From 1720fc77fe64dcb37ff96df0c45ffb7fa7a91364 Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Sun, 24 Nov 2024 22:48:48 -0500
Subject: [PATCH] examples: Added input/02-joystick-events
---
examples/CMakeLists.txt | 1 +
examples/input/02-joystick-events/README.txt | 2 +
.../02-joystick-events/joystick-events.c | 232 ++++++++++++++++++
3 files changed, 235 insertions(+)
create mode 100644 examples/input/02-joystick-events/README.txt
create mode 100644 examples/input/02-joystick-events/joystick-events.c
diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt
index 799eda79bfa81..39bb253f616b0 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 0000000000000..d87ac0a0fbf17
--- /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 0000000000000..cc01d84aac575
--- /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 <SDL3/SDL.h>
+#include <SDL3/SDL_main.h>
+
+/* 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. */
+}