目录
2.3 Hid report description描述符生成工具
一，背景介绍
日常生活中，各种物理遥控器和鼠标等设备，需要摆放和携带，便捷性有待考验。根据蓝牙HID特性，可以用蓝牙协议模仿鼠标事件，来实现空中鼠标等功能。
二，技术方案
自Android 9开放BluetoothHidDevice功能后，Android平台可以很简单的通过BluetoothHidDevice模拟键盘鼠标等蓝牙hid device角色。
2.1 获取BluetoothHidDevice实例
BluetoothAdapter bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
bluetoothAdapter.setName("MOUSE BT");
bluetoothAdapter.getProfileProxy(context,mProfileServiceListener,BluetoothProfile.HID_DEVICE);2.2 注册/解除注册HID实例
public static BluetoothProfile.ServiceListener mProfileServiceListener = new BluetoothProfile.ServiceListener() {
@Override
public void onServiceDisconnected(int profile) {
Log.e(TAG, "hid onServiceDisconnected");
if (profile == BluetoothProfile.HID_DEVICE) {
mHidDevice.unregisterApp();
}
}
@SuppressLint("NewApi")
@Override
public void onServiceConnected(int profile, BluetoothProfile proxy) {
Log.e(TAG, "hid onServiceConnected");
bluetoothProfile = proxy;
if (profile == BluetoothProfile.HID_DEVICE) {
mHidDevice = (BluetoothHidDevice) proxy;
HidConsts.HidDevice = mHidDevice;
BluetoothHidDeviceAppSdpSettings sdp = new BluetoothHidDeviceAppSdpSettings(HidConsts.NAME, HidConsts.DESCRIPTION, HidConsts.PROVIDER, BluetoothHidDevice.SUBCLASS1_COMBO, HidConsts.Descriptor);
mHidDevice.registerApp(sdp, null, null, Executors.newCachedThreadPool(), mCallback);
}
}
};在获取到BluetoothHidDevice实例后通过registerApp注册hid device，此时hid host角色会被禁用，因此在不需要hid device功能时要及时解除hid device的注册。
registerApp函数中最重要的一个参数BluetoothHidDeviceAppSdpSettings，主要是给对端host提供hid device角色的名称，描述信息，供应商信息，以及Hid device的Reports Descriptor。
2.3 Hid report description描述符生成工具
参考文章《官网HID描述符工具》
public class HidConfig {
public final static String NAME = "My Keyboard";
public final static String DESCRIPTION = "Lgd's Keyboard";
public final static String PROVIDER = "Lgd";
public static final byte[] KEYBOARD_DESCRIPTOR =
{
(byte) 0x05, (byte) 0x01, // USAGE_PAGE (Generic Desktop)
(byte) 0x09, (byte) 0x06, // USAGE (Keyboard)
(byte) 0xa1, (byte) 0x01, // COLLECTION (Application)
(byte) 0x85, (byte) 0x02, //REPORT_ID (2)
(byte) 0x05, (byte) 0x07, // USAGE_PAGE (Keyboard)
(byte) 0x19, (byte) 0xe0, // USAGE_MINIMUM (Keyboard LeftControl)
(byte) 0x29, (byte) 0xe7, // USAGE_MAXIMUM (Keyboard Right GUI)
(byte) 0x15, (byte) 0x00, // LOGICAL_MINIMUM (0)
(byte) 0x25, (byte) 0x01, // LOGICAL_MAXIMUM (1)
(byte) 0x75, (byte) 0x01, // REPORT_SIZE (1)
(byte) 0x95, (byte) 0x08, // REPORT_COUNT (8)
(byte) 0x81, (byte) 0x02, // INPUT (Data,Var,Abs)
(byte) 0x95, (byte) 0x01, // REPORT_COUNT (1)
(byte) 0x75, (byte) 0x08, // REPORT_SIZE (8)
(byte) 0x81, (byte) 0x03, // INPUT (Cnst,Var,Abs)
(byte) 0x95, (byte) 0x05, // REPORT_COUNT (5)
(byte) 0x75, (byte) 0x01, // REPORT_SIZE (1)
(byte) 0x05, (byte) 0x08, // USAGE_PAGE (LEDs)
(byte) 0x19, (byte) 0x01, // USAGE_MINIMUM (Num Lock)
(byte) 0x29, (byte) 0x05, // USAGE_MAXIMUM (Kana)
(byte) 0x91, (byte) 0x02, // OUTPUT (Data,Var,Abs)
(byte) 0x95, (byte) 0x01, // REPORT_COUNT (1)
(byte) 0x75, (byte) 0x03, // REPORT_SIZE (3)
(byte) 0x91, (byte) 0x03, // OUTPUT (Cnst,Var,Abs)
(byte) 0x95, (byte) 0x06, // REPORT_COUNT (6)
(byte) 0x75, (byte) 0x08, // REPORT_SIZE (8)
(byte) 0x15, (byte) 0x00, // LOGICAL_MINIMUM (0)
(byte) 0x25, (byte) 0x65, // LOGICAL_MAXIMUM (101)
(byte) 0x05, (byte) 0x07, // USAGE_PAGE (Keyboard)
(byte) 0x19, (byte) 0x00, // USAGE_MINIMUM (Reserved (no event indicated))
(byte) 0x29, (byte) 0x65, // USAGE_MAXIMUM (Keyboard Application)
(byte) 0x81, (byte) 0x00, // INPUT (Data,Ary,Abs)
(byte) 0xc0 // END_COLLECTION
};
}
上面的描述符只是适配键盘，可以不定义report id，如果是多个hid功能复合的设备，例如复合键盘鼠标，就需要再添加鼠标的报告描述符，同时每个功能都需要有对应的report id。
0x05, 0x01, // USAGE_PAGE (Generic Desktop)
0x09, 0x02, // USAGE (Mouse)
0xa1, 0x01, // COLLECTION (Application)
0x85, 0x01, // REPORT_ID (1)
0x75, 0x10, // REPORT_SIZE (16)
0x95, 0x01, // REPORT_COUNT (1)
0x15, 0x0b, // LOGICAL_MINIMUM (11)
0x25, 0x1c, // LOGICAL_MAXIMUM (28)
0x09, 0x30, // USAGE (X)
0x81, 0x22, // INPUT (Data,Var,Abs,NPrf)
0xc0, // END_COLLECTION
0x09, 0x06, // USAGE (Keyboard)
0xa1, 0x01, // COLLECTION (Application)
0x85, 0x02, // REPORT_ID (2)
0x75, 0x08, // REPORT_SIZE (8)
0x95, 0x01, // REPORT_COUNT (1)
0x15, 0x00, // LOGICAL_MINIMUM (0)
0x25, 0x40, // LOGICAL_MAXIMUM (64)
0x09, 0x31, // USAGE (Y)
0x81, 0x02, // INPUT (Data,Var,Abs)
0xc0
2.4 通过sendReport想host发送按键信息
第二个参数是report description中定义的report id，如果没有定义传入0。
第三个参数是按键数据，根据report description，总共有8字节，前2字节是功能键，后6字节是对应的键值信息
mHidDevice.sendReport(device, 2, new byte[]{0, 0, (byte) code, 0, 0, 0, 0, 0});