蓝牙HID——将android设备变成蓝牙鼠标/触控板（BluetoothHidDevice）

前言

本篇为蓝牙HID系列篇章之一，本篇以红米K30（MIUI13即Android 12）手机作为蓝牙HID设备，可以与电脑、手机、平板等其他蓝牙主机进行配对从而实现鼠标触控板的功能。
蓝牙HID系列篇章：
蓝牙HID——将android设备变成蓝牙键盘（BluetoothHidDevice）
蓝牙HID——android利用手机来解锁电脑/平板/iPhone
蓝牙HID——Android手机注册HID时出现 Could not bind to Bluetooth (HID Device) Service with Intent * 的问题分析

HID开发

Android 9开放了 BluetoothHidDevice 等HID相关的API，通过与系统蓝牙HID服务通信注册成蓝牙HID设备。首先通过 BluetoothProfile.HID_DEVICE 的描述类型得到 BluetoothHidDevice 抽象实例：

    private BluetoothAdapter mBtAdapter;
    private BluetoothHidDevice mHidDevice;
    
    private void callBluetooth() {
        Log.d(TAG, "callBluetooth");
        mBtAdapter = BluetoothAdapter.getDefaultAdapter();
        mBtAdapter.getProfileProxy(mContext, new BluetoothProfile.ServiceListener() {
            @Override
            public 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();
                }
            }

            @Override
            public void onServiceDisconnected(int i) {
                Log.d(TAG, "onServiceDisconnected:" + i);
            }
        }, BluetoothProfile.HID_DEVICE);
    }

再调用 BluetoothHidDevice.registerApp() 将 Android 设备注册成蓝牙HID设备：

    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() {
            @Override
            public 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);
                }
            }

            @Override
            public 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);
                }
            }
        });
    }

蓝牙鼠标Mouse的描述信息如下，主要 为 MOUSE_COMBO 的描述协议，正确的描述协议才能成功与其他设备通信。

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)
            //水平滚轮
            (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
    };

在注册完成后启动设备发现，让HID能被其他设备发现，下面ActivityResultLauncher.launch(new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE) 相当于调用 BluetoothAdapter.setScanMode() 的隐藏API

    private ActivityResultLauncher<Intent> mActivityResultLauncher;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_mouse);
      
        mActivityResultLauncher = registerForActivityResult(new ActivityResultContracts.StartActivityForResult(), result -> {
            Log.d(TAG, "onActivityResult:" + result.toString());
        });
    }

   @Override
    public 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 的相关方法也可用 startActivityForResult(new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE), REQUEST_CODE) 来替代，但 startActivityForResult() 是废弃的方法，不建议使用。
接下来与蓝牙主机（电脑、手机等）进行蓝牙配对，已配对过需要取消配对。配对完成即可实现对蓝牙主机的鼠标触摸控制。

手势识别

手势识别通过对触摸事件以及手势监听进行各种手势的判断（移动鼠标、左键单击、左键双击、右键双指单击、双指垂直/水平滚动）。

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

手势逻辑处理代码如下：

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());
    }

    @Override
    public boolean onSingleTapConfirmed(MotionEvent e) {
        return false;
    }

    @Override
    public boolean onDoubleTap(MotionEvent e) {
        return false;
    }

    @Override
    public boolean onDoubleTapEvent(MotionEvent e) {
        //左键单指双击（选中文本的效果）
        if (e.getAction() == MotionEvent.ACTION_DOWN) {
            mBluetoothHidManager.sendLeftClick(true);
        } else if (e.getAction() == MotionEvent.ACTION_UP) {
            mBluetoothHidManager.sendLeftClick(false);
        }
        return true;
    }

    @Override
    public boolean onDown(MotionEvent e) {
        return false;
    }

    @Override
    public void onShowPress(MotionEvent e) {
    }

    @Override
    public boolean onSingleTapUp(MotionEvent e) {
        //左键单击
        mBluetoothHidManager.sendLeftClick(true);
        mBluetoothHidManager.sendLeftClick(false);
        return true;
    }

    @Override
    public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
        //双指滚动，x为水平滚动，y为垂直滚动，消抖处理
        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;
    }

    @Override
    public void onLongPress(MotionEvent e) {
        //单键长按效果
        mBluetoothHidManager.sendLeftClick(true);
        mLongPress = true;
    }

    @Override
    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
        return false;
    }

    @Override
    public 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:
                //双指单击代表右键记录时间
                if (event.getPointerCount() == 2) {
                    mDoubleFingerTime = System.currentTimeMillis();
                }
                break;
            case MotionEvent.ACTION_MOVE:
                //单指代表移动鼠标
                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:
                //双指按下代表右键
                if (event.getPointerCount() == 2 && System.currentTimeMillis() - mDoubleFingerTime < ViewConfiguration.getDoubleTapTimeout()) {
                    mBluetoothHidManager.sendRightClick(true);
                    //延时释放避免无效
                    mExecutorService.scheduleWithFixedDelay(new Runnable() {
                        @Override
                        public void run() {
                            mBluetoothHidManager.sendRightClick(false);
                        }
                    }, 0, 50, TimeUnit.MILLISECONDS);                }
                break;
            default:
                break;
        }
        mPreX = x;
        mPreY = y;
        return true;
    }
}

向蓝牙主机发送的鼠标触摸按键的报告如下：

    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]字节：bit0: 1表示左键按下 0表示左键抬起 | bit1: 1表示右键按下 0表示右键抬起 | bit2: 1表示中键按下 | bit7～3：补充的常数，无意义，这里为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; //垂直滚轮
        bytes[4] = hWheel; //水平滚轮
        Log.d(TAG, "sendWheel vWheel:" + vWheel + ",hWheel：" + hWheel);
        mHidDevice.sendReport(mHostDevice, 4, bytes);
    }

效果

实现以上步骤即可将手机变成蓝牙鼠标/触控板，下面是实现的效果：

鼠标移动：

左键单击：

左键单指快速双击：

右键双指单击：

双指水平左右滚动：

双指垂直上下滚动：

完整视频效果展示：

蓝牙HID——将android设备变成蓝牙鼠标/触控板