Fix #2602: music doesn't change immediately on loading a save

This time I added an option to disable the feature to allow the currently
playing track to finish when changing the playlist. This allows more
fine-grained control of distinct use cases.

In wesnoth.cpp:do_gameloop(), I reversed the order of the title screen
music and default music because otherwise adding the default music would
enable play_once for the title screen music and prevent instant music
change when the player loads a save. I play title screen music with
immediate=yes, so it's still played first.

src/playsingle_controller.cpp

@@ -222,7 +222,7 @@ LEVEL_RESULT playsingle_controller::play_scenario(const config& level)
 
 	// Start music.
 	for(const config &m : level.child_range("music")) {
-		sound::play_music_config(m);
+		sound::play_music_config(m, true);
 	}
 	sound::commit_music_changes();
 

src/scripting/lua_audio.cpp

@@ -137,7 +137,7 @@ static int impl_music_set(lua_State* L) {
 				// Remove the track at that index and add the new one in its place
 				// It's a little inefficient though...
 				sound::remove_track(i);
-				sound::play_music_config(cfg, i);
+				sound::play_music_config(cfg, false, i);
 			}
 		} else {
 			lua_music_track& track = *get_track(L, 3);
@@ -206,7 +206,7 @@ static int intf_music_add(lua_State* L) {
 			return luaL_argerror(L, i, "unrecognized argument");
 		}
 	}
-	sound::play_music_config(cfg, index);
+	sound::play_music_config(cfg, false, index);
 	return 0;
 }
 

src/sound.cpp

@@ -663,7 +663,7 @@ void play_music_repeatedly(const std::string& id)
 	last_track.reset();
 }
 
-void play_music_config(const config& music_node, int i)
+void play_music_config(const config& music_node, bool allow_interrupt_current_track, int i)
 {
 	//
 	// FIXME: there is a memory leak somewhere in this function, seemingly related to the shared_ptrs
@@ -720,7 +720,8 @@ void play_music_config(const config& music_node, int i)
 		current_track = *iter;
 		current_track_index = iter - current_track_list.begin();
 		play_music();
-	} else if(!track.append() && current_track) { // Make sure the current track is finished
+	} else if(!track.append() && !allow_interrupt_current_track && current_track) {
+		// Make sure the current track will finish first
 		current_track->set_play_once(true);
 	}
 }

src/sound.hpp

@@ -43,7 +43,7 @@ void stop_UI_sound();
 void stop_bell();
 
 // Read config entry, alter track list accordingly.
-void play_music_config(const config &music_node, int i = -1);
+void play_music_config(const config &music_node, bool allow_interrupt_current_track = false, int i = -1);
 // Act on any track list changes from above.
 void commit_music_changes();
 

src/wesnoth.cpp

@@ -744,13 +744,15 @@ static int do_gameloop(const std::vector<std::string>& args)
 		if(!game->is_loading()) {
 			const config& cfg = config_manager.game_config().child("titlescreen_music");
 			if(cfg) {
-				sound::play_music_repeatedly(game_config::title_music);
-
 				for(const config& i : cfg.child_range("music")) {
 					sound::play_music_config(i);
 				}
 
-				sound::commit_music_changes();
+				config title_music_config;
+				title_music_config["name"] = game_config::title_music;
+				title_music_config["append"] = true;
+				title_music_config["immediate"] = true;
+				sound::play_music_config(title_music_config);
 			} else {
 				sound::empty_playlist();
 				sound::stop_music();