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。