Android系统输入事件产生的底层主要是输入子系统，Android 中的输入设备有很多，例如屏幕，鼠标，键盘等都是输入设备，对于应用开发者，接触最多的也就是屏幕了。
1. 当输入设备可用时，Linux会在 /dev/input 中创建对应的设备节点。
2. 用户操作输入设备就会产生各种事件，这些事件的原始信息就会被 Linux内核中的输入子系统采集，原始信息由 Kernel space 的驱动层一直传递到设备结点。
3. InputReader读取设备节点数据并对输入事件信息进行加工处理，加工处理后的事件会交给 InputDispatcher 来处理。
以下是InputReader创建InputDevice设备、读取事件和交给InputDispatcher事件的调用流程
@frameworks/native/services/inputflinger/reader/InputReader.cpp
InputReader::startloopOnce()processEventsLocked(mEventBuffer, count);case EventHubInterface::DEVICE_ADDED: addDeviceLocked(rawEvent->when, rawEvent->deviceId); //添加设备InputDeviceIdentifier identifier = mEventHub->getDeviceIdentifier(eventHubId);if(identifier.vendor == 8183 && identifier.product == 4084) { return; } //根据keyboard设备类型判断,不添加设备，以免vd启动异常std::shared_ptr<InputDevice> device = createDeviceLocked(eventHubId, identifier)
@frameworks/native/services/inputflinger/reader/InputDevice.cpp device->addEventHubDevice(eventHubId); //添加触摸光标设备if (classes.test(InputDeviceClass::BATTERY) || classes.test(InputDeviceClass::LIGHT)) { mController = std::make_unique<PeripheralController>(*contextPtr); }if (classes.test(InputDeviceClass::CURSOR)) { mappers.push_back(std::make_unique<CursorInputMapper>(*contextPtr)); }//addDeviceLocked Device added: id=3, eventHubId=8, name='hyn_ts', descriptor='dd768709fe8e1221a31cd1cbe2fb6da013ae6c46',sources=0x00002002mDevices.insert({eventHubId, std::make_pair(std::move(contextPtr), std::move(mappers))}); processEventsForDeviceLocked(deviceId, rawEvent, batchSize);auto deviceIt = mDevices.find(eventHubId);device->process(rawEvents, count);
@frameworks/native/services/inputflinger/reader/InputDevice.cppfor_each_mapper_in_subdevice(rawEvent->deviceId, [rawEvent](InputMapper& mapper)auto deviceIt = mDevices.find(eventHubDevice); //eventHubDevice=8
@frameworks/native/services/inputflinger/reader/mapper/CursorInputMapper.cpp mapper.process(rawEvent); //CursorInputMapper::processmCursorButtonAccumulator.process(rawEvent);mCursorMotionAccumulator.process(rawEvent);mCursorScrollAccumulator.process(rawEvent);sync(rawEvent->when, rawEvent->readTime);getListener()->notifyMotion(&args);InputDispatcher::notifyMotionmPolicy->interceptMotionBeforeQueueing(args->displayId, args->eventTime, /*byref*/ policyFlags);needWake = enqueueInboundEventLocked(std::move(newEntry));mInboundQueue.push_back(std::move(newEntry)); //放入mInboundQueue队列
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