Add sdl_hints:add_callback/3 function

This also sets up esdl2 to start accepting callbacks.
The module/process esdl2_callbacks must always be running
for that purpose, so esdl2 was made an OTP application
instead of a simple library.

Implementation of the rest of SDL_hints will follow in
subsequent commits.

9 files changed, 323 insertions, 3 deletions

diff --git a/c_src/esdl2.h b/c_src/esdl2.h
index 530abc4..df16664 100644
--- a/c_src/esdl2.h
+++ b/c_src/esdl2.h
@@ -27,6 +27,7 @@
 	A(blend) \
 	A(borderless) \
 	A(button) \
+	A(callback) \
 	A(caps) \
 	A(centered) \
 	A(charged) \
@@ -133,6 +134,8 @@
 
 #define NIF_FUNCTION_NAME(f) esdl2_ ## f
 #define NIF_FUNCTIONS(F) \
+	/* internal */ \
+	F(register_callback_process, 0) \
 	/* sdl */ \
 	F(init, 1) \
 	F(init_subsystem, 1) \
@@ -166,6 +169,8 @@
 	/* sdl_gl */ \
 	F(gl_create_context, 1) \
 	F(gl_swap_window, 1) \
+	/* sdl_hints */ \
+	F(add_hint_callback, 3) \
 	/* sdl_keyboard */ \
 	F(is_text_input_active, 0) \
 	F(start_text_input, 0) \
@@ -254,6 +259,8 @@ NIF_FUNCTIONS(NIF_FUNCTION_H_DECL)
 
 // --
 
+ErlNifPid* get_callback_process();
+
 #define sdl_error_tuple(env) \
 	enif_make_tuple2(env, \
 		atom_error, \
diff --git a/c_src/internal.c b/c_src/internal.c
new file mode 100644
index 0000000..0c58476
--- /dev/null
+++ b/c_src/internal.c
@@ -0,0 +1,35 @@
+// Copyright (c) 2015, Loïc Hoguin <[email protected]>
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+#include "esdl2.h"
+
+// @todo Make thread-safe.
+
+// register_callback_process
+
+ErlNifPid callback_process;
+
+NIF_FUNCTION(register_callback_process)
+{
+	BADARG_IF(!enif_self(env, &callback_process));
+
+	return atom_ok;
+}
+
+// get_callback_process
+
+ErlNifPid* get_callback_process()
+{
+	return &callback_process;
+}
diff --git a/c_src/sdl_hints.c b/c_src/sdl_hints.c
new file mode 100644
index 0000000..fe4eceb
--- /dev/null
+++ b/c_src/sdl_hints.c
@@ -0,0 +1,101 @@
+// Copyright (c) 2015, Loïc Hoguin <[email protected]>
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+#include "esdl2.h"
+
+// SDL_HintCallback
+
+typedef struct esdl2_callback {
+	char* module;
+	char* function;
+} esdl2_callback;
+
+void esdl2_hint_callback(void* userdata, const char* name, const char* oldValue, const char* newValue)
+{
+	ErlNifEnv* env = enif_alloc_env();
+	esdl2_callback* callback = (esdl2_callback*)userdata;
+	ERL_NIF_TERM old;
+	ERL_NIF_TERM new;
+
+	if (oldValue == NULL)
+		old = atom_undefined;
+	else
+		old = enif_make_string(env, oldValue, ERL_NIF_LATIN1);
+
+	if (newValue == NULL)
+		new = atom_undefined;
+	else
+		new = enif_make_string(env, newValue, ERL_NIF_LATIN1);
+
+	enif_send(NULL, get_callback_process(), env,
+		enif_make_tuple4(env, atom_callback,
+			enif_make_atom(env, callback->module),
+			enif_make_atom(env, callback->function),
+			enif_make_list3(env,
+				enif_make_string(env, name, ERL_NIF_LATIN1),
+				old,
+				new)));
+
+	enif_free_env(env);
+}
+
+// add_hint_callback
+// @todo We must free the userdata in SDL_DelHintCallback.
+
+NIF_CAST_HANDLER(thread_add_hint_callback)
+{
+	esdl2_callback* callback = (esdl2_callback*)enif_alloc(sizeof(esdl2_callback));
+
+	callback->module = args[1];
+	callback->function = args[2];
+
+	SDL_AddHintCallback(args[0], &esdl2_hint_callback, callback);
+
+	enif_free(args[0]);
+}
+
+NIF_FUNCTION(add_hint_callback)
+{
+	unsigned int hint_len, module_len, function_len;
+	char* hint;
+	char* module;
+	char* function;
+
+	BADARG_IF(!enif_get_list_length(env, argv[0], &hint_len));
+	BADARG_IF(!enif_get_atom_length(env, argv[1], &module_len, ERL_NIF_LATIN1));
+	BADARG_IF(!enif_get_atom_length(env, argv[2], &function_len, ERL_NIF_LATIN1));
+
+	hint = (char*)enif_alloc(hint_len + 1);
+	if (!enif_get_string(env, argv[0], hint, hint_len + 1, ERL_NIF_LATIN1)) {
+		enif_free(hint);
+		return enif_make_badarg(env);
+	}
+
+	module = (char*)enif_alloc(module_len + 1);
+	if (!enif_get_atom(env, argv[1], module, module_len + 1, ERL_NIF_LATIN1)) {
+		enif_free(hint);
+		enif_free(module);
+		return enif_make_badarg(env);
+	}
+
+	function = (char*)enif_alloc(function_len + 1);
+	if (!enif_get_atom(env, argv[2], function, function_len + 1, ERL_NIF_LATIN1)) {
+		enif_free(hint);
+		enif_free(module);
+		enif_free(function);
+		return enif_make_badarg(env);
+	}
+
+	return nif_thread_cast(env, thread_add_hint_callback, 3, hint, module, function);
+}
diff --git a/src/esdl2.erl b/src/esdl2.erl
index 3e0db38..7bacb71 100644
--- a/src/esdl2.erl
+++ b/src/esdl2.erl
@@ -14,6 +14,9 @@
 
 -module(esdl2).
 
+%% internal
+-export([register_callback_process/0]).
+
 %% sdl
 -export([init/1]).
 -export([init_subsystem/1]).
@@ -53,6 +56,9 @@
 -export([gl_create_context/1]).
 -export([gl_swap_window/1]).
 
+%% sdl_hints
+-export([add_hint_callback/3]).
+
 %% sdl_keyboard
 -export([is_text_input_active/0]).
 -export([start_text_input/0]).
@@ -137,6 +143,8 @@
 -export([set_window_title/2]).
 -export([show_window/1]).
 
+%% internal
+
 %% @todo We probably want to accept an env variable or somthing for the location.
 -on_load(on_load/0).
 on_load() ->
@@ -149,6 +157,9 @@ on_load() ->
 	end,
 	erlang:load_nif(filename:join(PrivDir, atom_to_list(?MODULE)), 0).
 
+register_callback_process() ->
+	erlang:nif_error({not_loaded, ?MODULE}).
+
 %% sdl
 
 init(_) ->
@@ -242,6 +253,11 @@ gl_create_context(_) ->
 gl_swap_window(_) ->
 	erlang:nif_error({not_loaded, ?MODULE}).
 
+%% sdl_hints
+
+add_hint_callback(_, _, _) ->
+	erlang:nif_error({not_loaded, ?MODULE}).
+
 %% sdl_keyboard
 
 is_text_input_active() ->
diff --git a/src/esdl2_app.erl b/src/esdl2_app.erl
new file mode 100644
index 0000000..2e90bcb
--- /dev/null
+++ b/src/esdl2_app.erl
@@ -0,0 +1,25 @@
+%% Copyright (c) 2015, Loïc Hoguin <[email protected]>
+%%
+%% Permission to use, copy, modify, and/or distribute this software for any
+%% purpose with or without fee is hereby granted, provided that the above
+%% copyright notice and this permission notice appear in all copies.
+%%
+%% THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+%% WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+%% MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+%% ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+%% WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+%% ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+%% OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+-module(esdl2_app).
+-behaviour(application).
+
+-export([start/2]).
+-export([stop/1]).
+
+start(_, _) ->
+	esdl2_sup:start_link().
+
+stop(_) ->
+	ok.
diff --git a/src/esdl2_callbacks.erl b/src/esdl2_callbacks.erl
new file mode 100644
index 0000000..d683992
--- /dev/null
+++ b/src/esdl2_callbacks.erl
@@ -0,0 +1,64 @@
+%% Copyright (c) 2015, Loïc Hoguin <[email protected]>
+%%
+%% Permission to use, copy, modify, and/or distribute this software for any
+%% purpose with or without fee is hereby granted, provided that the above
+%% copyright notice and this permission notice appear in all copies.
+%%
+%% THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+%% WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+%% MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+%% ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+%% WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+%% ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+%% OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+-module(esdl2_callbacks).
+-behaviour(gen_server).
+
+%% API.
+-export([start_link/0]).
+
+%% gen_server.
+-export([init/1]).
+-export([handle_call/3]).
+-export([handle_cast/2]).
+-export([handle_info/2]).
+-export([terminate/2]).
+-export([code_change/3]).
+
+-record(state, {
+}).
+
+%% API.
+
+-spec start_link() -> {ok, pid()}.
+start_link() ->
+	gen_server:start_link(?MODULE, [], []).
+
+%% gen_server.
+
+init([]) ->
+	ok = esdl2:register_callback_process(),
+	{ok, #state{}}.
+
+handle_call(_Request, _From, State) ->
+	{reply, ignored, State}.
+
+handle_cast(_Msg, State) ->
+	{noreply, State}.
+
+handle_info({callback, M, F, A}, State) ->
+	try
+		apply(M, F, A)
+	catch Class:Reason ->
+		error_logger:error_msg("Exception ~p:~p with callback:~n{~p,~p,~p}~n", [Class, Reason, M, F, A])
+	end,
+	{noreply, State};
+handle_info(_Info, State) ->
+	{noreply, State}.
+
+terminate(_Reason, _State) ->
+	ok.
+
+code_change(_OldVsn, State, _Extra) ->
+	{ok, State}.
diff --git a/src/esdl2_sup.erl b/src/esdl2_sup.erl
new file mode 100644
index 0000000..bacda01
--- /dev/null
+++ b/src/esdl2_sup.erl
@@ -0,0 +1,27 @@
+%% Copyright (c) 2015, Loïc Hoguin <[email protected]>
+%%
+%% Permission to use, copy, modify, and/or distribute this software for any
+%% purpose with or without fee is hereby granted, provided that the above
+%% copyright notice and this permission notice appear in all copies.
+%%
+%% THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+%% WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+%% MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+%% ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+%% WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+%% ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+%% OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+-module(esdl2_sup).
+-behaviour(supervisor).
+
+-export([start_link/0]).
+-export([init/1]).
+
+start_link() ->
+	supervisor:start_link({local, ?MODULE}, ?MODULE, []).
+
+init([]) ->
+	{ok, {#{}, [
+		#{id => esdl2_callbacks, start => {esdl2_callbacks, start_link, []}}
+	]}}.
diff --git a/src/sdl.erl b/src/sdl.erl
index 5391d32..8706eff 100644
--- a/src/sdl.erl
+++ b/src/sdl.erl
@@ -33,10 +33,25 @@
 start() ->
 	start([]).
 
--spec start([subsystem()]) -> ok | error().
+-spec start([subsystem()]) -> ok | {application_start_error, term()} | error().
 start(Subsystems) ->
-	esdl2:init(Subsystems),
-	receive {'_nif_thread_ret_', Ret} -> Ret end.
+	case ensure_started() of
+		ok ->
+			esdl2:init(Subsystems),
+			receive {'_nif_thread_ret_', Ret} -> Ret end;
+		Error ->
+			Error
+	end.
+
+ensure_started() ->
+	case application:start(esdl2) of
+		ok ->
+			ok;
+		{error, {already_started, esdl2}} ->
+			ok;
+		{error, Reason} ->
+			{application_start_error, Reason}
+	end.
 
 -spec stop() -> ok.
 stop() ->
diff --git a/src/sdl_hints.erl b/src/sdl_hints.erl
new file mode 100644
index 0000000..a6921b0
--- /dev/null
+++ b/src/sdl_hints.erl
@@ -0,0 +1,30 @@
+%% Copyright (c) 2015, Loïc Hoguin <[email protected]>
+%%
+%% Permission to use, copy, modify, and/or distribute this software for any
+%% purpose with or without fee is hereby granted, provided that the above
+%% copyright notice and this permission notice appear in all copies.
+%%
+%% THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+%% WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+%% MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+%% ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+%% WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+%% ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+%% OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+-module(sdl_hints).
+
+-export([add_callback/3]).
+-export([test_callback/3]).
+
+%% The hint names are the same as the environment variable names
+%% that SDL2 accepts.
+
+-spec add_callback(string(), module(), atom()) -> ok.
+add_callback(Hint, Module, Function) ->
+	esdl2:add_hint_callback(Hint, Module, Function).
+
+%% This callback can be used to test hints.
+-spec test_callback(string(), undefined | string(), undefined | string()) -> ok.
+test_callback(Hint, OldValue, NewValue) ->
+	io:format("Hint ~p has value changed from ~p to ~p~n", [Hint, OldValue, NewValue]).