藍牙HID——將android設備變成藍牙鼠標-觸控板（BluetoothHidDevice）

前言

本篇為藍牙HID系列篇章之一，本篇以紅米K30（MIUI13即Android 12）手機作為藍牙HID設備，可以與電腦、手機、平板等其他藍牙主機進行配對從而實現鼠標觸控板的功能。
藍牙HID系列篇章：
藍牙HID——將android設備變成藍牙鍵盤（BluetoothHidDevice）
藍牙HID——android利用手機來解鎖電腦/平板/iPhone
藍牙HID——Android手機注冊HID時出現 Could not bind to Bluetooth (HID Device) Service with Intent * 的問題分析

HID開發

Android 9開放了 BluetoothHidDevice 等HID相關的API，通過與系統藍牙HID服務通信注冊成藍牙HID設備。首先通過 BluetoothProfile.HID_DEVICE 的描述類型得到 BluetoothHidDevice 抽象實例：

private BluetoothAdapter mBtAdapter;private BluetoothHidDevice mHidDevice;private void callBluetooth() {Log.d(TAG, "callBluetooth");mBtAdapter = BluetoothAdapter.getDefaultAdapter();mBtAdapter.getProfileProxy(mContext, new BluetoothProfile.ServiceListener() {@Overridepublic void onServiceConnected(int i, BluetoothProfile bluetoothProfile) {Log.d(TAG, "onServiceConnected:" + i);if (i == BluetoothProfile.HID_DEVICE) {if (!(bluetoothProfile instanceof BluetoothHidDevice)) {Log.e(TAG, "Proxy received but it's not BluetoothHidDevice");return;}mHidDevice = (BluetoothHidDevice) bluetoothProfile;registerBluetoothHid();}}@Overridepublic void onServiceDisconnected(int i) {Log.d(TAG, "onServiceDisconnected:" + i);}}, BluetoothProfile.HID_DEVICE);}

再調用 BluetoothHidDevice.registerApp() 將 Android 設備注冊成藍牙HID設備：

private BluetoothDevice mHostDevice;private final BluetoothHidDeviceAppQosSettings qosSettings= new BluetoothHidDeviceAppQosSettings(BluetoothHidDeviceAppQosSettings.SERVICE_BEST_EFFORT,800, 9, 0, 11250, BluetoothHidDeviceAppQosSettings.MAX);private final BluetoothHidDeviceAppSdpSettings mouseSdpSettings = new BluetoothHidDeviceAppSdpSettings(HidConfig.MOUSE_NAME, HidConfig.DESCRIPTION, HidConfig.PROVIDER,BluetoothHidDevice.SUBCLASS1_MOUSE, HidConfig.MOUSE_COMBO);private void registerBluetoothHid() {if (mHidDevice == null) {Log.e(TAG, "hid device is null");return;}mHidDevice.registerApp(mouseSdpSettings, null, qosSettings, Executors.newCachedThreadPool(), new BluetoothHidDevice.Callback() {@Overridepublic void onAppStatusChanged(BluetoothDevice pluggedDevice, boolean registered) {Log.d(TAG, "onAppStatusChanged:" + (pluggedDevice != null ? pluggedDevice.getName() : "null") + " registered:" + registered);if (registered) {Log.d(TAG, "paired devices: " + mHidDevice.getConnectionState(pluggedDevice));if (pluggedDevice != null && mHidDevice.getConnectionState(pluggedDevice) != BluetoothProfile.STATE_CONNECTED) {boolean result = mHidDevice.connect(pluggedDevice);Log.d(TAG, "hidDevice connect:" + result);}}if (mBluetoothHidStateListener != null) {mBluetoothHidStateListener.onRegisterStateChanged(registered, pluggedDevice != null);}}@Overridepublic void onConnectionStateChanged(BluetoothDevice device, int state) {Log.d(TAG, "onConnectionStateChanged:" + device + " state:" + state);if (state == BluetoothProfile.STATE_CONNECTED) {mHostDevice = device;}if (state == BluetoothProfile.STATE_DISCONNECTED) {mHostDevice = null;}if (mBluetoothHidStateListener != null) {mBluetoothHidStateListener.onConnectionStateChanged(state);}}});}

藍牙鼠標Mouse的描述信息如下，主要 為 MOUSE_COMBO 的描述協議，正確的描述協議才能成功與其他設備通信。

public class HidConfig {public final static String MOUSE_NAME = "VV Mouse";public final static String DESCRIPTION = "VV for you";public final static String PROVIDER = "VV";public static final byte[] MOUSE_COMBO = {(byte) 0x05, (byte) 0x01, // USAGE_PAGE (Generic Desktop)(byte) 0x09, (byte) 0x02, // USAGE (Mouse)(byte) 0xa1, (byte) 0x01, // COLLECTION (Application)(byte) 0x85, (byte) 0x04, // REPORT_ID (4)(byte) 0x09, (byte) 0x01, // USAGE (Pointer)(byte) 0xa1, (byte) 0x00, // COLLECTION (Physical)(byte) 0x05, (byte) 0x09, // USAGE_PAGE (Button)(byte) 0x19, (byte) 0x01, // USAGE_MINIMUM (Button 1)(byte) 0x29, (byte) 0x02, // USAGE_MAXIMUM (Button 2)(byte) 0x15, (byte) 0x00, // LOGICAL_MINIMUM (0)(byte) 0x25, (byte) 0x01, // LOGICAL_MAXIMUM (1)(byte) 0x95, (byte) 0x03, // REPORT_COUNT (3)(byte) 0x75, (byte) 0x01, // REPORT_SIZE (1)(byte) 0x81, (byte) 0x02, // INPUT (Data,Var,Abs)(byte) 0x95, (byte) 0x01, // REPORT_COUNT (1)(byte) 0x75, (byte) 0x05, // REPORT_SIZE (5)(byte) 0x81, (byte) 0x03, // INPUT (Cnst,Var,Abs)(byte) 0x05, (byte) 0x01, // USAGE_PAGE (Generic Desktop)(byte) 0x09, (byte) 0x30, // USAGE (X)(byte) 0x09, (byte) 0x31, // USAGE (Y)(byte) 0x09, (byte) 0x38, // USAGE (Wheel)(byte) 0x15, (byte) 0x81, // LOGICAL_MINIMUM (-127)(byte) 0x25, (byte) 0x7F, // LOGICAL_MAXIMUM (127)(byte) 0x75, (byte) 0x08, // REPORT_SIZE (8)(byte) 0x95, (byte) 0x03, // REPORT_COUNT (3)(byte) 0x81, (byte) 0x06, // INPUT (Data,Var,Rel)//水平滾輪(byte) 0x05, (byte) 0x0c, // USAGE_PAGE (Consumer Devices)(byte) 0x0a, (byte) 0x38, (byte) 0x02, // USAGE (AC Pan)(byte) 0x15, (byte) 0x81, // LOGICAL_MINIMUM (-127)(byte) 0x25, (byte) 0x7f, // LOGICAL_MAXIMUM (127)(byte) 0x75, (byte) 0x08, // REPORT_SIZE (8)(byte) 0x95, (byte) 0x01, // REPORT_COUNT (1)(byte) 0x81, (byte) 0x06, // INPUT (Data,Var,Rel)(byte) 0xc0, // END_COLLECTION(byte) 0xc0, // END_COLLECTION};

在注冊完成后啟動設備發現，讓HID能被其他設備發現，下面ActivityResultLauncher.launch(new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE) 相當于調用 BluetoothAdapter.setScanMode() 的隱藏API

private ActivityResultLauncher<Intent> mActivityResultLauncher;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_mouse);mActivityResultLauncher = registerForActivityResult(new ActivityResultContracts.StartActivityForResult(), result -> {Log.d(TAG, "onActivityResult:" + result.toString());});}@Overridepublic void onRegisterStateChanged(boolean registered, boolean hasDevice) {if (registered) {if (!hasDevice) {// startActivityForResult(new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE), 1);mActivityResultLauncher.launch(new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE));}}}

ActivityResultLauncher 的相關方法也可用 startActivityForResult(new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE), REQUEST_CODE) 來替代，但 startActivityForResult() 是廢棄的方法，不建議使用。
接下來與藍牙主機（電腦、手機等）進行藍牙配對，已配對過需要取消配對。配對完成即可實現對藍牙主機的鼠標觸摸控制。

手勢識別

手勢識別通過對觸摸事件以及手勢監聽進行各種手勢的判斷（移動鼠標、左鍵單擊、左鍵雙擊、右鍵雙指單擊、雙指垂直/水平滾動）。

CustomMotionListener customMotionListener = new CustomMotionListener(this, mBluetoothHidManager); findViewById(R.id.layout_touch).setOnTouchListener(customMotionListener);

手勢邏輯處理代碼如下：

package com.example.bluetoothproject;import android.content.Context; import android.view.GestureDetector; import android.view.MotionEvent; import android.view.View; import android.view.ViewConfiguration;import org.apache.commons.lang3.concurrent.BasicThreadFactory;import java.util.concurrent.ScheduledExecutorService; import java.util.concurrent.ScheduledThreadPoolExecutor; import java.util.concurrent.TimeUnit;public class CustomMotionListener implements View.OnTouchListener, GestureDetector.OnGestureListener, GestureDetector.OnDoubleTapListener {private final GestureDetector mGestureDetector;private BluetoothHidManager mBluetoothHidManager;private int mPointCount;private long mDoubleFingerTime;private final ScheduledExecutorService mExecutorService;private float mPreX;private float mPreY;private boolean mLongPress;public CustomMotionListener(Context context, BluetoothHidManager bluetoothHidManager) {mBluetoothHidManager = bluetoothHidManager;mGestureDetector = new GestureDetector(context, this);mGestureDetector.setOnDoubleTapListener(this);mExecutorService = new ScheduledThreadPoolExecutor(1,new BasicThreadFactory.Builder().namingPattern("mouse-schedule-pool-%d").daemon(true).build());}@Overridepublic boolean onSingleTapConfirmed(MotionEvent e) {return false;}@Overridepublic boolean onDoubleTap(MotionEvent e) {return false;}@Overridepublic boolean onDoubleTapEvent(MotionEvent e) {//左鍵單指雙擊（選中文本的效果）if (e.getAction() == MotionEvent.ACTION_DOWN) {mBluetoothHidManager.sendLeftClick(true);} else if (e.getAction() == MotionEvent.ACTION_UP) {mBluetoothHidManager.sendLeftClick(false);}return true;}@Overridepublic boolean onDown(MotionEvent e) {return false;}@Overridepublic void onShowPress(MotionEvent e) {}@Overridepublic boolean onSingleTapUp(MotionEvent e) {//左鍵單擊mBluetoothHidManager.sendLeftClick(true);mBluetoothHidManager.sendLeftClick(false);return true;}@Overridepublic boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {//雙指滾動，x為水平滾動，y為垂直滾動，消抖處理if (mPointCount == 2) {if (Math.abs(distanceX) > Math.abs(distanceY)) {distanceX = distanceX > 0 ? 1 : distanceX < 0 ? -1 : 0;distanceY = 0;} else {distanceY = distanceY > 0 ? -1 : distanceY < 0 ? 1 : 0;distanceX = 0;}mBluetoothHidManager.sendWheel((byte) (distanceX), (byte) (distanceY));}return false;}@Overridepublic void onLongPress(MotionEvent e) {//單鍵長按效果mBluetoothHidManager.sendLeftClick(true);mLongPress = true;}@Overridepublic boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {return false;}@Overridepublic boolean onTouch(View v, MotionEvent event) {float x = event.getX();float y = event.getY();if (mGestureDetector.onTouchEvent(event)) {return true;}mPointCount = event.getPointerCount();switch (event.getActionMasked()) {case MotionEvent.ACTION_POINTER_DOWN://雙指單擊代表右鍵記錄時間if (event.getPointerCount() == 2) {mDoubleFingerTime = System.currentTimeMillis();}break;case MotionEvent.ACTION_MOVE://單指代表移動鼠標if (event.getPointerCount() == 1) {float dx = x - mPreX;if (dx > 127) dx = 127;if (dx < -128) dx = -128;float dy = y - mPreY;if (dy > 127) dy = 127;if (dy < -128) dy = -128;mBluetoothHidManager.senMouse((byte) dx, (byte) dy);} else {mBluetoothHidManager.senMouse((byte) 0, (byte) 0);}break;case MotionEvent.ACTION_UP:if (mLongPress) {mBluetoothHidManager.sendLeftClick(false);mLongPress = false;}break;case MotionEvent.ACTION_POINTER_UP://雙指按下代表右鍵if (event.getPointerCount() == 2 && System.currentTimeMillis() - mDoubleFingerTime < ViewConfiguration.getDoubleTapTimeout()) {mBluetoothHidManager.sendRightClick(true);//延時釋放避免無效mExecutorService.scheduleWithFixedDelay(new Runnable() {@Overridepublic void run() {mBluetoothHidManager.sendRightClick(false);}}, 0, 50, TimeUnit.MILLISECONDS); }break;default:break;}mPreX = x;mPreY = y;return true;} }

向藍牙主機發送的鼠標觸摸按鍵的報告如下：

private boolean mLeftClick;private boolean mRightClick;public void sendLeftClick(boolean click) {mLeftClick = click;senMouse((byte) 0x00, (byte) 0x00);}public void sendRightClick(boolean click) {mRightClick = click;senMouse((byte) 0x00, (byte) 0x00);}public void senMouse(byte dx, byte dy) {if (mHidDevice == null) {Log.e(TAG, "senMouse failed, hid device is null!");return;}if (mHostDevice == null) {Log.e(TAG, "senMouse failed, hid device is not connected!");return;}byte[] bytes = new byte[5];//bytes[0]字節：bit0: 1表示左鍵按下 0表示左鍵抬起 | bit1: 1表示右鍵按下 0表示右鍵抬起 | bit2: 1表示中鍵按下 | bit7～3：補充的常數，無意義，這里為0即可bytes[0] = (byte) (bytes[0] | (mLeftClick ? 1 : 0));bytes[0] = (byte) (bytes[0] | (mRightClick ? 1 : 0) << 1);bytes[1] = dx;bytes[2] = dy;Log.d(TAG, "senMouse Left:" + mLeftClick+ ",Right:" + mRightClick + ",bytes: " + BluetoothUtils.bytesToHexString(bytes));mHidDevice.sendReport(mHostDevice, 4, bytes);}public void sendWheel(byte hWheel, byte vWheel) {if (mHidDevice == null) {Log.e(TAG, "sendWheel failed, hid device is null!");return;}if (mHostDevice == null) {Log.e(TAG, "sendWheel failed, hid device is not connected!");return;}byte[] bytes = new byte[5];bytes[3] = vWheel; //垂直滾輪bytes[4] = hWheel; //水平滾輪Log.d(TAG, "sendWheel vWheel:" + vWheel + ",hWheel：" + hWheel);mHidDevice.sendReport(mHostDevice, 4, bytes);}

效果

實現以上步驟即可將手機變成藍牙鼠標/觸控板，下面是實現的效果：

鼠標移動：

左鍵單擊：

左鍵單指快速雙擊：

右鍵雙指單擊：

雙指垂直上下滾動：

雙指水平左右滾動：

完整視頻效果展示：

藍牙HID——將android設備變成藍牙鼠標/觸控板