from __future__ import annotations
import threading
from typing import TYPE_CHECKING
import sdl2
from genesis_forge.gamepads.common import Key
if TYPE_CHECKING:
from collections.abc import Callable
__all__ = ["ControllerEventLoop", "controller_key_from_event"]
AXIS_NAMES: dict[int, str] = {
sdl2.SDL_CONTROLLER_AXIS_LEFTX: "leftx",
sdl2.SDL_CONTROLLER_AXIS_LEFTY: "lefty",
sdl2.SDL_CONTROLLER_AXIS_RIGHTX: "rightx",
sdl2.SDL_CONTROLLER_AXIS_RIGHTY: "righty",
sdl2.SDL_CONTROLLER_AXIS_TRIGGERLEFT: "lefttrigger",
sdl2.SDL_CONTROLLER_AXIS_TRIGGERRIGHT: "righttrigger",
}
BUTTON_NAMES: dict[int, str] = {
sdl2.SDL_CONTROLLER_BUTTON_A: "a",
sdl2.SDL_CONTROLLER_BUTTON_B: "b",
sdl2.SDL_CONTROLLER_BUTTON_X: "x",
sdl2.SDL_CONTROLLER_BUTTON_Y: "y",
sdl2.SDL_CONTROLLER_BUTTON_BACK: "back",
sdl2.SDL_CONTROLLER_BUTTON_GUIDE: "guide",
sdl2.SDL_CONTROLLER_BUTTON_START: "start",
sdl2.SDL_CONTROLLER_BUTTON_LEFTSTICK: "leftstick",
sdl2.SDL_CONTROLLER_BUTTON_RIGHTSTICK: "rightstick",
sdl2.SDL_CONTROLLER_BUTTON_LEFTSHOULDER: "leftshoulder",
sdl2.SDL_CONTROLLER_BUTTON_RIGHTSHOULDER: "rightshoulder",
sdl2.SDL_CONTROLLER_BUTTON_DPAD_UP: "dpup",
sdl2.SDL_CONTROLLER_BUTTON_DPAD_DOWN: "dpdown",
sdl2.SDL_CONTROLLER_BUTTON_DPAD_LEFT: "dpleft",
sdl2.SDL_CONTROLLER_BUTTON_DPAD_RIGHT: "dpright",
}
def _rescale(
value: int, in_min: int, in_max: int, out_min: float, out_max: float
) -> float:
span_in = in_max - in_min
if span_in == 0:
return out_min
return (float(value - in_min) / span_in) * (out_max - out_min) + out_min
def _is_trigger_axis(axis: int) -> bool:
return axis in (
sdl2.SDL_CONTROLLER_AXIS_TRIGGERLEFT,
sdl2.SDL_CONTROLLER_AXIS_TRIGGERRIGHT,
)
[docs]
def controller_key_from_event(
event: sdl2.SDL_Event, deadzone: float = 0.05
) -> Key | None:
etype = event.type
if etype == sdl2.SDL_CONTROLLERAXISMOTION:
axis = event.caxis.axis
raw = event.caxis.value
limits = (0.0, 1.0) if _is_trigger_axis(axis) else (-1.0, 1.0)
value = _rescale(raw, -32768, 32767, limits[0], limits[1])
if not _is_trigger_axis(axis) and abs(value) < deadzone:
value = 0.0
return Key(Key.AXIS, axis, AXIS_NAMES.get(axis), value)
if etype in (sdl2.SDL_CONTROLLERBUTTONDOWN, sdl2.SDL_CONTROLLERBUTTONUP):
button = event.cbutton.button
val = 1 if etype == sdl2.SDL_CONTROLLERBUTTONDOWN else 0
return Key(Key.BUTTON, button, BUTTON_NAMES.get(button), val)
return None
[docs]
class ControllerEventLoop:
"""
Minimal SDL2 controller event loop for genesis-forge.
This class runs in a background thread and processes SDL2 controller events,
converting them to Key objects and passing them to a callback function.
Args:
handle_key: Callback function that receives Key objects for each controller event
alive: Optional threading.Event to control the event loop. When cleared, the loop exits.
timeout: Milliseconds to wait for events before checking the alive flag (default: 2000ms)
Example::
def on_key(key: Key):
print(f"Key event: {key}")
loop = ControllerEventLoop(handle_key=on_key)
thread = threading.Thread(target=loop.run, daemon=True)
thread.start()
# Later, to stop:
loop.stop()
"""
def __init__(
self,
handle_key: Callable[[Key], None],
alive: threading.Event | None = None,
timeout: int = 2000,
) -> None:
self.handle_key = handle_key
self.alive = alive or threading.Event()
if not self.alive.is_set():
self.alive.set()
self.timeout = timeout
self._controllers: dict[int, sdl2.SDL_GameController] = {}
[docs]
def stop(self) -> None:
self.alive.clear()
def _open_controller(self, device_index: int) -> None:
controller = sdl2.SDL_GameControllerOpen(device_index)
if controller:
joy = sdl2.SDL_GameControllerGetJoystick(controller)
instance_id = sdl2.SDL_JoystickInstanceID(joy)
self._controllers[int(instance_id)] = controller
def _close_controller(self, instance_id: int) -> None:
controller = self._controllers.pop(instance_id, None)
if controller:
sdl2.SDL_GameControllerClose(controller)
def _handle_event(self, event: sdl2.SDL_Event) -> None:
etype = event.type
if etype == sdl2.SDL_CONTROLLERDEVICEADDED:
self._open_controller(event.cdevice.which)
return
if etype == sdl2.SDL_CONTROLLERDEVICEREMOVED:
self._close_controller(event.cdevice.which)
return
key = controller_key_from_event(event)
if key and self.handle_key:
self.handle_key(key)
[docs]
def run(self) -> None:
if sdl2.SDL_WasInit(sdl2.SDL_INIT_GAMECONTROLLER) == 0:
sdl2.SDL_InitSubSystem(sdl2.SDL_INIT_GAMECONTROLLER)
for idx in range(sdl2.SDL_NumJoysticks()):
if sdl2.SDL_IsGameController(idx):
self._open_controller(idx)
event = sdl2.SDL_Event()
try:
while self.alive.is_set():
if sdl2.SDL_WaitEventTimeout(event, self.timeout):
self._handle_event(event)
finally:
for instance_id in list(self._controllers.keys()):
self._close_controller(instance_id)
sdl2.SDL_QuitSubSystem(sdl2.SDL_INIT_GAMECONTROLLER)
