本文主要是介绍Android11 InputDispatcher 分发事件流程分析，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
在 Android11 InputReader分析 一文中分析到，InputReader将数据放入iq队列后，唤醒InputDispatcher线程，执行InputDispatcher的dispatchOnce方法
//frameworks\native\services\inputflinger\dispatcher\InputDispatcher.cpp
void InputDispatcher::dispatchOnce() {nsecs_t nextWakeupTime = LONG_LONG_MAX;{ // acquire lockstd::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()) {//此时mCommandQueue中没有命令dispatchOnceInnerLocked(&nextWakeupTime);//1}// Run all pending commands if there are any.// If any commands were run then force the next poll to wake up immediately.if (runCommandsLockedInterruptible()) {//执行mCommandQueue中的命令nextWakeupTime = LONG_LONG_MIN;}//省略
}
继续调用注释1处的dispatchOnceInnerLocked进行处理
//frameworks\native\services\inputflinger\dispatcher\InputDispatcher.cpp
void InputDispatcher::dispatchOnceInnerLocked(nsecs_t* nextWakeupTime) {//省略if (!mPendingEvent) {//省略}else {// Inbound queue has at least one entry.mPendingEvent = mInboundQueue.front();//1mInboundQueue.pop_front();traceInboundQueueLengthLocked();}// Poke user activity for this event.if (mPendingEvent->policyFlags & POLICY_FLAG_PASS_TO_USER) {pokeUserActivityLocked(*mPendingEvent);//这个方法会向mCommandQueue中放入命令，后面在dispatchOnce中，调用 runCommandsLockedInterruptible执行这个命令，通过JNI调用，调用PowerManagerService的userActivityFromNative方法 }ALOG_ASSERT(mPendingEvent != nullptr);bool done = false;DropReason dropReason = DropReason::NOT_DROPPED;//标记事件是否需要抛弃掉，不传给应用窗口if (!(mPendingEvent->policyFlags & POLICY_FLAG_PASS_TO_USER)) {dropReason = DropReason::POLICY;} else if (!mDispatchEnabled) {dropReason = DropReason::DISABLED;}if (mNextUnblockedEvent == mPendingEvent) {mNextUnblockedEvent = nullptr;}switch (mPendingEvent->type) {//省略case EventEntry::Type::MOTION: {MotionEntry* typedEntry = static_cast<MotionEntry*>(mPendingEvent);if (dropReason == DropReason::NOT_DROPPED && isAppSwitchDue) {dropReason = DropReason::APP_SWITCH;}if (dropReason == DropReason::NOT_DROPPED && isStaleEvent(currentTime, *typedEntry)) {dropReason = DropReason::STALE;}if (dropReason == DropReason::NOT_DROPPED && mNextUnblockedEvent) {dropReason = DropReason::BLOCKED;}done = dispatchMotionLocked(currentTime, typedEntry, &dropReason, nextWakeupTime);//2break;}//省略
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注释1处，先从iq队列中取出事件，对于触摸事件，调用注释2处的dispatchMotionLocked继续处理
//frameworks\native\services\inputflinger\dispatcher\InputDispatcher.cpp
bool InputDispatcher::dispatchMotionLocked(nsecs_t currentTime, MotionEntry* entry,DropReason* dropReason, nsecs_t* nextWakeupTime) {//省略bool isPointerEvent = entry->source & AINPUT_SOURCE_CLASS_POINTER;if (isPointerEvent) {// Pointer event. (eg. touchscreen)injectionResult =findTouchedWindowTargetsLocked(currentTime, *entry, inputTargets, nextWakeupTime,&conflictingPointerActions);//1}//省略dispatchEventLocked(currentTime, entry, inputTargets);//2return true;}
注释1处，InputDispatcher需要知道，输入事件应该派发给哪个窗口，所以需要找到目标窗口，将其放入inputTargets中，这个流程在文章的后面再分析。注释2处，查找到目标窗口后，调用dispatchEventLocked继续处理
//frameworks\native\services\inputflinger\dispatcher\InputDispatcher.cpp
void InputDispatcher::dispatchEventLocked(nsecs_t currentTime, EventEntry* eventEntry,const std::vector<InputTarget>& inputTargets) {pokeUserActivityLocked(*eventEntry);for (const InputTarget& inputTarget : inputTargets) {//遍历sp<Connection> connection =getConnectionLocked(inputTarget.inputChannel->getConnectionToken());//根据token取出connection if (connection != nullptr) {prepareDispatchCycleLocked(currentTime, connection, eventEntry, inputTarget);//继续处理} 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().c_str());}}}
}
遍历inputTargets查找到对应的connection ，然后使用prepareDispatchCycleLocked继续处理，在prepareDispatchCycleLocked方法中，对于支持触摸事件分离的窗口，则是直接调用enqueueDispatchEntriesLocked来处理
//frameworks\native\services\inputflinger\dispatcher\InputDispatcher.cpp
void InputDispatcher::enqueueDispatchEntriesLocked(nsecs_t currentTime,const sp<Connection>& connection,EventEntry* eventEntry,bool wasEmpty = connection->outboundQueue.empty();// 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);//放入队列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.empty()) {startDispatchCycleLocked(currentTime, connection);//分发}
}
首先是将事件放入oq队列，然后调用startDispatchCycleLocked继续处理
放入队列：
//frameworks\native\services\inputflinger\dispatcher\InputDispatcher.cpp
void InputDispatcher::enqueueDispatchEntryLocked(const sp<Connection>& connection,EventEntry* eventEntry,const InputTarget& inputTarget,int32_t dispatchMode) {//省略// Enqueue the dispatch entry.connection->outboundQueue.push_back(dispatchEntry.release());//放入队列traceOutboundQueueLength(connection);//这里就是能在trace中看到oq的原因}
startDispatchCycleLocked
//frameworks\native\services\inputflinger\dispatcher\InputDispatcher.cpp
void InputDispatcher::startDispatchCycleLocked(nsecs_t currentTime,const sp<Connection>& connection) {//省略while (connection->status == Connection::STATUS_NORMAL && !connection->outboundQueue.empty()) {DispatchEntry* dispatchEntry = connection->outboundQueue.front();//从oq中取出事件dispatchEntry->deliveryTime = currentTime;const nsecs_t timeout =getDispatchingTimeoutLocked(connection->inputChannel->getConnectionToken());dispatchEntry->timeoutTime = currentTime + timeout;// Publish the event.status_t status;EventEntry* eventEntry = dispatchEntry->eventEntry;switch (eventEntry->type) {//省略case EventEntry::Type::MOTION: {// Publish the motion event.status = connection->inputPublisher.publishMotionEvent(dispatchEntry->seq,dispatchEntry->resolvedEventId,motionEntry->deviceId, motionEntry->source,motionEntry->displayId, std::move(hmac),dispatchEntry->resolvedAction,motionEntry->actionButton,dispatchEntry->resolvedFlags,motionEntry->edgeFlags, motionEntry->metaState,motionEntry->buttonState,motionEntry->classification, xScale, yScale,xOffset, yOffset, motionEntry->xPrecision,motionEntry->yPrecision,motionEntry->xCursorPosition,motionEntry->yCursorPosition,motionEntry->downTime, motionEntry->eventTime,motionEntry->pointerCount,motionEntry->pointerProperties, usingCoords);//1reportTouchEventForStatistics(*motionEntry);break;}//省略// Re-enqueue the event on the wait queue.connection->outboundQueue.erase(std::remove(connection->outboundQueue.begin(),connection->outboundQueue.end(),dispatchEntry));traceOutboundQueueLength(connection);connection->waitQueue.push_back(dispatchEntry);//放入wq队列traceWaitQueueLength(connection);//这就是trace中可以看到wq的原因}
}
可以看出，该方法主要是从oq队列中取出事件，然后调用connection->inputPublisher的publishMotionEvent方法继续处理，处理完成后，将事件从oq队列中删除，并又添加到wq队列中。
connection的inputPublisher成员指向的是inputChannel，在Android 11 输入系统之InputDispatcher和应用窗口建立联系一文中分析到，使用inputChannel构造connection对象
//frameworks\native\services\inputflinger\dispatcher\Connection.cpp
Connection::Connection(const sp<InputChannel>& inputChannel, bool monitor,const IdGenerator& idGenerator): status(STATUS_NORMAL),inputChannel(inputChannel),monitor(monitor),inputPublisher(inputChannel),//初始化inputPublisherinputState(idGenerator) {}
继续来看InputChannel的publishMotionEvent方法
//frameworks\native\libs\input\InputTransport.cpp
status_t InputPublisher::publishMotionEvent(uint32_t seq, int32_t eventId, int32_t deviceId, int32_t source, int32_t displayId,std::array<uint8_t, 32> hmac, int32_t action, int32_t actionButton, int32_t flags,int32_t edgeFlags, int32_t metaState, int32_t buttonState,MotionClassification classification, float xScale, float yScale, float xOffset,float yOffset, float xPrecision, float yPrecision, float xCursorPosition,float yCursorPosition, nsecs_t downTime, nsecs_t eventTime, uint32_t pointerCount,const PointerProperties* pointerProperties, const PointerCoords* pointerCoords) {//省略InputMessage msg;msg.header.type = InputMessage::Type::MOTION;msg.body.motion.seq = seq;msg.body.motion.eventId = eventId;msg.body.motion.deviceId = deviceId;msg.body.motion.source = source;msg.body.motion.displayId = displayId;msg.body.motion.hmac = std::move(hmac);msg.body.motion.action = action;msg.body.motion.actionButton = actionButton;msg.body.motion.flags = flags;msg.body.motion.edgeFlags = edgeFlags;msg.body.motion.metaState = metaState;msg.body.motion.buttonState = buttonState;msg.body.motion.classification = classification;msg.body.motion.xScale = xScale;msg.body.motion.yScale = yScale;msg.body.motion.xOffset = xOffset;msg.body.motion.yOffset = yOffset;msg.body.motion.xPrecision = xPrecision;msg.body.motion.yPrecision = yPrecision;msg.body.motion.xCursorPosition = xCursorPosition;msg.body.motion.yCursorPosition = yCursorPosition;msg.body.motion.downTime = downTime;msg.body.motion.eventTime = eventTime;msg.body.motion.pointerCount = pointerCount;for (uint32_t i = 0; i < pointerCount; i++) {msg.body.motion.pointers[i].properties.copyFrom(pointerProperties[i]);msg.body.motion.pointers[i].coords.copyFrom(pointerCoords[i]);}return mChannel->sendMessage(&msg);
}
构建InputMessage ，然后调用其sendMessage方法，将数据发送出去
//frameworks\native\libs\input\InputTransport.cpp
status_t InputChannel::sendMessage(const InputMessage* msg) {const size_t msgLength = msg->size();InputMessage cleanMsg;msg->getSanitizedCopy(&cleanMsg);ssize_t nWrite;do {nWrite = ::send(mFd.get(), &cleanMsg, msgLength, MSG_DONTWAIT | MSG_NOSIGNAL);//1} while (nWrite == -1 && errno == EINTR);//省略
注释1处，向fd中写入数据，InputDispatcher就将数据分发出去了。
查找目标窗口的过程
前面提到，InputDispatcher通过findTouchedWindowTargetsLocked方法，来查找到目标窗口，从而决定事件应该分发给谁
//frameworks\native\services\inputflinger\dispatcher\InputDispatcher.cpp
int32_t InputDispatcher::findTouchedWindowTargetsLocked(nsecs_t currentTime,const MotionEntry& entry,std::vector<InputTarget>& inputTargets,nsecs_t* nextWakeupTime,bool* outConflictingPointerActions) {//省略bool newGesture = (maskedAction == AMOTION_EVENT_ACTION_DOWN ||maskedAction == AMOTION_EVENT_ACTION_SCROLL || isHoverAction);//有新手指触摸const bool isFromMouse = entry.source == AINPUT_SOURCE_MOUSE;bool wrongDevice = false;if (newGesture) {//省略tempTouchState.reset();//先清空tempTouchState，然后重新赋值tempTouchState.down = down;tempTouchState.deviceId = entry.deviceId;tempTouchState.source = entry.source;tempTouchState.displayId = displayId;isSplit = false;}//省略if (newGesture || (isSplit && maskedAction == AMOTION_EVENT_ACTION_POINTER_DOWN)) {//省略sp<InputWindowHandle> newTouchedWindowHandle =findTouchedWindowAtLocked(displayId, x, y, &tempTouchState,isDown /*addOutsideTargets*/, true /*addPortalWindows*/);//1//省略if (newTouchedWindowHandle != nullptr) {// Set target flags.int32_t targetFlags = InputTarget::FLAG_FOREGROUND | InputTarget::FLAG_DISPATCH_AS_IS;if (isSplit) {targetFlags |= InputTarget::FLAG_SPLIT;}if (isWindowObscuredAtPointLocked(newTouchedWindowHandle, x, y)) {targetFlags |= InputTarget::FLAG_WINDOW_IS_OBSCURED;} else if (isWindowObscuredLocked(newTouchedWindowHandle)) {targetFlags |= InputTarget::FLAG_WINDOW_IS_PARTIALLY_OBSCURED;}//省略tempTouchState.addOrUpdateWindow(newTouchedWindowHandle, targetFlags, pointerIds);//2}//省略for (const TouchedWindow& touchedWindow : tempTouchState.windows) {//3addWindowTargetLocked(touchedWindow.windowHandle, touchedWindow.targetFlags,touchedWindow.pointerIds, inputTargets);}}
}
注释1处通过findTouchedWindowAtLocked方法查找到InputWindowHandle，注释2处将改InputWindowHandle添加到TouchedWindow中，并添加到tempTouchState的windows集合。上面省略了部分代码，还有其他的满足条件的InputWindowHandle，也会添加进来。注释3处遍历tempTouchState的windows，取出其中的TouchedWindow调用addWindowTargetLocked，来填充inputTargets集合。
先来看看findTouchedWindowAtLocked方法是怎么查找到符合条件的InputWindowHandle
//frameworks\native\services\inputflinger\dispatcher\InputDispatcher.cpp
sp<InputWindowHandle> InputDispatcher::findTouchedWindowAtLocked(int32_t displayId, int32_t x,int32_t y, TouchState* touchState,bool addOutsideTargets,bool addPortalWindows) {//省略// Traverse windows from front to back to find touched window.const std::vector<sp<InputWindowHandle>> windowHandles = getWindowHandlesLocked(displayId);//1for (const sp<InputWindowHandle>& windowHandle : windowHandles) {//2const InputWindowInfo* windowInfo = windowHandle->getInfo();if (windowInfo->displayId == displayId) {int32_t flags = windowInfo->layoutParamsFlags;if (windowInfo->visible) {if (!(flags & InputWindowInfo::FLAG_NOT_TOUCHABLE)) {bool isTouchModal = (flags &(InputWindowInfo::FLAG_NOT_FOCUSABLE |InputWindowInfo::FLAG_NOT_TOUCH_MODAL)) == 0;if (isTouchModal || windowInfo->touchableRegionContainsPoint(x, y)) {int32_t portalToDisplayId = windowInfo->portalToDisplayId;//省略return windowHandle;//省略注释1处返回的InputWindowHandle集合是根据displayID从mWindowHandlesByDisplay中取出来的，mWindowHandlesByDisplay中的元素是SurfaceFlinger中，调用 updateInputWindowInfo方法，最后调用到InputDispatcher的updateWindowHandlesForDisplayLocked添加的。
注释2处遍历前面得到的InputWindowHandle集合，判断触摸的区域是否是在该InputWindowHandle，如果是，则返回该InputWindowHandle。
查找到InputWindowHandle后，就会将其加入到tempTouchState的windows集合中
//frameworks\native\services\inputflinger\dispatcher\TouchState.cpp
void TouchState::addOrUpdateWindow(const sp<InputWindowHandle>& windowHandle, int32_t targetFlags,BitSet32 pointerIds) {//省略TouchedWindow touchedWindow;//构建TouchedWindowtouchedWindow.windowHandle = windowHandle;touchedWindow.targetFlags = targetFlags;touchedWindow.pointerIds = pointerIds;windows.push_back(touchedWindow);//添加进windows集合
}
最后就是遍历windows集合，根据InputWindowHandle信息来填充inputTargets集合了
//frameworks\native\services\inputflinger\dispatcher\InputDispatcher.cpp
void InputDispatcher::addWindowTargetLocked(const sp<InputWindowHandle>& windowHandle,int32_t targetFlags, BitSet32 pointerIds,std::vector<InputTarget>& inputTargets) {//省略if (it == inputTargets.end()) {InputTarget inputTarget;sp<InputChannel> inputChannel = getInputChannelLocked(windowHandle->getToken());//取出inputChannel inputTarget.inputChannel = inputChannel;inputTarget.flags = targetFlags;inputTarget.globalScaleFactor = windowInfo->globalScaleFactor;inputTargets.push_back(inputTarget);//添加进集合it = inputTargets.end() - 1;}//省略
}
首先是根据windowHandle中的token，取出对应的inputChanel，然后根据inputChanel构造inputTarget并放入集合 中。这样inputTargets集合中就包含了一个个的inputTarget，而inputTarget就包含了窗口对应的inputChannel 信息。
总结
InputDispatcher所做的工作就是从iq队列中取出数据，然后找到目标窗口，进而找到目标窗口对应的connect，将数据放入connection的oq队列，后面取出oq队列的数据并将其通过fd发送出去。分发完成后，将数据移至wq队列。
流程图如下
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