Proposal: SDL2 DCM

[VyrCossont]

Feature Description

Buttplug currently supports rumble for XInput gamepads on Windows (including both the 360 and Xbox One/Series X|S generations). But gamepads are the vibrator almost everyone already has, so we'd also like to support Switch joycons (#151), Switch Pro Controllers, DualShock 4 and DualSense PlayStation gamepads, and BLE-capable Xbox One/Series X|S gamepads on platforms other than Windows.

I'd like to propose a DCM (device communication manager) that supports all of these and some more using SDL2 (which can be static linked) and the sdl2 wrapper crate.

SDL2 presents a gamepad API very similar to XInput, and can talk to gamepads using the following backends:

• cross-platform including desktop Linux and Android:
  • hidapi: covers DS4/DualSense, Xbone, Switch, and generic BT/USB HID gamepads, as well as some oddballs like the Steam, Stadia, and Luna gamepads. Might support Wiimote and Wii U controllers?
• macOS:
  • GameController.framework: DS4/DualSense, Xbone, Switch, and MFi (may provide more reliable rumble than hidapi: I've had some issues using a DS4's rumble through sdl2 that weren't present when using the same controller through the GC API directly)
  • IOKit HID alongside ForceFeedback.framework: generic HID gamepads
• iOS, iPadOS, macOS, tvOS:
  • GameController.framework
• Windows:
  • XInput (so this could subsume the XInput DCM eventually)
  • DirectInput: generic HID gamepads
  • Windows.Gaming.Input (UWP-era XInput successor, supports more than 4 gamepads)

Scope: very similar to the existing XInput DCM but on more platforms and supporting more than 4 connected gamepads. Would support common low-frequency and high-frequency vibration motors as well as battery level. (I might try to implement support for the extra set of trigger vibration motors on newer Xbone controllers, if I have one at home that has them.) Inputs would be ignored; anyone needing that much functionality should just be using SDL directly.

Testing: I have access to 360 (wired and wireless), Xbone, DualShock 4, DualSense, Switch joycon, Switch Pro Controller, Wiimote, Wii U Pro Controller, and Steam gamepads, as well as macOS, Windows, Linux, and iOS devices, and thus can test most interesting devices myself.