Android事件的产生和底层分发

目录

事件的产生

系统分发

EventHub

InputReader

InputDispatcher

接收事件

---

事件的产生

当屏幕被触摸，Linux内核会将硬件产生的触摸事件包装为Event存到/dev/input/event[x]目录下。

可以通过命令监控event

adb shell getevent

androidSource/system/core/toolbox目录下的getevent.c和sendevent.c是解析的实现

系统分发

EventHub

文件在frameworks/native/services/inputflinger/EventHub.cpp

EventHub主要是访问/dev/input下的所有设备节点，并将输入事件、设备节点的增删返给InputReader

InputReader

文件在frameworks/native/services/inputflinger/InputReader.cpp

void InputReader::loopOnce() {
    int32_t oldGeneration;
    int32_t timeoutMillis;
    bool inputDevicesChanged = false;
    Vector inputDevices;
    { // acquire lock
        AutoMutex _l(mLock);
        oldGeneration = mGeneration;
        timeoutMillis = -1;
        uint32_t changes = mConfigurationChangesToRefresh;
        if (changes) {
            mConfigurationChangesToRefresh = 0;
            timeoutMillis = 0;
            refreshConfigurationLocked(changes);
        } else if (mNextTimeout != LLONG_MAX) {
            nsecs_t now = systemTime(SYSTEM_TIME_MONOTONIC);
            timeoutMillis = toMillisecondTimeoutDelay(now, mNextTimeout);
        }
    } // release lock
    size_t count = mEventHub->getEvents(timeoutMillis, mEventBuffer, EVENT_BUFFER_SIZE);
    { // acquire lock
        AutoMutex _l(mLock);
        mReaderIsAliveCondition.broadcast();
        if (count) {
            processEventsLocked(mEventBuffer, count);
        }
        if (mNextTimeout != LLONG_MAX) {
            nsecs_t now = systemTime(SYSTEM_TIME_MONOTONIC);
            if (now >= mNextTimeout) {
#if DEBUG_RAW_EVENTS
                ALOGD("Timeout expired, latency=%0.3fms", (now - mNextTimeout) * 0.000001f);
#endif
                mNextTimeout = LLONG_MAX;
                timeoutExpiredLocked(now);
            }
        }
        if (oldGeneration != mGeneration) {
            inputDevicesChanged = true;
            getInputDevicesLocked(inputDevices);
        }
    } // release lock
    // Send out a message that the describes the changed input devices.
    if (inputDevicesChanged) {
        mPolicy->notifyInputDevicesChanged(inputDevices);
    }
    // Flush queued events out to the listener.
    // This must happen outside of the lock because the listener could potentially call
    // back into the InputReader's methods, such as getScanCodeState, or become blocked
    // on another thread similarly waiting to acquire the InputReader lock thereby
    // resulting in a deadlock.  This situation is actually quite plausible because the
    // listener is actually the input dispatcher, which calls into the window manager,
    // which occasionally calls into the input reader.
    mQueuedListener->flush();
}

依次调用方法

void TouchInputMapper::process(const RawEvent* rawEvent)
void TouchInputMapper::sync(nsecs_t when)
void TouchInputMapper::processRawTouches(bool timeout)
void TouchInputMapper::cookAndDispatch(nsecs_t when)
void TouchInputMapper::dispatchTouches(nsecs_t when, uint32_t policyFlags)
void TouchInputMapper::dispatchMotion(nsecs_t when, uint32_t policyFlags, uint32_t source,
int32_t action, int32_t actionButton, int32_t flags,
int32_t metaState, int32_t buttonState, int32_t edgeFlags,
const PointerProperties* properties, const PointerCoords* coords,
const uint32_t* idToIndex, BitSet32 idBits, int32_t changedId,
float xPrecision, float yPrecision, nsecs_t downTime)

void TouchInputMapper::dispatchMotion(nsecs_t when, uint32_t policyFlags, uint32_t source,
        int32_t action, int32_t actionButton, int32_t flags,
        int32_t metaState, int32_t buttonState, int32_t edgeFlags,
        const PointerProperties* properties, const PointerCoords* coords,
        const uint32_t* idToIndex, BitSet32 idBits, int32_t changedId,
        float xPrecision, float yPrecision, nsecs_t downTime) {
    PointerCoords pointerCoords[MAX_POINTERS];
    PointerProperties pointerProperties[MAX_POINTERS];
    uint32_t pointerCount = 0;
    while (!idBits.isEmpty()) {
        uint32_t id = idBits.clearFirstMarkedBit();
        uint32_t index = idToIndex[id];
        pointerProperties[pointerCount].copyFrom(properties[index]);
        pointerCoords[pointerCount].copyFrom(coords[index]);

        if (changedId >= 0 && id == uint32_t(changedId)) {
            action |= pointerCount << AMOTION_EVENT_ACTION_POINTER_INDEX_SHIFT;
        }

        pointerCount += 1;
    }

    ALOG_ASSERT(pointerCount != 0);

    if (changedId >= 0 && pointerCount == 1) {
        // Replace initial down and final up action.
        // We can compare the action without masking off the changed pointer index
        // because we know the index is 0.
        if (action == AMOTION_EVENT_ACTION_POINTER_DOWN) {
            action = AMOTION_EVENT_ACTION_DOWN;
        } else if (action == AMOTION_EVENT_ACTION_POINTER_UP) {
            action = AMOTION_EVENT_ACTION_UP;
        } else {
            // Can't happen.
            ALOG_ASSERT(false);
        }
    }

    NotifyMotionArgs args(when, getDeviceId(), source, policyFlags,
            action, actionButton, flags, metaState, buttonState, edgeFlags,
            mViewport.displayId, pointerCount, pointerProperties, pointerCoords,
            xPrecision, yPrecision, downTime);
    getListener()->notifyMotion(&args);
}
InputListenerInterface* InputReader::ContextImpl::getListener() {
    return mReader->mQueuedListener.get();
}
InputReader::InputReader(const sp& eventHub,
        const sp& policy,
        const sp& listener) :
        mContext(this), mEventHub(eventHub), mPolicy(policy),
        mGlobalMetaState(0), mGeneration(1),
        mDisableVirtualKeysTimeout(LLONG_MIN), mNextTimeout(LLONG_MAX),
        mConfigurationChangesToRefresh(0) {
    mQueuedListener = new QueuedInputListener(listener);

    { // acquire lock
        AutoMutex _l(mLock);

        refreshConfigurationLocked(0);
        updateGlobalMetaStateLocked();
    } // release lock
}

getListener获取到的是mDispatcher也就是InputDispatcher对象。

InputDispatcher

void InputDispatcher::notifyMotion(const NotifyMotionArgs* args) {
#if DEBUG_INBOUND_EVENT_DETAILS
    ALOGD("notifyMotion - eventTime=%lld, deviceId=%d, source=0x%x, policyFlags=0x%x, "
            "action=0x%x, flags=0x%x, metaState=0x%x, buttonState=0x%x, edgeFlags=0x%x, "
            "xPrecision=%f, yPrecision=%f, downTime=%lld",
            args->eventTime, args->deviceId, args->source, args->policyFlags,
            args->action, args->flags, args->metaState, args->buttonState,
            args->edgeFlags, args->xPrecision, args->yPrecision, args->downTime);
    for (uint32_t i = 0; i < args->pointerCount; i++) {
        ALOGD("  Pointer %d: id=%d, toolType=%d, "
                "x=%f, y=%f, pressure=%f, size=%f, "
                "touchMajor=%f, touchMinor=%f, toolMajor=%f, toolMinor=%f, "
                "orientation=%f",
                i, args->pointerProperties[i].id,
                args->pointerProperties[i].toolType,
                args->pointerCoords[i].getAxisValue(AMOTION_EVENT_AXIS_X),
                args->pointerCoords[i].getAxisValue(AMOTION_EVENT_AXIS_Y),
                args->pointerCoords[i].getAxisValue(AMOTION_EVENT_AXIS_PRESSURE),
                args->pointerCoords[i].getAxisValue(AMOTION_EVENT_AXIS_SIZE),
                args->pointerCoords[i].getAxisValue(AMOTION_EVENT_AXIS_TOUCH_MAJOR),
                args->pointerCoords[i].getAxisValue(AMOTION_EVENT_AXIS_TOUCH_MINOR),
                args->pointerCoords[i].getAxisValue(AMOTION_EVENT_AXIS_TOOL_MAJOR),
                args->pointerCoords[i].getAxisValue(AMOTION_EVENT_AXIS_TOOL_MINOR),
                args->pointerCoords[i].getAxisValue(AMOTION_EVENT_AXIS_ORIENTATION));
    }
#endif
    if (!validateMotionEvent(args->action, args->pointerCount, args->pointerProperties)) {
        return;
    }
    uint32_t policyFlags = args->policyFlags;
    policyFlags |= POLICY_FLAG_TRUSTED;
    mPolicy->interceptMotionBeforeQueueing(args->eventTime, /*byref*/ policyFlags);
    bool needWake;
    { // acquire lock
        mLock.lock();
        if (shouldSendMotionToInputFilterLocked(args)) {
            mLock.unlock();
            MotionEvent event;
            event.initialize(args->deviceId, args->source, args->action, args->flags,
                    args->edgeFlags, args->metaState, args->buttonState, 0, 0,
                    args->xPrecision, args->yPrecision,
                    args->downTime, args->eventTime,
                    args->pointerCount, args->pointerProperties, args->pointerCoords);
            policyFlags |= POLICY_FLAG_FILTERED;
            if (!mPolicy->filterInputEvent(&event, policyFlags)) {
                return; // event was consumed by the filter
            }
            mLock.lock();
        }
        // Just enqueue a new motion event.
        MotionEntry* newEntry = new MotionEntry(args->eventTime,
                args->deviceId, args->source, policyFlags,
                args->action, args->flags, args->metaState, args->buttonState,
                args->edgeFlags, args->xPrecision, args->yPrecision, args->downTime,
                args->displayId,
                args->pointerCount, args->pointerProperties, args->pointerCoords);
        needWake = enqueueInboundEventLocked(newEntry);
        mLock.unlock();
    } // release lock
    if (needWake) {
        mLooper->wake();
    }
}
bool InputDispatcher::enqueueInboundEventLocked(EventEntry* entry) {
    bool needWake = mInboundQueue.isEmpty();
    mInboundQueue.enqueueAtTail(entry);
    traceInboundQueueLengthLocked();
    switch (entry->type) {
    case EventEntry::TYPE_KEY: {
        // Optimize app switch latency.
        // If the application takes too long to catch up then we drop all events preceding
        // the app switch key.
        KeyEntry* keyEntry = static_cast(entry);
        if (isAppSwitchKeyEventLocked(keyEntry)) {
            if (keyEntry->action == AKEY_EVENT_ACTION_DOWN) {
                mAppSwitchSawKeyDown = true;
            } else if (keyEntry->action == AKEY_EVENT_ACTION_UP) {
                if (mAppSwitchSawKeyDown) {
#if DEBUG_APP_SWITCH
                    ALOGD("App switch is pending!");
#endif
                    mAppSwitchDueTime = keyEntry->eventTime + APP_SWITCH_TIMEOUT;
                    mAppSwitchSawKeyDown = false;
                    needWake = true;
                }
            }
        }
        break;
    }
    case EventEntry::TYPE_MOTION: {
        // Optimize case where the current application is unresponsive and the user
        // decides to touch a window in a different application.
        // If the application takes too long to catch up then we drop all events preceding
        // the touch into the other window.
        MotionEntry* motionEntry = static_cast(entry);
        if (motionEntry->action == AMOTION_EVENT_ACTION_DOWN
                && (motionEntry->source & AINPUT_SOURCE_CLASS_POINTER)
                && mInputTargetWaitCause == INPUT_TARGET_WAIT_CAUSE_APPLICATION_NOT_READY
                && mInputTargetWaitApplicationHandle != NULL) {
            int32_t displayId = motionEntry->displayId;
            int32_t x = int32_t(motionEntry->pointerCoords[0].
                    getAxisValue(AMOTION_EVENT_AXIS_X));
            int32_t y = int32_t(motionEntry->pointerCoords[0].
                    getAxisValue(AMOTION_EVENT_AXIS_Y));
            sp touchedWindowHandle = findTouchedWindowAtLocked(displayId, x, y);
            if (touchedWindowHandle != NULL
                    && touchedWindowHandle->inputApplicationHandle
                            != mInputTargetWaitApplicationHandle) {
                // User touched a different application than the one we are waiting on.
                // Flag the event, and start pruning the input queue.
                mNextUnblockedEvent = motionEntry;
                needWake = true;
            }
        }
        break;
    }
    }
    return needWake;
}

新建并初始化了一个MotionEvent，然后包装成一个Entry，然后调用enqueueInboundEventLocked()函数：

mInboundQueue.enqueueAtTail(entry);

在enqueueInboundEventLocked()函数中将这个entry插入到了mInboundQueue这个InputDispatcher维护的成员变量中。

到这里我们可以看到事件经过一系列的处理和传递以后最终作为一个entry插入到了InputDispatcher的队列中等待被进一步分发。

InputDispatcherThread不断调用 mDispatcher->dispatchOnce();分发事件

void InputDispatcher::dispatchOnce() {
    nsecs_t nextWakeupTime = LONG_LONG_MAX;
    { // acquire lock
        AutoMutex _l(mLock);
        mDispatcherIsAliveCondition.broadcast();
        // Run a dispatch loop if there are no pending commands.
        // The dispatch loop might enqueue commands to run afterwards.
        if (!haveCommandsLocked()) {
            dispatchOnceInnerLocked(&nextWakeupTime);
        }
        // Run all pending commands if there are any.
        // If any commands were run then force the next poll to wake up immediately.
        if (runCommandsLockedInterruptible()) {
            nextWakeupTime = LONG_LONG_MIN;
        }
    } // release lock
    // Wait for callback or timeout or wake.  (make sure we round up, not down)
    nsecs_t currentTime = now();
    int timeoutMillis = toMillisecondTimeoutDelay(currentTime, nextWakeupTime);
    mLooper->pollOnce(timeoutMillis);
}
void InputDispatcher::dispatchOnceInnerLocked(nsecs_t* nextWakeupTime) {
    nsecs_t currentTime = now();
    // Reset the key repeat timer whenever we disallow key events, even if the next event
    // is not a key.  This is to ensure that we abort a key repeat if the device is just coming
    // out of sleep.
    if (!mPolicy->isKeyRepeatEnabled()) {
        resetKeyRepeatLocked();
    }
    // If dispatching is frozen, do not process timeouts or try to deliver any new events.
    if (mDispatchFrozen) {
#if DEBUG_FOCUS
        ALOGD("Dispatch frozen.  Waiting some more.");
#endif
        return;
    }
    // Optimize latency of app switches.
    // Essentially we start a short timeout when an app switch key (HOME / ENDCALL) has
    // been pressed.  When it expires, we preempt dispatch and drop all other pending events.
    bool isAppSwitchDue = mAppSwitchDueTime <= currentTime;
    if (mAppSwitchDueTime < *nextWakeupTime) {
        *nextWakeupTime = mAppSwitchDueTime;
    }
    // Ready to start a new event.
    // If we don't already have a pending event, go grab one.
    if (! mPendingEvent) {
        if (mInboundQueue.isEmpty()) {
            if (isAppSwitchDue) {
                // The inbound queue is empty so the app switch key we were waiting
                // for will never arrive.  Stop waiting for it.
                resetPendingAppSwitchLocked(false);
                isAppSwitchDue = false;
            }
            // Synthesize a key repeat if appropriate.
            if (mKeyRepeatState.lastKeyEntry) {
                if (currentTime >= mKeyRepeatState.nextRepeatTime) {
                    mPendingEvent = synthesizeKeyRepeatLocked(currentTime);
                } else {
                    if (mKeyRepeatState.nextRepeatTime < *nextWakeupTime) {
                        *nextWakeupTime = mKeyRepeatState.nextRepeatTime;
                    }
                }
            }
            // Nothing to do if there is no pending event.
            if (!mPendingEvent) {
                return;
            }
        } else {
            // Inbound queue has at least one entry.
            mPendingEvent = mInboundQueue.dequeueAtHead();
            traceInboundQueueLengthLocked();
        }
        // Poke user activity for this event.
        if (mPendingEvent->policyFlags & POLICY_FLAG_PASS_TO_USER) {
            pokeUserActivityLocked(mPendingEvent);
        }
        // Get ready to dispatch the event.
        resetANRTimeoutsLocked();
    }
    // Now we have an event to dispatch.
    // All events are eventually dequeued and processed this way, even if we intend to drop them.
    ALOG_ASSERT(mPendingEvent != NULL);
    bool done = false;
    DropReason dropReason = DROP_REASON_NOT_DROPPED;
    if (!(mPendingEvent->policyFlags & POLICY_FLAG_PASS_TO_USER)) {
        dropReason = DROP_REASON_POLICY;
    } else if (!mDispatchEnabled) {
        dropReason = DROP_REASON_DISABLED;
    }
    if (mNextUnblockedEvent == mPendingEvent) {
        mNextUnblockedEvent = NULL;
    }
    switch (mPendingEvent->type) {
    case EventEntry::TYPE_CONFIGURATION_CHANGED: {
        ConfigurationChangedEntry* typedEntry =
                static_cast(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(mPendingEvent);
        done = dispatchDeviceResetLocked(currentTime, typedEntry);
        dropReason = DROP_REASON_NOT_DROPPED; // device resets are never dropped
        break;
    }
    case EventEntry::TYPE_KEY: {
        KeyEntry* typedEntry = static_cast(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(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;
    }
    default:
        ALOG_ASSERT(false);
        break;
    }
    if (done) {
        if (dropReason != DROP_REASON_NOT_DROPPED) {
            dropInboundEventLocked(mPendingEvent, dropReason);
        }
        releasePendingEventLocked();
        *nextWakeupTime = LONG_LONG_MIN;  // force next poll to wake up immediately
    }
}
bool InputDispatcher::dispatchMotionLocked(
        nsecs_t currentTime, MotionEntry* entry, DropReason* dropReason, nsecs_t* nextWakeupTime) {
    // Preprocessing.
    if (! entry->dispatchInProgress) {
        entry->dispatchInProgress = true;
        logOutboundMotionDetailsLocked("dispatchMotion - ", entry);
    }
    // Clean up if dropping the event.
    if (*dropReason != DROP_REASON_NOT_DROPPED) {
        setInjectionResultLocked(entry, *dropReason == DROP_REASON_POLICY
                ? INPUT_EVENT_INJECTION_SUCCEEDED : INPUT_EVENT_INJECTION_FAILED);
        return true;
    }
    bool isPointerEvent = entry->source & AINPUT_SOURCE_CLASS_POINTER;
    // Identify targets.
    Vector inputTargets;
    bool conflictingPointerActions = false;
    int32_t injectionResult;
    if (isPointerEvent) {
        // Pointer event.  (eg. touchscreen)
        injectionResult = findTouchedWindowTargetsLocked(currentTime,
                entry, inputTargets, nextWakeupTime, &conflictingPointerActions);
    } else {
        // Non touch event.  (eg. trackball)
        injectionResult = findFocusedWindowTargetsLocked(currentTime,
                entry, inputTargets, nextWakeupTime);
    }
    if (injectionResult == INPUT_EVENT_INJECTION_PENDING) {
        return false;
    }
    setInjectionResultLocked(entry, injectionResult);
    if (injectionResult != INPUT_EVENT_INJECTION_SUCCEEDED) {
        return true;
    }
    // TODO: support sending secondary display events to input monitors
    if (isMainDisplay(entry->displayId)) {
        addMonitoringTargetsLocked(inputTargets);
    }
    // Dispatch the motion.
    if (conflictingPointerActions) {
        CancelationOptions options(CancelationOptions::CANCEL_POINTER_EVENTS,
                "conflicting pointer actions");
        synthesizeCancelationEventsForAllConnectionsLocked(options);
    }
    dispatchEventLocked(currentTime, entry, inputTargets);
    return true;
}

findTouchedWindowTargesLocked方法获取到window，如果遍历后没有找到合适的window，那就取第一个前台的window。

通过 dispatchEventLocked(currentTime, entry, inputTargets)向window分发事件

void InputDispatcher::dispatchEventLocked(nsecs_t currentTime,
        EventEntry* eventEntry, const Vector& inputTargets) {
#if DEBUG_DISPATCH_CYCLE
    ALOGD("dispatchEventToCurrentInputTargets");
#endif
    ALOG_ASSERT(eventEntry->dispatchInProgress); // should already have been set to true
    pokeUserActivityLocked(eventEntry);
    for (size_t i = 0; i < inputTargets.size(); i++) {
        const InputTarget& inputTarget = inputTargets.itemAt(i);
        ssize_t connectionIndex = getConnectionIndexLocked(inputTarget.inputChannel);
        if (connectionIndex >= 0) {
            sp connection = mConnectionsByFd.valueAt(connectionIndex);
            prepareDispatchCycleLocked(currentTime, connection, eventEntry, &inputTarget);
        } else {
#if DEBUG_FOCUS
            ALOGD("Dropping event delivery to target with channel '%s' because it "
                    "is no longer registered with the input dispatcher.",
                    inputTarget.inputChannel->getName().string());
#endif
        }
    }
}


void InputDispatcher::startDispatchCycleLocked(nsecs_t currentTime,
        const sp& connection) {
  //省略其它处理...
  case EventEntry::TYPE_MOTION: {
            MotionEntry* motionEntry = static_cast(eventEntry);
            PointerCoords scaledCoords[MAX_POINTERS];
            const PointerCoords* usingCoords = motionEntry->pointerCoords;
            // Set the X and Y offset depending on the input source.
            float xOffset, yOffset, scaleFactor;
            if ((motionEntry->source & AINPUT_SOURCE_CLASS_POINTER)
                    && !(dispatchEntry->targetFlags & InputTarget::FLAG_ZERO_COORDS)) {
                scaleFactor = dispatchEntry->scaleFactor;
                xOffset = dispatchEntry->xOffset * scaleFactor;
                yOffset = dispatchEntry->yOffset * scaleFactor;
                if (scaleFactor != 1.0f) {
                    for (size_t i = 0; i < motionEntry->pointerCount; i++) {
                        scaledCoords[i] = motionEntry->pointerCoords[i];
                        scaledCoords[i].scale(scaleFactor);
                    }
                    usingCoords = scaledCoords;
                }
            } else {
                xOffset = 0.0f;
                yOffset = 0.0f;
                scaleFactor = 1.0f;
                // We don't want the dispatch target to know.
                if (dispatchEntry->targetFlags & InputTarget::FLAG_ZERO_COORDS) {
                    for (size_t i = 0; i < motionEntry->pointerCount; i++) {
                        scaledCoords[i].clear();
                    }
                    usingCoords = scaledCoords;
                }
            }
            // Publish the motion event.
            status = connection->inputPublisher.publishMotionEvent(dispatchEntry->seq,
                    motionEntry->deviceId, motionEntry->source,
                    dispatchEntry->resolvedAction, dispatchEntry->resolvedFlags,
                    motionEntry->edgeFlags, motionEntry->metaState, motionEntry->buttonState,
                    xOffset, yOffset,
                    motionEntry->xPrecision, motionEntry->yPrecision,
                    motionEntry->downTime, motionEntry->eventTime,
                    motionEntry->pointerCount, motionEntry->pointerProperties,
                    usingCoords);
            break;
        }
}

在对事件的坐标进行解析之后，通过socket通信，分发事件

InputPublisher的publishMotionEvent()函数，最终调用了mChannel的sendMessage()方法进行跨进程通信。

接收事件

WindowManagerGlobal的addView()方法将view添加到window，创建ViewRootImpl 对象root = new ViewRootImpl(view.getContext(), display);

ViewRootImpl的内部类 WindowInputEventReceiver接收事件

 

void enqueueInputEvent(InputEvent event) {
        enqueueInputEvent(event, null, 0, false);
    }

    @UnsupportedAppUsage
    void enqueueInputEvent(InputEvent event,
            InputEventReceiver receiver, int flags, boolean processImmediately) {
        adjustInputEventForCompatibility(event);
        QueuedInputEvent q = obtainQueuedInputEvent(event, receiver, flags);

        // Always enqueue the input event in order, regardless of its time stamp.
        // We do this because the application or the IME may inject key events
        // in response to touch events and we want to ensure that the injected keys
        // are processed in the order they were received and we cannot trust that
        // the time stamp of injected events are monotonic.
        QueuedInputEvent last = mPendingInputEventTail;
        if (last == null) {
            mPendingInputEventHead = q;
            mPendingInputEventTail = q;
        } else {
            last.mNext = q;
            mPendingInputEventTail = q;
        }
        mPendingInputEventCount += 1;
        Trace.traceCounter(Trace.TRACE_TAG_INPUT, mPendingInputEventQueueLengthCounterName,
                mPendingInputEventCount);

        if (processImmediately) {
            doProcessInputEvents();
        } else {
            scheduleProcessInputEvents();
        }
    }

  protected boolean shouldDropInputEvent(QueuedInputEvent q) {
            if (mView == null || !mAdded) {
                Slog.w(mTag, "Dropping event due to root view being removed: " + q.mEvent);
                return true;
            } else if ((!mAttachInfo.mHasWindowFocus
                    && !q.mEvent.isFromSource(InputDevice.SOURCE_CLASS_POINTER)
                    && !isAutofillUiShowing()) || mStopped
                    || (mIsAmbientMode && !q.mEvent.isFromSource(InputDevice.SOURCE_CLASS_BUTTON))
                    || (mPausedForTransition && !isBack(q.mEvent))) {
                // This is a focus event and the window doesn't currently have input focus or
                // has stopped. This could be an event that came back from the previous stage
                // but the window has lost focus or stopped in the meantime.
                if (isTerminalInputEvent(q.mEvent)) {
                    // Don't drop terminal input events, however mark them as canceled.
                    q.mEvent.cancel();
                    Slog.w(mTag, "Cancelling event due to no window focus: " + q.mEvent);
                    return false;
                }

                // Drop non-terminal input events.
                Slog.w(mTag, "Dropping event due to no window focus: " + q.mEvent);
                return true;
            }
            return false;
        }