Improve Gamepad DPad Button Detection (bevyengine#5220)

# Objective

- Enable the `axis_dpad_to_button` gilrs filter to map hats to dpad buttons on supported remotes.
- Fixes Leafwing-Studios/leafwing-input-manager#149
- Might have fixed the confusion related to bevyengine#3229

## Solution

- Enables the `axis_dpad_to_button` filter in `gilrs` which will use it's remote mapping information to see if there are hats mapped to dpads for that remote model. I don't really understand the logic it uses exactly, but it is usually enabled by default in gilrs and I believe it probably leads to more intuitive mapping compared to the current situation of dpad buttons being mapped to an axis.
- Removes the `GamepadAxisType::DPadX` and `GamepadAxisType::DPadY` enum variants to avoid user confusion. Those variants should never be emitted anyway, for all supported remotes.

---

## Changelog

### Changed

- Removed `GamepadAxisType::DPadX` and `GamepadAxisType::DPadY` in favor of using `GamepadButtonType::DPad[Up/Down/Left/Right]` instead.

## Migration Guide

If your game reads gamepad events or queries the axis state of `GamePadAxisType::DPadX` or `GamePadAxisType::DPadY`, then you must migrate your code to check whether or not the `GamepadButtonType::DPadUp`, `GamepadButtonType::DPadDown`, etc. buttons were pressed instead.

crates/bevy_gilrs/src/converter.rs

@@ -37,8 +37,9 @@ pub fn convert_axis(axis: gilrs::Axis) -> Option<GamepadAxisType> {
         gilrs::Axis::RightStickX => Some(GamepadAxisType::RightStickX),
         gilrs::Axis::RightStickY => Some(GamepadAxisType::RightStickY),
         gilrs::Axis::RightZ => Some(GamepadAxisType::RightZ),
-        gilrs::Axis::DPadX => Some(GamepadAxisType::DPadX),
-        gilrs::Axis::DPadY => Some(GamepadAxisType::DPadY),
-        gilrs::Axis::Unknown => None,
+        // The `axis_dpad_to_button` gilrs filter should filter out all DPadX and DPadY events. If
+        // it doesn't then we probably need an entry added to the following repo and an update to
+        // GilRs to use the updated database: https://github.com/gabomdq/SDL_GameControllerDB
+        gilrs::Axis::Unknown | gilrs::Axis::DPadX | gilrs::Axis::DPadY => None,
     }
 }

crates/bevy_gilrs/src/gilrs_system.rs

@@ -2,7 +2,7 @@ use crate::converter::{convert_axis, convert_button, convert_gamepad_id};
 use bevy_ecs::event::EventWriter;
 use bevy_ecs::system::{NonSend, NonSendMut};
 use bevy_input::{gamepad::GamepadEventRaw, prelude::*};
-use gilrs::{EventType, Gilrs};
+use gilrs::{ev::filter::axis_dpad_to_button, EventType, Filter, Gilrs};
 
 pub fn gilrs_event_startup_system(gilrs: NonSend<Gilrs>, mut events: EventWriter<GamepadEventRaw>) {
     for (id, _) in gilrs.gamepads() {
@@ -14,7 +14,12 @@ pub fn gilrs_event_startup_system(gilrs: NonSend<Gilrs>, mut events: EventWriter
 }
 
 pub fn gilrs_event_system(mut gilrs: NonSendMut<Gilrs>, mut events: EventWriter<GamepadEventRaw>) {
-    while let Some(gilrs_event) = gilrs.next_event() {
+    while let Some(gilrs_event) = gilrs
+        .next_event()
+        .filter_ev(&axis_dpad_to_button, &mut gilrs)
+    {
+        gilrs.update(&gilrs_event);
+
         match gilrs_event.event {
             EventType::Connected => {
                 events.send(GamepadEventRaw::new(

crates/bevy_input/src/gamepad.rs

@@ -135,8 +135,6 @@ pub enum GamepadAxisType {
     RightStickX,
     RightStickY,
     RightZ,
-    DPadX,
-    DPadY,
 }
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
@@ -412,15 +410,13 @@ const ALL_BUTTON_TYPES: [GamepadButtonType; 19] = [
     GamepadButtonType::DPadRight,
 ];
 
-const ALL_AXIS_TYPES: [GamepadAxisType; 8] = [
+const ALL_AXIS_TYPES: [GamepadAxisType; 6] = [
     GamepadAxisType::LeftStickX,
     GamepadAxisType::LeftStickY,
     GamepadAxisType::LeftZ,
     GamepadAxisType::RightStickX,
     GamepadAxisType::RightStickY,
     GamepadAxisType::RightZ,
-    GamepadAxisType::DPadX,
-    GamepadAxisType::DPadY,
 ];
 
 #[cfg(test)]