Event分发源码分析(五)

4,分发Event

4.1 System分发

流程长而杂,仅分析关键点,

dispatchOnceInnerLocked方法首先从mInboundQueue中取出KeyEntry,然后根据不同类型的KeyEntry分别进行处理。

void InputDispatcher::dispatchOnceInnerLocked(nsecs_t* nextWakeupTime) {•••mPendingEvent = mInboundQueue.dequeueAtHead();•••switch (mPendingEvent->type) {    case EventEntry::TYPE_CONFIGURATION_CHANGED: {        ConfigurationChangedEntry* typedEntry =                static_cast<ConfigurationChangedEntry*>(mPendingEvent);        done = dispatchConfigurationChangedLocked(currentTime, typedEntry);        dropReason = DROP_REASON_NOT_DROPPED; // configuration changes are never dropped        break;    }    case EventEntry::TYPE_DEVICE_RESET: {        DeviceResetEntry* typedEntry =                static_cast<DeviceResetEntry*>(mPendingEvent);        done = dispatchDeviceResetLocked(currentTime, typedEntry);        dropReason = DROP_REASON_NOT_DROPPED; // device resets are never dropped        break;    }    case EventEntry::TYPE_KEY: {        KeyEntry* typedEntry = static_cast<KeyEntry*>(mPendingEvent);        if (isAppSwitchDue) {            if (isAppSwitchKeyEventLocked(typedEntry)) {                resetPendingAppSwitchLocked(true);                isAppSwitchDue = false;            } else if (dropReason == DROP_REASON_NOT_DROPPED) {                dropReason = DROP_REASON_APP_SWITCH;            }        }        if (dropReason == DROP_REASON_NOT_DROPPED                && isStaleEventLocked(currentTime, typedEntry)) {            dropReason = DROP_REASON_STALE;        }        if (dropReason == DROP_REASON_NOT_DROPPED && mNextUnblockedEvent) {            dropReason = DROP_REASON_BLOCKED;        }        done = dispatchKeyLocked(currentTime, typedEntry, &dropReason, nextWakeupTime);        break;    }    case EventEntry::TYPE_MOTION: {        MotionEntry* typedEntry = static_cast<MotionEntry*>(mPendingEvent);        if (dropReason == DROP_REASON_NOT_DROPPED && isAppSwitchDue) {            dropReason = DROP_REASON_APP_SWITCH;        }        if (dropReason == DROP_REASON_NOT_DROPPED                && isStaleEventLocked(currentTime, typedEntry)) {            dropReason = DROP_REASON_STALE;        }        if (dropReason == DROP_REASON_NOT_DROPPED && mNextUnblockedEvent) {            dropReason = DROP_REASON_BLOCKED;        }        done = dispatchMotionLocked(currentTime, typedEntry,                &dropReason, nextWakeupTime);        break;}•••}

void InputDispatcher::startDispatchCycleLocked(nsecs_t currentTime,        const sp<Connection>& connection) {•••switch (eventEntry->type) {        case EventEntry::TYPE_KEY: {            KeyEntry* keyEntry = static_cast<KeyEntry*>(eventEntry);            // Publish the key event.            status = connection->inputPublisher.publishKeyEvent(dispatchEntry->seq,                    keyEntry->deviceId, keyEntry->source,                    dispatchEntry->resolvedAction, dispatchEntry->resolvedFlags,                    keyEntry->keyCode, keyEntry->scanCode,                    keyEntry->metaState, keyEntry->repeatCount, keyEntry->downTime,                    keyEntry->eventTime);            break;        }case EventEntry::TYPE_MOTION: { •••status = connection->inputPublisher.publishMotionEvent(dispatchEntry->seq,                    motionEntry->deviceId, motionEntry->source,                    dispatchEntry->resolvedAction, motionEntry->actionButton,                    dispatchEntry->resolvedFlags, motionEntry->edgeFlags,                    motionEntry->metaState, motionEntry->buttonState,                    xOffset, yOffset, motionEntry->xPrecision, motionEntry->yPrecision,                    motionEntry->downTime, motionEntry->eventTime,                    motionEntry->pointerCount, motionEntry->pointerProperties,                    usingCoords);            break;•••}

直接看最后的sendMessage方法,

status_t InputChannel::sendMessage(const InputMessage* msg) {    size_t msgLength = msg->size();    ssize_t nWrite;    do {        nWrite = ::send(mFd, msg, msgLength, MSG_DONTWAIT | MSG_NOSIGNAL);} while (nWrite == -1 && errno == EINTR);•••}

sendMessage方法调用系统的send()方法来发送输入消息,这样输入消息就通过socket从SystemServer进程传输到应用进程中了,那么应用进程在哪儿接收呢?

4.2 System分发原理

startDispatchCycleLocked根据方法的不同分别调用publishKeyEvent和publishMotionEvent方法,那么是谁的方法呢?  首先得弄清楚connection是什么对象,慢慢往回查看。

Connection 对象是dispatchEventLocked方法中获取的,

sp<Connection> connection = mConnectionsByFd.valueAt(connectionIndex);            prepareDispatchCycleLocked(currentTime, connection, eventEntry, &inputTarget);

mConnectionsByFd只是一个Connection数组,什么时候添加Connection呢?

KeyedVector<int, sp<Connection> > mConnectionsByFd;

sp<Connection> connection = new Connection(inputChannel, inputWindowHandle, monitor);        int fd = inputChannel->getFd();        mConnectionsByFd.add(fd, connection);

现在确定了 connection 就是Connection对象。

InputPublisher inputPublisher;

inputPublisher 只是Connection 类中的一个变量。

Connection 是 InputDispatcher.h 中的内部类,而InputPublisher 是InputTransport.h 中的内部类,这扯着有点远。

还是顺藤摸瓜, 首先看InputDispatcher.cpp 中Connection 的构造函数,

InputDispatcher::Connection::Connection(const sp<InputChannel>& inputChannel,        const sp<InputWindowHandle>& inputWindowHandle, bool monitor) :        status(STATUS_NORMAL), inputChannel(inputChannel), inputWindowHandle(inputWindowHandle),        monitor(monitor),        inputPublisher(inputChannel), inputPublisherBlocked(false) {}

Connection 构造函数中又调用了inputPublisher的构造函数,

InputPublisher::InputPublisher(const sp<InputChannel>& channel) :        mChannel(channel) {}

sp<InputChannel> mChannel;

mChannel只是InputPublisher的一个变量,至此,我们总算知道到底调用谁的publishKeyEvent和publishMotionEvent方法了, 非InputPublisher莫属。

   先暂停一下,那么registerInputChannel是如何调用的呢?完整的流程图如下:

IMS中registerInputChannel方法如下,

public void registerInputChannel(InputChannel inputChannel,            InputWindowHandle inputWindowHandle) {        if (inputChannel == null) {            throw new IllegalArgumentException("inputChannel must not be null.");        }        nativeRegisterInputChannel(mPtr, inputChannel, inputWindowHandle, false);    }

还有monitorInput方法,

public InputChannel monitorInput(String inputChannelName) { // 显示器        if (inputChannelName == null) {            throw new IllegalArgumentException("inputChannelName must not be null.");        }        InputChannel[] inputChannels = InputChannel.openInputChannelPair(inputChannelName);        nativeRegisterInputChannel(mPtr, inputChannels[0], null, true);        inputChannels[0].dispose(); // don't need to retain the Java object reference        return inputChannels[1];    }

在nativeRegisterInputChannel方法中,

static void nativeRegisterInputChannel(JNIEnv* env, jclass /* clazz */,        jlong ptr, jobject inputChannelObj, jobject inputWindowHandleObj, jboolean monitor) {    NativeInputManager* im = reinterpret_cast<NativeInputManager*>(ptr);    sp<InputChannel> inputChannel = android_view_InputChannel_getInputChannel(env,            inputChannelObj);    if (inputChannel == NULL) {        throwInputChannelNotInitialized(env);        return;    }    sp<InputWindowHandle> inputWindowHandle =            android_server_InputWindowHandle_getHandle(env, inputWindowHandleObj);    status_t status = im->registerInputChannel(            env, inputChannel, inputWindowHandle, monitor);    if (status) {        String8 message;        message.appendFormat("Failed to register input channel.  status=%d", status);        jniThrowRuntimeException(env, message.string());        return;    }    if (! monitor) {        android_view_InputChannel_setDisposeCallback(env, inputChannelObj,                handleInputChannelDisposed, im);    }}

看到了吧,将Java层的InputChannel, InputWindowHandle分别和C/C++层的NativeInputChannel等相对应。

sp<InputChannel> android_view_InputChannel_getInputChannel(JNIEnv* env, jobject inputChannelObj) {    NativeInputChannel* nativeInputChannel =            android_view_InputChannel_getNativeInputChannel(env, inputChannelObj);    return nativeInputChannel != NULL ? nativeInputChannel->getInputChannel() : NULL;}

static NativeInputChannel* android_view_InputChannel_getNativeInputChannel(JNIEnv* env,        jobject inputChannelObj) {    jlong longPtr = env->GetLongField(inputChannelObj, gInputChannelClassInfo.mPtr);    return reinterpret_cast<NativeInputChannel*>(longPtr);}

首先利用本java层的InputChannel 创建NativeInputChannel,然后返回其内部变量InputChannel,这个有点绕。

C/C++层的 InputChannel类是InputTransport.cpp的一个内部类。

现在的问题有2个,

1, registerInputChannel/ monitorInput一般什么时候调用?

2, InputChannel 还未露出真身。