Made HIDAPI device change notifications available via SDL_hid_device_change_count()

include/SDL_hidapi.h

@@ -122,9 +122,13 @@ typedef struct SDL_hid_device_info
  * be called at the beginning of execution however, if there is a chance of
  * HIDAPI handles being opened by different threads simultaneously.
  *
+ * Each call to this function should have a matching call to SDL_hid_exit()
+ *
  * \returns 0 on success and -1 on error.
  *
  * \since This function is available since SDL 2.0.18.
+ *
+ * \sa SDL_hid_exit
  */
 extern DECLSPEC int SDLCALL SDL_hid_init(void);
 
@@ -137,9 +141,32 @@ extern DECLSPEC int SDLCALL SDL_hid_init(void);
  * \returns 0 on success and -1 on error.
  *
  * \since This function is available since SDL 2.0.18.
+ *
+ * \sa SDL_hid_init
  */
 extern DECLSPEC int SDLCALL SDL_hid_exit(void);
 
+/**
+ * Check to see if devices may have been added or removed.
+ *
+ * Enumerating the HID devices is an expensive operation, so you can call this
+ * to see if there have been any system device changes since the last call to
+ * this function. A change in the counter returned doesn't necessarily mean
+ * that anything has changed, but you can call SDL_hid_enumerate() to get an
+ * updated device list.
+ *
+ * Calling this function for the first time may cause a thread or other
+ * system resource to be allocated to track device change notifications.
+ *
+ * \returns a change counter that is incremented with each potential device
+ *          change, or 0 if device change detection isn't available.
+ *
+ * \since This function is available since SDL 2.0.18.
+ *
+ * \sa SDL_hid_enumerate
+ */
+extern DECLSPEC Uint32 SDLCALL SDL_hid_device_change_count(void);
+
 /**
  * Enumerate the HID Devices.
  *
@@ -157,6 +184,8 @@ extern DECLSPEC int SDLCALL SDL_hid_exit(void);
  *          SDL_hid_free_enumeration().
  *
  * \since This function is available since SDL 2.0.18.
+ *
+ * \sa SDL_hid_device_change_count
  */
 extern DECLSPEC SDL_hid_device_info * SDLCALL SDL_hid_enumerate(unsigned short vendor_id, unsigned short product_id);
 

src/dynapi/SDL_dynapi_overrides.h

@@ -846,3 +846,4 @@
 #define SDL_GetWindowMouseRect SDL_GetWindowMouseRect_REAL
 #define SDL_RenderWindowToLogical SDL_RenderWindowToLogical_REAL
 #define SDL_RenderLogicalToWindow SDL_RenderLogicalToWindow_REAL
+#define SDL_hid_device_change_count SDL_hid_device_change_count_REAL

src/dynapi/SDL_dynapi_procs.h

@@ -915,3 +915,4 @@ SDL_DYNAPI_PROC(int,SDL_SetWindowMouseRect,(SDL_Window *a, const SDL_Rect *b),(a
 SDL_DYNAPI_PROC(const SDL_Rect*,SDL_GetWindowMouseRect,(SDL_Window *a),(a),return)
 SDL_DYNAPI_PROC(void,SDL_RenderWindowToLogical,(SDL_Renderer *a, int b, int c, float *d, float *e),(a,b,c,d,e),)
 SDL_DYNAPI_PROC(void,SDL_RenderLogicalToWindow,(SDL_Renderer *a, float b, float c, int *d, int *e),(a,b,c,d,e),)
+SDL_DYNAPI_PROC(Uint32,SDL_hid_device_change_count,(void),(),return)