Bug 1680982 - Implement Linux/Unix Gamepad support using evdev. r=stransky

Based on work by: Val Packett <val@packett.cool> and coolreader18
<coolreader18@gmail.com>.

Differential Revision: https://phabricator.services.mozilla.com/D197865

Author: evilpie

dom/gamepad/GamepadRemapping.cpp

@@ -19,53 +19,12 @@
 
 namespace mozilla::dom {
 
-// Follow the canonical ordering recommendation for the "Standard Gamepad"
-// from https://www.w3.org/TR/gamepad/#remapping.
-enum CanonicalButtonIndex {
-  BUTTON_INDEX_PRIMARY,
-  BUTTON_INDEX_SECONDARY,
-  BUTTON_INDEX_TERTIARY,
-  BUTTON_INDEX_QUATERNARY,
-  BUTTON_INDEX_LEFT_SHOULDER,
-  BUTTON_INDEX_RIGHT_SHOULDER,
-  BUTTON_INDEX_LEFT_TRIGGER,
-  BUTTON_INDEX_RIGHT_TRIGGER,
-  BUTTON_INDEX_BACK_SELECT,
-  BUTTON_INDEX_START,
-  BUTTON_INDEX_LEFT_THUMBSTICK,
-  BUTTON_INDEX_RIGHT_THUMBSTICK,
-  BUTTON_INDEX_DPAD_UP,
-  BUTTON_INDEX_DPAD_DOWN,
-  BUTTON_INDEX_DPAD_LEFT,
-  BUTTON_INDEX_DPAD_RIGHT,
-  BUTTON_INDEX_META,
-  BUTTON_INDEX_COUNT
-};
-
-enum CanonicalAxisIndex {
-  AXIS_INDEX_LEFT_STICK_X,
-  AXIS_INDEX_LEFT_STICK_Y,
-  AXIS_INDEX_RIGHT_STICK_X,
-  AXIS_INDEX_RIGHT_STICK_Y,
-  AXIS_INDEX_COUNT
-};
-
 const float BUTTON_THRESHOLD_VALUE = 0.1f;
 
 float NormalizeTouch(long aValue, long aMin, long aMax) {
   return (2.f * (aValue - aMin) / static_cast<float>(aMax - aMin)) - 1.f;
 }
 
-bool AxisNegativeAsButton(float input) {
-  const float value = (input < -0.5f) ? 1.f : 0.f;
-  return value > BUTTON_THRESHOLD_VALUE;
-}
-
-bool AxisPositiveAsButton(float input) {
-  const float value = (input > 0.5f) ? 1.f : 0.f;
-  return value > BUTTON_THRESHOLD_VALUE;
-}
-
 double AxisToButtonValue(double aValue) {
   // Mapping axis value range from (-1, +1) to (0, +1).
   return (aValue + 1.0f) * 0.5f;

dom/gamepad/GamepadRemapping.h

@@ -98,6 +98,41 @@ enum class GamepadId : uint32_t {
   kVendor2836Product0001 = 0x28360001,
 };
 
+// Follow the canonical ordering recommendation for the "Standard Gamepad"
+// from https://www.w3.org/TR/gamepad/#remapping.
+enum CanonicalButtonIndex {
+  BUTTON_INDEX_PRIMARY,
+  BUTTON_INDEX_SECONDARY,
+  BUTTON_INDEX_TERTIARY,
+  BUTTON_INDEX_QUATERNARY,
+  BUTTON_INDEX_LEFT_SHOULDER,
+  BUTTON_INDEX_RIGHT_SHOULDER,
+  BUTTON_INDEX_LEFT_TRIGGER,
+  BUTTON_INDEX_RIGHT_TRIGGER,
+  BUTTON_INDEX_BACK_SELECT,
+  BUTTON_INDEX_START,
+  BUTTON_INDEX_LEFT_THUMBSTICK,
+  BUTTON_INDEX_RIGHT_THUMBSTICK,
+  BUTTON_INDEX_DPAD_UP,
+  BUTTON_INDEX_DPAD_DOWN,
+  BUTTON_INDEX_DPAD_LEFT,
+  BUTTON_INDEX_DPAD_RIGHT,
+  BUTTON_INDEX_META,
+  BUTTON_INDEX_COUNT
+};
+
+enum CanonicalAxisIndex {
+  AXIS_INDEX_LEFT_STICK_X,
+  AXIS_INDEX_LEFT_STICK_Y,
+  AXIS_INDEX_RIGHT_STICK_X,
+  AXIS_INDEX_RIGHT_STICK_Y,
+  AXIS_INDEX_COUNT
+};
+
+static inline bool AxisNegativeAsButton(double input) { return input < -0.5; }
+
+static inline bool AxisPositiveAsButton(double input) { return input > 0.5; }
+
 class GamepadRemapper {
   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(GamepadRemapper)