Stop/Start/Pause/Resume for Fluidsynth

The fluidsynth player would resume from the point when the track
was stopped instead of the beginning when Play was called. This
was the desired behaviour for the unsupported Pause/Resume
functions, so I moved the definitions to those functions and
added new Start/Stop functions that seek to the beginning of the
track before playing.

When paused SDL_mixer should return true for IsPlaying. Fix
supplied by Wohlstand.

src/codecs/music_fluidsynth.c

@@ -39,6 +39,7 @@ typedef struct {
 #if (FLUIDSYNTH_VERSION_MAJOR >= 2)
     void (*delete_fluid_player)(fluid_player_t*);
     void (*delete_fluid_synth)(fluid_synth_t*);
+    int (*fluid_player_seek)(fluid_player_t *, int);
 #else
     int (*delete_fluid_player)(fluid_player_t*);
     int (*delete_fluid_synth)(fluid_synth_t*);
@@ -85,6 +86,7 @@ static int FLUIDSYNTH_Load()
 #if (FLUIDSYNTH_VERSION_MAJOR >= 2)
         FUNCTION_LOADER(delete_fluid_player, void (*)(fluid_player_t*))
         FUNCTION_LOADER(delete_fluid_synth, void (*)(fluid_synth_t*))
+        FUNCTION_LOADER(fluid_player_seek, int (*)(fluid_player_t *, int))
 #else
         FUNCTION_LOADER(delete_fluid_player, int (*)(fluid_player_t*))
         FUNCTION_LOADER(delete_fluid_synth, int (*)(fluid_synth_t*))
@@ -135,6 +137,7 @@ typedef struct {
     void *buffer;
     int buffer_size;
     int volume;
+    SDL_bool is_paused;
 } FLUIDSYNTH_Music;
 
 static void FLUIDSYNTH_Delete(void *context);
@@ -277,14 +280,25 @@ static int FLUIDSYNTH_Play(void *context, int play_count)
 {
     FLUIDSYNTH_Music *music = (FLUIDSYNTH_Music *)context;
     fluidsynth.fluid_player_set_loop(music->player, play_count);
+#if (FLUIDSYNTH_VERSION_MAJOR >= 2)
+    fluidsynth.fluid_player_seek(music->player, 0);
+#endif
     fluidsynth.fluid_player_play(music->player);
+    music->is_paused = SDL_FALSE;
     return 0;
 }
 
+static void FLUIDSYNTH_Resume(void *context)
+{
+    FLUIDSYNTH_Music *music = (FLUIDSYNTH_Music *)context;
+    fluidsynth.fluid_player_play(music->player);
+    music->is_paused = SDL_FALSE;
+}
+
 static SDL_bool FLUIDSYNTH_IsPlaying(void *context)
 {
     FLUIDSYNTH_Music *music = (FLUIDSYNTH_Music *)context;
-    return fluidsynth.fluid_player_get_status(music->player) == FLUID_PLAYER_PLAYING ? SDL_TRUE : SDL_FALSE;
+    return music->is_paused || fluidsynth.fluid_player_get_status(music->player) == FLUID_PLAYER_PLAYING ? SDL_TRUE : SDL_FALSE;
 }
 
 static int FLUIDSYNTH_GetSome(void *context, void *data, int bytes, SDL_bool *done)
@@ -316,6 +330,17 @@ static void FLUIDSYNTH_Stop(void *context)
 {
     FLUIDSYNTH_Music *music = (FLUIDSYNTH_Music *)context;
     fluidsynth.fluid_player_stop(music->player);
+#if (FLUIDSYNTH_VERSION_MAJOR >= 2)
+    fluidsynth.fluid_player_seek(music->player, 0);
+#endif
+    music->is_paused = SDL_FALSE;
+}
+
+static void FLUIDSYNTH_Pause(void *context)
+{
+    FLUIDSYNTH_Music *music = (FLUIDSYNTH_Music *)context;
+    fluidsynth.fluid_player_stop(music->player);
+    music->is_paused = SDL_TRUE;
 }
 
 static void FLUIDSYNTH_Delete(void *context)
@@ -367,8 +392,8 @@ Mix_MusicInterface Mix_MusicInterface_FLUIDSYNTH =
     NULL,   /* GetMetaTag */
     NULL,   /* GetNumTracks */
     NULL,   /* StartTrack */
-    NULL,   /* Pause */
-    NULL,   /* Resume */
+    FLUIDSYNTH_Pause,
+    FLUIDSYNTH_Resume,
     FLUIDSYNTH_Stop,
     FLUIDSYNTH_Delete,
     NULL,   /* Close */