mobile/ebitenmobileview: Implement gamepads' SDLID on Android

Fixes #1083

cmd/ebitenmobile/gobind.go

@@ -532,7 +532,140 @@ public class EbitenView extends ViewGroup implements InputManager.InputDeviceLis
             axisNum--;
         }
 
-        Ebitenmobileview.onGamepadAdded(deviceId, inputDevice.getName(), buttonNum, axisNum);
+        String descriptor = inputDevice.getDescriptor();
+        int vendorId = inputDevice.getVendorId();
+        int productId = inputDevice.getProductId();
+
+        // These values are required to calculate SDL's GUID.
+        int buttonMask = getButtonMask(inputDevice);
+        int axisMask = getAxisMask(inputDevice);
+
+        Ebitenmobileview.onGamepadAdded(deviceId, inputDevice.getName(), buttonNum, axisNum, descriptor, vendorId, productId, buttonMask, axisMask);
+    }
+
+    // The implementation is copied from SDL:
+    // https://hg.libsdl.org/SDL/file/bc90ce38f1e2/android-project/app/src/main/java/org/libsdl/app/SDLControllerManager.java#l308
+    private int getButtonMask(InputDevice joystickDevice) {
+        int button_mask = 0;
+        int[] keys = new int[] {
+            KeyEvent.KEYCODE_BUTTON_A,
+            KeyEvent.KEYCODE_BUTTON_B,
+            KeyEvent.KEYCODE_BUTTON_X,
+            KeyEvent.KEYCODE_BUTTON_Y,
+            KeyEvent.KEYCODE_BACK,
+            KeyEvent.KEYCODE_BUTTON_MODE,
+            KeyEvent.KEYCODE_BUTTON_START,
+            KeyEvent.KEYCODE_BUTTON_THUMBL,
+            KeyEvent.KEYCODE_BUTTON_THUMBR,
+            KeyEvent.KEYCODE_BUTTON_L1,
+            KeyEvent.KEYCODE_BUTTON_R1,
+            KeyEvent.KEYCODE_DPAD_UP,
+            KeyEvent.KEYCODE_DPAD_DOWN,
+            KeyEvent.KEYCODE_DPAD_LEFT,
+            KeyEvent.KEYCODE_DPAD_RIGHT,
+            KeyEvent.KEYCODE_BUTTON_SELECT,
+            KeyEvent.KEYCODE_DPAD_CENTER,
+
+            // These don't map into any SDL controller buttons directly
+            KeyEvent.KEYCODE_BUTTON_L2,
+            KeyEvent.KEYCODE_BUTTON_R2,
+            KeyEvent.KEYCODE_BUTTON_C,
+            KeyEvent.KEYCODE_BUTTON_Z,
+            KeyEvent.KEYCODE_BUTTON_1,
+            KeyEvent.KEYCODE_BUTTON_2,
+            KeyEvent.KEYCODE_BUTTON_3,
+            KeyEvent.KEYCODE_BUTTON_4,
+            KeyEvent.KEYCODE_BUTTON_5,
+            KeyEvent.KEYCODE_BUTTON_6,
+            KeyEvent.KEYCODE_BUTTON_7,
+            KeyEvent.KEYCODE_BUTTON_8,
+            KeyEvent.KEYCODE_BUTTON_9,
+            KeyEvent.KEYCODE_BUTTON_10,
+            KeyEvent.KEYCODE_BUTTON_11,
+            KeyEvent.KEYCODE_BUTTON_12,
+            KeyEvent.KEYCODE_BUTTON_13,
+            KeyEvent.KEYCODE_BUTTON_14,
+            KeyEvent.KEYCODE_BUTTON_15,
+            KeyEvent.KEYCODE_BUTTON_16,
+        };
+        int[] masks = new int[] {
+            (1 << 0),   // A -> A
+            (1 << 1),   // B -> B
+            (1 << 2),   // X -> X
+            (1 << 3),   // Y -> Y
+            (1 << 4),   // BACK -> BACK
+            (1 << 5),   // MODE -> GUIDE
+            (1 << 6),   // START -> START
+            (1 << 7),   // THUMBL -> LEFTSTICK
+            (1 << 8),   // THUMBR -> RIGHTSTICK
+            (1 << 9),   // L1 -> LEFTSHOULDER
+            (1 << 10),  // R1 -> RIGHTSHOULDER
+            (1 << 11),  // DPAD_UP -> DPAD_UP
+            (1 << 12),  // DPAD_DOWN -> DPAD_DOWN
+            (1 << 13),  // DPAD_LEFT -> DPAD_LEFT
+            (1 << 14),  // DPAD_RIGHT -> DPAD_RIGHT
+            (1 << 4),   // SELECT -> BACK
+            (1 << 0),   // DPAD_CENTER -> A
+            (1 << 15),  // L2 -> ??
+            (1 << 16),  // R2 -> ??
+            (1 << 17),  // C -> ??
+            (1 << 18),  // Z -> ??
+            (1 << 20),  // 1 -> ??
+            (1 << 21),  // 2 -> ??
+            (1 << 22),  // 3 -> ??
+            (1 << 23),  // 4 -> ??
+            (1 << 24),  // 5 -> ??
+            (1 << 25),  // 6 -> ??
+            (1 << 26),  // 7 -> ??
+            (1 << 27),  // 8 -> ??
+            (1 << 28),  // 9 -> ??
+            (1 << 29),  // 10 -> ??
+            (1 << 30),  // 11 -> ??
+            (1 << 31),  // 12 -> ??
+            // We're out of room...
+            0xFFFFFFFF,  // 13 -> ??
+            0xFFFFFFFF,  // 14 -> ??
+            0xFFFFFFFF,  // 15 -> ??
+            0xFFFFFFFF,  // 16 -> ??
+        };
+        boolean[] has_keys = joystickDevice.hasKeys(keys);
+        for (int i = 0; i < keys.length; ++i) {
+            if (has_keys[i]) {
+                button_mask |= masks[i];
+            }
+        }
+        return button_mask;
+    }
+
+    private int getAxisMask(InputDevice joystickDevice) {
+        final int SDL_CONTROLLER_AXIS_LEFTX = 0;
+        final int SDL_CONTROLLER_AXIS_LEFTY = 1;
+        final int SDL_CONTROLLER_AXIS_RIGHTX = 2;
+        final int SDL_CONTROLLER_AXIS_RIGHTY = 3;
+        final int SDL_CONTROLLER_AXIS_TRIGGERLEFT = 4;
+        final int SDL_CONTROLLER_AXIS_TRIGGERRIGHT = 5;
+
+        int naxes = 0;
+        for (InputDevice.MotionRange range : joystickDevice.getMotionRanges()) {
+            if ((range.getSource() & InputDevice.SOURCE_CLASS_JOYSTICK) != 0) {
+                if (range.getAxis() != MotionEvent.AXIS_HAT_X && range.getAxis() != MotionEvent.AXIS_HAT_Y) {
+                    naxes++;
+                }
+            }
+        }
+        // The variable is_accelerometer seems always false, then skip the checking:
+        // https://hg.libsdl.org/SDL/file/bc90ce38f1e2/android-project/app/src/main/java/org/libsdl/app/SDLControllerManager.java#l207
+        int axisMask = 0;
+        if (naxes >= 2) {
+            axisMask |= ((1 << SDL_CONTROLLER_AXIS_LEFTX) | (1 << SDL_CONTROLLER_AXIS_LEFTY));
+        }
+        if (naxes >= 4) {
+            axisMask |= ((1 << SDL_CONTROLLER_AXIS_RIGHTX) | (1 << SDL_CONTROLLER_AXIS_RIGHTY));
+        }
+        if (naxes >= 6) {
+            axisMask |= ((1 << SDL_CONTROLLER_AXIS_TRIGGERLEFT) | (1 << SDL_CONTROLLER_AXIS_TRIGGERRIGHT));
+        }
+        return axisMask;
     }
 
     @Override

mobile/ebitenmobileview/input_android.go

@@ -15,6 +15,8 @@
 package ebitenmobileview
 
 import (
+	"encoding/hex"
+	"hash/crc32"
 	"unicode"
 
 	"github.com/hajimehoshi/ebiten/internal/driver"
@@ -277,11 +279,36 @@ func OnGamepadAxesChanged(deviceID int, axisID int, value float32) {
 	updateInput()
 }
 
-func OnGamepadAdded(deviceID int, name string, buttonNum int, axisNum int) {
+func OnGamepadAdded(deviceID int, name string, buttonNum int, axisNum int, descriptor string, vendorID int, productID int, buttonMask int, axisMask int) {
+	// This emulates the implementation of Android_AddJoystick.
+	// https://hg.libsdl.org/SDL/file/bc90ce38f1e2/src/joystick/android/SDL_sysjoystick.c#l386
+	const SDL_HARDWARE_BUS_BLUETOOTH = 0x05
+
+	var sdlid [16]byte
+	sdlid[0] = byte(SDL_HARDWARE_BUS_BLUETOOTH)
+	sdlid[1] = byte(SDL_HARDWARE_BUS_BLUETOOTH >> 8)
+	if vendorID != 0 && productID != 0 {
+		sdlid[4] = byte(vendorID)
+		sdlid[5] = byte(vendorID >> 8)
+		sdlid[8] = byte(productID)
+		sdlid[9] = byte(productID >> 8)
+	} else {
+		crc := crc32.ChecksumIEEE(([]byte)(descriptor))
+		copy(sdlid[4:8], ([]byte)(descriptor))
+		sdlid[8] = byte(crc)
+		sdlid[9] = byte(crc >> 8)
+		sdlid[10] = byte(crc >> 16)
+		sdlid[11] = byte(crc >> 24)
+	}
+	sdlid[12] = byte(buttonMask)
+	sdlid[13] = byte(buttonMask >> 8)
+	sdlid[14] = byte(axisMask)
+	sdlid[15] = byte(axisMask >> 8)
+
 	id := gamepadIDFromDeviceID(deviceID)
 	gamepads[id] = &mobile.Gamepad{
 		ID:        id,
-		SDLID:     "", // TODO: Implement this
+		SDLID:     hex.EncodeToString(sdlid[:]),
 		Name:      name,
 		ButtonNum: buttonNum,
 		AxisNum:   axisNum,