indexing

	description: "[

		Singleton factory that creates objects of type EM_MUSIC, EM_SOUND
		and/or to initialize an audio stream.
		
		Use EM_SHARED_AUDIO_FACTORY to access this singleton.
		
		Whenever possible, use creation from file or from pointer.
		
		Avoid creating sound from memory except you know what you're doing.
		Audio format has to be the same as output settings in this case.
		
		Streaming will likely boost your CPU if you're doing a lot of other
		stuff the same time.

	]"
	date: "$Date$"
	revision: "$Revision$"

class EM_AUDIO_FACTORY

inherit

	EM_SHARED_SUBSYSTEMS

	EM_SHARED_ERROR_HANDLER
		export {NONE} all end

	EM_AUDIO_CONSTANTS
		export {NONE} all end

	SDL_MIXER_FUNCTIONS_EXTERNAL
		export {NONE} all end

	SDL_RWOPS_FUNCTIONS_EXTERNAL
		export {NONE} all end

create {EM_SHARED_AUDIO_FACTORY}

	make

feature {NONE} -- Initialization

	make is
			-- Create new audio factory.
		do
		end

feature -- Access

	last_music: EM_MUSIC
			-- Last music created

	last_sound: EM_SOUND
			-- Last sound created

feature -- Music player

	set_player (a_command: STRING) is
			-- Set internal or external music player. This can be used to support more file formats.
			--
			-- If `a_command' is an empty string, the internal player will be used (should be default).
			--
			-- Set `a_command' to a complete command as if typed into the command line, but it should
			-- expect the filename to be added as last argument.
			--
			-- Attention: This may not work on your system as sound device has to be opened twice.
		require
			a_command_not_void: a_command /= Void
		local
			c_string: EWG_ZERO_TERMINATED_STRING
			i: INTEGER
		do
			-- Use appropiate player (a_command = "" implies using internal player)
			create c_string.make_unshared_from_string (a_command)
			i := mix_set_music_cmd_external (c_string.item)
			if i /= 0 then
				error_handler.raise_error (error_handler.Em_error_using_audio_player, [a_command])
			end
		end

feature -- Music creation

	create_music_from_file (a_filename: STRING) is
			-- Load music file from `a_filename' into `last_music'.
			--
			-- This can load WAVE, MOD, MIDI, OGG, MP3 and any file that can be played by a command.
		require
			a_filename_not_void: a_filename /= Void
		local
			c_string: EWG_ZERO_TERMINATED_STRING
			temp_music_pointer: POINTER
		do
			last_music := Void
			last_sound := Void
			create c_string.make_unshared_from_string (a_filename)

			temp_music_pointer := mix_load_mus_external (c_string.item)
			if temp_music_pointer /= default_pointer then
				-- We are ready for playing now.
				create last_music.make_from_pointer (temp_music_pointer)
				last_music.set_filename (a_filename)
			else
				error_handler.raise_error (error_handler.Em_error_loading_audio_file, [a_filename])
			end
		ensure
			music_created: last_music /= Void
		end

feature -- Sound creation

	create_sound_from_file (a_filename: STRING) is
			-- Load sound from file `a_filename' into `last_sound'.
			--
			-- This can load WAVE, AIFF, RIFF, OGG, and VOC files.
			--
			-- Attention: You must have an open mixer before using this function
			--			as it must know the output characteristics so it can
			--			convert this sample for playback. This conversion is done
			--			at load time.
		require
			a_filename_not_void: a_filename /= Void
			mixer_open: audio_subsystem.mixer.is_open
		local
			c_string_filename: EWG_ZERO_TERMINATED_STRING
			c_string_filemode: EWG_ZERO_TERMINATED_STRING
			temp_sound_pointer: POINTER
		do
			last_music := Void
			last_sound := Void
			create c_string_filename.make_unshared_from_string (a_filename)
			create c_string_filemode.make_unshared_from_string ("rb")

			temp_sound_pointer := mix_load_wav_rw_external (sdl_rwfrom_file_external (c_string_filename.item, c_string_filemode.item), 1)
			if temp_sound_pointer /= default_pointer then
				-- We are ready for playing now.
				create last_sound.make_from_pointer (temp_sound_pointer)
				last_sound.set_filename (a_filename)
			else
				error_handler.raise_error (error_handler.Em_error_loading_audio_file, [a_filename])
			end
		ensure
			sound_created: last_sound /= Void
		end

feature -- Stream creation

	create_stream (a_callback: EM_AUDIO_STREAM; an_argument: POINTER) is
			-- Create stream hook from `a_callback'.
			--
			-- Pass in `an_argument' if you need some userdata in the callback.
			-- This argument will be present as `a_userdata' in later callbacks.
			--
			-- Note: Streaming may cause your application to crash if you're doing
			--		 a lot of CPU intensive work in parallel.
		require
			callback_not_void: a_callback /= Void
			mixer_open: audio_subsystem.mixer.is_open
		local
			stream_dispatcher: VOID_VOIDP_UINT8P_INT_ANONYMOUS_CALLBACK_DISPATCHER
		do
			last_music := Void
			last_sound := Void
			create stream_dispatcher.make (a_callback)
			mix_hook_music_external (stream_dispatcher.c_dispatcher, an_argument)
		ensure
			no_music_created: last_music = Void
			no_sound_created: last_sound = Void
		end

invariant
	no_music_and_sound_created_at_the_same_time: not (last_music /= Void and then last_sound /= Void)

end