diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt index 799eda79bf..39bb253f61 100644 --- a/examples/CMakeLists.txt +++ b/examples/CMakeLists.txt @@ -141,6 +141,7 @@ add_sdl_example_executable(audio-simple-playback-callback SOURCES audio/02-simpl add_sdl_example_executable(audio-load-wav SOURCES audio/03-load-wav/load-wav.c DATAFILES ${CMAKE_CURRENT_SOURCE_DIR}/../test/sample.wav) add_sdl_example_executable(audio-multiple-streams SOURCES audio/04-multiple-streams/multiple-streams.c) add_sdl_example_executable(input-joystick-polling SOURCES input/01-joystick-polling/joystick-polling.c) +add_sdl_example_executable(input-joystick-events SOURCES input/02-joystick-events/joystick-events.c) add_sdl_example_executable(camera-read-and-draw SOURCES camera/01-read-and-draw/read-and-draw.c) add_sdl_example_executable(pen-drawing-lines SOURCES pen/01-drawing-lines/drawing-lines.c) add_sdl_example_executable(demo-snake SOURCES demo/01-snake/snake.c) diff --git a/examples/input/02-joystick-events/README.txt b/examples/input/02-joystick-events/README.txt new file mode 100644 index 0000000000..d87ac0a0fb --- /dev/null +++ b/examples/input/02-joystick-events/README.txt @@ -0,0 +1,2 @@ +This example code looks for joystick input in the event handler, and +reports any changes as a flood of info. diff --git a/examples/input/02-joystick-events/joystick-events.c b/examples/input/02-joystick-events/joystick-events.c new file mode 100644 index 0000000000..cc01d84aac --- /dev/null +++ b/examples/input/02-joystick-events/joystick-events.c @@ -0,0 +1,232 @@ +/* + * This example code looks for joystick input in the event handler, and + * reports any changes as a flood of info. + * + * This code is public domain. Feel free to use it for any purpose! + */ + +/* Joysticks are low-level interfaces: there's something with a bunch of + buttons, axes and hats, in no understood order or position. This is + a flexible interface, but you'll need to build some sort of configuration + UI to let people tell you what button, etc, does what. On top of this + interface, SDL offers the "gamepad" API, which works with lots of devices, + and knows how to map arbitrary buttons and such to look like an + Xbox/PlayStation/etc gamepad. This is easier, and better, for many games, + but isn't necessarily a good fit for complex apps and hardware. A flight + simulator, a realistic racing game, etc, might want this interface instead + of gamepads. */ + +#define SDL_MAIN_USE_CALLBACKS 1 /* use the callbacks instead of main() */ +#include +#include + +/* We will use this renderer to draw into this window every frame. */ +static SDL_Window *window = NULL; +static SDL_Renderer *renderer = NULL; +static SDL_Color colors[64]; + +#define MOTION_EVENT_COOLDOWN 40 + +typedef struct EventMessage +{ + char *str; + SDL_Color color; + Uint64 start_ticks; + struct EventMessage *next; +} EventMessage; + +static EventMessage messages; +static EventMessage *messages_tail = &messages; + +static const char *hat_state_string(Uint8 state) +{ + switch (state) { + case SDL_HAT_CENTERED: return "CENTERED"; + case SDL_HAT_UP: return "UP"; + case SDL_HAT_RIGHT: return "RIGHT"; + case SDL_HAT_DOWN: return "DOWN"; + case SDL_HAT_LEFT: return "LEFT"; + case SDL_HAT_RIGHTUP: return "RIGHT+UP"; + case SDL_HAT_RIGHTDOWN: return "RIGHT+DOWN"; + case SDL_HAT_LEFTUP: return "LEFT+UP"; + case SDL_HAT_LEFTDOWN: return "LEFT+DOWN"; + default: break; + } + return "UNKNOWN"; +} + +static const char *battery_state_string(SDL_PowerState state) +{ + switch (state) { + case SDL_POWERSTATE_ERROR: return "ERROR"; + case SDL_POWERSTATE_UNKNOWN: return "UNKNOWN"; + case SDL_POWERSTATE_ON_BATTERY: return "ON BATTERY"; + case SDL_POWERSTATE_NO_BATTERY: return "NO BATTERY"; + case SDL_POWERSTATE_CHARGING: return "CHARGING"; + case SDL_POWERSTATE_CHARGED: return "CHARGED"; + default: break; + } + return "UNKNOWN"; +} + +static void add_message(SDL_JoystickID jid, const char *fmt, ...) +{ + const SDL_Color *color = &colors[((size_t) jid) % SDL_arraysize(colors)]; + EventMessage *msg = NULL; + char *str = NULL; + va_list ap; + + msg = (EventMessage *) SDL_calloc(1, sizeof (*msg)); + if (!msg) { + return; // oh well. + } + + va_start(ap, fmt); + SDL_vasprintf(&str, fmt, ap); + va_end(ap); + if (!str) { + SDL_free(msg); + return; // oh well. + } + + msg->str = str; + SDL_copyp(&msg->color, color); + msg->start_ticks = SDL_GetTicks(); + msg->next = NULL; + + messages_tail->next = msg; + messages_tail = msg; +} + + +/* This function runs once at startup. */ +SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[]) +{ + int i; + + SDL_SetAppMetadata("Example Input Joystick Events", "1.0", "com.example.input-joystick-events"); + + if (!SDL_Init(SDL_INIT_VIDEO | SDL_INIT_JOYSTICK)) { + SDL_Log("Couldn't initialize SDL: %s", SDL_GetError()); + return SDL_APP_FAILURE; + } + + if (!SDL_CreateWindowAndRenderer("examples/input/joystick-events", 640, 480, 0, &window, &renderer)) { + SDL_Log("Couldn't create window/renderer: %s", SDL_GetError()); + return SDL_APP_FAILURE; + } + + colors[0].r = colors[0].g = colors[0].b = colors[0].a = 255; + for (i = 1; i < SDL_arraysize(colors); i++) { + colors[i].r = SDL_rand(255); + colors[i].g = SDL_rand(255); + colors[i].b = SDL_rand(255); + colors[i].a = 255; + } + + add_message(0, "Please plug in a joystick."); + + return SDL_APP_CONTINUE; /* carry on with the program! */ +} + +/* This function runs when a new event (mouse input, keypresses, etc) occurs. */ +SDL_AppResult SDL_AppEvent(void *appstate, SDL_Event *event) +{ + if (event->type == SDL_EVENT_QUIT) { + return SDL_APP_SUCCESS; /* end the program, reporting success to the OS. */ + } else if (event->type == SDL_EVENT_JOYSTICK_ADDED) { + /* this event is sent for each hotplugged stick, but also each already-connected joystick during SDL_Init(). */ + const SDL_JoystickID which = event->jdevice.which; + SDL_Joystick *joystick = SDL_OpenJoystick(which); + if (!joystick) { + add_message(which, "Joystick #%u add, but not opened: %s", (unsigned int) which, SDL_GetError()); + } else { + add_message(which, "Joystick #%u ('%s') added", (unsigned int) which, SDL_GetJoystickName(joystick)); + } + } else if (event->type == SDL_EVENT_JOYSTICK_REMOVED) { + const SDL_JoystickID which = event->jdevice.which; + SDL_Joystick *joystick = SDL_GetJoystickFromID(which); + if (joystick) { + SDL_CloseJoystick(joystick); /* the joystick was unplugged. */ + } + add_message(which, "Joystick #%u removed", (unsigned int) which); + } else if (event->type == SDL_EVENT_JOYSTICK_AXIS_MOTION) { + static Uint64 axis_motion_cooldown_time = 0; /* these are spammy, only show every X milliseconds. */ + const Uint64 now = SDL_GetTicks(); + if (now >= axis_motion_cooldown_time) { + const SDL_JoystickID which = event->jaxis.which; + axis_motion_cooldown_time = now + MOTION_EVENT_COOLDOWN; + add_message(which, "Joystick #%u axis %d -> %d", (unsigned int) which, (int) event->jaxis.axis, (int) event->jaxis.value); + } + } else if (event->type == SDL_EVENT_JOYSTICK_BALL_MOTION) { + static Uint64 ball_motion_cooldown_time = 0; /* these are spammy, only show every X milliseconds. */ + const Uint64 now = SDL_GetTicks(); + if (now >= ball_motion_cooldown_time) { + const SDL_JoystickID which = event->jball.which; + ball_motion_cooldown_time = now + MOTION_EVENT_COOLDOWN; + add_message(which, "Joystick #%u ball %d -> %d, %d", (unsigned int) which, (int) event->jball.ball, (int) event->jball.xrel, (int) event->jball.yrel); + } + } else if (event->type == SDL_EVENT_JOYSTICK_HAT_MOTION) { + const SDL_JoystickID which = event->jhat.which; + add_message(which, "Joystick #%u hat %d -> %s", (unsigned int) which, (int) event->jhat.hat, hat_state_string(event->jhat.value)); + } else if ((event->type == SDL_EVENT_JOYSTICK_BUTTON_UP) || (event->type == SDL_EVENT_JOYSTICK_BUTTON_DOWN)) { + const SDL_JoystickID which = event->jbutton.which; + add_message(which, "Joystick #%u button %d -> %s", (unsigned int) which, (int) event->jbutton.button, event->jbutton.down ? "PRESSED" : "RELEASED"); + } else if (event->type == SDL_EVENT_JOYSTICK_BATTERY_UPDATED) { + const SDL_JoystickID which = event->jbattery.which; + add_message(which, "Joystick #%u battery -> %s - %d%%", (unsigned int) which, battery_state_string(event->jbattery.state), event->jbattery.percent); + } + + return SDL_APP_CONTINUE; /* carry on with the program! */ +} + +/* This function runs once per frame, and is the heart of the program. */ +SDL_AppResult SDL_AppIterate(void *appstate) +{ + const Uint64 now = SDL_GetTicks(); + const float msg_lifetime = 3500.0f; /* milliseconds a message lives for. */ + EventMessage *msg = messages.next; + float prev_y = 0.0f; + int winw = 640, winh = 480; + + SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255); + SDL_RenderClear(renderer); + SDL_GetWindowSize(window, &winw, &winh); + + while (msg) { + float x, y; + const float life_percent = ((float) (now - msg->start_ticks)) / msg_lifetime; + if (life_percent >= 1.0f) { /* msg is done. */ + messages.next = msg->next; + if (messages_tail == msg) { + messages_tail = &messages; + } + SDL_free(msg->str); + SDL_free(msg); + msg = messages.next; + continue; + } + x = (((float) winw) - (SDL_strlen(msg->str) * SDL_DEBUG_TEXT_FONT_CHARACTER_SIZE)) / 2.0f; + y = ((float) winh) * life_percent; + if ((prev_y != 0.0f) && ((prev_y - y) < ((float) SDL_DEBUG_TEXT_FONT_CHARACTER_SIZE))) { + msg->start_ticks = now; + break; // wait for the previous message to tick up a little. + } + + SDL_SetRenderDrawColor(renderer, msg->color.r, msg->color.g, msg->color.b, (Uint8) (((float) msg->color.a) * (1.0f - life_percent))); + SDL_RenderDebugText(renderer, x, y, msg->str); + + prev_y = y; + msg = msg->next; + } + + SDL_RenderPresent(renderer); + + return SDL_APP_CONTINUE; /* carry on with the program! */ +} + +/* This function runs once at shutdown. */ +void SDL_AppQuit(void *appstate, SDL_AppResult result) +{ + /* SDL will clean up the window/renderer for us. We let the joysticks leak. */ +}