MacOS: Don't use usage numbers as button ids on OSX.

Add a compatibility config option, "[compatibility] joystick_version=xx.yy.zz"
if it is necessary to restore the old behavior.

Fixes #1527

allegro5.cfg

@@ -252,3 +252,7 @@ automatic_menu_display_resize = true
 # to a graphical application. This may be undesirable for console applications. Set
 # this to false to disable this behavior.
 osx_tell_dock_outside_bundle = true
+
+# To restore behavior of older code versions, specify this value to the
+# Allegro version that had the desired old behavior.
+# joystick_version = 5.2.9

include/allegro5/internal/aintern_system.h

@@ -72,6 +72,7 @@ AL_VAR(_AL_DTOR_LIST *, _al_dtor_list);
 AL_FUNC(void *, _al_open_library, (const char *filename));
 AL_FUNC(void *, _al_import_symbol, (void *library, const char *symbol));
 AL_FUNC(void, _al_close_library, (void *library));
+AL_FUNC(uint32_t, _al_get_joystick_compat_version, (void));
 
 #ifdef __cplusplus
 }

src/joynu.c

@@ -300,6 +300,25 @@ void al_get_joystick_state(ALLEGRO_JOYSTICK *joy, ALLEGRO_JOYSTICK_STATE *ret_st
    new_joystick_driver->get_joystick_state(joy, ret_state);
 }
 
+
+
+uint32_t _al_get_joystick_compat_version(void)
+{
+   ALLEGRO_CONFIG *system_config = al_get_system_config();
+   const char* compat_version = al_get_config_value(system_config, "compatibility", "joystick_version");
+   if (!compat_version)
+      return al_get_allegro_version();
+   /* 4 2 digit numbers + 3 dot separators */
+   if (strlen(compat_version) > 4 * 2 + 3)
+      return al_get_allegro_version();
+   int version = 0;
+   int sub_version = 0;
+   int wip_version = 0;
+   /* Ignore the release number, we don't expect that to make a difference */
+   sscanf(compat_version, "%d.%d.%d", &version, &sub_version, &wip_version);
+   return AL_ID(version, sub_version, wip_version, 0);
+}
+
 /*
  * Local Variables:
  * c-basic-offset: 3

src/macosx/hidjoy.m

@@ -189,6 +189,7 @@ static void add_elements(CFArrayRef elements, ALLEGRO_JOYSTICK_OSX *joy)
    char default_name[100];
    int stick_class = -1;
    int axis_index = 0;
+   bool old_style = _al_get_joystick_compat_version() < AL_ID(5, 2, 10, 0);
 
    joy_null(joy);
 
@@ -199,15 +200,25 @@ static void add_elements(CFArrayRef elements, ALLEGRO_JOYSTICK_OSX *joy)
       );
 
       int usage = IOHIDElementGetUsage(elem);
+      int usage_page = IOHIDElementGetUsagePage(elem);
       if (IOHIDElementGetType(elem) == kIOHIDElementTypeInput_Button) {
-         if (usage >= 0 && usage < _AL_MAX_JOYSTICK_BUTTONS &&
-            !joy->buttons[usage-1]) {
-            joy->buttons[usage-1] = elem;
-            sprintf(default_name, "Button %d", usage-1);
+         int idx;
+         if (old_style)
+            idx = usage - 1;
+         else {
+            idx = joy->parent.info.num_buttons;
+            // 0x09 is the Button Page.
+            if (usage_page != 0x09)
+               continue;
+         }
+         if (idx >= 0 && idx < _AL_MAX_JOYSTICK_BUTTONS &&
+            !joy->buttons[idx]) {
+            joy->buttons[idx] = elem;
+            sprintf(default_name, "Button %d", idx);
             const char *name = get_element_name(elem, default_name);
             char *str = al_malloc(strlen(name)+1);
             strcpy(str, name);
-            joy->parent.info.button[usage-1].name = str;
+            joy->parent.info.button[idx].name = str;
             joy->parent.info.num_buttons++;
          }
       }