Haddock

src/Sound.hs

@@ -2,8 +2,10 @@
 Module      : Sound
 Description : Channel selection and storage
 
-This module checks for empty channels and plays sounds on them, using data chunks loaded into an IntMap,
+This module checks for empty channels and plays sounds on them.
-and sound specifications of type 'Sound' loaded into a Map.
+It uses data chunks loaded into an IntMap to determine the actual sounds played,
+and sound specifications of type 'Sound' loaded into a Map to 
+keep track of which sounds are playing.
 Uses SDL.Mixer.
 -}
 module Sound
@@ -18,11 +20,19 @@ import Control.Monad
 import Control.Lens
 
 {- | Play sounds from a list of indices.
-Each sound is played once if there is a free channel.
+Each sound starts playing (and will not repeat) if there is a free channel.
+Use this if you don't care about timing, overlapping, fading, etc.
 -}
 playSoundQueue :: SoundData a -> [Int] -> IO ()
 playSoundQueue sd ns = forM_ ns $ \n -> playIfFree (_loadedChunks sd IM.! n) Mix.Once
 
+{- | Start playing new sounds and update sound specifications.
+I think that this expects that unfinished sounds get passed forwards within the Map, to be rethought:
+there may be a leak in the current typical usage.
+ -}
+playAndUpdate :: Ord a => M.Map a Sound -> SoundData a -> IO (SoundData a)
+playAndUpdate new sd = playSounds $ over playingSounds (updatePlaying new) sd
+
 {- | Given a chunk, attempt to play this on a free channel a given number of
 times. Returns 'Just' the channel if succeeds.
 -}
@@ -44,23 +54,24 @@ playSoundIfFree c s = case _soundTime s of
     f :: Maybe Mix.Channel -> Maybe Sound
     f = fmap ( \chan -> s & soundChannel ?~ chan)
 
-{- Stop a channel if it was playing.
+{- | Stop a channel if it was playing.
 Always returns 'IO' 'Nothing'.
 -}
 haltMaybe :: Maybe Mix.Channel -> IO (Maybe Sound)
 haltMaybe (Just x) = Mix.halt x >> return Nothing
 haltMaybe Nothing = return Nothing
 
-{- Play a sound according to it's specification.
+{- | Play a sound according to it's specification.
 Logic: check if sound is playing:
 
-    - If so, decrement timers, and/or stop playing and remove 
+    1. If so, decrement timers, and/or stop playing and remove 
-    - If not, check if there is free channel:
+    2. If not, check if there is free channel:
-        - If so, start playing
+
-        - If not, remove sound.
+        * If so, start playing
+        * If not, remove sound.
 -}
-playSound :: SoundData a -> Sound -> IO (Maybe Sound)
+updateOrStartSound :: SoundData a -> Sound -> IO (Maybe Sound)
-playSound sd s = case _soundChannel s of
+updateOrStartSound sd s = case _soundChannel s of
     Just i  -> case _soundTime s of
         Just t | t > 0     -> return $ Just $ set soundTime (Just $ t - 1) s
                | otherwise -> haltMaybe (_soundChannel s)
@@ -70,14 +81,14 @@ playSound sd s = case _soundChannel s of
                                     )
     Nothing -> playSoundIfFree (_loadedChunks sd IM.! _soundType s) s
 
-{- Play all sounds and create new sound data.
+{- | Play all sounds and create new sound data.
  -}
 playSounds :: SoundData a -> IO (SoundData a)
 playSounds sd = do
-    newSounds <- mapM (playSound sd) (_playingSounds sd)
+    newSounds <- mapM (updateOrStartSound sd) (_playingSounds sd)
     return $ sd & playingSounds .~ M.mapMaybe id newSounds
 
-{- Update sound specifications by overwriting an old Map with a new Map.
+{- | Update sound specifications by overwriting an old Map with a new Map.
 Copies any information about channels from the old Map to the new Map.
 -} 
 updatePlaying :: Ord a => M.Map a Sound -> M.Map a Sound -> M.Map a Sound
@@ -85,7 +96,3 @@ updatePlaying new old = M.unionWith f new old
   where 
     f newSound oldSound = newSound {_soundChannel = _soundChannel oldSound}
 
-{- Start playing new sounds and update sound specifications.
- -}
-playAndUpdate :: Ord a => M.Map a Sound -> SoundData a -> IO (SoundData a)
-playAndUpdate new sd = playSounds $ over playingSounds (updatePlaying new) sd