PROGRAM Sound;
(* The sound example. *)

USES
  allegro5, al5font, al5primitives, al5audio, al5acodec;



(* Helper to test intialization. *)
  PROCEDURE MustInit (aTest: BOOLEAN; aDescription: STRING);
  BEGIN
    IF NOT aTest THEN
    BEGIN
      WriteLn ('couldn''t initialize ', aDescription, '.');
      WriteLn ('Press [Enter] to close.');
      ReadLn;
      Halt (1)
    END
  END;

VAR
  Timer: ALLEGRO_TIMERptr;
  Queue: ALLEGRO_EVENT_QUEUEptr;
  Event: ALLEGRO_EVENT;
  Display: ALLEGRO_DISPLAYptr;
  Font: ALLEGRO_FONTptr;

  Redraw, EndProgram: BOOLEAN;

  Elephant: ALLEGRO_SAMPLEptr;
  Music: ALLEGRO_AUDIO_STREAMptr;

BEGIN
{ Initialization. }
  MustInit (al_init, 'Allegro');
  MustInit (al_install_keyboard, 'keyboard');

  Timer := al_create_timer (1.0 / 30.0);
  MustInit (Assigned (Timer), 'timer');

{ Create display. }
  al_set_new_display_option (ALLEGRO_SAMPLE_BUFFERS, 1, ALLEGRO_SUGGEST);
  al_set_new_display_option (ALLEGRO_SAMPLES, 8, ALLEGRO_SUGGEST);
  al_set_new_bitmap_flags (ALLEGRO_MIN_LINEAR OR ALLEGRO_MAG_LINEAR);
  Display := al_create_display (640, 480);
  MustInit (Assigned (Display), 'display');

{ Init/load graphics. }
  Font := al_create_builtin_font;
  MustInit (Font <> NIL, 'font');

  MustInit (al_init_primitives_addon, 'primitives');

{ Init sound. }
  MustInit (al_install_audio, 'audio');
  MustInit (al_init_acodec_addon, 'audio codecs');
  MustInit (al_reserve_samples (16), 'reserve samples');

{ Load sound. }
  Elephant := al_load_sample ('elephant.wav');
  MustInit (Assigned (Elephant), 'elephant.wav');

{ Music. }
  Music := al_load_audio_stream ('music.opus', 2, 2048);
  MustInit (Assigned (Music), 'music.opus');
  al_set_audio_stream_playmode (Music, ALLEGRO_PLAYMODE_LOOP);
  al_attach_audio_stream_to_mixer (Music, al_get_default_mixer);

{ Create event queue. }
  Queue := al_create_event_queue;
  MustInit (Assigned (Queue), 'queue');

  al_register_event_source (Queue, al_get_keyboard_event_source);
  al_register_event_source (Queue, al_get_display_event_source(Display));
  al_register_event_source (Queue, al_get_timer_event_source (Timer));

{ Initialize loop stuff. }
  Redraw := TRUE;
  EndProgram := FALSE;

  al_start_timer (Timer);
{ Main loop. }
  REPEAT
    al_wait_for_event (Queue, @Event);

    CASE Event.ftype OF
    ALLEGRO_EVENT_TIMER:
    { Game logic goes here. }
      Redraw := TRUE;
    ALLEGRO_EVENT_KEY_DOWN:
      BEGIN
        IF Event.keyboard.keycode = ALLEGRO_KEY_E THEN
          al_play_sample (Elephant, 1, 0, 1, ALLEGRO_PLAYMODE_ONCE, NIL)
        ELSE IF Event.keyboard.keycode = ALLEGRO_KEY_ESCAPE THEN
          EndProgram := TRUE
      END;
    ALLEGRO_EVENT_DISPLAY_CLOSE:
      EndProgram := TRUE;
    END;

  { If must redraw and there's nothing pending... }
    IF Redraw AND al_is_event_queue_empty (Queue) THEN
    BEGIN
      al_clear_to_color (al_map_rgb (0, 0, 0));
      al_draw_text (
        Font, al_map_rgb (255, 255, 255),
        640 DIV 2, 480 DIV 2, ALLEGRO_ALIGN_CENTER,
        'Knock knock, it''s Nelly'
      );
    { Drawing was done in a backbuffer. }
      al_flip_display;
    { Updated. }
      Redraw := FALSE
    END
  UNTIL EndProgram;
{ Release resources. }
  al_destroy_audio_stream (Music);
  al_destroy_sample (Elephant);
  al_destroy_font (Font);
  al_destroy_display (Display);
  al_destroy_timer (Timer);
  al_destroy_event_queue (Queue)
END.