examples/input/05-gamepad-rumble: add some visual feedback.

examples/input/05-gamepad-rumble/gamepad-rumble.c

@@ -12,6 +12,25 @@
 static SDL_Window *window = NULL;
 static SDL_Renderer *renderer = NULL;
 
+typedef struct GamepadInfo
+{
+    SDL_JoystickID gamepad_id;
+    const char *action;
+} GamepadInfo;
+
+static GamepadInfo gamepads_info[16];  /* if you have more than this, we'll ignore it. */
+
+static GamepadInfo *FindGamepadInfo(SDL_JoystickID which)
+{
+    int i;
+    for (i = 0; i < SDL_arraysize(gamepads_info); i++) {
+        if (gamepads_info[i].gamepad_id == which) {
+            return &gamepads_info[i];
+        }
+    }
+    return NULL;  /* not found */
+}
+
 /* This function runs once at startup. */
 SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[])
 {
@@ -33,22 +52,39 @@ SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[])
 /* This function runs when a new event (mouse input, keypresses, etc) occurs. */
 SDL_AppResult SDL_AppEvent(void *appstate, SDL_Event *event)
 {
+    GamepadInfo *info;
     if (event->type == SDL_EVENT_QUIT) {
         return SDL_APP_SUCCESS;  /* end the program, reporting success to the OS. */
     } else if (event->type == SDL_EVENT_GAMEPAD_ADDED) {
         /* this event is sent for each hotplugged stick, but also each already-connected gamepad during SDL_Init(). */
         SDL_OpenGamepad(event->gdevice.which);
+        info = FindGamepadInfo(0);  /* find an empty space */
+        if (info) {
+            info->gamepad_id = event->gdevice.which;
+            info->action = "idle";
+        }
     } else if (event->type == SDL_EVENT_GAMEPAD_REMOVED) {
         SDL_Gamepad *gamepad = SDL_GetGamepadFromID(event->gdevice.which);
         SDL_CloseGamepad(gamepad);
+        info = FindGamepadInfo(event->gdevice.which);
+        if (info) {
+            info->gamepad_id = 0;
+        }
     } else if (event->type == SDL_EVENT_GAMEPAD_BUTTON_DOWN) {
         SDL_Gamepad *gamepad = SDL_GetGamepadFromID(event->gbutton.which);
+        info = FindGamepadInfo(event->gbutton.which);
         switch (event->gbutton.button) {
         case SDL_GAMEPAD_BUTTON_SOUTH:
             SDL_RumbleGamepad(gamepad, 0xFFFF, 0x0000, 5000);
+            if (info) {
+                info->action = "rumble high frequency";
+            }
             break;
         case SDL_GAMEPAD_BUTTON_EAST:
             SDL_RumbleGamepad(gamepad, 0x0000, 0xFFFF, 5000);
+            if (info) {
+                info->action = "rumble low frequency";
+            }
             break;
         default:
             break;
@@ -56,19 +92,49 @@ SDL_AppResult SDL_AppEvent(void *appstate, SDL_Event *event)
     } else if (event->type == SDL_EVENT_GAMEPAD_BUTTON_UP) {
         SDL_Gamepad *gamepad = SDL_GetGamepadFromID(event->gbutton.which);
         SDL_RumbleGamepad(gamepad, 0x0000, 0x0000, 0);
+        info = FindGamepadInfo(event->gbutton.which);
+        if (info) {
+            info->action = "idle";
+        }
     }
 
     return SDL_APP_CONTINUE;  /* carry on with the program! */
 }
 
+static void draw_centered_text(const int rw, int *y, const char *str)
+{
+    const int x = (rw - (((int) SDL_strlen(str)) * SDL_DEBUG_TEXT_FONT_CHARACTER_SIZE)) / 2;
+    if (*str) {
+        SDL_RenderDebugText(renderer, (float) x, (float) *y, str);
+    }
+    *y += SDL_DEBUG_TEXT_FONT_CHARACTER_SIZE * 2;
+}
+
 /* This function runs once per frame, and is the heart of the program. */
 SDL_AppResult SDL_AppIterate(void *appstate)
 {
-    SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
+    int rw, rh, y, i;
+    SDL_GetCurrentRenderOutputSize(renderer, &rw, &rh);
+    SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);  /* clear to black */
     SDL_RenderClear(renderer);
 
-    SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255);
-    SDL_RenderDebugText(renderer, 8, 8, "Connect gamepad and press buttons to rumble");
+    y = SDL_DEBUG_TEXT_FONT_CHARACTER_SIZE * 8;
+    SDL_SetRenderDrawColor(renderer, 255, 255, 0, 255);  /* yellow text */
+    draw_centered_text(rw, &y, "Connect gamepads and press buttons to rumble.");
+    y += SDL_DEBUG_TEXT_FONT_CHARACTER_SIZE * 3;
+
+    /* report all the visible joysticks and what they are doing at the moment. */
+    SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255);  /* white text */
+    for (i = 0; i < SDL_arraysize(gamepads_info); i++) {
+        const SDL_JoystickID which = gamepads_info[i].gamepad_id;
+        if (which == 0) {
+            draw_centered_text(rw, &y, "");  /* just leave a blank line. */
+        } else {
+            char str[128];
+            SDL_snprintf(str, sizeof (str), "%s: %s", SDL_GetGamepadNameForID(which), gamepads_info[i].action);
+            draw_centered_text(rw, &y, str);
+        }
+    }
 
     SDL_RenderPresent(renderer);