android6.0 otg连接设备 点亮屏幕（案例）

现在我们otg连接设备的时候有点亮屏幕的需求。

解决方法我们可以在识别设备的时候，去调用PowerManager的wakeup唤醒(点亮）设备。

void InputReader::processEventsLocked(const RawEvent* rawEvents, size_t count) {    for (const RawEvent* rawEvent = rawEvents; count;) {        int32_t type = rawEvent->type;        size_t batchSize = 1;        if (type < EventHubInterface::FIRST_SYNTHETIC_EVENT) {            int32_t deviceId = rawEvent->deviceId;            while (batchSize < count) {                if (rawEvent[batchSize].type >= EventHubInterface::FIRST_SYNTHETIC_EVENT                        || rawEvent[batchSize].deviceId != deviceId) {                    break;                }                batchSize += 1;            }            processEventsForDeviceLocked(deviceId, rawEvent, batchSize);        } else {            switch (rawEvent->type) {            case EventHubInterface::DEVICE_ADDED:                addDeviceLocked(rawEvent->when, rawEvent->deviceId);//识别设备后添加设备到链表保存                break;            case EventHubInterface::DEVICE_REMOVED:                removeDeviceLocked(rawEvent->when, rawEvent->deviceId);                break;            case EventHubInterface::FINISHED_DEVICE_SCAN:                handleConfigurationChangedLocked(rawEvent->when);                break;            default:                ALOG_ASSERT(false); // can't happen                break;            }        }        count -= batchSize;        rawEvent += batchSize;    }}

所以我们可以在addDeviceLocked中唤醒设备

void InputReader::addDeviceLocked(nsecs_t when, int32_t deviceId) {    ssize_t deviceIndex = mDevices.indexOfKey(deviceId);    if (deviceIndex >= 0) {        ALOGW("Ignoring spurious device added event for deviceId %d.", deviceId);        return;    }    InputDeviceIdentifier identifier = mEventHub->getDeviceIdentifier(deviceId);    uint32_t classes = mEventHub->getDeviceClasses(deviceId);    int32_t controllerNumber = mEventHub->getDeviceControllerNumber(deviceId);    InputDevice* device = createDeviceLocked(deviceId, controllerNumber, identifier, classes);    device->configure(when, &mConfig, 0);    device->reset(when);    if (device->isIgnored()) {        ALOGI("Device added: id=%d, name='%s' (ignored non-input device)", deviceId,                identifier.name.string());    } else {        ALOGI("Device added: id=%d, name='%s', sources=0x%08x", deviceId,                identifier.name.string(), device->getSources());    }    //when add the device to notify wakeup device.    mPolicy->notifyWakeUpDevice(when);//这里是我们添加的用来唤醒设备    mDevices.add(deviceId, device);    bumpGenerationLocked();    if (device->getClasses() & INPUT_DEVICE_CLASS_EXTERNAL_STYLUS) {        notifyExternalStylusPresenceChanged();    }}

上面mPolicy实际上是NativeInputManager，所以调用了NativeInputManager的notifyWakeUpDevice，这个函数是我们自己添加的

//notify PhoneWindowManager to wakeup the device.void NativeInputManager::notifyWakeUpDevice(nsecs_t when) {    uint32_t policyFlags = 0;    policyFlags |= POLICY_FLAG_TRUSTED;    policyFlags |= POLICY_FLAG_WAKE;    JNIEnv* env = jniEnv();    jint wmActions = env->CallIntMethod(mServiceObj,//调用了PhoneWindowManager的interceptMotionBeforeQueueingNonInteractive                gServiceClassInfo.interceptMotionBeforeQueueingNonInteractive,                when, policyFlags);    checkAndClearExceptionFromCallback(env,                "interceptMotionBeforeQueueingNonInteractive");}

这个函数主要调用了PhoneWindowManager的interceptMotionBeforeQueueingNonInteractive函数，本来这个函数是在notfifyMotion中调用的，是有Motion事件，比如鼠标按键事件，用来唤醒(点亮）设备的我们来看下这个函数。

    @Override    public int interceptMotionBeforeQueueingNonInteractive(long whenNanos, int policyFlags) {        if ((policyFlags & FLAG_WAKE) != 0) {            if (wakeUp(whenNanos / 1000000, mAllowTheaterModeWakeFromMotion,                    "android.policy:MOTION")) {                return 0;            }        }        if (shouldDispatchInputWhenNonInteractive()) {            return ACTION_PASS_TO_USER;        }        // If we have not passed the action up and we are in theater mode without dreaming,        // there will be no dream to intercept the touch and wake into ambient.  The device should        // wake up in this case.        if (isTheaterModeEnabled() && (policyFlags & FLAG_WAKE) != 0) {            wakeUp(whenNanos / 1000000, mAllowTheaterModeWakeFromMotionWhenNotDreaming,                    "android.policy:MOTION");        }        return 0;    }

这个函数主要调用了wakeup来唤醒设备，这个wakeup最终会调用PowerManager的wakeup函数。

因此我们现在借用了原先有motion事件，用来点亮屏幕的函数。在识别设备的时候，调用这个函数也点亮屏幕。