1.1 --- a/sound/src/main/java/net/java/html/sound/AudioClip.java	Sat Aug 17 14:31:06 2013 +0200
     1.2 +++ b/sound/src/main/java/net/java/html/sound/AudioClip.java	Wed Aug 21 17:38:59 2013 +0200
     1.3 @@ -34,6 +34,9 @@
     1.4      }
     1.5  
     1.6      /** Creates new instance of an audio clip based on the provided URL.
     1.7 +     * If no suitable audio environment provider is found, the method 
     1.8 +     * returns a dummy instance that does nothing and only returns
     1.9 +     * false from its {@link #isSupported()} method.
    1.10       * 
    1.11       * @param src the URL where to find the audio clip
    1.12       * @return the audio clip handle
    1.13 @@ -47,7 +50,7 @@
    1.14                  return handle;
    1.15              }
    1.16          }
    1.17 -        throw new IllegalStateException();
    1.18 +        return DummyClip.INSTANCE;
    1.19      }
    1.20      
    1.21      /** Plays the clip from begining to the end.
    1.22 @@ -69,6 +72,12 @@
    1.23       * @param volume for the playback
    1.24       */
    1.25      public abstract void setVolume(double volume);
    1.26 +    
    1.27 +    /** Check whether the audio clip is supported and can be played.
    1.28 +     * @return true if it is likely that after calling {@link #play()} 
    1.29 +     *   a sound will be produced
    1.30 +     */
    1.31 +    public abstract boolean isSupported();
    1.32  
    1.33  //    public abstract void playFrom(int seconds);
    1.34  
    1.35 @@ -112,6 +121,11 @@
    1.36          }
    1.37  
    1.38          @Override
    1.39 +        public boolean isSupported() {
    1.40 +            return env.isSupported(clip);
    1.41 +        }
    1.42 +
    1.43 +        @Override
    1.44          public int hashCode() {
    1.45              return 59 * src.hashCode();
    1.46          }
    1.47 @@ -124,4 +138,25 @@
    1.48              return false;
    1.49          }
    1.50      } // end of Impl
    1.51 +    
    1.52 +    private static final class DummyClip extends AudioClip {
    1.53 +        static AudioClip INSTANCE = new DummyClip();
    1.54 +        
    1.55 +        @Override
    1.56 +        public void play() {
    1.57 +        }
    1.58 +
    1.59 +        @Override
    1.60 +        public void pause() {
    1.61 +        }
    1.62 +
    1.63 +        @Override
    1.64 +        public void setVolume(double volume) {
    1.65 +        }
    1.66 +
    1.67 +        @Override
    1.68 +        public boolean isSupported() {
    1.69 +            return false;
    1.70 +        }
    1.71 +    } // end of DummyClip
    1.72  }
    1.73 \ No newline at end of file

     2.1 --- a/sound/src/main/java/org/apidesign/html/sound/spi/AudioEnvironment.java	Sat Aug 17 14:31:06 2013 +0200
     2.2 +++ b/sound/src/main/java/org/apidesign/html/sound/spi/AudioEnvironment.java	Wed Aug 21 17:38:59 2013 +0200
     2.3 @@ -33,4 +33,6 @@
     2.4      public void pause(Audio a);
     2.5  
     2.6      public void setVolume(Audio a, double volume);
     2.7 +    
     2.8 +    public boolean isSupported(Audio a);
     2.9  }