);
 
  public slots:
@@ -80,6 +80,8 @@ signals:
   void InsertTag(const QString& tag);
   void UpdatePreviews();
 
+  void DestDataChanged(const QModelIndex& begin, const QModelIndex& end);
+
   void OrganiseFinished(const QStringList& files_with_errors);
 
  private:
@@ -93,6 +95,8 @@ signals:
   TaskManager* task_manager_;
   LibraryBackend* backend_;
 
+  QMetaObject::Connection model_connection_;
+
   OrganiseFormat format_;
 
   QFuture<SongList> songs_future_;