A few more improvements to the music API

- Handle all plausible cases of assigning into the playlist
- Allow changing the current track to an existing one on the playlist
- Allow getting playlist as a real array instead of an array-like proxy
  (Could be useful for storing it to a WML variable, for example)

changelog

@@ -26,9 +26,12 @@ Version 1.13.7+dev:
 	 * #wesnoth.music_list counts the number of tracks on the playlist
 	 * wesnoth.music_list.current returns mutable information about the currently-playing track
 	 * wesnoth.music_list.current_i returns the index of the current track on the list
+       It is writeable, allowing you to switch to any track on the list. This respects fade values.
+     * wesnoth.music_list.all returns a copy of the playlist that can be stored in a variable.
 	 * wesnoth.music_list.play plays a specific track (as [music]play_once=yes)
 	 * wesnoth.music_list.add appends a track to the playlist (as [music]append=yes)
 	 * wesnoth.music_list.clear clears the current playlist
+	 * wesnoth.music_list.next fades out the current track and moves to a new track on the playlist
 	 * wesnoth.music_list.force_refresh forces any pending playlist changes to be immediately applied
 	 * wesnoth.music_list.volume attribute gets/sets the current music volume, as [volume]music=
 	 * Each track has modifiable shuffle, once, ms_before, ms_after attributes and

src/scripting/lua_audio.cpp

@@ -16,6 +16,7 @@ See the COPYING file for more details.
 #include "lua/lua.h"
 #include "lua/lauxlib.h"
 #include "scripting/lua_common.hpp"
+#include "scripting/push_check.hpp"
 #include "sound.hpp"
 #include "sound_music_track.hpp"
 #include "config_assign.hpp"
@@ -74,6 +75,14 @@ static int impl_music_get(lua_State* L) {
 		}
 		return 1;
 	}
+	if(strcmp(m, "all") == 0) {
+		config playlist;
+		sound::write_music_play_list(playlist);
+		const auto& range = playlist.child_range("music");
+		std::vector<config> tracks(range.begin(), range.end());
+		lua_push(L, tracks);
+		return 1;
+	}
 	// This calculation reverses the one used in [volume] to get back the relative volume level.
 	// (Which is the same calculation that's duplicated in impl_music_set.)
 	return_float_attrib("volume", sound::get_music_volume() * 100.0f / preferences::music_volume());
@@ -82,28 +91,39 @@ static int impl_music_get(lua_State* L) {
 
 static int impl_music_set(lua_State* L) {
 	if(lua_isnumber(L, 2)) {
-		int i = lua_tointeger(L, 2) - 1;
+		unsigned int i = lua_tointeger(L, 2) - 1;
 		config cfg;
 		if(lua_isnil(L, 3)) {
-			sound::remove_track(i);
+			if(i < sound::get_num_tracks()) {
+				sound::remove_track(i);
+			}
 		} else if(luaW_toconfig(L, 3, cfg)) {
 			// Don't allow play_once=yes
 			if(cfg["play_once"]) {
 				return luaL_argerror(L, 3, "For play_once, use wesnoth.music_list.play instead");
 			}
-			// 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);
+			if(i < sound::get_num_tracks()) {
+				sound::play_music_config(cfg);
+			} else {
+				// 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);
+			}
 		} else {
 			music_track& track = *get_track(L, 3);
-			sound::set_track(i, track.operator->());
+			if(i < sound::get_num_tracks()) {
+				sound::set_track(i, track.operator->());
+			} else {
+				track->write(cfg, true);
+				sound::play_music_config(cfg);
+			}
 		}
 		return 0;
 	}
 	const char* m = luaL_checkstring(L, 2);
 	modify_float_attrib_check_range("volume", sound::set_music_volume(value * preferences::music_volume() / 100.0f), 0.0, 100.0);
-	// TODO: Set "current" and "current_i"
+	modify_int_attrib_check_range("current_i", sound::play_track(value - 1), 1, static_cast<int>(sound::get_num_tracks()));
 	return 0;
 }
 
@@ -117,6 +137,14 @@ static int intf_music_play(lua_State* L) {
 	return 0;
 }
 
+static int intf_music_next(lua_State* L) {
+	size_t n = sound::get_num_tracks();
+	if(n > 0) {
+		sound::play_track(n);
+	}
+	return 0;
+}
+
 static int intf_music_add(lua_State* L) {
 	int i = -1;
 	if(lua_isinteger(L, 1)) {
@@ -239,6 +267,7 @@ namespace lua_audio {
 			{ "add", intf_music_add },
 			{ "clear", intf_music_clear },
 			{ "remove", intf_music_remove },
+			{ "next", intf_music_next },
 			{ "force_refresh", intf_music_commit },
 			{ nullptr, nullptr },
 		};

src/sound.cpp

@@ -288,9 +288,9 @@ static std::shared_ptr<sound::music_track> choose_track()
 		current_track_index = track;
 	}
 
-	//LOG_AUDIO << "Next track will be " << current_track_list[track].file_path() << "\n";
+	DBG_AUDIO << "Next track will be " << current_track_list[current_track_index]->file_path() << "\n";
 	played_before.push_back( current_track_list[current_track_index]->file_path() );
-	return current_track_list[current_track_index++];
+	return current_track_list[current_track_index];
 }
 
 static std::string pick_one(const std::string &files)
@@ -524,6 +524,16 @@ void play_music()
 	fadingout_time = current_track->ms_after();
 }
 
+void play_track(unsigned int i) {
+	if(i >= current_track_list.size()) {
+		current_track = choose_track();
+	} else {
+		current_track_index = i;
+		current_track = current_track_list[i];
+	}
+	play_music();
+}
+
 static void play_new_music()
 {
 	music_start_time = 0; //reset status: no start time

src/sound.hpp

@@ -106,6 +106,7 @@ void set_UI_volume(int vol);
 unsigned int get_current_track();
 unsigned int get_num_tracks();
 void remove_track(unsigned int i);
+void play_track(unsigned int i);
 
 }