play: add flags to play_startup()

Introduce flags for disabling audio/video/gamecontroller caps

Most of the time, all of these will be desirable for a game.  But
sometimes I might use this as a quick bootstrap into SDL land,
especially as I accumulate play_ops_t boilerplate I'd like to
be maximally reusable.  The video-only use case is particularly
likely especially for development tools, and I'm likely to have
a corpus of play_ops_t integrations for the myriad GL/vulkan
flavors...

Note the flags are plumbed down to the play_ops_t.init hook so
ops implementations can also be flags-aware.

I didn't try make things like audio samplerate/channels
configurable, as this library is intended to be a vendored .a
anyways there's no hard ABI/API commitments.  It can always
grow and evolve when the need arises.

2 files changed, 76 insertions, 37 deletions

diff --git a/src/play.c b/src/play.c
index ca51c2e..fdd1bd8 100644
--- a/src/play.c
+++ b/src/play.c
@@ -34,6 +34,7 @@ typedef struct play_t {
 	Uint32			ticks_paused_at;
 	unsigned		ticks_paused:1;
 	unsigned		update_needed:1;
+	unsigned		has_audio:1;
 	const play_ops_t	**ops;
 	int			n_ops;
 	int			context;
@@ -51,6 +52,9 @@ void play_music_set(play_t *play, unsigned flags, const char *fmt, ...)
 	Mix_Music	*new;
 	va_list		ap;
 
+	assert(play);
+	assert(play->has_audio);
+
 	va_start(ap, fmt);
 	vsnprintf(file, sizeof(file), fmt, ap);
 	va_end(ap);
@@ -140,12 +144,18 @@ static void music_finished(void)
 
 void play_music_pause(play_t *play)
 {
+	assert(play);
+	assert(play->has_audio);
+
 	Mix_PauseMusic();
 }
 
 
 void play_music_resume(play_t *play)
 {
+	assert(play);
+	assert(play->has_audio);
+
 	Mix_ResumeMusic();
 }
 
@@ -268,11 +278,16 @@ void play_quit(play_t *play)
 
 /* This initializes a bunch of SDL stuff and calls all the ops.init() hooks
  * serially, in-order, before returning a handle to it all.
+ *
  * Note this doesn't create an SDL window or OpenGL context, as that's all
  * quite game-specific so it's left for presumably the first init hook.
+ *
+ * Flags may be used to disable audio/video/gamepad support, simply use empty flags
+ * to get all three.
  */
-play_t * play_startup(int argc, char *argv[], const play_ops_t *ops[])
+play_t * play_startup(int argc, char *argv[], unsigned flags, const play_ops_t *ops[])
 {
+	Uint32	sdl_flags = 0;
 	size_t	n_ops;
 	play_t	*play;
 
@@ -285,54 +300,74 @@ play_t * play_startup(int argc, char *argv[], const play_ops_t *ops[])
 	fatal_if(!play,
 		"Unable to allocate play_t");
 
-	fatal_if(SDL_Init(SDL_INIT_VIDEO|SDL_INIT_AUDIO|SDL_INIT_GAMECONTROLLER) != 0,
+	/* since it's expected that the vast majority of callers will want
+	 * sound+video+gamecontroller this is inverted so those may pass
+	 * empty flags, and instead the exceptions turn off which things
+	 * they don't want.
+	 */
+	if (!(flags & PLAY_FLAG_NOAUDIO)) {
+		sdl_flags |= SDL_INIT_AUDIO;
+		play->has_audio = 1;
+	}
+
+	if (!(flags & PLAY_FLAG_NOVIDEO))
+		sdl_flags |= SDL_INIT_VIDEO;
+
+	if (!(flags & PLAY_FLAG_NOGAMEPAD))
+		sdl_flags |= SDL_INIT_GAMECONTROLLER;
+
+	fatal_if(SDL_Init(sdl_flags) != 0,
 		"Unable to initialize SDL");
 
 	fatal_if(atexit(SDL_Quit),
 		"Unable to set exit handler");
 
-	fatal_if(Mix_OpenAudio(44100, MIX_DEFAULT_FORMAT, 2, 2048) == -1,
-		"Unable to open audio");
-
-	__play_ptr_for_music_fixme = play;
-	Mix_HookMusicFinished(music_finished);
-	Mix_AllocateChannels(32);
-
-	/* Just in case the user has dropped a game controller mapping */
-	SDL_GameControllerAddMappingsFromFile("gamecontrollerdb.txt");
+	if (play->has_audio) {
+		fatal_if(Mix_OpenAudio(44100, MIX_DEFAULT_FORMAT, 2, 2048) == -1,
+			"Unable to open audio");
 
-	/* I don't want to get too crazy over here with controller handling, just open all
-	 * the attached controllers at startup and get on with it.
-	 */
-	for (int i = 0; i < SDL_NumJoysticks(); ++i) {
-		SDL_GameController	*controller;
-		char			guid[64] = {};
-
-		SDL_JoystickGetGUIDString(SDL_JoystickGetDeviceGUID(i), guid, sizeof(guid));
-
-		if (!SDL_IsGameController(i)) {
-			fprintf(stderr,
-				"Ignoring unrecognized joystick \"%s\",\n"
-				"add a \"gamecontrollerdb.txt\" to use it.\n",
-				guid);
-			continue;
-		}
+		__play_ptr_for_music_fixme = play;
+		Mix_HookMusicFinished(music_finished);
+		Mix_AllocateChannels(32);
+	}
 
-		controller = SDL_GameControllerOpen(i);
-		warn_if(!controller,
-			"Could not open game controller \"%s\": %s",
-			guid, SDL_GetError());
+	if (!(flags & PLAY_FLAG_NOGAMEPAD)) {
+		/* Just in case the user has dropped a game controller mapping */
+		SDL_GameControllerAddMappingsFromFile("gamecontrollerdb.txt");
 
-		/* XXX: For now I'm just opening all of them and losing their handles,
-		 * it seems benign enough, the events will be delivered just the same.
-		 * If the controller handle is needed for things then it gets more tricky..
+		/* I don't want to get too crazy over here with controller handling, just open all
+		 * the attached controllers at startup and get on with it.
 		 */
+		for (int i = 0; i < SDL_NumJoysticks(); ++i) {
+			SDL_GameController	*controller;
+			char			guid[64] = {};
+
+			SDL_JoystickGetGUIDString(SDL_JoystickGetDeviceGUID(i), guid, sizeof(guid));
+
+			if (!SDL_IsGameController(i)) {
+				fprintf(stderr,
+					"Ignoring unrecognized joystick \"%s\",\n"
+					"add a \"gamecontrollerdb.txt\" to use it.\n",
+					guid);
+				continue;
+			}
+
+			controller = SDL_GameControllerOpen(i);
+			warn_if(!controller,
+				"Could not open game controller \"%s\": %s",
+				guid, SDL_GetError());
+
+			/* XXX: For now I'm just opening all of them and losing their handles,
+			 * it seems benign enough, the events will be delivered just the same.
+			 * If the controller handle is needed for things then it gets more tricky..
+			 */
+		}
 	}
 
 	for (size_t i = 0; i < n_ops; i++) {
 		play->n_ops++;
 		if (ops[i]->init)
-			play->contexts[i] = ops[i]->init(play, argc, argv);
+			play->contexts[i] = ops[i]->init(play, argc, argv, flags);
 	}
 	play->ops = ops;
 
diff --git a/src/play.h b/src/play.h
index 0f1d2da..73d3815 100644
--- a/src/play.h
+++ b/src/play.h
@@ -33,6 +33,10 @@ typedef enum play_ticks_t {
 	PLAY_TICKS_CNT
 } play_ticks_t;
 
+#define PLAY_FLAG_NOAUDIO		(1L)
+#define PLAY_FLAG_NOVIDEO		(1L << 1)
+#define PLAY_FLAG_NOGAMEPAD		(1L << 2)
+
 #define PLAY_MUSIC_FLAG_LOOP		(1L)
 #define PLAY_MUSIC_FLAG_FADEIN		(1L << 1)
 #define PLAY_MUSIC_FLAG_OPTIONAL	(1L << 2)
@@ -42,7 +46,7 @@ typedef enum play_ticks_t {
 typedef struct play_t play_t;
 
 typedef struct play_ops_t {
-	void *	(*init)(play_t *play, int argc, char *argv[]);
+	void *	(*init)(play_t *play, int argc, char *argv[], unsigned flags);
 	void	(*destroy)(play_t *play, void *context);
 	void	(*enter)(play_t *play, void *context);
 	void	(*leave)(play_t *play, void *context);
@@ -51,7 +55,7 @@ typedef struct play_ops_t {
 	void	(*dispatch)(play_t *play, void *context, SDL_Event *event);
 } play_ops_t;
 
-play_t * play_startup(int argc, char *argv[], const play_ops_t *ops[]);
+play_t * play_startup(int argc, char *argv[], unsigned flags, const play_ops_t *ops[]);
 int play_shutdown(play_t *play);
 void play_run(play_t *play);