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;;; Chickadee Game Toolkit
;;; Copyright © 2017 David Thompson <davet@gnu.org>
;;;
;;; Chickadee is free software: you can redistribute it and/or modify
;;; it under the terms of the GNU General Public License as published
;;; by the Free Software Foundation, either version 3 of the License,
;;; or (at your option) any later version.
;;;
;;; Chickadee is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;;; General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with this program. If not, see
;;; <http://www.gnu.org/licenses/>.
;;; Commentary:
;;
;; Sound effects and music.
;;
;;; Code:
(define-module (chickadee audio)
#:use-module (ice-9 format)
#:use-module (srfi srfi-9)
#:use-module (srfi srfi-9 gnu)
#:use-module ((sdl2 mixer) #:prefix sdl2:)
#:export (load-sample
sample?
sample-audio
set-sample-volume!
play-sample
load-music
music?
music-audio
music-volume
play-music
set-music-volume!
pause-music
resume-music
rewind-music
stop-music
music-paused?
music-playing?))
(define (enable-audio)
;; The SDL mixer will throw an exception if it cannot initialize a
;; particular audio format. We don't want this to be fatal, so we
;; ignore it.
(false-if-exception (sdl2:mixer-init))
(sdl2:open-audio))
;; Used to wrap SDL audio functions whose return values should be
;; ignored.
(define-syntax-rule (ignore-value body ...)
(begin
body ...
*unspecified*))
;; Wrapper over SDL audio objects.
(define-record-type <sample>
(make-sample audio)
sample?
(audio sample-audio))
(define (display-sample sample port)
(format port "#<sample ~x>" (object-address sample)))
(set-record-type-printer! <sample> display-sample)
(define (load-sample file)
"Load audio sample from FILE."
(let ((audio (sdl2:load-chunk file)))
(if audio
(make-sample audio)
(error "cannot load audio sample:" file))))
(define (set-sample-volume! volume)
"Set the volume that all samples are played at to VOLUME, an integer
value between 0 and 128."
(ignore-value (sdl2:set-channel-volume! #f volume)))
(define (play-sample sample)
"Play SAMPLE."
(ignore-value
;; An exception will be thrown if too many samples are being played
;; at once, but it can be safely ignored.
(false-if-exception
(sdl2:play-chunk! (sample-audio sample)))))
;; Wrapper over SDL music objects.
(define-record-type <music>
(make-music audio)
music?
(audio music-audio))
(define (display-music music port)
(format port "#<music ~x>" (object-address music)))
(set-record-type-printer! <music> display-music)
(define (load-music file)
"Load music from FILE."
(make-music (sdl2:load-music file)))
(define (music-volume)
"Return the volume level for music, an integer value between 0 and
128."
(sdl2:music-volume))
(define (set-music-volume! volume)
"Set the volume that music is played at to VOLUME, an integer value
between 0 and 128."
(ignore-value (sdl2:set-music-volume! volume)))
(define* (play-music music #:key loop?)
"Play MUSIC. If LOOP?, play it over and over and over and over
and..."
(sdl2:play-music! (music-audio music) (if loop? #f 1)))
(define (pause-music)
"Pause the current music track."
(sdl2:pause-music!))
(define (resume-music)
"Resume the current music track."
(sdl2:resume-music!))
(define (rewind-music)
"Restart the current music track from the beginning."
(sdl2:rewind-music!))
(define (stop-music)
"Stop playing the current music track."
(sdl2:stop-music!))
(define (music-playing?)
"Return #t if music is currently playing."
(sdl2:music-playing?))
(define (music-paused?)
"Return #t if music is currently paused."
(sdl2:music-paused?))
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