media library: add data fetch delay after position changes

src/actions.cpp

@@ -2784,11 +2784,16 @@ void listsChangeFinisher()
 		if (myScreen->activeWindow() == &myLibrary->Tags)
 		{
 			myLibrary->Albums.clear();
+			myLibrary->Albums.refresh();
 			myLibrary->Songs.clear();
+			myLibrary->Songs.refresh();
+			myLibrary->updateTimer();
 		}
 		else if (myScreen->activeWindow() == &myLibrary->Albums)
 		{
 			myLibrary->Songs.clear();
+			myLibrary->Songs.refresh();
+			myLibrary->updateTimer();
 		}
 		else if (myScreen->isActiveWindow(myPlaylistEditor->Playlists))
 		{

src/media_library.cpp

@@ -45,7 +45,9 @@ using Global::myScreen;
 
 MediaLibrary *myLibrary;
 
-namespace {//
+namespace {
+
+const auto fetch_delay = boost::posix_time::milliseconds(500);
 
 bool hasTwoColumns;
 size_t itsLeftColStartX;
@@ -144,6 +146,7 @@ public:
 }
 
 MediaLibrary::MediaLibrary()
+: m_timer(boost::posix_time::from_time_t(0))
 {
 	hasTwoColumns = 0;
 	itsLeftColWidth = COLS/3-1;
@@ -336,7 +339,9 @@ void MediaLibrary::update()
 			Tags.refresh();
 		}
 		
-		if ((!Tags.empty() && Albums.reallyEmpty()) || m_albums_update_request)
+		if (!Tags.empty()
+		&& ((Albums.reallyEmpty() && Global::Timer - m_timer > fetch_delay) || m_albums_update_request)
+		)
 		{
 			Albums.clearSearchResults();
 			m_albums_update_request = false;
@@ -382,7 +387,9 @@ void MediaLibrary::update()
 		}
 	}
 	
-	if ((!Albums.empty() && Songs.reallyEmpty()) || m_songs_update_request)
+	if (!Albums.empty()
+	&& ((Songs.reallyEmpty() && Global::Timer - m_timer > fetch_delay) || m_songs_update_request)
+	)
 	{
 		Songs.clearSearchResults();
 		m_songs_update_request = false;
@@ -851,6 +858,11 @@ void MediaLibrary::nextColumn()
 
 /***********************************************************************/
 
+void MediaLibrary::updateTimer()
+{
+	m_timer = Global::Timer;
+}
+
 void MediaLibrary::toggleColumnsMode()
 {
 	hasTwoColumns = !hasTwoColumns;

src/media_library.h

@@ -69,6 +69,7 @@ struct MediaLibrary: Screen<NC::Window *>, Filterable, HasColumns, HasSongs, Sea
 	virtual void nextColumn() OVERRIDE;
 	
 	// private members
+	void updateTimer();
 	void toggleColumnsMode();
 	int Columns();
 	void LocateSong(const MPD::Song &);
@@ -143,6 +144,8 @@ private:
 	bool m_tags_update_request;
 	bool m_albums_update_request;
 	bool m_songs_update_request;
+
+	boost::posix_time::ptime m_timer;
 };
 
 extern MediaLibrary *myLibrary;