internal/gamepad: make nativeGamepad(s) interfaces

This is a preparation to switch the gamepad implementation for Xbox.

Updates #2084

internal/gamepad/api_ios.go

@@ -407,14 +407,16 @@ func (g *gamepads) addIOSGamepad(controller C.uintptr_t, prop *C.struct_Controll
 	name := C.GoString(&prop.name[0])
 	sdlID := C.GoStringN(&prop.guid[0], 16)
 	gp := g.add(name, sdlID)
-	gp.native.controller = uintptr(controller)
+	gp.native = &nativeGamepadImpl{
-	gp.native.axes = make([]float64, prop.nAxes)
+		controller:           uintptr(controller),
-	gp.native.buttons = make([]bool, prop.nButtons+prop.nHats*4)
+		axes:                 make([]float64, prop.nAxes),
-	gp.native.hats = make([]int, prop.nHats)
+		buttons:              make([]bool, prop.nButtons+prop.nHats*4),
-	gp.native.buttonMask = uint16(prop.buttonMask)
+		hats:                 make([]int, prop.nHats),
-	gp.native.hasDualshockTouchpad = bool(prop.hasDualshockTouchpad)
+		buttonMask:           uint16(prop.buttonMask),
-	gp.native.hasXboxPaddles = bool(prop.hasXboxPaddles)
+		hasDualshockTouchpad: bool(prop.hasDualshockTouchpad),
-	gp.native.hasXboxShareButton = bool(prop.hasXboxShareButton)
+		hasXboxPaddles:       bool(prop.hasXboxPaddles),
+		hasXboxShareButton:   bool(prop.hasXboxShareButton),
+	}
 }
 
 func (g *gamepads) removeIOSGamepad(controller C.uintptr_t) {
@@ -422,7 +424,7 @@ func (g *gamepads) removeIOSGamepad(controller C.uintptr_t) {
 	defer g.m.Unlock()
 
 	g.remove(func(gamepad *Gamepad) bool {
-		return gamepad.native.controller == uintptr(controller)
+		return gamepad.native.(*nativeGamepadImpl).controller == uintptr(controller)
 	})
 }
 
@@ -430,7 +432,7 @@ func initializeIOSGamepads() {
 	C.initializeGamepads()
 }
 
-func (g *nativeGamepad) updateIOSGamepad() {
+func (g *nativeGamepadImpl) updateIOSGamepad() {
 	var state C.struct_ControllerState
 	C.getControllerState(C.uintptr_t(g.controller), &state, C.uint16_t(g.buttonMask), C.uint8_t(len(g.hats)),
 		C.bool(g.hasDualshockTouchpad), C.bool(g.hasXboxPaddles), C.bool(g.hasXboxShareButton))

internal/gamepad/extern_android.go

@@ -53,10 +53,12 @@ func (g *gamepads) addAndroidGamepad(androidDeviceID int, name, sdlID string, ax
 	defer g.m.Unlock()
 
 	gp := g.add(name, sdlID)
-	gp.native.androidDeviceID = androidDeviceID
+	gp.native = &nativeGamepadImpl{
-	gp.native.axes = make([]float64, axisCount)
+		androidDeviceID: androidDeviceID,
-	gp.native.buttons = make([]bool, buttonCount)
+		axes:            make([]float64, axisCount),
-	gp.native.hats = make([]int, hatCount)
+		buttons:         make([]bool, buttonCount),
+		hats:            make([]int, hatCount),
+	}
 }
 
 func (g *gamepads) removeAndroidGamepad(androidDeviceID int) {
@@ -64,7 +66,7 @@ func (g *gamepads) removeAndroidGamepad(androidDeviceID int) {
 	defer g.m.Unlock()
 
 	g.remove(func(gamepad *Gamepad) bool {
-		return gamepad.native.androidDeviceID == androidDeviceID
+		return gamepad.native.(*nativeGamepadImpl).androidDeviceID == androidDeviceID
 	})
 }
 
@@ -73,7 +75,7 @@ func (g *gamepads) updateAndroidGamepadAxis(androidDeviceID int, axis int, value
 	defer g.m.Unlock()
 
 	gp := g.find(func(gamepad *Gamepad) bool {
-		return gamepad.native.androidDeviceID == androidDeviceID
+		return gamepad.native.(*nativeGamepadImpl).androidDeviceID == androidDeviceID
 	})
 	if gp == nil {
 		return
@@ -86,7 +88,7 @@ func (g *gamepads) updateAndroidGamepadButton(androidDeviceID int, button Button
 	defer g.m.Unlock()
 
 	gp := g.find(func(gamepad *Gamepad) bool {
-		return gamepad.native.androidDeviceID == androidDeviceID
+		return gamepad.native.(*nativeGamepadImpl).androidDeviceID == androidDeviceID
 	})
 	if gp == nil {
 		return
@@ -99,7 +101,7 @@ func (g *gamepads) updateAndroidGamepadHat(androidDeviceID int, hat int, dir And
 	defer g.m.Unlock()
 
 	gp := g.find(func(gamepad *Gamepad) bool {
-		return gamepad.native.androidDeviceID == androidDeviceID
+		return gamepad.native.(*nativeGamepadImpl).androidDeviceID == androidDeviceID
 	})
 	if gp == nil {
 		return
@@ -111,30 +113,33 @@ func (g *Gamepad) updateAndroidGamepadAxis(axis int, value float64) {
 	g.m.Lock()
 	defer g.m.Unlock()
 
-	if axis < 0 || axis >= len(g.native.axes) {
+	n := g.native.(*nativeGamepadImpl)
+	if axis < 0 || axis >= len(n.axes) {
 		return
 	}
-	g.native.axes[axis] = value
+	n.axes[axis] = value
 }
 
 func (g *Gamepad) updateAndroidGamepadButton(button Button, pressed bool) {
 	g.m.Lock()
 	defer g.m.Unlock()
 
-	if button < 0 || int(button) >= len(g.native.buttons) {
+	n := g.native.(*nativeGamepadImpl)
+	if button < 0 || int(button) >= len(n.buttons) {
 		return
 	}
-	g.native.buttons[button] = pressed
+	n.buttons[button] = pressed
 }
 
 func (g *Gamepad) updateAndroidGamepadHat(hat int, dir AndroidHatDirection, value int) {
 	g.m.Lock()
 	defer g.m.Unlock()
 
-	if hat < 0 || hat >= len(g.native.hats) {
+	n := g.native.(*nativeGamepadImpl)
+	if hat < 0 || hat >= len(n.hats) {
 		return
 	}
-	v := g.native.hats[hat]
+	v := n.hats[hat]
 	switch dir {
 	case AndroidHatDirectionX:
 		switch {
@@ -161,5 +166,5 @@ func (g *Gamepad) updateAndroidGamepadHat(hat int, dir AndroidHatDirection, valu
 	default:
 		panic(fmt.Sprintf("gamepad: invalid direction: %d", dir))
 	}
-	g.native.hats[hat] = v
+	n.hats[hat] = v
 }

internal/gamepad/gamepad.go

@@ -43,7 +43,14 @@ type gamepads struct {
 	native nativeGamepads
 }
 
-var theGamepads gamepads
+type nativeGamepads interface {
+	init(gamepads *gamepads) error
+	update(gamepads *gamepads) error
+}
+
+var theGamepads = gamepads{
+	native: newNativeGamepadsImpl(),
+}
 
 // AppendGamepadIDs is concurrent-safe.
 func AppendGamepadIDs(ids []ID) []ID {
@@ -166,7 +173,7 @@ func (g *gamepads) setNativeWindow(nativeWindow uintptr) {
 	g.m.Lock()
 	defer g.m.Unlock()
 
-	var n interface{} = &g.native
+	var n interface{} = g.native
 	if n, ok := n.(interface{ setNativeWindow(uintptr) }); ok {
 		n.setNativeWindow(nativeWindow)
 	}
@@ -180,6 +187,19 @@ type Gamepad struct {
 	native nativeGamepad
 }
 
+type nativeGamepad interface {
+	update(gamepads *gamepads) error
+	hasOwnStandardLayoutMapping() bool
+	axisCount() int
+	buttonCount() int
+	hatCount() int
+	axisValue(axis int) float64
+	buttonValue(button int) float64
+	isButtonPressed(button int) bool
+	hatState(hat int) int
+	vibrate(duration time.Duration, strongMagnitude float64, weakMagnitude float64)
+}
+
 func (g *Gamepad) update(gamepads *gamepads) error {
 	g.m.Lock()
 	defer g.m.Unlock()

internal/gamepad/gamepad_android.go

@@ -21,17 +21,21 @@ import (
 	"time"
 )
 
-type nativeGamepads struct{}
+type nativeGamepadsImpl struct{}
 
-func (*nativeGamepads) init(gamepads *gamepads) error {
+func newNativeGamepadsImpl() nativeGamepads {
+	return &nativeGamepadsImpl{}
+}
+
+func (*nativeGamepadsImpl) init(gamepads *gamepads) error {
 	return nil
 }
 
-func (*nativeGamepads) update(gamepads *gamepads) error {
+func (*nativeGamepadsImpl) update(gamepads *gamepads) error {
 	return nil
 }
 
-type nativeGamepad struct {
+type nativeGamepadImpl struct {
 	androidDeviceID int
 
 	axes    []float64
@@ -39,52 +43,52 @@ type nativeGamepad struct {
 	hats    []int
 }
 
-func (*nativeGamepad) update(gamepad *gamepads) error {
+func (*nativeGamepadImpl) update(gamepad *gamepads) error {
 	// Do nothing. The state of gamepads are given via APIs in extern_android.go.
 	return nil
 }
 
-func (*nativeGamepad) hasOwnStandardLayoutMapping() bool {
+func (*nativeGamepadImpl) hasOwnStandardLayoutMapping() bool {
 	return false
 }
 
-func (g *nativeGamepad) axisCount() int {
+func (g *nativeGamepadImpl) axisCount() int {
 	return len(g.axes)
 }
 
-func (g *nativeGamepad) buttonCount() int {
+func (g *nativeGamepadImpl) buttonCount() int {
 	return len(g.buttons)
 }
 
-func (g *nativeGamepad) hatCount() int {
+func (g *nativeGamepadImpl) hatCount() int {
 	return len(g.hats)
 }
 
-func (g *nativeGamepad) axisValue(axis int) float64 {
+func (g *nativeGamepadImpl) axisValue(axis int) float64 {
 	if axis < 0 || axis >= len(g.axes) {
 		return 0
 	}
 	return g.axes[axis]
 }
 
-func (g *nativeGamepad) isButtonPressed(button int) bool {
+func (g *nativeGamepadImpl) isButtonPressed(button int) bool {
 	if button < 0 || button >= len(g.buttons) {
 		return false
 	}
 	return g.buttons[button]
 }
 
-func (*nativeGamepad) buttonValue(button int) float64 {
+func (*nativeGamepadImpl) buttonValue(button int) float64 {
 	panic("gamepad: buttonValue is not implemented")
 }
 
-func (g *nativeGamepad) hatState(hat int) int {
+func (g *nativeGamepadImpl) hatState(hat int) int {
 	if hat < 0 || hat >= len(g.hats) {
 		return 0
 	}
 	return g.hats[hat]
 }
 
-func (g *nativeGamepad) vibrate(duration time.Duration, strongMagnitude float64, weakMagnitude float64) {
+func (g *nativeGamepadImpl) vibrate(duration time.Duration, strongMagnitude float64, weakMagnitude float64) {
 	// TODO: Implement this (#1452)
 }

internal/gamepad/gamepad_cbackend.go

@@ -23,16 +23,20 @@ import (
 	"github.com/hajimehoshi/ebiten/v2/internal/cbackend"
 )
 
-type nativeGamepads struct {
+type nativeGamepadsImpl struct {
 	gamepads []cbackend.Gamepad
 	ids      map[int]struct{}
 }
 
-func (*nativeGamepads) init(gamepads *gamepads) error {
+func newNativeGamepadsImpl() nativeGamepads {
+	return &nativeGamepadsImpl{}
+}
+
+func (*nativeGamepadsImpl) init(gamepads *gamepads) error {
 	return nil
 }
 
-func (g *nativeGamepads) update(gamepads *gamepads) error {
+func (g *nativeGamepadsImpl) update(gamepads *gamepads) error {
 	g.gamepads = g.gamepads[:0]
 	g.gamepads = cbackend.AppendGamepads(g.gamepads)
 
@@ -47,34 +51,37 @@ func (g *nativeGamepads) update(gamepads *gamepads) error {
 		g.ids[gp.ID] = struct{}{}
 
 		gamepad := gamepads.find(func(gamepad *Gamepad) bool {
-			return gamepad.native.id == gp.ID
+			return gamepad.native.(*nativeGamepadImpl).id == gp.ID
 		})
 		if gamepad == nil {
 			gamepad = gamepads.add("", "")
-			gamepad.native.id = gp.ID
+			gamepad.native = &nativeGamepadImpl{
-			gamepad.native.standard = gp.Standard
+				id:            gp.ID,
-			gamepad.native.axisValues = make([]float64, gp.AxisCount)
+				standard:      gp.Standard,
-			gamepad.native.buttonPressed = make([]bool, gp.ButtonCount)
+				axisValues:    make([]float64, gp.AxisCount),
-			gamepad.native.buttonValues = make([]float64, gp.ButtonCount)
+				buttonPressed: make([]bool, gp.ButtonCount),
+				buttonValues:  make([]float64, gp.ButtonCount),
+			}
 		}
 
 		gamepad.m.Lock()
-		copy(gamepad.native.axisValues, gp.AxisValues[:])
+		n := gamepad.native.(*nativeGamepadImpl)
-		copy(gamepad.native.buttonValues, gp.ButtonValues[:])
+		copy(n.axisValues, gp.AxisValues[:])
-		copy(gamepad.native.buttonPressed, gp.ButtonPressed[:])
+		copy(n.buttonValues, gp.ButtonValues[:])
+		copy(n.buttonPressed, gp.ButtonPressed[:])
 		gamepad.m.Unlock()
 	}
 
 	// Remove an unused gamepads.
 	gamepads.remove(func(gamepad *Gamepad) bool {
-		_, ok := g.ids[gamepad.native.id]
+		_, ok := g.ids[gamepad.native.(*nativeGamepadImpl).id]
 		return !ok
 	})
 
 	return nil
 }
 
-type nativeGamepad struct {
+type nativeGamepadImpl struct {
 	id       int
 	standard bool
 
@@ -83,51 +90,51 @@ type nativeGamepad struct {
 	buttonValues  []float64
 }
 
-func (*nativeGamepad) update(gamepad *gamepads) error {
+func (*nativeGamepadImpl) update(gamepad *gamepads) error {
 	return nil
 }
 
-func (g *nativeGamepad) hasOwnStandardLayoutMapping() bool {
+func (g *nativeGamepadImpl) hasOwnStandardLayoutMapping() bool {
 	return g.standard
 }
 
-func (g *nativeGamepad) axisCount() int {
+func (g *nativeGamepadImpl) axisCount() int {
 	return len(g.axisValues)
 }
 
-func (g *nativeGamepad) buttonCount() int {
+func (g *nativeGamepadImpl) buttonCount() int {
 	return len(g.buttonValues)
 }
 
-func (g *nativeGamepad) hatCount() int {
+func (g *nativeGamepadImpl) hatCount() int {
 	return 0
 }
 
-func (g *nativeGamepad) axisValue(axis int) float64 {
+func (g *nativeGamepadImpl) axisValue(axis int) float64 {
 	if axis < 0 || axis >= len(g.axisValues) {
 		return 0
 	}
 	return g.axisValues[axis]
 }
 
-func (g *nativeGamepad) isButtonPressed(button int) bool {
+func (g *nativeGamepadImpl) isButtonPressed(button int) bool {
 	if button < 0 || button >= len(g.buttonPressed) {
 		return false
 	}
 	return g.buttonPressed[button]
 }
 
-func (g *nativeGamepad) buttonValue(button int) float64 {
+func (g *nativeGamepadImpl) buttonValue(button int) float64 {
 	if button < 0 || button >= len(g.buttonValues) {
 		return 0
 	}
 	return g.buttonValues[button]
 }
 
-func (*nativeGamepad) hatState(hat int) int {
+func (*nativeGamepadImpl) hatState(hat int) int {
 	return hatCentered
 }
 
-func (g *nativeGamepad) vibrate(duration time.Duration, strongMagnitude float64, weakMagnitude float64) {
+func (g *nativeGamepadImpl) vibrate(duration time.Duration, strongMagnitude float64, weakMagnitude float64) {
 	cbackend.VibrateGamepad(g.id, duration, strongMagnitude, weakMagnitude)
 }

internal/gamepad/gamepad_darwin.go

@@ -59,14 +59,18 @@ import (
 // void ebitenGamepadRemovalCallback(void *ctx, IOReturn res, void *sender, IOHIDDeviceRef device);
 import "C"
 
-type nativeGamepads struct {
+type nativeGamepadsImpl struct {
 	hidManager      C.IOHIDManagerRef
 	devicesToAdd    []C.IOHIDDeviceRef
 	devicesToRemove []C.IOHIDDeviceRef
 	devicesM        sync.Mutex
 }
 
-func (g *nativeGamepads) init(gamepads *gamepads) error {
+func newNativeGamepadsImpl() nativeGamepads {
+	return &nativeGamepadsImpl{}
+}
+
+func (g *nativeGamepadsImpl) init(gamepads *gamepads) error {
 	var dicts []C.CFDictionaryRef
 
 	page := C.kHIDPage_GenericDesktop
@@ -135,28 +139,31 @@ func (g *nativeGamepads) init(gamepads *gamepads) error {
 
 //export ebitenGamepadMatchingCallback
 func ebitenGamepadMatchingCallback(ctx unsafe.Pointer, res C.IOReturn, sender unsafe.Pointer, device C.IOHIDDeviceRef) {
-	theGamepads.native.devicesM.Lock()
+	n := theGamepads.native.(*nativeGamepadsImpl)
-	defer theGamepads.native.devicesM.Unlock()
+	n.devicesM.Lock()
-	theGamepads.native.devicesToAdd = append(theGamepads.native.devicesToAdd, device)
+	defer n.devicesM.Unlock()
+	n.devicesToAdd = append(n.devicesToAdd, device)
 }
 
 //export ebitenGamepadRemovalCallback
 func ebitenGamepadRemovalCallback(ctx unsafe.Pointer, res C.IOReturn, sender unsafe.Pointer, device C.IOHIDDeviceRef) {
-	theGamepads.native.devicesM.Lock()
+	n := theGamepads.native.(*nativeGamepadsImpl)
-	defer theGamepads.native.devicesM.Unlock()
+	n.devicesM.Lock()
-	theGamepads.native.devicesToRemove = append(theGamepads.native.devicesToRemove, device)
+	defer n.devicesM.Unlock()
+	n.devicesToRemove = append(n.devicesToRemove, device)
 }
 
-func (g *nativeGamepads) update(gamepads *gamepads) error {
+func (g *nativeGamepadsImpl) update(gamepads *gamepads) error {
-	theGamepads.native.devicesM.Lock()
+	n := theGamepads.native.(*nativeGamepadsImpl)
-	defer theGamepads.native.devicesM.Unlock()
+	n.devicesM.Lock()
+	defer n.devicesM.Unlock()
 
 	for _, device := range g.devicesToAdd {
 		g.addDevice(device, gamepads)
 	}
 	for _, device := range g.devicesToRemove {
 		gamepads.remove(func(g *Gamepad) bool {
-			return g.native.device == device
+			return g.native.(*nativeGamepadImpl).device == device
 		})
 	}
 	g.devicesToAdd = g.devicesToAdd[:0]
@@ -164,9 +171,9 @@ func (g *nativeGamepads) update(gamepads *gamepads) error {
 	return nil
 }
 
-func (g *nativeGamepads) addDevice(device C.IOHIDDeviceRef, gamepads *gamepads) {
+func (g *nativeGamepadsImpl) addDevice(device C.IOHIDDeviceRef, gamepads *gamepads) {
 	if gamepads.find(func(g *Gamepad) bool {
-		return g.native.device == device
+		return g.native.(*nativeGamepadImpl).device == device
 	}) != nil {
 		return
 	}
@@ -211,8 +218,11 @@ func (g *nativeGamepads) addDevice(device C.IOHIDDeviceRef, gamepads *gamepads)
 	elements := C.IOHIDDeviceCopyMatchingElements(device, 0, C.kIOHIDOptionsTypeNone)
 	defer C.CFRelease(C.CFTypeRef(elements))
 
+	n := &nativeGamepadImpl{
+		device: device,
+	}
 	gp := gamepads.add(name, sdlID)
-	gp.native.device = device
+	gp.native = n
 
 	for i := C.CFIndex(0); i < C.CFArrayGetCount(elements); i++ {
 		native := (C.IOHIDElementRef)(C.CFArrayGetValueAtIndex(elements, i))
@@ -236,27 +246,27 @@ func (g *nativeGamepads) addDevice(device C.IOHIDDeviceRef, gamepads *gamepads)
 			case C.kHIDUsage_GD_X, C.kHIDUsage_GD_Y, C.kHIDUsage_GD_Z,
 				C.kHIDUsage_GD_Rx, C.kHIDUsage_GD_Ry, C.kHIDUsage_GD_Rz,
 				C.kHIDUsage_GD_Slider, C.kHIDUsage_GD_Dial, C.kHIDUsage_GD_Wheel:
-				gp.native.axes = append(gp.native.axes, element{
+				n.axes = append(n.axes, element{
 					native:  native,
 					usage:   int(usage),
-					index:   len(gp.native.axes),
+					index:   len(n.axes),
 					minimum: int(C.IOHIDElementGetLogicalMin(native)),
 					maximum: int(C.IOHIDElementGetLogicalMax(native)),
 				})
 			case C.kHIDUsage_GD_Hatswitch:
-				gp.native.hats = append(gp.native.hats, element{
+				n.hats = append(n.hats, element{
 					native:  native,
 					usage:   int(usage),
-					index:   len(gp.native.hats),
+					index:   len(n.hats),
 					minimum: int(C.IOHIDElementGetLogicalMin(native)),
 					maximum: int(C.IOHIDElementGetLogicalMax(native)),
 				})
 			case C.kHIDUsage_GD_DPadUp, C.kHIDUsage_GD_DPadRight, C.kHIDUsage_GD_DPadDown, C.kHIDUsage_GD_DPadLeft,
 				C.kHIDUsage_GD_SystemMainMenu, C.kHIDUsage_GD_Select, C.kHIDUsage_GD_Start:
-				gp.native.buttons = append(gp.native.buttons, element{
+				n.buttons = append(n.buttons, element{
 					native:  native,
 					usage:   int(usage),
-					index:   len(gp.native.buttons),
+					index:   len(n.buttons),
 					minimum: int(C.IOHIDElementGetLogicalMin(native)),
 					maximum: int(C.IOHIDElementGetLogicalMax(native)),
 				})
@@ -264,28 +274,28 @@ func (g *nativeGamepads) addDevice(device C.IOHIDDeviceRef, gamepads *gamepads)
 		case C.kHIDPage_Simulation:
 			switch usage {
 			case C.kHIDUsage_Sim_Accelerator, C.kHIDUsage_Sim_Brake, C.kHIDUsage_Sim_Throttle, C.kHIDUsage_Sim_Rudder, C.kHIDUsage_Sim_Steering:
-				gp.native.axes = append(gp.native.axes, element{
+				n.axes = append(n.axes, element{
 					native:  native,
 					usage:   int(usage),
-					index:   len(gp.native.axes),
+					index:   len(n.axes),
 					minimum: int(C.IOHIDElementGetLogicalMin(native)),
 					maximum: int(C.IOHIDElementGetLogicalMax(native)),
 				})
 			}
 		case C.kHIDPage_Button, C.kHIDPage_Consumer:
-			gp.native.buttons = append(gp.native.buttons, element{
+			n.buttons = append(n.buttons, element{
 				native:  native,
 				usage:   int(usage),
-				index:   len(gp.native.buttons),
+				index:   len(n.buttons),
 				minimum: int(C.IOHIDElementGetLogicalMin(native)),
 				maximum: int(C.IOHIDElementGetLogicalMax(native)),
 			})
 		}
 	}
 
-	sort.Stable(gp.native.axes)
+	sort.Stable(n.axes)
-	sort.Stable(gp.native.buttons)
+	sort.Stable(n.buttons)
-	sort.Stable(gp.native.hats)
+	sort.Stable(n.hats)
 }
 
 type element struct {
@@ -316,7 +326,7 @@ func (e elements) Swap(i, j int) {
 	e[i], e[j] = e[j], e[i]
 }
 
-type nativeGamepad struct {
+type nativeGamepadImpl struct {
 	device  C.IOHIDDeviceRef
 	axes    elements
 	buttons elements
@@ -327,7 +337,7 @@ type nativeGamepad struct {
 	hatValues    []int
 }
 
-func (g *nativeGamepad) elementValue(e *element) int {
+func (g *nativeGamepadImpl) elementValue(e *element) int {
 	var valueRef C.IOHIDValueRef
 	if C.IOHIDDeviceGetValue(g.device, e.native, &valueRef) == C.kIOReturnSuccess {
 		return int(C.IOHIDValueGetIntegerValue(valueRef))
@@ -336,7 +346,7 @@ func (g *nativeGamepad) elementValue(e *element) int {
 	return 0
 }
 
-func (g *nativeGamepad) update(gamepads *gamepads) error {
+func (g *nativeGamepadImpl) update(gamepads *gamepads) error {
 	if cap(g.axisValues) < len(g.axes) {
 		g.axisValues = make([]float64, len(g.axes))
 	}
@@ -392,47 +402,47 @@ func (g *nativeGamepad) update(gamepads *gamepads) error {
 	return nil
 }
 
-func (g *nativeGamepad) hasOwnStandardLayoutMapping() bool {
+func (g *nativeGamepadImpl) hasOwnStandardLayoutMapping() bool {
 	return false
 }
 
-func (g *nativeGamepad) axisCount() int {
+func (g *nativeGamepadImpl) axisCount() int {
 	return len(g.axisValues)
 }
 
-func (g *nativeGamepad) buttonCount() int {
+func (g *nativeGamepadImpl) buttonCount() int {
 	return len(g.buttonValues)
 }
 
-func (g *nativeGamepad) hatCount() int {
+func (g *nativeGamepadImpl) hatCount() int {
 	return len(g.hatValues)
 }
 
-func (g *nativeGamepad) axisValue(axis int) float64 {
+func (g *nativeGamepadImpl) axisValue(axis int) float64 {
 	if axis < 0 || axis >= len(g.axisValues) {
 		return 0
 	}
 	return g.axisValues[axis]
 }
 
-func (g *nativeGamepad) buttonValue(button int) float64 {
+func (g *nativeGamepadImpl) buttonValue(button int) float64 {
 	panic("gamepad: buttonValue is not implemented")
 }
 
-func (g *nativeGamepad) isButtonPressed(button int) bool {
+func (g *nativeGamepadImpl) isButtonPressed(button int) bool {
 	if button < 0 || button >= len(g.buttonValues) {
 		return false
 	}
 	return g.buttonValues[button]
 }
 
-func (g *nativeGamepad) hatState(hat int) int {
+func (g *nativeGamepadImpl) hatState(hat int) int {
 	if hat < 0 || hat >= len(g.hatValues) {
 		return hatCentered
 	}
 	return g.hatValues[hat]
 }
 
-func (g *nativeGamepad) vibrate(duration time.Duration, strongMagnitude float64, weakMagnitude float64) {
+func (g *nativeGamepadImpl) vibrate(duration time.Duration, strongMagnitude float64, weakMagnitude float64) {
 	// TODO: Implement this (#1452)
 }

internal/gamepad/gamepad_ios.go

@@ -21,18 +21,22 @@ import (
 	"time"
 )
 
-type nativeGamepads struct{}
+type nativeGamepadsImpl struct{}
 
-func (*nativeGamepads) init(gamepads *gamepads) error {
+func newNativeGamepadsImpl() nativeGamepads {
+	return &nativeGamepadsImpl{}
+}
+
+func (*nativeGamepadsImpl) init(gamepads *gamepads) error {
 	initializeIOSGamepads()
 	return nil
 }
 
-func (*nativeGamepads) update(gamepads *gamepads) error {
+func (*nativeGamepadsImpl) update(gamepads *gamepads) error {
 	return nil
 }
 
-type nativeGamepad struct {
+type nativeGamepadImpl struct {
 	controller           uintptr
 	buttonMask           uint16
 	hasDualshockTouchpad bool
@@ -44,52 +48,52 @@ type nativeGamepad struct {
 	hats    []int
 }
 
-func (g *nativeGamepad) update(gamepad *gamepads) error {
+func (g *nativeGamepadImpl) update(gamepad *gamepads) error {
 	g.updateIOSGamepad()
 	return nil
 }
 
-func (*nativeGamepad) hasOwnStandardLayoutMapping() bool {
+func (*nativeGamepadImpl) hasOwnStandardLayoutMapping() bool {
 	return false
 }
 
-func (g *nativeGamepad) axisCount() int {
+func (g *nativeGamepadImpl) axisCount() int {
 	return len(g.axes)
 }
 
-func (g *nativeGamepad) buttonCount() int {
+func (g *nativeGamepadImpl) buttonCount() int {
 	return len(g.buttons)
 }
 
-func (g *nativeGamepad) hatCount() int {
+func (g *nativeGamepadImpl) hatCount() int {
 	return len(g.hats)
 }
 
-func (g *nativeGamepad) axisValue(axis int) float64 {
+func (g *nativeGamepadImpl) axisValue(axis int) float64 {
 	if axis < 0 || axis >= len(g.axes) {
 		return 0
 	}
 	return g.axes[axis]
 }
 
-func (g *nativeGamepad) isButtonPressed(button int) bool {
+func (g *nativeGamepadImpl) isButtonPressed(button int) bool {
 	if button < 0 || button >= len(g.buttons) {
 		return false
 	}
 	return g.buttons[button]
 }
 
-func (*nativeGamepad) buttonValue(button int) float64 {
+func (*nativeGamepadImpl) buttonValue(button int) float64 {
 	panic("gamepad: buttonValue is not implemented")
 }
 
-func (g *nativeGamepad) hatState(hat int) int {
+func (g *nativeGamepadImpl) hatState(hat int) int {
 	if hat < 0 || hat >= len(g.hats) {
 		return 0
 	}
 	return g.hats[hat]
 }
 
-func (g *nativeGamepad) vibrate(duration time.Duration, strongMagnitude float64, weakMagnitude float64) {
+func (g *nativeGamepadImpl) vibrate(duration time.Duration, strongMagnitude float64, weakMagnitude float64) {
 	// TODO: Implement this (#1452)
 }

internal/gamepad/gamepad_js.go

@@ -25,15 +25,19 @@ var (
 	go2cpp = js.Global().Get("go2cpp")
 )
 
-type nativeGamepads struct {
+type nativeGamepadsImpl struct {
 	indices map[int]struct{}
 }
 
-func (g *nativeGamepads) init(gamepads *gamepads) error {
+func newNativeGamepadsImpl() nativeGamepads {
+	return &nativeGamepadsImpl{}
+}
+
+func (g *nativeGamepadsImpl) init(gamepads *gamepads) error {
 	return nil
 }
 
-func (g *nativeGamepads) update(gamepads *gamepads) error {
+func (g *nativeGamepadsImpl) update(gamepads *gamepads) error {
 	// TODO: Use the gamepad events instead of navigator.getGamepads after go2cpp is removed.
 
 	defer func() {
@@ -73,7 +77,7 @@ func (g *nativeGamepads) update(gamepads *gamepads) error {
 
 		// The gamepad is not registered yet, register this.
 		gamepad := gamepads.find(func(gamepad *Gamepad) bool {
-			return index == gamepad.native.index
+			return index == gamepad.native.(*nativeGamepadImpl).index
 		})
 		if gamepad == nil {
 			name := gp.Get("id").String()
@@ -84,28 +88,30 @@ func (g *nativeGamepads) update(gamepads *gamepads) error {
 			copy(sdlID[:], []byte(name))
 
 			gamepad = gamepads.add(name, hex.EncodeToString(sdlID[:]))
-			gamepad.native.index = index
+			gamepad.native = &nativeGamepadImpl{
-			gamepad.native.mapping = gp.Get("mapping").String()
+				index:   index,
+				mapping: gp.Get("mapping").String(),
+			}
 		}
-		gamepad.native.value = gp
+		gamepad.native.(*nativeGamepadImpl).value = gp
 	}
 
 	// Remove an unused gamepads.
 	gamepads.remove(func(gamepad *Gamepad) bool {
-		_, ok := g.indices[gamepad.native.index]
+		_, ok := g.indices[gamepad.native.(*nativeGamepadImpl).index]
 		return !ok
 	})
 
 	return nil
 }
 
-type nativeGamepad struct {
+type nativeGamepadImpl struct {
 	value   js.Value
 	index   int
 	mapping string
 }
 
-func (g *nativeGamepad) hasOwnStandardLayoutMapping() bool {
+func (g *nativeGamepadImpl) hasOwnStandardLayoutMapping() bool {
 	// With go2cpp, the controller must have the standard
 	if go2cpp.Truthy() {
 		return true
@@ -113,23 +119,23 @@ func (g *nativeGamepad) hasOwnStandardLayoutMapping() bool {
 	return g.mapping == "standard"
 }
 
-func (g *nativeGamepad) update(gamepads *gamepads) error {
+func (g *nativeGamepadImpl) update(gamepads *gamepads) error {
 	return nil
 }
 
-func (g *nativeGamepad) axisCount() int {
+func (g *nativeGamepadImpl) axisCount() int {
 	return g.value.Get("axes").Length()
 }
 
-func (g *nativeGamepad) buttonCount() int {
+func (g *nativeGamepadImpl) buttonCount() int {
 	return g.value.Get("buttons").Length()
 }
 
-func (g *nativeGamepad) hatCount() int {
+func (g *nativeGamepadImpl) hatCount() int {
 	return 0
 }
 
-func (g *nativeGamepad) axisValue(axis int) float64 {
+func (g *nativeGamepadImpl) axisValue(axis int) float64 {
 	axes := g.value.Get("axes")
 	if axis < 0 || axis >= axes.Length() {
 		return 0
@@ -137,7 +143,7 @@ func (g *nativeGamepad) axisValue(axis int) float64 {
 	return axes.Index(axis).Float()
 }
 
-func (g *nativeGamepad) buttonValue(button int) float64 {
+func (g *nativeGamepadImpl) buttonValue(button int) float64 {
 	buttons := g.value.Get("buttons")
 	if button < 0 || button >= buttons.Length() {
 		return 0
@@ -145,7 +151,7 @@ func (g *nativeGamepad) buttonValue(button int) float64 {
 	return buttons.Index(button).Get("value").Float()
 }
 
-func (g *nativeGamepad) isButtonPressed(button int) bool {
+func (g *nativeGamepadImpl) isButtonPressed(button int) bool {
 	buttons := g.value.Get("buttons")
 	if button < 0 || button >= buttons.Length() {
 		return false
@@ -153,11 +159,11 @@ func (g *nativeGamepad) isButtonPressed(button int) bool {
 	return buttons.Index(button).Get("pressed").Bool()
 }
 
-func (g *nativeGamepad) hatState(hat int) int {
+func (g *nativeGamepadImpl) hatState(hat int) int {
 	return hatCentered
 }
 
-func (g *nativeGamepad) vibrate(duration time.Duration, strongMagnitude float64, weakMagnitude float64) {
+func (g *nativeGamepadImpl) vibrate(duration time.Duration, strongMagnitude float64, weakMagnitude float64) {
 	// vibrationActuator is avaialble on Chrome.
 	if va := g.value.Get("vibrationActuator"); va.Truthy() {
 		if !va.Get("playEffect").Truthy() {

internal/gamepad/gamepad_linux.go

@@ -37,12 +37,16 @@ func isBitSet(s []byte, bit int) bool {
 	return s[bit/8]&(1<<(bit%8)) != 0
 }
 
-type nativeGamepads struct {
+type nativeGamepadsImpl struct {
 	inotify int
 	watch   int
 }
 
-func (g *nativeGamepads) init(gamepads *gamepads) error {
+func newNativeGamepadsImpl() nativeGamepads {
+	return &nativeGamepadsImpl{}
+}
+
+func (g *nativeGamepadsImpl) init(gamepads *gamepads) error {
 	// Check the existence of the directory `dirName`.
 	var stat unix.Stat_t
 	if err := unix.Stat(dirName, &stat); err != nil {
@@ -90,9 +94,9 @@ func (g *nativeGamepads) init(gamepads *gamepads) error {
 	return nil
 }
 
-func (*nativeGamepads) openGamepad(gamepads *gamepads, path string) (err error) {
+func (*nativeGamepadsImpl) openGamepad(gamepads *gamepads, path string) (err error) {
 	if gamepads.find(func(gamepad *Gamepad) bool {
-		return gamepad.native.path == path
+		return gamepad.native.(*nativeGamepadImpl).path == path
 	}) != nil {
 		return nil
 	}
@@ -164,11 +168,14 @@ func (*nativeGamepads) openGamepad(gamepads *gamepads, path string) (err error)
 			bs[0], bs[1], bs[2], bs[3], bs[4], bs[5], bs[6], bs[7], bs[8], bs[9], bs[10], bs[11])
 	}
 
+	n := &nativeGamepadImpl{
+		path: path,
+		fd:   fd,
+	}
 	gp := gamepads.add(name, sdlID)
-	gp.native.path = path
+	gp.native = n
-	gp.native.fd = fd
 	runtime.SetFinalizer(gp, func(gp *Gamepad) {
-		gp.native.close()
+		n.close()
 	})
 
 	var axisCount int
@@ -178,40 +185,40 @@ func (*nativeGamepads) openGamepad(gamepads *gamepads, path string) (err error)
 		if !isBitSet(keyBits, code) {
 			continue
 		}
-		gp.native.keyMap[code-_BTN_MISC] = buttonCount
+		n.keyMap[code-_BTN_MISC] = buttonCount
 		buttonCount++
 	}
 	for code := 0; code < _ABS_CNT; code++ {
-		gp.native.absMap[code] = -1
+		n.absMap[code] = -1
 		if !isBitSet(absBits, code) {
 			continue
 		}
 		if code >= _ABS_HAT0X && code <= _ABS_HAT3Y {
-			gp.native.absMap[code] = hatCount
+			n.absMap[code] = hatCount
 			hatCount++
 			// Skip Y.
 			code++
 			continue
 		}
-		if err := ioctl(gp.native.fd, uint(_EVIOCGABS(uint(code))), unsafe.Pointer(&gp.native.absInfo[code])); err != nil {
+		if err := ioctl(n.fd, uint(_EVIOCGABS(uint(code))), unsafe.Pointer(&n.absInfo[code])); err != nil {
 			return fmt.Errorf("gamepad: ioctl for an abs at openGamepad failed: %w", err)
 		}
-		gp.native.absMap[code] = axisCount
+		n.absMap[code] = axisCount
 		axisCount++
 	}
 
-	gp.native.axisCount_ = axisCount
+	n.axisCount_ = axisCount
-	gp.native.buttonCount_ = buttonCount
+	n.buttonCount_ = buttonCount
-	gp.native.hatCount_ = hatCount
+	n.hatCount_ = hatCount
 
-	if err := gp.native.pollAbsState(); err != nil {
+	if err := n.pollAbsState(); err != nil {
 		return err
 	}
 
 	return nil
 }
 
-func (g *nativeGamepads) update(gamepads *gamepads) error {
+func (g *nativeGamepadsImpl) update(gamepads *gamepads) error {
 	if g.inotify <= 0 {
 		return nil
 	}
@@ -248,9 +255,9 @@ func (g *nativeGamepads) update(gamepads *gamepads) error {
 		}
 		if e.Mask&unix.IN_DELETE != 0 {
 			if gp := gamepads.find(func(gamepad *Gamepad) bool {
-				return gamepad.native.path == path
+				return gamepad.native.(*nativeGamepadImpl).path == path
 			}); gp != nil {
-				gp.native.close()
+				gp.native.(*nativeGamepadImpl).close()
 				gamepads.remove(func(gamepad *Gamepad) bool {
 					return gamepad == gp
 				})
@@ -262,7 +269,7 @@ func (g *nativeGamepads) update(gamepads *gamepads) error {
 	return nil
 }
 
-type nativeGamepad struct {
+type nativeGamepadImpl struct {
 	fd      int
 	path    string
 	keyMap  [_KEY_CNT - _BTN_MISC]int
@@ -279,14 +286,14 @@ type nativeGamepad struct {
 	hatCount_    int
 }
 
-func (g *nativeGamepad) close() {
+func (g *nativeGamepadImpl) close() {
 	if g.fd != 0 {
 		unix.Close(g.fd)
 	}
 	g.fd = 0
 }
 
-func (g *nativeGamepad) update(gamepad *gamepads) error {
+func (g *nativeGamepadImpl) update(gamepad *gamepads) error {
 	if g.fd == 0 {
 		return nil
 	}
@@ -344,7 +351,7 @@ func (g *nativeGamepad) update(gamepad *gamepads) error {
 	return nil
 }
 
-func (g *nativeGamepad) pollAbsState() error {
+func (g *nativeGamepadImpl) pollAbsState() error {
 	for code := 0; code < _ABS_CNT; code++ {
 		if g.absMap[code] < 0 {
 			continue
@@ -357,7 +364,7 @@ func (g *nativeGamepad) pollAbsState() error {
 	return nil
 }
 
-func (g *nativeGamepad) handleAbsEvent(code int, value int32) {
+func (g *nativeGamepadImpl) handleAbsEvent(code int, value int32) {
 	index := g.absMap[code]
 
 	if code >= _ABS_HAT0X && code <= _ABS_HAT3Y {
@@ -399,47 +406,47 @@ func (g *nativeGamepad) handleAbsEvent(code int, value int32) {
 	g.axes[index] = v
 }
 
-func (*nativeGamepad) hasOwnStandardLayoutMapping() bool {
+func (*nativeGamepadImpl) hasOwnStandardLayoutMapping() bool {
 	return false
 }
 
-func (g *nativeGamepad) axisCount() int {
+func (g *nativeGamepadImpl) axisCount() int {
 	return g.axisCount_
 }
 
-func (g *nativeGamepad) buttonCount() int {
+func (g *nativeGamepadImpl) buttonCount() int {
 	return g.buttonCount_
 }
 
-func (g *nativeGamepad) hatCount() int {
+func (g *nativeGamepadImpl) hatCount() int {
 	return g.hatCount_
 }
 
-func (g *nativeGamepad) axisValue(axis int) float64 {
+func (g *nativeGamepadImpl) axisValue(axis int) float64 {
 	if axis < 0 || axis >= g.axisCount_ {
 		return 0
 	}
 	return g.axes[axis]
 }
 
-func (g *nativeGamepad) isButtonPressed(button int) bool {
+func (g *nativeGamepadImpl) isButtonPressed(button int) bool {
 	if button < 0 || button >= g.buttonCount_ {
 		return false
 	}
 	return g.buttons[button]
 }
 
-func (*nativeGamepad) buttonValue(button int) float64 {
+func (*nativeGamepadImpl) buttonValue(button int) float64 {
 	panic("gamepad: buttonValue is not implemented")
 }
 
-func (g *nativeGamepad) hatState(hat int) int {
+func (g *nativeGamepadImpl) hatState(hat int) int {
 	if hat < 0 || hat >= g.hatCount_ {
 		return hatCentered
 	}
 	return g.hats[hat]
 }
 
-func (g *nativeGamepad) vibrate(duration time.Duration, strongMagnitude float64, weakMagnitude float64) {
+func (g *nativeGamepadImpl) vibrate(duration time.Duration, strongMagnitude float64, weakMagnitude float64) {
 	// TODO: Implement this (#1452)
 }

internal/gamepad/gamepad_windows.go

@@ -99,7 +99,7 @@ var xinputButtons = []uint16{
 	_XINPUT_GAMEPAD_RIGHT_THUMB,
 }
 
-type nativeGamepads struct {
+type nativeGamepadsImpl struct {
 	dinput8    windows.Handle
 	dinput8API *_IDirectInput8W
 	xinput     windows.Handle
@@ -118,6 +118,10 @@ type nativeGamepads struct {
 	err           error
 }
 
+func newNativeGamepadsImpl() nativeGamepads {
+	return &nativeGamepadsImpl{}
+}
+
 type dinputObject struct {
 	objectType dinputObjectType
 	index      int
@@ -132,7 +136,7 @@ type enumObjectsContext struct {
 	povCount    int
 }
 
-func (g *nativeGamepads) init(gamepads *gamepads) error {
+func (g *nativeGamepadsImpl) init(gamepads *gamepads) error {
 	// As there is no guarantee that the DLL exists, NewLazySystemDLL is not available.
 	// TODO: Is there a 'system' version of LoadLibrary?
 	if h, err := windows.LoadLibrary("dinput8.dll"); err == nil {
@@ -194,7 +198,7 @@ func (g *nativeGamepads) init(gamepads *gamepads) error {
 	return nil
 }
 
-func (g *nativeGamepads) directInput8Create(hinst uintptr, dwVersion uint32, riidltf *windows.GUID, ppvOut **_IDirectInput8W, punkOuter unsafe.Pointer) error {
+func (g *nativeGamepadsImpl) directInput8Create(hinst uintptr, dwVersion uint32, riidltf *windows.GUID, ppvOut **_IDirectInput8W, punkOuter unsafe.Pointer) error {
 	r, _, _ := syscall.Syscall6(g.procDirectInput8Create, 5,
 		hinst, uintptr(dwVersion), uintptr(unsafe.Pointer(riidltf)), uintptr(unsafe.Pointer(ppvOut)), uintptr(punkOuter),
 		0)
@@ -204,7 +208,7 @@ func (g *nativeGamepads) directInput8Create(hinst uintptr, dwVersion uint32, rii
 	return nil
 }
 
-func (g *nativeGamepads) xinputGetCapabilities(dwUserIndex uint32, dwFlags uint32, pCapabilities *_XINPUT_CAPABILITIES) error {
+func (g *nativeGamepadsImpl) xinputGetCapabilities(dwUserIndex uint32, dwFlags uint32, pCapabilities *_XINPUT_CAPABILITIES) error {
 	// XInputGetCapabilities doesn't call SetLastError and returns an error code directly.
 	r, _, _ := syscall.Syscall(g.procXInputGetCapabilities, 3,
 		uintptr(dwUserIndex), uintptr(dwFlags), uintptr(unsafe.Pointer(pCapabilities)))
@@ -214,7 +218,7 @@ func (g *nativeGamepads) xinputGetCapabilities(dwUserIndex uint32, dwFlags uint3
 	return nil
 }
 
-func (g *nativeGamepads) xinputGetState(dwUserIndex uint32, pState *_XINPUT_STATE) error {
+func (g *nativeGamepadsImpl) xinputGetState(dwUserIndex uint32, pState *_XINPUT_STATE) error {
 	// XInputGetState doesn't call SetLastError and returns an error code directly.
 	r, _, _ := syscall.Syscall(g.procXInputGetState, 2,
 		uintptr(dwUserIndex), uintptr(unsafe.Pointer(pState)), 0)
@@ -224,7 +228,7 @@ func (g *nativeGamepads) xinputGetState(dwUserIndex uint32, pState *_XINPUT_STAT
 	return nil
 }
 
-func (g *nativeGamepads) detectConnection(gamepads *gamepads) error {
+func (g *nativeGamepadsImpl) detectConnection(gamepads *gamepads) error {
 	if g.dinput8 != 0 {
 		if g.enumDevicesCallback == 0 {
 			g.enumDevicesCallback = windows.NewCallback(g.dinput8EnumDevicesCallback)
@@ -241,7 +245,8 @@ func (g *nativeGamepads) detectConnection(gamepads *gamepads) error {
 
 		for i := 0; i < xuserMaxCount; i++ {
 			if gamepads.find(func(g *Gamepad) bool {
-				return g.native.dinputDevice == nil && g.native.xinputIndex == i
+				n := g.native.(*nativeGamepadImpl)
+				return n.dinputDevice == nil && n.xinputIndex == i
 			}) != nil {
 				continue
 			}
@@ -278,13 +283,15 @@ func (g *nativeGamepads) detectConnection(gamepads *gamepads) error {
 			}
 
 			gp := gamepads.add(name, sdlID)
-			gp.native.xinputIndex = i
+			gp.native = &nativeGamepadImpl{
+				xinputIndex: i,
+			}
 		}
 	}
 	return nil
 }
 
-func (g *nativeGamepads) dinput8EnumDevicesCallback(lpddi *_DIDEVICEINSTANCEW, pvRef unsafe.Pointer) uintptr {
+func (g *nativeGamepadsImpl) dinput8EnumDevicesCallback(lpddi *_DIDEVICEINSTANCEW, pvRef unsafe.Pointer) uintptr {
 	gamepads := (*gamepads)(pvRef)
 
 	if g.err != nil {
@@ -292,7 +299,7 @@ func (g *nativeGamepads) dinput8EnumDevicesCallback(lpddi *_DIDEVICEINSTANCEW, p
 	}
 
 	if gamepads.find(func(g *Gamepad) bool {
-		return g.native.dinputGUID == lpddi.guidInstance
+		return g.native.(*nativeGamepadImpl).dinputGUID == lpddi.guidInstance
 	}) != nil {
 		return _DIENUM_CONTINUE
 	}
@@ -389,12 +396,14 @@ func (g *nativeGamepads) dinput8EnumDevicesCallback(lpddi *_DIDEVICEINSTANCEW, p
 	}
 
 	gp := gamepads.add(name, sdlID)
-	gp.native.dinputDevice = device
+	gp.native = &nativeGamepadImpl{
-	gp.native.dinputObjects = ctx.objects
+		dinputDevice:  device,
-	gp.native.dinputGUID = lpddi.guidInstance
+		dinputObjects: ctx.objects,
-	gp.native.dinputAxes = make([]float64, ctx.axisCount+ctx.sliderCount)
+		dinputGUID:    lpddi.guidInstance,
-	gp.native.dinputButtons = make([]bool, ctx.buttonCount)
+		dinputAxes:    make([]float64, ctx.axisCount+ctx.sliderCount),
-	gp.native.dinputHats = make([]int, ctx.povCount)
+		dinputButtons: make([]bool, ctx.buttonCount),
+		dinputHats:    make([]int, ctx.povCount),
+	}
 
 	return _DIENUM_CONTINUE
 }
@@ -443,7 +452,7 @@ func supportsXInput(guid windows.GUID) (bool, error) {
 	return false, nil
 }
 
-func (g *nativeGamepads) dinputDevice8EnumObjectsCallback(lpddoi *_DIDEVICEOBJECTINSTANCEW, pvRef unsafe.Pointer) uintptr {
+func (g *nativeGamepadsImpl) dinputDevice8EnumObjectsCallback(lpddoi *_DIDEVICEOBJECTINSTANCEW, pvRef unsafe.Pointer) uintptr {
 	ctx := (*enumObjectsContext)(pvRef)
 
 	switch {
@@ -511,7 +520,7 @@ func (g *nativeGamepads) dinputDevice8EnumObjectsCallback(lpddoi *_DIDEVICEOBJEC
 	return _DIENUM_CONTINUE
 }
 
-func (g *nativeGamepads) update(gamepads *gamepads) error {
+func (g *nativeGamepadsImpl) update(gamepads *gamepads) error {
 	if g.err != nil {
 		return g.err
 	}
@@ -537,7 +546,7 @@ func (g *nativeGamepads) update(gamepads *gamepads) error {
 	return nil
 }
 
-func (g *nativeGamepads) wndProc(hWnd uintptr, uMsg uint32, wParam, lParam uintptr) uintptr {
+func (g *nativeGamepadsImpl) wndProc(hWnd uintptr, uMsg uint32, wParam, lParam uintptr) uintptr {
 	switch uMsg {
 	case _WM_DEVICECHANGE:
 		atomic.StoreInt32(&g.deviceChanged, 1)
@@ -545,11 +554,11 @@ func (g *nativeGamepads) wndProc(hWnd uintptr, uMsg uint32, wParam, lParam uintp
 	return _CallWindowProcW(g.origWndProc, hWnd, uMsg, wParam, lParam)
 }
 
-func (g *nativeGamepads) setNativeWindow(nativeWindow uintptr) {
+func (g *nativeGamepadsImpl) setNativeWindow(nativeWindow uintptr) {
 	g.nativeWindow = windows.HWND(nativeWindow)
 }
 
-type nativeGamepad struct {
+type nativeGamepadImpl struct {
 	dinputDevice  *_IDirectInputDevice8W
 	dinputObjects []dinputObject
 	dinputGUID    windows.GUID
@@ -561,22 +570,22 @@ type nativeGamepad struct {
 	xinputState _XINPUT_STATE
 }
 
-func (*nativeGamepad) hasOwnStandardLayoutMapping() bool {
+func (*nativeGamepadImpl) hasOwnStandardLayoutMapping() bool {
 	return false
 }
 
-func (g *nativeGamepad) usesDInput() bool {
+func (g *nativeGamepadImpl) usesDInput() bool {
 	return g.dinputDevice != nil
 }
 
-func (g *nativeGamepad) update(gamepads *gamepads) (err error) {
+func (g *nativeGamepadImpl) update(gamepads *gamepads) (err error) {
 	var disconnected bool
 	defer func() {
 		if !disconnected && err == nil {
 			return
 		}
 		gamepads.remove(func(gamepad *Gamepad) bool {
-			return &gamepad.native == g
+			return gamepad.native == g
 		})
 	}()
 
@@ -666,7 +675,7 @@ func (g *nativeGamepad) update(gamepads *gamepads) (err error) {
 	}
 
 	var state _XINPUT_STATE
-	if err := gamepads.native.xinputGetState(uint32(g.xinputIndex), &state); err != nil {
+	if err := gamepads.native.(*nativeGamepadsImpl).xinputGetState(uint32(g.xinputIndex), &state); err != nil {
 		if !errors.Is(err, windows.ERROR_DEVICE_NOT_CONNECTED) {
 			return err
 		}
@@ -677,28 +686,28 @@ func (g *nativeGamepad) update(gamepads *gamepads) (err error) {
 	return nil
 }
 
-func (g *nativeGamepad) axisCount() int {
+func (g *nativeGamepadImpl) axisCount() int {
 	if g.usesDInput() {
 		return len(g.dinputAxes)
 	}
 	return 6
 }
 
-func (g *nativeGamepad) buttonCount() int {
+func (g *nativeGamepadImpl) buttonCount() int {
 	if g.usesDInput() {
 		return len(g.dinputButtons)
 	}
 	return len(xinputButtons)
 }
 
-func (g *nativeGamepad) hatCount() int {
+func (g *nativeGamepadImpl) hatCount() int {
 	if g.usesDInput() {
 		return len(g.dinputHats)
 	}
 	return 1
 }
 
-func (g *nativeGamepad) axisValue(axis int) float64 {
+func (g *nativeGamepadImpl) axisValue(axis int) float64 {
 	if g.usesDInput() {
 		if axis < 0 || axis >= len(g.dinputAxes) {
 			return 0
@@ -724,7 +733,7 @@ func (g *nativeGamepad) axisValue(axis int) float64 {
 	return v
 }
 
-func (g *nativeGamepad) isButtonPressed(button int) bool {
+func (g *nativeGamepadImpl) isButtonPressed(button int) bool {
 	if g.usesDInput() {
 		if button < 0 || button >= len(g.dinputButtons) {
 			return false
@@ -738,11 +747,11 @@ func (g *nativeGamepad) isButtonPressed(button int) bool {
 	return g.xinputState.Gamepad.wButtons&xinputButtons[button] != 0
 }
 
-func (g *nativeGamepad) buttonValue(button int) float64 {
+func (g *nativeGamepadImpl) buttonValue(button int) float64 {
 	panic("gamepad: buttonValue is not implemented")
 }
 
-func (g *nativeGamepad) hatState(hat int) int {
+func (g *nativeGamepadImpl) hatState(hat int) int {
 	if g.usesDInput() {
 		if hat < 0 || hat >= len(g.dinputHats) {
 			return 0
@@ -769,6 +778,6 @@ func (g *nativeGamepad) hatState(hat int) int {
 	return v
 }
 
-func (g *nativeGamepad) vibrate(duration time.Duration, strongMagnitude float64, weakMagnitude float64) {
+func (g *nativeGamepadImpl) vibrate(duration time.Duration, strongMagnitude float64, weakMagnitude float64) {
 	// TODO: Implement this (#1452)
 }