APP获取Sensor对象-Android12

Posted 2022-07-11 xhBruce

APP获取Sensor对象-android12

android12-release

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1. getSystemService(SENSOR_SERVICE)获取服务

mSensorManager = (SensorManager)getSystemService(Context.SENSOR_SERVICE);

• 查看图片Context关联类，Activity -> ContextImpl -> SystemServiceRegistry
  
  frameworks/base/core/java/android/app/ContextImpl.java

    @Override
    public Object getSystemService(String name) 
        // ... ...
        return SystemServiceRegistry.getSystemService(this, name);
    

• 获取SensorManager子类SystemSensorManager

registerService(Context.SENSOR_SERVICE, SensorManager.class,
        new CachedServiceFetcher<SensorManager>() 
    @Override
    public SensorManager createService(ContextImpl ctx) 
        return new SystemSensorManager(ctx.getOuterContext(),
          ctx.mMainThread.getHandler().getLooper());
    );

2. getDefaultSensor(Sensor.TYPE_ACCELEROMETER) 获取Sensor对象

mAccelerometer = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);

• 最终在mFullSensorsList中找到对应Sensor

frameworks/base/core/java/android/hardware/SensorManager.java

public Sensor getDefaultSensor(int type) 
    // TODO: need to be smarter, for now, just return the 1st sensor
    List<Sensor> l = getSensorList(type);
    boolean wakeUpSensor = false;
    // ... ...


public List<Sensor> getSensorList(int type) 
    // cache the returned lists the first time
    List<Sensor> list;
    final List<Sensor> fullList = getFullSensorList();
    synchronized (mSensorListByType) 
        list = mSensorListByType.get(type);
        if (list == null) 
            if (type == Sensor.TYPE_ALL) 
                list = fullList;
             else 
                list = new ArrayList<Sensor>();
                for (Sensor i : fullList) 
                    if (i.getType() == type) 
                        list.add(i);
                    
                
            
            list = Collections.unmodifiableList(list);
            mSensorListByType.append(type, list);
        
    
    return list;

frameworks/base/core/java/android/hardware/SystemSensorManager.java

protected List<Sensor> getFullSensorList() 
    return mFullSensorsList;

---

mFullSensorsList数据

• nativeGetSensorAtIndex JNI获取SensorManager.cpp中数据mSensorList

frameworks/base/core/java/android/hardware/SystemSensorManager.java

    public SystemSensorManager(Context context, Looper mainLooper) 
        // ... ...
        // initialize the sensor list
        for (int index = 0;; ++index) 
            Sensor sensor = new Sensor();
            if (!nativeGetSensorAtIndex(mNativeInstance, sensor, index)) break;
            mFullSensorsList.add(sensor);
            mHandleToSensor.put(sensor.getHandle(), sensor);
        
    

frameworks/base/core/jni/android_hardware_SensorManager.cpp

static jboolean
nativeGetSensorAtIndex(JNIEnv *env, jclass clazz, jlong sensorManager, jobject sensor, jint index)

    SensorManager* mgr = reinterpret_cast<SensorManager*>(sensorManager);

    Sensor const* const* sensorList;
    ssize_t count = mgr->getSensorList(&sensorList);
    if (ssize_t(index) >= count) 
        return false;
    

    return translateNativeSensorToJavaSensor(env, sensor, *sensorList[index]) != NULL;

• mSensorServer->getSensorList() Binder调用，从SensorService.cpp中SensorList mSensors获取
  frameworks/native/libs/sensor/SensorManager.cpp

status_t SensorManager::assertStateLocked() 
    // ... ...
    if (initSensorManager) 
        waitForSensorService(&mSensorServer);
        LOG_ALWAYS_FATAL_IF(mSensorServer == nullptr, "getService(SensorService) NULL");
        // ... ...
        mSensors = mSensorServer->getSensorList(mOpPackageName);
        // ... ...
        for (size_t i=0 ; i<count ; i++) 
            mSensorList[i] = mSensors.array() + i;
        
    

    return NO_ERROR;


ssize_t SensorManager::getSensorList(Sensor const* const** list) 
    Mutex::Autolock _l(mLock);
    status_t err = assertStateLocked();
    if (err < 0) 
        return static_cast<ssize_t>(err);
    
    *list = mSensorList;
    return static_cast<ssize_t>(mSensors.size());

frameworks/native/services/sensorservice/SensorService.cpp

Vector<Sensor> SensorService::getSensorList(const String16& opPackageName) 
    char value[PROPERTY_VALUE_MAX];
    property_get("debug.sensors", value, "0");
    const Vector<Sensor>& initialSensorList = (atoi(value)) ?
            mSensors.getUserDebugSensors() : mSensors.getUserSensors();
    // ... ...

SensorList mSensors

SensorService启动-Android12 过程 registerSensor() 注册时添加，包含HardwareSensor、VirtualSensor

const Sensor& SensorService::registerSensor(SensorInterface* s, bool isDebug, bool isVirtual) 
    int handle = s->getSensor().getHandle();
    int type = s->getSensor().getType();
    if (mSensors.add(handle, s, isDebug, isVirtual))
        mRecentEvent.emplace(handle, new SensorServiceUtil::RecentEventLogger(type));
        return s->getSensor();
     else 
        return mSensors.getNonSensor();
    

frameworks/native/services/sensorservice/SensorList.cpp

bool SensorList::add(
        int handle, SensorInterface* si, bool isForDebug, bool isVirtual) 
    std::lock_guard<std::mutex> lk(mLock);
    if (handle == si->getSensor().getHandle() &&
        mUsedHandle.insert(handle).second) 
        // will succeed as the mUsedHandle does not have this handle
        mHandleMap.emplace(handle, Entry(si, isForDebug, isVirtual));
        return true;
    
    // handle exist already or handle mismatch
    return false;

3. HardwareSensor相关

frameworks/native/services/sensorservice/SensorInterface.h
frameworks/native/services/sensorservice/SensorInterface.cpp
frameworks/native/libs/sensor/include/sensor/Sensor.h
frameworks/native/libs/sensor/Sensor.cpp

Sensor::Sensor(struct sensor_t const& hwSensor, const uuid_t& uuid, int halVersion) :
        Sensor("") 
    mName = hwSensor.name;
    mVendor = hwSensor.vendor;
    mVersion = hwSensor.version;
    mHandle = hwSensor.handle;
    mType = hwSensor.type;
    mMinValue = 0;                      // FIXME: minValue
    mMaxValue = hwSensor.maxRange;      // FIXME: maxValue
    mResolution = hwSensor.resolution;
    mPower = hwSensor.power;
    mMinDelay = hwSensor.minDelay;
    mFlags = 0;
    mUuid = uuid;
    // ... ...

3.1 HAL 硬件接口 sensor_t

# 常用设备HAL标准接口的头文件
hardware/libhardware/include/hardware
# 常用设备HAL标准接口实现
hardware/libhardware/modules/

hardware/libhardware/include/hardware/sensors.h

struct sensor_t 
    // ... ...
    /* this sensor's type. */
    int             type;
    // ... ...
;

4. VirtualSensor相关

frameworks/native/services/sensorservice/SensorInterface.h
frameworks/native/services/sensorservice/SensorInterface.cpp
frameworks/native/services/sensorservice/OrientationSensor.h
frameworks/native/services/sensorservice/OrientationSensor.cpp
例如SENSOR_TYPE_ORIENTATION

OrientationSensor::OrientationSensor() 
    const sensor_t sensor = 
        .name       = "Orientation Sensor",
        .vendor     = "AOSP",
        .version    = 1,
        .handle     = '_ypr',
        .type       = SENSOR_TYPE_ORIENTATION,
        .maxRange   = 360.0f,
        .resolution = 1.0f/256.0f, // FIXME: real value here
        .power      = mSensorFusion.getPowerUsage(),
        .minDelay   = mSensorFusion.getMinDelay(),
    ;
    mSensor = Sensor(&sensor);

时序图