Fade volume

playdate_example/src/playdate_example.nim

@@ -3,6 +3,10 @@ import playdate/api
 const FONT_PATH = "/System/Fonts/Asheville-Sans-14-Bold.pft"
 const NIM_IMAGE_PATH = "/images/nim_logo"
 const PLAYDATE_NIM_IMAGE_PATH = "/images/playdate_nim"
+const BACKGROUND_MUSIC_PATH = "/audio/finally_see_the_light"
+const BACKGROUND_MUSIC_SAMPLE_RATE = 48_000
+const BACKGROUND_MUSIC_FADE_IN_SECONDS = 4.0
+const BACKGROUND_MUSIC_FADE_IN_SAMPLES = (BACKGROUND_MUSIC_SAMPLE_RATE * BACKGROUND_MUSIC_FADE_IN_SECONDS).int32
 
 var font: LCDFont
 
@@ -80,9 +84,11 @@ proc handler(event: PDSystemEvent, keycode: uint) {.raises: [].} =
         except:
             playdate.system.logToConsole(getCurrentExceptionMsg())
         # Inline try/except
-        filePlayer = try: playdate.sound.newFilePlayer("/audio/finally_see_the_light") except: nil
+        filePlayer = try: playdate.sound.newFilePlayer(BACKGROUND_MUSIC_PATH) except: nil
 
         filePlayer.play(0)
+        fileplayer.volume = 0.0 # first set folume to 0%
+        filePlayer.fadeVolume(1.0, 1.0, BACKGROUND_MUSIC_FADE_IN_SAMPLES, nil) # then fade to 100%
 
         # Add a checkmark menu item that plays a sound when switched and unpaused
         discard playdate.system.addCheckmarkMenuItem("Checkmark", false,

src/playdate/bindings/sound.nim

@@ -38,15 +38,15 @@ type PlaydateSoundFileplayer {.importc: "const struct playdate_sound_fileplayer"
     #     start: cfloat; `end`: cfloat) {.cdecl.}
     # didUnderrun* {.importc: "didUnderrun".}: proc (player: ptr FilePlayer): cint {.cdecl.}
     setFinishCallback* {.importc: "setFinishCallback".}: proc (
-        player: FilePlayerPtr; callback: PDSndCallbackProcRaw, userData: pointer = nil) {.cdecl, raises: [].}
+        player: FilePlayerPtr; callback: PDSndCallbackProcRaw, userdata: pointer = nil) {.cdecl, raises: [].}
     # setLoopCallback* {.importc: "setLoopCallback".}: proc (player: ptr FilePlayer;
     #     callback: SndCallbackProc) {.cdecl.}
     getOffset {.importc: "getOffset".}: proc (player: FilePlayerPtr): cfloat {.cdecl, raises: [].}
     # getRate* {.importc: "getRate".}: proc (player: ptr FilePlayer): cfloat {.cdecl.}
     # setStopOnUnderrun* {.importc: "setStopOnUnderrun".}: proc (
     #     player: ptr FilePlayer; flag: cint) {.cdecl.}
-    # fadeVolume* {.importc: "fadeVolume".}: proc (player: ptr FilePlayer; left: cfloat;
-    #     right: cfloat; len: int32T; finishCallback: SndCallbackProc) {.cdecl.}
+    fadeVolume* {.importc: "fadeVolume".}: proc (player: FilePlayerPtr; left: cfloat;
+        right: cfloat; len: cint; finishCallback: PDSndCallbackProcRaw, userdata: pointer = nil) {.cdecl, raises:[].}
     # setMP3StreamSource* {.importc: "setMP3StreamSource".}: proc (
     #     player: ptr FilePlayer; dataSource: proc (data: ptr uint8T; bytes: cint;
     #     userdata: pointer): cint {.cdecl.}; userdata: pointer; bufferLen: cfloat) {.
@@ -90,7 +90,7 @@ type PlaydateSoundSampleplayer {.importc: "const struct playdate_sound_samplepla
     setPlayRange* {.importc: "setPlayRange".}: proc (player: SamplePlayerPtr;
         start: cint; `end`: cint) {.cdecl, raises: [].}
     setFinishCallback* {.importc: "setFinishCallback".}: proc (
-        player: SamplePlayerPtr; callback: PDSndCallbackProcRaw, userData: pointer = nil) {.cdecl, raises: [].}
+        player: SamplePlayerPtr; callback: PDSndCallbackProcRaw, userdata: pointer = nil) {.cdecl, raises: [].}
     # setLoopCallback* {.importc: "setLoopCallback".}: proc (player: ptr SamplePlayer;
     #     callback: SndCallbackProc) {.cdecl.}
     getOffset* {.importc: "getOffset".}: proc (player: SamplePlayerPtr): cfloat {.cdecl , raises: [].}

src/playdate/sound.nim

@@ -16,7 +16,7 @@ type
         resource: AudioSamplePtr
     AudioSample* = ref AudioSampleObj
 
-    PDSoundCallbackFunction* = proc(userData: pointer) {.raises: [].}
+    PDSoundCallbackFunction* = proc(userdata: pointer) {.raises: [].}
 
 proc `=destroy`(this: var AudioSampleObj) =
     privateAccess(PlaydateSound)
@@ -55,6 +55,7 @@ type SoundSource* = ref SoundSourceObj
 type
     FilePlayerObj = object of SoundSourceObj
         finishCallback: PDFilePlayerCallbackFunction
+        fadeVolumeCallback: PDFilePlayerCallbackFunction
     FilePlayer* = ref FilePlayerObj
 
     PDFilePlayerCallbackFunction* = proc(player: FilePlayer) {.raises: [].}
@@ -139,6 +140,11 @@ proc privateFilePlayerFinishCallback(soundSource: SoundSourcePtr, userdata: poin
     if filePlayer.finishCallback != nil:
         filePlayer.finishCallback(filePlayer)
 
+proc privateFilePlayerFadeVolumeCallback(soundSource: SoundSourcePtr, userdata: pointer) {.cdecl, raises: [].} =
+    let filePlayer = cast[FilePlayer](userdata)
+    if filePlayer.fadeVolumeCallback != nil:
+        filePlayer.fadeVolumeCallback(filePlayer)
+
 proc setFinishCallback*(this: FilePlayer, callback: PDFilePlayerCallbackFunction) =
     privateAccess(PlaydateSound)
     privateAccess(PlaydateSoundFileplayer)
@@ -148,6 +154,15 @@ proc setFinishCallback*(this: FilePlayer, callback: PDFilePlayerCallbackFunction
     else:
         playdate.sound.fileplayer.setFinishCallback(this.resource, privateFilePlayerFinishCallback, cast[pointer](this))
 
+proc fadeVolume*(this: FilePlayer, left, right: float32, len: int32, callback: PDFilePlayerCallbackFunction) =
+    privateAccess(PlaydateSound)
+    privateAccess(PlaydateSoundFileplayer)
+    this.fadeVolumeCallback = callback
+    if callback == nil:
+        playdate.sound.fileplayer.fadeVolume(this.resource, left.cfloat, right.cfloat, len.cint , nil, nil)
+    else:
+        playdate.sound.fileplayer.fadeVolume(this.resource, left.cfloat, right.cfloat, len.cint , privateFilePlayerFadeVolumeCallback, cast[pointer](this))
+
 proc finishCallback*(this: FilePlayer): PDFilePlayerCallbackFunction =
     return this.finishCallback