Fix SDL3 joystick enumeration using device indices as instance IDs (#182)

* Fix SDL3 joystick enumeration using device indices as instance IDs

  get_joysticks/get_controllers/_get_all passed range(count) indices into
  SDL_OpenJoystick/SDL_OpenGamepad/SDL_IsGamepad, which on SDL3 take an
  SDL_JoystickID instance ID. _get_number discarded the instance-ID array
  that SDL_GetJoysticks returns, so enumeration opened the wrong device or
  failed once instance IDs diverged from device indices (e.g. after a pad
  was reconnected).

  Replace _get_number with _get_instance_ids, which keeps and frees the
  SDL_GetJoysticks array, and enumerate by instance ID.

  Fixes #181

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Kyle Benesch <4b796c65+github@gmail.com>

Author: 3 people

CHANGELOG.md

@@ -11,6 +11,10 @@ This project adheres to [Semantic Versioning](https://semver.org/) since version
 - PyPy wheels switched from PyPy 3.10 to PyPy 3.11.
 - Experimental Pyodide wheels are now uploaded to PyPI.
 
+### Fixed
+
+- `tcod.sdl.joystick.get_joysticks`, `get_controllers`, and related enumeration passed device indices to SDL3 functions expecting instance IDs, so enumeration could fail or open the wrong device after a joystick was reconnected.
+
 ## [21.2.0] - 2026-04-04
 
 ### Added

tcod/sdl/joystick.py

@@ -126,9 +126,9 @@ def __init__(self, sdl_joystick_p: Any) -> None:  # noqa: ANN401
         self._by_instance_id[self.id] = self
 
     @classmethod
-    def _open(cls, device_index: int) -> Joystick:
+    def _open(cls, instance_id: int) -> Joystick:
         tcod.sdl.sys.init(tcod.sdl.sys.Subsystem.JOYSTICK)
-        p = _check_p(ffi.gc(lib.SDL_OpenJoystick(device_index), lib.SDL_CloseJoystick))
+        p = _check_p(ffi.gc(lib.SDL_OpenJoystick(instance_id), lib.SDL_CloseJoystick))
         return cls(p)
 
     @classmethod
@@ -184,8 +184,8 @@ def __init__(self, sdl_controller_p: Any) -> None:  # noqa: ANN401
         self._by_instance_id[self.joystick.id] = self
 
     @classmethod
-    def _open(cls, joystick_index: int) -> GameController:
-        return cls(_check_p(ffi.gc(lib.SDL_OpenGamepad(joystick_index), lib.SDL_CloseGamepad)))
+    def _open(cls, instance_id: int) -> GameController:
+        return cls(_check_p(ffi.gc(lib.SDL_OpenGamepad(instance_id), lib.SDL_CloseGamepad)))
 
     @classmethod
     def _from_instance_id(cls, instance_id: int) -> GameController:
@@ -347,25 +347,30 @@ def init() -> None:
     tcod.sdl.sys.init(controller_systems)
 
 
-def _get_number() -> int:
-    """Return the number of attached joysticks."""
+def _get_instance_ids() -> list[int]:
+    """Return the instance IDs of all attached joysticks.
+
+    SDL3's ``SDL_GetJoysticks`` returns an array of instance IDs, which is what
+    ``SDL_OpenJoystick``/``SDL_OpenGamepad``/``SDL_IsGamepad`` expect.  These are not
+    contiguous device indices, so they must not be replaced with ``range``.
+    """
     init()
     count = ffi.new("int*")
-    lib.SDL_GetJoysticks(count)
-    return int(count[0])
+    joysticks_p = _check_p(ffi.gc(lib.SDL_GetJoysticks(count), lib.SDL_free))  # SDL_JoystickID array
+    return [int(i) for i in joysticks_p[0 : count[0]]]
 
 
 def get_joysticks() -> list[Joystick]:
     """Return a list of all connected joystick devices."""
-    return [Joystick._open(i) for i in range(_get_number())]
+    return [Joystick._open(instance_id) for instance_id in _get_instance_ids()]
 
 
 def get_controllers() -> list[GameController]:
     """Return a list of all connected game controllers.
 
     This ignores joysticks without a game controller mapping.
     """
-    return [GameController._open(i) for i in range(_get_number()) if lib.SDL_IsGamepad(i)]
+    return [GameController._open(instance_id) for instance_id in _get_instance_ids() if lib.SDL_IsGamepad(instance_id)]
 
 
 def _get_all() -> list[Joystick | GameController]:
@@ -374,7 +379,10 @@ def _get_all() -> list[Joystick | GameController]:
     If the joystick has a controller mapping then it is returned as a :any:`GameController`.
     Otherwise it is returned as a :any:`Joystick`.
     """
-    return [GameController._open(i) if lib.SDL_IsGamepad(i) else Joystick._open(i) for i in range(_get_number())]
+    return [
+        GameController._open(instance_id) if lib.SDL_IsGamepad(instance_id) else Joystick._open(instance_id)
+        for instance_id in _get_instance_ids()
+    ]
 
 
 def joystick_event_state(new_state: bool | None = None) -> bool:  # noqa: FBT001