Android—IMS的InputDispatcher

前文说到InputReader调用mQueuedListener->flush()会去换下InputDispatcher的Looper然后处理输入事件。

frameworks\native\services\inputflinger\InputDispatcher.cpp:

bool InputDispatcherThread::threadLoop() {
    mDispatcher->dispatchOnce();
    return true;
}

void InputDispatcher::dispatchOnce() {
    nsecs_t nextWakeupTime = LONG_LONG_MAX;
    { // acquire lock
        std::scoped_lock _l(mLock);
        mDispatcherIsAlive.notify_all();

        // 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) {
    ....
    switch (mPendingEvent->type) {
    case EventEntry::TYPE_CONFIGURATION_CHANGED:
        ....
    case EventEntry::TYPE_DEVICE_RESET: 
        ....
    case EventEntry::TYPE_KEY: 
        ....
    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
                && isStaleEvent(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);
        }
        mLastDropReason = dropReason;

        releasePendingEventLocked();
        *nextWakeupTime = LONG_LONG_MIN;  // force next poll to wake up immediately
    }
}

我们主要看Motion屏幕输入事件的

bool InputDispatcher::dispatchMotionLocked(
        nsecs_t currentTime, MotionEntry* entry, DropReason* dropReason, nsecs_t* nextWakeupTime) {
    ....
    bool isPointerEvent = entry->source & AINPUT_SOURCE_CLASS_POINTER;
    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);
    }
    ....
    // Dispatch the motion.
    dispatchEventLocked(currentTime, entry, inputTargets);
    return true;
}

1.findTouchedWindowTargetsLocked  寻找目标Window

2.WMS与IMS的联系

3.dispatchEventLocked 分发事件

1.findTouchedWindowTargetsLocked

int32_t InputDispatcher::findTouchedWindowTargetsLocked(nsecs_t currentTime,
                                                        const MotionEntry& entry,
                                                        std::vector& inputTargets,
                                                        nsecs_t* nextWakeupTime,
                                                        bool* outConflictingPointerActions) {
    ATRACE_CALL();
    ...
    // 读取触控事件所属的Display的id信息
    int32_t displayId = entry.displayId;
    ...
    // 只有ACTION_DOWN类型代表新的触控事件,需要寻找新的目标窗口,后续的ACTION_MOVE或ACTION_UP类型的触控事件直接发送导已经找到的目标窗口
    bool newGesture = (maskedAction == AMOTION_EVENT_ACTION_DOWN ||
                       maskedAction == AMOTION_EVENT_ACTION_SCROLL || isHoverAction);
    ...

    if (newGesture || (isSplit && maskedAction == AMOTION_EVENT_ACTION_POINTER_DOWN)) {
        // 读取触控事件的x、y坐标位置
        int32_t x;
        int32_t y;
        if (isFromMouse) {
            ...
        } else {
            x = int32_t(entry.pointerCoords[pointerIndex].getAxisValue(AMOTION_EVENT_AXIS_X));
            y = int32_t(entry.pointerCoords[pointerIndex].getAxisValue(AMOTION_EVENT_AXIS_Y));
        }
        // 根据触控事件所属的displayid、x/y坐标位置等属性信息,调用findTouchedWindowAtLocked找到目标窗口
        sp newTouchedWindowHandle =
                findTouchedWindowAtLocked(displayId, x, y, &tempTouchState,
                                          isDown /*addOutsideTargets*/, true /*addPortalWindows*/);
        ...
    } else {
        ...
    }
    ...
}

sp InputDispatcher::findTouchedWindowAtLocked(int32_t displayId,
        int32_t x, int32_t y, bool addOutsideTargets, bool addPortalWindows) {
    // 从前到后遍历窗口找到被触摸的窗口。
    const std::vector> windowHandles = getWindowHandlesLocked(displayId);
    for (const sp& windowHandle : windowHandles) {
        const InputWindowInfo* windowInfo = windowHandle->getInfo();
        if (windowInfo->displayId == displayId) {
            int32_t flags = windowInfo->layoutParamsFlags;
            if (windowInfo->visible) {
                if (!(flags & InputWindowInfo::FLAG_NOT_TOUCHABLE)) {
                    ...
                    // 根据触控事件的x/y坐标位置信息与窗口的可见区域进行匹配找到目标窗口
                    if (isTouchModal || windowInfo->touchableRegionContainsPoint(x, y)) {
                        ...
                        return windowHandle;
                    }
                }
            ...

            }
        }
    }
    return nullptr;
}

std::vector> InputDispatcher::getWindowHandlesLocked(
        int32_t displayId) const {
    // 从集合mWindowHandlesByDisplay中根据传入的displayId取出对应的可见窗口集合
    return getValueByKey(mWindowHandlesByDisplay, displayId);
}

所以findTouchedWindowTargetsLocked就是用DeviceId和触摸的坐标轴来找到对应Window,那mWindowHandlesByDisplay的窗口数据是从哪里来的?

frameworks/native/services/inputflinger/dispatcher/InputDispatcher.cpp:

void InputDispatcher::updateWindowHandlesForDisplayLocked(
        const std::vector>& inputWindowHandles, int32_t displayId) {
    ...
    // Insert or replace
    mWindowHandlesByDisplay[displayId] = newHandles;
}

void InputDispatcher::setInputWindowsLocked(
        const std::vector>& inputWindowHandles, int32_t displayId) {
    ...
    updateWindowHandlesForDisplayLocked(inputWindowHandles, displayId);
    ...
}

void InputDispatcher::setInputWindows(
        const std::unordered_map>>& handlesPerDisplay) {
    { // acquire lock
        std::scoped_lock _l(mLock);
        for (auto const& i : handlesPerDisplay) {
            setInputWindowsLocked(i.second, i.first);
        }
    }
    ...
}

frameworks\base\services\core\jni\com_android_server_input_InputManagerService.cpp:

void NativeInputManager::setInputWindows(JNIEnv* env, jobjectArray windowHandleObjArray,
         int32_t displayId) {
    std::vector > windowHandles;

    if (windowHandleObjArray) {
        jsize length = env->GetArrayLength(windowHandleObjArray);
        for (jsize i = 0; i < length; i++) {
            jobject windowHandleObj = env->GetObjectArrayElement(windowHandleObjArray, i);
            if (! windowHandleObj) {
                break; // found null element indicating end of used portion of the array
            }

            sp windowHandle =
                    android_view_InputWindowHandle_getHandle(env, windowHandleObj);
            if (windowHandle != nullptr) {
                windowHandles.push_back(windowHandle);
            }
            env->DeleteLocalRef(windowHandleObj);
        }
    }

    mInputManager->getDispatcher()->setInputWindows(windowHandles, displayId);
    ....
}

static void nativeSetInputWindows(JNIEnv* env, jclass /* clazz */,
        jlong ptr, jobjectArray windowHandleObjArray) {
    NativeInputManager* im = reinterpret_cast(ptr);

    im->setInputWindows(env, windowHandleObjArray);
}

所以Java层可以调用IMS的nativeSetInputWindows方法给IMS设置窗口数据。

2.WMS与IMS的联系

在handleResumeActivity中,将 DecorView 添加到 WindowManager中,

wm.addView(decor, l);

frameworks\base\core\java\android\view\WindowManagerGlobal.java:

    public void addView(View view, ViewGroup.LayoutParams params,
            Display display, Window parentWindow) {
            ....
            root = new ViewRootImpl(view.getContext(), display);
            view.setLayoutParams(wparams);
            mViews.add(view);
            mRoots.add(root);
            mParams.add(wparams);
            // do this last because it fires off messages to start doing things
            try {
                root.setView(view, wparams, panelParentView);
            } catch (RuntimeException e) {
                // BadTokenException or InvalidDisplayException, clean up.
                if (index >= 0) {
                    removeViewLocked(index, true);
                }
                throw e;
            }
        }
    }

frameworks\base\core\java\android\view\ViewRootImpl.java:

   public void setView(View view, WindowManager.LayoutParams attrs, View panelParentView) {
        synchronized (this) {
            if (mView == null) {
                mView = view;
                ......
                if ((mWindowAttributes.inputFeatures
                        & WindowManager.LayoutParams.INPUT_FEATURE_NO_INPUT_CHANNEL) == 0) {
                    mInputChannel = new InputChannel();
                }
                try {
                    ......
                    res = mWindowSession.addToDisplay(mWindow, mSeq, mWindowAttributes,
                            getHostVisibility(), mDisplay.getDisplayId(),
                            mAttachInfo.mContentInsets, mAttachInfo.mStableInsets,
                            mAttachInfo.mOutsets, mInputChannel);
                } catch (RemoteException e) {
                    ......
                } finally {
                    ......
                }
                ......
                if (mInputChannel != null) {
                    if (mInputQueueCallback != null) {
                        mInputQueue = new InputQueue();
                        mInputQueueCallback.onInputQueueCreated(mInputQueue);
                    }
                    // 接收输入事件
                    mInputEventReceiver = new WindowInputEventReceiver(mInputChannel,
                            Looper.myLooper());
                }
                ......
            }
        }
    }
  1. 在mWindowSession.addToDisplay中,会调用setInputWindows设置窗口数据。
  2. 创建了InputChannel用于接受输入事件。
  3. new WindowInputEventReceiver(mInputChannel, Looper.myLooper());接受处理事件。

mWindowSession.addToDisplay会调用WMS的addWindow,InputChannel是参数之一,把InputChannel传给了WMS。

frameworks\base\services\core\java\com\android\server\wm\WindowManagerService.java:

    public int addWindow(Session session, IWindow client, int seq,
            LayoutParams attrs, int viewVisibility, int displayId, Rect outFrame,
            Rect outContentInsets, Rect outStableInsets, Rect outOutsets,
            DisplayCutout.ParcelableWrapper outDisplayCutout, InputChannel outInputChannel,
            InsetsState outInsetsState) {
            ....
            final boolean openInputChannels = (outInputChannel != null
                    && (attrs.inputFeatures & INPUT_FEATURE_NO_INPUT_CHANNEL) == 0);
            if  (openInputChannels) {
                win.openInputChannel(outInputChannel);
            }
            ....
    }

frameworks\base\services\core\java\com\android\server\wm\WindowState.java:

    void openInputChannel(InputChannel outInputChannel) {
        if (mInputChannel != null) {
            throw new IllegalStateException("Window already has an input channel.");
        }
        String name = getName();
        InputChannel[] inputChannels = InputChannel.openInputChannelPair(name);
        mInputChannel = inputChannels[0];
        mClientChannel = inputChannels[1];
        mInputWindowHandle.token = mClient.asBinder();
        if (outInputChannel != null) {
            mClientChannel.transferTo(outInputChannel);
            mClientChannel.dispose();
            mClientChannel = null;
        } else {
            // If the window died visible, we setup a dummy input channel, so that taps
            // can still detected by input monitor channel, and we can relaunch the app.
            // Create dummy event receiver that simply reports all events as handled.
            mDeadWindowEventReceiver = new DeadWindowEventReceiver(mClientChannel);
        }
        mWmService.mInputManager.registerInputChannel(mInputChannel, mClient.asBinder());
    }

frameworks\base\core\java\android\view\InputChannel.java:

    public static InputChannel[] openInputChannelPair(String name) {
        if (name == null) {
            throw new IllegalArgumentException("name must not be null");
        }

        if (DEBUG) {
            Slog.d(TAG, "Opening input channel pair '" + name + "'");
        }
        return nativeOpenInputChannelPair(name);
    }

frameworks\base\core\jni\android_view_InputChannel.cpp:

static jobjectArray android_view_InputChannel_nativeOpenInputChannelPair(JNIEnv* env,
        jclass clazz, jstring nameObj) {
    ScopedUtfChars nameChars(env, nameObj);
    std::string name = nameChars.c_str();

    sp serverChannel;
    sp clientChannel;
    status_t result = InputChannel::openInputChannelPair(name, serverChannel, clientChannel);

    if (result) {
        String8 message;
        message.appendFormat("Could not open input channel pair.  status=%d", result);
        jniThrowRuntimeException(env, message.string());
        return NULL;
    }

    jobjectArray channelPair = env->NewObjectArray(2, gInputChannelClassInfo.clazz, NULL);
    if (env->ExceptionCheck()) {
        return NULL;
    }

    jobject serverChannelObj = android_view_InputChannel_createInputChannel(env,
            std::make_unique(serverChannel));
    if (env->ExceptionCheck()) {
        return NULL;
    }

    jobject clientChannelObj = android_view_InputChannel_createInputChannel(env,
            std::make_unique(clientChannel));
    if (env->ExceptionCheck()) {
        return NULL;
    }

    env->SetObjectArrayElement(channelPair, 0, serverChannelObj);
    env->SetObjectArrayElement(channelPair, 1, clientChannelObj);
    return channelPair;
}

frameworks\native\libs\input\InputTransport.cpp:

status_t InputChannel::openInputChannelPair(const std::string& name,
        sp& outServerChannel, sp& outClientChannel) {
    int sockets[2];
    if (socketpair(AF_UNIX, SOCK_SEQPACKET, 0, sockets)) {
        status_t result = -errno;
        ALOGE("channel '%s' ~ Could not create socket pair.  errno=%d",
                name.c_str(), errno);
        outServerChannel.clear();
        outClientChannel.clear();
        return result;
    }

    int bufferSize = SOCKET_BUFFER_SIZE;
    setsockopt(sockets[0], SOL_SOCKET, SO_SNDBUF, &bufferSize, sizeof(bufferSize));
    setsockopt(sockets[0], SOL_SOCKET, SO_RCVBUF, &bufferSize, sizeof(bufferSize));
    setsockopt(sockets[1], SOL_SOCKET, SO_SNDBUF, &bufferSize, sizeof(bufferSize));
    setsockopt(sockets[1], SOL_SOCKET, SO_RCVBUF, &bufferSize, sizeof(bufferSize));

    std::string serverChannelName = name;
    serverChannelName += " (server)";
    outServerChannel = new InputChannel(serverChannelName, sockets[0]);

    std::string clientChannelName = name;
    clientChannelName += " (client)";
    outClientChannel = new InputChannel(clientChannelName, sockets[1]);
    return OK;
}

openInputChannel里面创建一对InputChannel,然后将Server端的InputChannel注册到InputDispatcher中,将Client端的InputChannel返回给客户端即ViewRootImpl使用。InputChannel封装了name和fd。通过文件描述符fd实现进程通信。

3.dispatchEventLocked 分发事件

void InputDispatcher::dispatchEventLocked(nsecs_t currentTime,
        EventEntry* eventEntry, const std::vector& inputTargets) {
    ....
    for (const InputTarget& inputTarget : inputTargets) {
        ssize_t connectionIndex = getConnectionIndexLocked(inputTarget.inputChannel);
        if (connectionIndex >= 0) {
            sp connection = mConnectionsByFd.valueAt(connectionIndex);
            prepareDispatchCycleLocked(currentTime, connection, eventEntry, &inputTarget);
        }
        ....
    }
}

ssize_t InputDispatcher::getConnectionIndexLocked(const sp& inputChannel) {
    if (inputChannel == nullptr) {
        return -1;
    }

    for (size_t i = 0; i < mConnectionsByFd.size(); i++) {
        sp connection = mConnectionsByFd.valueAt(i);
        if (connection->inputChannel->getToken() == inputChannel->getToken()) {
            return i;
        }
    }

    return -1;
}

getConnectionIndexLocked通过inputChannel获取Connection对象。

所以说dispatchEventLocked会获取窗口对应的inputChannel,并调用prepareDispatchCycleLocked进行处理。 prepareDispatchCycleLocked方法内部调用了enqueueDispatchEntriesLocked方法,后续通过inputChannel传输事件。

void InputDispatcher::prepareDispatchCycleLocked(nsecs_t currentTime,
        const sp& connection, EventEntry* eventEntry, const InputTarget* inputTarget) {
    ....
    // Not splitting.  Enqueue dispatch entries for the event as is.
    enqueueDispatchEntriesLocked(currentTime, connection, eventEntry, inputTarget);
}

void InputDispatcher::enqueueDispatchEntriesLocked(nsecs_t currentTime,
        const sp& connection, EventEntry* eventEntry, const InputTarget* inputTarget) {
    bool wasEmpty = connection->outboundQueue.isEmpty();

    // Enqueue dispatch entries for the requested modes.
    enqueueDispatchEntryLocked(connection, eventEntry, inputTarget,
            InputTarget::FLAG_DISPATCH_AS_HOVER_EXIT);
    enqueueDispatchEntryLocked(connection, eventEntry, inputTarget,
            InputTarget::FLAG_DISPATCH_AS_OUTSIDE);
    enqueueDispatchEntryLocked(connection, eventEntry, inputTarget,
            InputTarget::FLAG_DISPATCH_AS_HOVER_ENTER);
    enqueueDispatchEntryLocked(connection, eventEntry, inputTarget,
            InputTarget::FLAG_DISPATCH_AS_IS);
    enqueueDispatchEntryLocked(connection, eventEntry, inputTarget,
            InputTarget::FLAG_DISPATCH_AS_SLIPPERY_EXIT);
    enqueueDispatchEntryLocked(connection, eventEntry, inputTarget,
            InputTarget::FLAG_DISPATCH_AS_SLIPPERY_ENTER);

    // If the outbound queue was previously empty, start the dispatch cycle going.
    if (wasEmpty && !connection->outboundQueue.isEmpty()) {
        startDispatchCycleLocked(currentTime, connection);
    }
}

1.enqueueDispatchEntryLocked将事件插入队列

2.startDispatchCycleLocked开始分发事件

1.enqueueDispatchEntryLocked将事件插入队列

void InputDispatcher::enqueueDispatchEntryLocked(
        const sp& connection, EventEntry* eventEntry, const InputTarget* inputTarget,
        int32_t dispatchMode) {
    ....
    // This is a new event.
    // Enqueue a new dispatch entry onto the outbound queue for this connection.
    DispatchEntry* dispatchEntry = new DispatchEntry(eventEntry, // increments ref
            inputTargetFlags, inputTarget->xOffset, inputTarget->yOffset,
            inputTarget->globalScaleFactor, inputTarget->windowXScale,
            inputTarget->windowYScale);

    // Apply target flags and update the connection's input state.
    switch (eventEntry->type) {
    case EventEntry::TYPE_KEY: {
        KeyEntry* keyEntry = static_cast(eventEntry);
        dispatchEntry->resolvedAction = keyEntry->action;
        dispatchEntry->resolvedFlags = keyEntry->flags;

        if (!connection->inputState.trackKey(keyEntry,
                dispatchEntry->resolvedAction, dispatchEntry->resolvedFlags)) {
#if DEBUG_DISPATCH_CYCLE
            ALOGD("channel '%s' ~ enqueueDispatchEntryLocked: skipping inconsistent key event",
                    connection->getInputChannelName().c_str());
#endif
            delete dispatchEntry;
            return; // skip the inconsistent event
        }
        break;
    }

    case EventEntry::TYPE_MOTION: {
        MotionEntry* motionEntry = static_cast(eventEntry);
        if (dispatchMode & InputTarget::FLAG_DISPATCH_AS_OUTSIDE) {
            dispatchEntry->resolvedAction = AMOTION_EVENT_ACTION_OUTSIDE;
        } else if (dispatchMode & InputTarget::FLAG_DISPATCH_AS_HOVER_EXIT) {
            dispatchEntry->resolvedAction = AMOTION_EVENT_ACTION_HOVER_EXIT;
        } else if (dispatchMode & InputTarget::FLAG_DISPATCH_AS_HOVER_ENTER) {
            dispatchEntry->resolvedAction = AMOTION_EVENT_ACTION_HOVER_ENTER;
        } else if (dispatchMode & InputTarget::FLAG_DISPATCH_AS_SLIPPERY_EXIT) {
            dispatchEntry->resolvedAction = AMOTION_EVENT_ACTION_CANCEL;
        } else if (dispatchMode & InputTarget::FLAG_DISPATCH_AS_SLIPPERY_ENTER) {
            dispatchEntry->resolvedAction = AMOTION_EVENT_ACTION_DOWN;
        } else {
            dispatchEntry->resolvedAction = motionEntry->action;
        }
        if (dispatchEntry->resolvedAction == AMOTION_EVENT_ACTION_HOVER_MOVE
                && !connection->inputState.isHovering(
                        motionEntry->deviceId, motionEntry->source, motionEntry->displayId)) {
#if DEBUG_DISPATCH_CYCLE
        ALOGD("channel '%s' ~ enqueueDispatchEntryLocked: filling in missing hover enter event",
                connection->getInputChannelName().c_str());
#endif
            dispatchEntry->resolvedAction = AMOTION_EVENT_ACTION_HOVER_ENTER;
        }

        dispatchEntry->resolvedFlags = motionEntry->flags;
        if (dispatchEntry->targetFlags & InputTarget::FLAG_WINDOW_IS_OBSCURED) {
            dispatchEntry->resolvedFlags |= AMOTION_EVENT_FLAG_WINDOW_IS_OBSCURED;
        }
        if (dispatchEntry->targetFlags & InputTarget::FLAG_WINDOW_IS_PARTIALLY_OBSCURED) {
            dispatchEntry->resolvedFlags |= AMOTION_EVENT_FLAG_WINDOW_IS_PARTIALLY_OBSCURED;
        }

        if (!connection->inputState.trackMotion(motionEntry,
                dispatchEntry->resolvedAction, dispatchEntry->resolvedFlags)) {
#if DEBUG_DISPATCH_CYCLE
            ALOGD("channel '%s' ~ enqueueDispatchEntryLocked: skipping inconsistent motion event",
                    connection->getInputChannelName().c_str());
#endif
            delete dispatchEntry;
            return; // skip the inconsistent event
        }

        dispatchPointerDownOutsideFocus(motionEntry->source,
                dispatchEntry->resolvedAction, inputTarget->inputChannel->getToken());

        break;
    }
    }

    // Remember that we are waiting for this dispatch to complete.
    if (dispatchEntry->hasForegroundTarget()) {
        incrementPendingForegroundDispatches(eventEntry);
    }

    // Enqueue the dispatch entry.
    connection->outboundQueue.enqueueAtTail(dispatchEntry);
    traceOutboundQueueLength(connection);

}

enqueueDispatchEntryLocked里面将输入事件重新封装为一个DispatchEntry,根据不同的Event填充数据,然后放到connection的outboundQueue队列中。

2.startDispatchCycleLocked开始分发事件

void InputDispatcher::startDispatchCycleLocked(nsecs_t currentTime,
        const sp& connection) {

    while (connection->status == Connection::STATUS_NORMAL
            && !connection->outboundQueue.isEmpty()) {
        DispatchEntry* dispatchEntry = connection->outboundQueue.head;
        dispatchEntry->deliveryTime = currentTime;

        // Publish the event.
        status_t status;
        EventEntry* eventEntry = dispatchEntry->eventEntry;
        switch (eventEntry->type) {
        case EventEntry::TYPE_KEY: {
            KeyEntry* keyEntry = static_cast(eventEntry);

            // Publish the key event.
            status = connection->inputPublisher.publishKeyEvent(dispatchEntry->seq,
                    keyEntry->deviceId, keyEntry->source, keyEntry->displayId,
                    dispatchEntry->resolvedAction, dispatchEntry->resolvedFlags,
                    keyEntry->keyCode, keyEntry->scanCode,
                    keyEntry->metaState, keyEntry->repeatCount, keyEntry->downTime,
                    keyEntry->eventTime);
            break;
        }

        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;
            if ((motionEntry->source & AINPUT_SOURCE_CLASS_POINTER)
                    && !(dispatchEntry->targetFlags & InputTarget::FLAG_ZERO_COORDS)) {
                float globalScaleFactor = dispatchEntry->globalScaleFactor;
                float wxs = dispatchEntry->windowXScale;
                float wys = dispatchEntry->windowYScale;
                xOffset = dispatchEntry->xOffset * wxs;
                yOffset = dispatchEntry->yOffset * wys;
                if (wxs != 1.0f || wys != 1.0f || globalScaleFactor != 1.0f) {
                    for (uint32_t i = 0; i < motionEntry->pointerCount; i++) {
                        scaledCoords[i] = motionEntry->pointerCoords[i];
                        scaledCoords[i].scale(globalScaleFactor, wxs, wys);
                    }
                    usingCoords = scaledCoords;
                }
            } else {
                xOffset = 0.0f;
                yOffset = 0.0f;

                // We don't want the dispatch target to know.
                if (dispatchEntry->targetFlags & InputTarget::FLAG_ZERO_COORDS) {
                    for (uint32_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, motionEntry->displayId,
                    dispatchEntry->resolvedAction, motionEntry->actionButton,
                    dispatchEntry->resolvedFlags, motionEntry->edgeFlags,
                    motionEntry->metaState, motionEntry->buttonState, motionEntry->classification,
                    xOffset, yOffset, motionEntry->xPrecision, motionEntry->yPrecision,
                    motionEntry->downTime, motionEntry->eventTime,
                    motionEntry->pointerCount, motionEntry->pointerProperties,
                    usingCoords);
            break;
        }

        default:
            ALOG_ASSERT(false);
            return;
        }

        // Check the result.
        if (status) {
            if (status == WOULD_BLOCK) {
                if (connection->waitQueue.isEmpty()) {
                    ALOGE("channel '%s' ~ Could not publish event because the pipe is full. "
                            "This is unexpected because the wait queue is empty, so the pipe "
                            "should be empty and we shouldn't have any problems writing an "
                            "event to it, status=%d", connection->getInputChannelName().c_str(),
                            status);
                    abortBrokenDispatchCycleLocked(currentTime, connection, true /*notify*/);
                } else {
                    // Pipe is full and we are waiting for the app to finish process some events
                    // before sending more events to it.
#if DEBUG_DISPATCH_CYCLE
                    ALOGD("channel '%s' ~ Could not publish event because the pipe is full, "
                            "waiting for the application to catch up",
                            connection->getInputChannelName().c_str());
#endif
                    connection->inputPublisherBlocked = true;
                }
            } else {
                ALOGE("channel '%s' ~ Could not publish event due to an unexpected error, "
                        "status=%d", connection->getInputChannelName().c_str(), status);
                abortBrokenDispatchCycleLocked(currentTime, connection, true /*notify*/);
            }
            return;
        }

        // Re-enqueue the event on the wait queue.
        connection->outboundQueue.dequeue(dispatchEntry);
        traceOutboundQueueLength(connection);
        connection->waitQueue.enqueueAtTail(dispatchEntry);
        traceWaitQueueLength(connection);
    }
}

startDispatchCycleLocked会根据事件类型选择inputPublisher.publishKeyEvent和inputPublisher.publishMotionEvent,这两个方法将事件写入InputChannel通道中。这样ViewRootImpl端的InputChannel就可以通过socket获取到事件信息,然后在WindowInputEventReceiver中将事件传递到DecorView最后传到对应的View上。

在发送完毕后会将事件移出connection->outboundQueue队列,并放入到waitQueue等待队列中,等待事件处理完毕后再移出。

总结:ViewRootImpl的setView中,会调用WMS.addWindow,会先创建一对InputChannel,给到ViewRootImpl和IMS,InputChannel是由通过文件描述符fd创建的,并通过fd实现两个服务的进程通信。在InputDispatcher被唤醒后,InputDispatcher会遍历窗口数据,找到对应窗口的InputChannel,根据事件类型key或者motion封装输入事件,然后将事件通过InputChannel发送给WindowInputEventReceiver中处理,最后发送到对应的View中

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