4【Android 12】InputDispatcher分发事件
在Input相关服务的创建和启动中，我们知道了InputManager在start函数中会创建一个InputDispatcher对象，其内部有一个线程会循环调用InputDispatcher.dispatchOnce，实现InputDispatcher对事件的分发，那么我们以此为起点，分析一下InputDispatcher分发事件流程。
void InputDispatcher::dispatchOnce() {
nsecs_t nextWakeupTime = LONG_LONG_MAX;
{ // acquire lock
......
// Run a dispatch loop if there are no pending commands.
// The dispatch loop might enqueue commands to run afterwards.
if (!haveCommandsLocked()) {
dispatchOnceInnerLocked(&nextWakeupTime);
}
......
} // release lock
......
mLooper->pollOnce(timeoutMillis);
}
在之前的分析中，我们知道了InputDispatcher.dispatchOnce函数在分发完事件后，会调用Looper.pollOnce将当前线程挂起，后续InputReader的读取线程会将新的事件发送给InputDispatcher，并且唤醒InputDispatcher的分发线程，因此这里我们只需要分析InputDispatcher分发事件的流程即可，也就是InputDispatcher.dispatchOnceInnerLocked函数。
本文的侧重点在Motion事件的分发，因此以Motion事件的流程为例看一下整个流程：
可能需要提前了解的和输入窗口相关的类有：
1 InputDispatcher.dispatchOnceInnerLocked
void InputDispatcher::dispatchOnceInnerLocked(nsecs_t* nextWakeupTime) {
......
// Ready to start a new event.
// If we don't already have a pending event, go grab one.
if (!mPendingEvent) {
if (mInboundQueue.empty()) {
......
} else {
// 1.1 从事件队列中获取待处理的输入事件
// Inbound queue has at least one entry.
mPendingEvent = mInboundQueue.front();
mInboundQueue.pop_front();
traceInboundQueueLengthLocked();
}
......
}
......
switch (mPendingEvent->type) {
......
case EventEntry::Type::KEY: {
std::shared_ptr keyEntry = std::static_pointer_cast(mPendingEvent);
......
// 1.2 根据事件类型调用相应函数处理
done = dispatchKeyLocked(currentTime, keyEntry, &dropReason, nextWakeupTime);
break;
}
case EventEntry::Type::MOTION: {
......
// 1.2 根据事件类型调用相应函数处理
done = dispatchMotionLocked(currentTime, motionEntry, &dropReason, nextWakeupTime);
break;
}
......
}
......
}
1.1 从事件队列中获取待处理的输入事件
之前InputReader分发线程通过InputDispatcher.enqueueInboundEventLocked，向InputDispatcher.mInboundQueue加入了当前要处理的输入事件。假设当前没有等待处理的事件，那就从InputDispatcher.mInboundQueue取出一个EventEntry类型的事件赋值给mPendingEvent。
1.2 根据事件类型调用相应函数处理
判断mPendingEvent的类型，如果是Key事件则调用InputDispatcher.dispatchKeyLocked函数处理，如果是Motion事件则调用InputDispatcher.dispatchMotionLocked函数处理，当然还有其他类型的事件，这里我们主要分析这两种事件。
2 Key事件
bool InputDispatcher::dispatchKeyLocked(nsecs_t currentTime, std::shared_ptr entry,
DropReason* dropReason, nsecs_t* nextWakeupTime) {
// Preprocessing.
......
// Handle case where the policy asked us to try again later last time.
......
// Give the policy a chance to intercept the key.
......
// Clean up if dropping the event.
......
// Identify targets.
std::vector inputTargets;
InputEventInjectionResult injectionResult =
findFocusedWindowTargetsLocked(currentTime, *entry, inputTargets, nextWakeupTime);
if (injectionResult == InputEventInjectionResult::PENDING) {
return false;
}
setInjectionResult(*entry, injectionResult);
if (injectionResult != InputEventInjectionResult::SUCCEEDED) {
return true;
}
// Add monitor channels from event's or focused display.
addGlobalMonitoringTargetsLocked(inputTargets, getTargetDisplayId(*entry));
// Dispatch the key.
dispatchEventLocked(currentTime, entry, inputTargets);
return true;
}
1)、调用InputDispatcher.findFocusedWindowTargetsLocked寻找焦点窗口，将结果存放在inputTargets中。
2)、调用InputDispatcher.dispatchEventLocked继续分发事件，这个方法在处理Motion事件的时候也会用到，因此后续Motion事件分析完后再放到一起说。
那么本节我们重点分析InputDispatcher.findFocusedWindowTargetsLocked函数是如何寻找焦点窗口的。
InputEventInjectionResult InputDispatcher::findFocusedWindowTargetsLocked(
nsecs_t currentTime, const EventEntry& entry, std::vector& inputTargets,
nsecs_t* nextWakeupTime) {
std::string reason;
int32_t displayId = getTargetDisplayId(entry);
sp focusedWindowHandle = getFocusedWindowHandleLocked(displayId);
std::shared_ptr focusedApplicationHandle =
getValueByKey(mFocusedApplicationHandlesByDisplay, displayId);
// If there is no currently focused window and no focused application
// then drop the event.
if (focusedWindowHandle == nullptr && focusedApplicationHandle == nullptr) {
ALOGI("Dropping %s event because there is no focused window or focused application in "
"display %" PRId32 ".",
NamedEnum::string(entry.type).c_str(), displayId);
return InputEventInjectionResult::FAILED;
}
// Compatibility behavior: raise ANR if there is a focused application, but no focused window.
// Only start counting when we have a focused event to dispatch. The ANR is canceled if we
// start interacting with another application via touch (app switch). This code can be removed
// if the "no focused window ANR" is moved to the policy. Input doesn't know whether
// an app is expected to have a focused window.
if (focusedWindowHandle == nullptr && focusedApplicationHandle != nullptr) {
if (!mNoFocusedWindowTimeoutTime.has_value()) {
// We just discovered that there's no focused window. Start the ANR timer
std::chrono::nanoseconds timeout = focusedApplicationHandle->getDispatchingTimeout(
DEFAULT_INPUT_DISPATCHING_TIMEOUT);
mNoFocusedWindowTimeoutTime = currentTime + timeout.count();
mAwaitedFocusedApplication = focusedApplicationHandle;
mAwaitedApplicationDisplayId = displayId;
ALOGW("Waiting because no window has focus but %s may eventually add a "
"window when it finishes starting up. Will wait for %" PRId64 "ms",
mAwaitedFocusedApplication->getName().c_str(), millis(timeout));
*nextWakeupTime = *mNoFocusedWindowTimeoutTime;
return InputEventInjectionResult::PENDING;
} else if (currentTime > *mNoFocusedWindowTimeoutTime) {
// Already raised ANR. Drop the event
ALOGE("Dropping %s event because there is no focused window",
NamedEnum::string(entry.type).c_str());
return InputEventInjectionResult::FAILED;
} else {
// Still waiting for the focused window
return InputEventInjectionResult::PENDING;
}
}
// we have a valid, non-null focused window
resetNoFocusedWindowTimeoutLocked();
// Check permissions.
......
// If the event is a key event, then we must wait for all previous events to
// complete before delivering it because previous events may have the
// side-effect of transferring focus to a different window and we want to
// ensure that the following keys are sent to the new window.
//
// Suppose the user touches a button in a window then immediately presses "A".
// If the button causes a pop-up window to appear then we want to ensure that
// the "A" key is delivered to the new pop-up window. This is because users
// often anticipate pending UI changes when typing on a keyboard.
// To obtain this behavior, we must serialize key events with respect to all
// prior input events.
if (entry.type == EventEntry::Type::KEY) {
if (shouldWaitToSendKeyLocked(currentTime, focusedWindowHandle->getName().c_str())) {
*nextWakeupTime = *mKeyIsWaitingForEventsTimeout;
return InputEventInjectionResult::PENDING;
}
}
// Success! Output targets.
addWindowTargetLocked(focusedWindowHandle,
InputTarget::FLAG_FOREGROUND | InputTarget::FLAG_DISPATCH_AS_IS,
BitSet32(0), inputTargets);
// Done.
return InputEventInjectionResult::SUCCEEDED;
}
1)、如果当前没有焦点Window和焦点Application，那么丢弃当前事件。
2)、如果当前只有焦点App，但是没有焦点Window，那么启动ANR计时并且开始等待，如果在规定时间内没有找到一个焦点Window，那么此时已经发生了ANR，寻找失败；如果找到则继续往下执行，并且重置ANR计时。
3)、如果当前事件是按键事件，那么必须等待之前所有的等待处理的事件完成，因为如果之前的事件引起了窗口切换，那么我们希望将当前事件能够传递到切换后的新窗口。
4)、调用InputDispatcher.addWindowTargetLocked将焦点窗口添加到inputTargets中，这个方法在处理Motion事件的时候也会用到，因此后续Motion事件分析完后再放到一起说。
从这里看到，焦点窗口的设置在其他地方，另一条线负责寻找焦点窗口并且保存焦点窗口，分发事件这条线只需要把之前保存的焦点窗口取出即可（如果有的话）。
3 Motion事件
bool InputDispatcher::dispatchMotionLocked(nsecs_t currentTime, std::shared_ptr entry,
DropReason* dropReason, nsecs_t* nextWakeupTime) {
......
// Identify targets.
std::vector inputTargets;
bool conflictingPointerActions = false;
InputEventInjectionResult 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);
}
......
dispatchEventLocked(currentTime, entry, inputTargets);
return true;
}
1)、初始化一个InputTargets队列，通过InputDispatcher.findTouchedWindowTargetsLocked来往该队列填充数据。
2)、调用InputDispatcher.dispatchEventLocked继续分发，这个函数在处理Key的时候也用到了，在分析完InputDispatcher.findTouchedWindowTargetsLocked之后再说明。
因此本节重点分析InputDispatcher.findTouchedWindowTargetsLocked的内容：
InputEventInjectionResult InputDispatcher::findTouchedWindowTargetsLocked(
nsecs_t currentTime, const MotionEntry& entry, std::vector& inputTargets,
nsecs_t* nextWakeupTime, bool* outConflictingPointerActions) {
......
// Copy current touch state into tempTouchState.
// This state will be used to update mTouchStatesByDisplay at the end of this function.
// If no state for the specified display exists, then our initial state will be empty.
const TouchState* oldState = nullptr;
TouchState tempTouchState;
std::unordered_map::iterator oldStateIt =
mTouchStatesByDisplay.find(displayId);
// 3.1.1 获取上一次寻找的结果
if (oldStateIt != mTouchStatesByDisplay.end()) {
oldState = &(oldStateIt->second);
tempTouchState.copyFrom(*oldState);
}
......
bool newGesture = (maskedAction == AMOTION_EVENT_ACTION_DOWN ||
maskedAction == AMOTION_EVENT_ACTION_SCROLL || isHoverAction);
const bool isFromMouse = entry.source == AINPUT_SOURCE_MOUSE;
bool wrongDevice = false;
if (newGesture) {
......
// 3.1.2 重置tempTouchState
tempTouchState.reset();
tempTouchState.down = down;
tempTouchState.deviceId = entry.deviceId;
tempTouchState.source = entry.source;
tempTouchState.displayId = displayId;
isSplit = false;
} else if (switchedDevice && maskedAction == AMOTION_EVENT_ACTION_MOVE) {
......
}
if (newGesture || (isSplit && maskedAction == AMOTION_EVENT_ACTION_POINTER_DOWN)) {
/* Case 1: New splittable pointer going down, or need target for hover or scroll. */
......
// 3.2.1 InputDispatcher.findTouchedWindowAtLocked寻找可接收触摸事件的窗口
newTouchedWindowHandle =
findTouchedWindowAtLocked(displayId, x, y, &tempTouchState,
isDown /*addOutsideTargets*/, true /*addPortalWindows*/);
// 检验newTouchedWindowHandle的有效性
......
// 3.2.2 添加窗口Flag
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;
}
// Update hover state.
......
// Update the temporary touch state.
......
tempTouchState.addOrUpdateWindow(newTouchedWindowHandle, targetFlags, pointerIds);
}
tempTouchState.addGestureMonitors(newGestureMonitors);
} else {
/* Case 2: Pointer move, up, cancel or non-splittable pointer down. */
......
// 3.3 寻找触摸窗口——非DOWN事件的处理
// Check whether touches should slip outside of the current foreground window.
if (maskedAction == AMOTION_EVENT_ACTION_MOVE && entry.pointerCount == 1 &&
tempTouchState.isSlippery()) {
int32_t x = int32_t(entry.pointerCoords[0].getAxisValue(AMOTION_EVENT_AXIS_X));
int32_t y = int32_t(entry.pointerCoords[0].getAxisValue(AMOTION_EVENT_AXIS_Y));
sp oldTouchedWindowHandle =
tempTouchState.getFirstForegroundWindowHandle();
newTouchedWindowHandle = findTouchedWindowAtLocked(displayId, x, y, &tempTouchState);
if (oldTouchedWindowHandle != newTouchedWindowHandle &&
oldTouchedWindowHandle != nullptr && newTouchedWindowHandle != nullptr) {
if (DEBUG_FOCUS) {
ALOGD("Touch is slipping out of window %s into window %s in display %" PRId32,
oldTouchedWindowHandle->getName().c_str(),
newTouchedWindowHandle->getName().c_str(), displayId);
}
// Make a slippery exit from the old window.
tempTouchState.addOrUpdateWindow(oldTouchedWindowHandle,
InputTarget::FLAG_DISPATCH_AS_SLIPPERY_EXIT,
BitSet32(0));
// Make a slippery entrance into the new window.
if (newTouchedWindowHandle->getInfo()->supportsSplitTouch()) {
isSplit = true;
}
int32_t targetFlags =
InputTarget::FLAG_FOREGROUND | InputTarget::FLAG_DISPATCH_AS_SLIPPERY_ENTER;
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;
}
BitSet32 pointerIds;
if (isSplit) {
pointerIds.markBit(entry.pointerProperties[0].id);
}
tempTouchState.addOrUpdateWindow(newTouchedWindowHandle, targetFlags, pointerIds);
}
}
}
......
// 3.4 进行必要检查
// Check permission to inject into all touched foreground windows and ensure there
// is at least one touched foreground window.
{
bool haveForegroundWindow = false;
for (const TouchedWindow& touchedWindow : tempTouchState.windows) {
if (touchedWindow.targetFlags & InputTarget::FLAG_FOREGROUND) {
haveForegroundWindow = true;
if (!checkInjectionPermission(touchedWindow.windowHandle, entry.injectionState)) {
injectionResult = InputEventInjectionResult::PERMISSION_DENIED;
injectionPermission = INJECTION_PERMISSION_DENIED;
goto Failed;
}
}
}
bool hasGestureMonitor = !tempTouchState.gestureMonitors.empty();
if (!haveForegroundWindow && !hasGestureMonitor) {
ALOGI("Dropping event because there is no touched foreground window in display "
"%" PRId32 " or gesture monitor to receive it.",
displayId);
injectionResult = InputEventInjectionResult::FAILED;
goto Failed;
}
// Permission granted to injection into all touched foreground windows.
injectionPermission = INJECTION_PERMISSION_GRANTED;
}
// Check whether windows listening for outside touches are owned by the same UID. If it is
// set the policy flag that we will not reveal coordinate information to this window.
......
// If this is the first pointer going down and the touched window has a wallpaper
// then also add the touched wallpaper windows so they are locked in for the duration
// of the touch gesture.
// We do not collect wallpapers during HOVER_MOVE or SCROLL because the wallpaper
// engine only supports touch events. We would need to add a mechanism similar
// to View.onGenericMotionEvent to enable wallpapers to handle these events.
......
// Success! Output targets.
injectionResult = InputEventInjectionResult::SUCCEEDED;
// 3.5 通过addWindowTargetLocked将tempTouchState的结果传给inputTargets
for (const TouchedWindow& touchedWindow : tempTouchState.windows) {
addWindowTargetLocked(touchedWindow.windowHandle, touchedWindow.targetFlags,
touchedWindow.pointerIds, inputTargets);
}
for (const TouchedMonitor& touchedMonitor : tempTouchState.gestureMonitors) {
addMonitoringTargetLocked(touchedMonitor.monitor, touchedMonitor.xOffset,
touchedMonitor.yOffset, inputTargets);
}
// 3.1.4 裁剪tempTouchState
// Drop the outside or hover touch windows since we will not care about them
// in the next iteration.
tempTouchState.filterNonAsIsTouchWindows();
Failed:
// Check injection permission once and for all.
......
// Update final pieces of touch state if the injector had permission.
if (!wrongDevice) {
......
// 3.1.3 保存tempTouchState到mTouchStatesByDisplay
// Save changes unless the action was scroll in which case the temporary touch
// state was only valid for this one action.
if (maskedAction != AMOTION_EVENT_ACTION_SCROLL) {
if (tempTouchState.displayId >= 0) {
mTouchStatesByDisplay[displayId] = tempTouchState;
} else {
mTouchStatesByDisplay.erase(displayId);
}
}
// Update hover state.
mLastHoverWindowHandle = newHoverWindowHandle;
}
return injectionResult;
}
这个函数很长，接下来将这个函数分成以下几部分依次分析：
3.1 tempTouchState作用。
3.2 寻找Motion窗口——DOWN事件的处理。
3.3 寻找Motion窗口——非DOWN事件的处理。
3.4 进行必要检查
3.5 通过addWindowTargetLocked将tempTouchState的结果传给inputTargets。
3.1 tempTouchState作用
在函数的开始创建了一个TouchState类型的tempTouchState：
// Copy current touch state into tempTouchState.
// This state will be used to update mTouchStatesByDisplay at the end of this function.
// If no state for the specified display exists, then our initial state will be empty.
const TouchState* oldState = nullptr;
TouchState tempTouchState;
TouchState是一个显示设备可以接收Motion事件的窗口合集，它有一个窗口队列windows用来保存当前display中所有可以接收Motion事件的窗口：
int32_t displayId; // id to the display that currently has a touch, others are rejected
std::vector windows;
......
std::vector gestureMonitors;
InputDispatcher.findTouchedWindowTargetsLocked函数的最终目的是将所有可以接收当前输入事件的窗口加入到InputTargets，而我们需要提前将相关窗口信息收集到这里创建的TouchState类型的tempTouchState中，最后再将tempTouchState的结果赋值给inputTargets，接下来分析为什么要创建一个中间商tempTouchState。
3.1.1 获取上一次寻找的结果
每次开始寻找Motion窗口前，都先将从mTouchStatesByDisplay处获得的oldStated拷贝给tempTouchState。
// Copy current touch state into tempTouchState.
// This state will be used to update mTouchStatesByDisplay at the end of this function.
// If no state for the specified display exists, then our initial state will be empty.
const TouchState* oldState = nullptr;
TouchState tempTouchState;
std::unordered_map::iterator oldStateIt =
mTouchStatesByDisplay.find(displayId);
if (oldStateIt != mTouchStatesByDisplay.end()) {
oldState = &(oldStateIt->second);
tempTouchState.copyFrom(*oldState);
}
InputDispatcher有一个mTouchStatesByDisplay的Map：
std::unordered_map mTouchStatesByDisplay GUARDED_BY(mLock);
用来储存一个displayId和与其对应的TouchState对象。
稍后我们可以看到，在该函数的最后，会把tempTouchState的结果保存到mTouchStatesByDisplay中，因此在函数的开始，tempTouchstate是获取到了上一次寻找的结果。
3.1.2 重置tempTouchState
如果当前这一系列事件的起点，如ACTION_DOWN，那么此次不会复用上一次的结果，并且会清除掉之前保存的状态：
bool newGesture = (maskedAction == AMOTION_EVENT_ACTION_DOWN ||
maskedAction == AMOTION_EVENT_ACTION_SCROLL || isHoverAction);
......
if (newGesture) {
......
tempTouchState.reset();
tempTouchState.down = down;
tempTouchState.deviceId = entry.deviceId;
tempTouchState.source = entry.source;
tempTouchState.displayId = displayId;
isSplit = false;
}
很好理解，上一系列Motion事件和本系列Motion事件是完全独立的，上一系列Motion事件不应该影响到本次Motion事件中寻找可接收输入事件窗口的结果。
3.1.3 保存tempTouchState到mTouchStatesByDisplay
// Save changes unless the action was scroll in which case the temporary touch
// state was only valid for this one action.
if (maskedAction != AMOTION_EVENT_ACTION_SCROLL) {
if (tempTouchState.displayId >= 0) {
mTouchStatesByDisplay[displayId] = tempTouchState;
} else {
mTouchStatesByDisplay.erase(displayId);
}
}
这样做的是为了下一次再进到这个函数时，直接取上一次执行后的结果，不需要再去遍历所有的窗口寻找可以接收当前输入事件的窗口了。
很好理解，我们在DOWN的时候遍历所有窗口，找到了所有可以接收当前输入事件的窗口，那么在后续的MOVE、UP等事件的时候，遍历窗口的工作没必要再重复做了。
3.1.4 裁剪tempTouchState
tempTouchState中保存了我们寻找所有可以接收Motion事件的窗口信息，然后在函数的最后，会对tempTouchState进行一些裁剪:
// Drop the outside or hover touch windows since we will not care about them
// in the next iteration.
tempTouchState.filterNonAsIsTouchWindows();
由TouchState.filterNonAsIsTouchWindows函数完成：
void TouchState::filterNonAsIsTouchWindows() {
for (size_t i = 0; i < windows.size();) {
TouchedWindow& window = windows[i];
if (window.targetFlags &
(InputTarget::FLAG_DISPATCH_AS_IS | InputTarget::FLAG_DISPATCH_AS_SLIPPERY_ENTER)) {
window.targetFlags &= ~InputTarget::FLAG_DISPATCH_MASK;
window.targetFlags |= InputTarget::FLAG_DISPATCH_AS_IS;
i += 1;
} else {
windows.erase(windows.begin() + i);
}
}
}
将那些没有FLAG_DISPATCH_AS_IS和nputTarget::FLAG_DISPATCH_AS_SLIPPERY_ENTER这两个flag的窗口从tempTouchState中移除。
这些flag定义在InputTarget.h中，这里用到的比较重要的有：
/* This flag indicates that the event is being delivered to a foreground application. */
FLAG_FOREGROUND = 1 << 0,
FLAG_FOREGROUND，声明事件正在被发送给一个前台App。
/* This flag indicates that the event should be sent as is.
* Should always be set unless the event is to be transmuted. */
FLAG_DISPATCH_AS_IS = 1 << 8,
FLAG_DISPATCH_AS_IS，声明事件应该按原样发送。应该总是设置，除非事件被转化。
这部分需要结合下面的分析才能理解。
3.2 寻找Motion窗口——DOWN事件的处理
3.2.1 InputDispatcher.findTouchedWindowAtLocked寻找可接收Motion事件的窗口
每次开启新的Motion事件时，用InputDispatcher.findTouchedWindowAtLocked去寻找一个可以接收touch事件的Window：
bool newGesture = (maskedAction == AMOTION_EVENT_ACTION_DOWN ||
maskedAction == AMOTION_EVENT_ACTION_SCROLL || isHoverAction);
......
if (newGesture || (isSplit && maskedAction == AMOTION_EVENT_ACTION_POINTER_DOWN)) {
/* Case 1: New splittable pointer going down, or need target for hover or scroll. */
......
newTouchedWindowHandle =
findTouchedWindowAtLocked(displayId, x, y, &tempTouchState,
isDown /*addOutsideTargets*/, true /*addPortalWindows*/);
......
}
这里传入了当前touch事件的坐标，以及tempTouchState。
sp InputDispatcher::findTouchedWindowAtLocked(int32_t displayId, int32_t x,
int32_t y, TouchState* touchState,
bool addOutsideTargets,
bool addPortalWindows,
bool ignoreDragWindow) {
if ((addPortalWindows || addOutsideTargets) && touchState == nullptr) {
LOG_ALWAYS_FATAL(
"Must provide a valid touch state if adding portal windows or outside targets");
}
// Traverse windows from front to back to find touched window.
const std::vector>& windowHandles = getWindowHandlesLocked(displayId);
for (const sp& windowHandle : windowHandles) {
if (ignoreDragWindow && haveSameToken(windowHandle, mDragState->dragWindow)) {
continue;
}
const InputWindowInfo* windowInfo = windowHandle->getInfo();
if (windowInfo->displayId == displayId) {
auto flags = windowInfo->flags;
if (windowInfo->visible) {
if (!flags.test(InputWindowInfo::Flag::NOT_TOUCHABLE)) {
bool isTouchModal = !flags.test(InputWindowInfo::Flag::NOT_FOCUSABLE) &&
!flags.test(InputWindowInfo::Flag::NOT_TOUCH_MODAL);
if (isTouchModal || windowInfo->touchableRegionContainsPoint(x, y)) {
int32_t portalToDisplayId = windowInfo->portalToDisplayId;
if (portalToDisplayId != ADISPLAY_ID_NONE &&
portalToDisplayId != displayId) {
if (addPortalWindows) {
// For the monitoring channels of the display.
touchState->addPortalWindow(windowHandle);
}
return findTouchedWindowAtLocked(portalToDisplayId, x, y, touchState,
addOutsideTargets, addPortalWindows);
}
// Found window.
return windowHandle;
}
}
if (addOutsideTargets && flags.test(InputWindowInfo::Flag::WATCH_OUTSIDE_TOUCH)) {
touchState->addOrUpdateWindow(windowHandle,
InputTarget::FLAG_DISPATCH_AS_OUTSIDE,
BitSet32(0));
}
}
}
}
return nullptr;
}
这里通过InputDispatcher.getWindowHandlesLocked得到当前所有窗口信息，窗口信息保存在：
std::unordered_map>> mWindowHandlesByDisplay
GUARDED_BY(mLock);
该全局变量保存了所有display和每一个display下所有的窗口，通过InputDispatcher.updateWindowHandlesForDisplayLocked来更新，以后也许另开一篇详细说明。
findTouchedWindowAtLocked函数通过遍历所有窗口，寻找可以接收输入事件的窗口，需要满足以下条件：
1)、当前窗口必须是可见的。
2)、当前窗口不能包含InputWindowInfo::Flag::NOT_TOUCHABLE，设置了这个flag的窗口不能接收Motion事件。
3.1)、当前窗口不能包含InputWindowInfo::Flag::NOT_FOCUSABLE和InputWindowInfo::Flag::NOT_TOUCH_MODAL两个flag，如果某个窗口没有NOT_TOUCH_MODAL这个flag，表示这个窗口将会消费掉所有坐标事件，无论这些事件是否落在了这个窗口区域里面。
或者
3.2)、当前输入事件的坐标落在在当前窗口的Motion区域里，那么返回当前窗口。
特殊情况是：如果当前窗口包含InputWindowInfo::Flag::WATCH_OUTSIDE_TOUCH，那么直接调用TouchState.addOrUpdateWindow将当前窗口添加到tempTouchState中，但是这个窗口无法接收到完整的down/move/up手势，只会在down的时候接收到一次MotionEvent.ACTION_OUTSIDE事件。
3.2.2 添加窗口Flag
上面找到了一个符合条件的目标窗口后，没有直接通过TouchState.addOrUpdateWindow将找到的符合条件的InputWindowHandle添加到tempTouchState中，而是返回了一个InputWindowHandle并且赋值给newTouchedWindowHandle，是因为我们还想对这个符合条件的InputWindowHandle对象添加一些额外的flag：
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;
}
// Update hover state.
if (maskedAction == AMOTION_EVENT_ACTION_HOVER_EXIT) {
newHoverWindowHandle = nullptr;
} else if (isHoverAction) {
newHoverWindowHandle = newTouchedWindowHandle;
}
// Update the temporary touch state.
BitSet32 pointerIds;
if (isSplit) {
uint32_t pointerId = entry.pointerProperties[pointerIndex].id;
pointerIds.markBit(pointerId);
}
tempTouchState.addOrUpdateWindow(newTouchedWindowHandle, targetFlags, pointerIds);
}
这里为找到的Motion窗口添加了两个重要的flag：
InputTarget::FLAG_FOREGROUND | InputTarget::FLAG_DISPATCH_AS_IS
最后，再通过TouchState.addOrUpdateWindow将newTouchedWindowHandle带着这些设置的flag添加到tempTouchState中：
void TouchState::addOrUpdateWindow(const sp& windowHandle, int32_t targetFlags,
BitSet32 pointerIds) {
......
TouchedWindow touchedWindow;
touchedWindow.windowHandle = windowHandle;
touchedWindow.targetFlags = targetFlags;
touchedWindow.pointerIds = pointerIds;
const InputWindowInfo* windowInfo = windowHandle->getInfo();
windows.push_back(touchedWindow);
}
这个函数内容很简单，创建一个TouchWindow对象，整合之前的所有信息，然后加入到tempTouchState的windows队列中。
根据我们在3.1.1.4中对调用TouchState.filterNonAsIsTouchWindows的分析，只有这里对找到的Motion窗口加上FLAG_DISPATCH_AS_IS，这个窗口才不会在TouchState.filterNonAsIsTouchWindows中过滤掉。
与此对应的是，在findTouchedWindowAtLocked函数中，我们也会把声明了InputWindowInfo::Flag::WATCH_OUTSIDE_TOUCH的窗口通过addOrUpdateWindow函数添加到tempTouchState，但是这个窗口在添加的时候只加了 InputTarget::FLAG_DISPATCH_AS_OUTSIDE这一个flag，那么后续这个窗口只会在DOWN的时候收到一次事件（收到的还是outside事件，而不是down事件），后续不会再接收到事件，因此该窗口会在函数的最后被TouchState.filterNonAsIsTouchWindows从tempTouchState中移除。
3.3 寻找Motion窗口——非DOWN事件的处理
/* Case 2: Pointer move, up, cancel or non-splittable pointer down. */
// If the pointer is not currently down, then ignore the event.
......
// Check whether touches should slip outside of the current foreground window.
if (maskedAction == AMOTION_EVENT_ACTION_MOVE && entry.pointerCount == 1 &&
tempTouchState.isSlippery()) {
int32_t x = int32_t(entry.pointerCoords[0].getAxisValue(AMOTION_EVENT_AXIS_X));
int32_t y = int32_t(entry.pointerCoords[0].getAxisValue(AMOTION_EVENT_AXIS_Y));
sp oldTouchedWindowHandle =
tempTouchState.getFirstForegroundWindowHandle();
newTouchedWindowHandle = findTouchedWindowAtLocked(displayId, x, y, &tempTouchState);
if (oldTouchedWindowHandle != newTouchedWindowHandle &&
oldTouchedWindowHandle != nullptr && newTouchedWindowHandle != nullptr) {
if (DEBUG_FOCUS) {
ALOGI("Touch is slipping out of window %s into window %s in display %" PRId32,
oldTouchedWindowHandle->getName().c_str(),
newTouchedWindowHandle->getName().c_str(), displayId);
}
// Make a slippery exit from the old window.
tempTouchState.addOrUpdateWindow(oldTouchedWindowHandle,
InputTarget::FLAG_DISPATCH_AS_SLIPPERY_EXIT,
BitSet32(0));
// Make a slippery entrance into the new window.
if (newTouchedWindowHandle->getInfo()->supportsSplitTouch()) {
isSplit = true;
}
int32_t targetFlags =
InputTarget::FLAG_FOREGROUND | InputTarget::FLAG_DISPATCH_AS_SLIPPERY_ENTER;
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;
}
BitSet32 pointerIds;
if (isSplit) {
pointerIds.markBit(entry.pointerProperties[0].id);
}
tempTouchState.addOrUpdateWindow(newTouchedWindowHandle, targetFlags, pointerIds);
}
}
这个流程的主要内容是处理一种特殊情况：
1)、当前是MOVE事件。
2)、当前只有单点触摸屏幕。
3)、当前的前台窗口中有设置InputWindowInfo::Flag::SLIPPERY这个flag。
当这3个条件同时满足的时候，会重新调用InputDispatcher.findTouchedWindowAtLocked去重新寻找一个可以接收当前输入事件的窗口，如果找到一个不同的窗口newTouchedWindowHandle（其他函数里可能会通过TouchState.addOrUpdateWindow向tempTouchState.windows中添加窗口，如InputDispatcher.transferTouchFocus），那么会通过：
// Make a slippery exit from the old window.
tempTouchState.addOrUpdateWindow(oldTouchedWindowHandle,
InputTarget::FLAG_DISPATCH_AS_SLIPPERY_EXIT,
BitSet32(0));
把旧的前台窗口oldTouchedWindowHandle从tempTouchState移除掉。
将oldTouchedWindowHandle从tempTouchState移除掉，是通过调用TouchState.addOrUpdateWindow，传入InputTarget::FLAG_DISPATCH_AS_SLIPPERY_EXIT这个flag：
void TouchState::addOrUpdateWindow(const sp& windowHandle, int32_t targetFlags,
BitSet32 pointerIds) {
if (targetFlags & InputTarget::FLAG_SPLIT) {
split = true;
}
for (size_t i = 0; i < windows.size(); i++) {
TouchedWindow& touchedWindow = windows[i];
if (touchedWindow.windowHandle == windowHandle) {
touchedWindow.targetFlags |= targetFlags;
if (targetFlags & InputTarget::FLAG_DISPATCH_AS_SLIPPERY_EXIT) {
touchedWindow.targetFlags &= ~InputTarget::FLAG_DISPATCH_AS_IS;
}
touchedWindow.pointerIds.value |= pointerIds.value;
return;
}
}
TouchedWindow touchedWindow;
touchedWindow.windowHandle = windowHandle;
touchedWindow.targetFlags = targetFlags;
touchedWindow.pointerIds = pointerIds;
const InputWindowInfo* windowInfo = windowHandle->getInfo();
windows.push_back(touchedWindow);
}
在这里，由于检测到了InputTarget::FLAG_DISPATCH_AS_SLIPPERY_EXIT，会把oldTouchedWindowHandle的InputTarget::FLAG_DISPATCH_AS_IS这个flag去除掉，那么这旧前台窗口后续会因为函数最后调用TouchState.filterNonAsIsTouchWindows而被移除掉。
int32_t targetFlags =
InputTarget::FLAG_FOREGROUND | InputTarget::FLAG_DISPATCH_AS_SLIPPERY_ENTER;
......
tempTouchState.addOrUpdateWindow(newTouchedWindowHandle, targetFlags, pointerIds);
最后重新找到的窗口newTouchedWindowHandle会添加到tempTouchState，只不过这次添加的flag是：
InputTarget::FLAG_FOREGROUND | InputTarget::FLAG_DISPATCH_AS_SLIPPERY_ENTER
对比之前添加的是：
InputTarget::FLAG_FOREGROUND | InputTarget::FLAG_DISPATCH_AS_IS
FLAG_DISPATCH_AS_SLIPPERY_ENTER的定义是：
/* This flag indicates that the event should be dispatched as an initial down.
* It is used to transmute ACTION_MOVE into ACTION_DOWN when a touch slips
* into a new window. */
FLAG_DISPATCH_AS_SLIPPERY_ENTER = 1 << 13,
因为我们是在ACTION_MOVE的情况下检测到新的前台窗口，为了让前台窗口能接收到一次完整的Motion事件，需要将此次事件转化为ACTION_MOVE转化为ACTION_DOWN。
遇到过一次这种情况：
点击了一个设置了InputWindowInfo::Flag::SLIPPERY的窗口A，然后在抬起之前，触摸过程中，系统添加了一个窗口B（或者窗口B由原来的不可见变为可见），窗口B由于层级高于窗口A，导致findTouchedWindowAtLocked这里返回了窗口B，后续改为由窗口B接收输入事件，窗口A无法再接收到输入事件。
3.4 进行必要检查
挑一处我认为比较重要的地方分析：
// Check permission to inject into all touched foreground windows and ensure there
// is at least one touched foreground window.
{
bool haveForegroundWindow = false;
for (const TouchedWindow& touchedWindow : tempTouchState.windows) {
if (touchedWindow.targetFlags & InputTarget::FLAG_FOREGROUND) {
haveForegroundWindow = true;
if (!checkInjectionPermission(touchedWindow.windowHandle, entry.injectionState)) {
injectionResult = InputEventInjectionResult::PERMISSION_DENIED;
injectionPermission = INJECTION_PERMISSION_DENIED;
goto Failed;
}
}
}
bool hasGestureMonitor = !tempTouchState.gestureMonitors.empty();
if (!haveForegroundWindow && !hasGestureMonitor) {
ALOGI("Dropping event because there is no touched foreground window in display "
"%" PRId32 " or gesture monitor to receive it.",
displayId);
injectionResult = InputEventInjectionResult::FAILED;
goto Failed;
}
// Permission granted to injection into all touched foreground windows.
injectionPermission = INJECTION_PERMISSION_GRANTED;
}
检查当前是否至少有一个前台窗口或者gesture monitor可以接收当前输入事件，如果没有那么不传递本次事件，输出log：
ALOGI("Dropping event because there is no touched foreground window in display "
"%" PRId32 " or gesture monitor to receive it.",
displayId);
ANR有时候会打印这句log。
gesture monitor用来接收pointer事件，比如开启全面屏手势后，就会注册gesture monitor。
InputDispatcher.findTouchedWindowTargetsLocked中为触摸窗口添加InputTarget::FLAG_FOREGROUND的地方只有两处：
1)、在down流程中，当通过InputDispatcher.findTouchedWindowAtLocked找到了一个可以接收当前Motion事件的窗口时，为该其添加该flag。
2)、在move流程中的slippery情况。
情况2比较少见，主要是情况1。
想像这样一种情况，我们在Window1上滑动，然后可以通过adb命令去启动Window2，那么此时Window1会从tempTouchState.windows中移除，但是Window2也不会加上FLAG_FOREGROUND的flag，这会导致此时没有一个前台窗口来接收接下来的事件，导致事件分发流程直接在这里返回，不会再往下传递，那么不仅是所有窗口无法再接收到输入事件，我们注册的一些PointerEventListener也无法再接收到事件了（但仅仅是这样并不会发生ANR）。
3.5 通过addWindowTargetLocked将tempTouchState的结果传给inputTargets
for (const TouchedWindow& touchedWindow : tempTouchState.windows) {
addWindowTargetLocked(touchedWindow.windowHandle, touchedWindow.targetFlags,
touchedWindow.pointerIds, inputTargets);
}
for (const TouchedMonitor& touchedMonitor : tempTouchState.gestureMonitors) {
addMonitoringTargetLocked(touchedMonitor.monitor, touchedMonitor.xOffset,
touchedMonitor.yOffset, inputTargets);
}
// Drop the outside or hover touch windows since we will not care about them
// in the next iteration.
tempTouchState.filterNonAsIsTouchWindows();
函数的最后，通过InputDispatcher.addWindowTargetLocked完成inputTargets的赋值：
void InputDispatcher::addWindowTargetLocked(const sp& windowHandle,
int32_t targetFlags, BitSet32 pointerIds,
std::vector& inputTargets) {
std::vector::iterator it =
std::find_if(inputTargets.begin(), inputTargets.end(),
[&windowHandle](const InputTarget& inputTarget) {
return inputTarget.inputChannel->getConnectionToken() ==
windowHandle->getToken();
});
const InputWindowInfo* windowInfo = windowHandle->getInfo();
if (it == inputTargets.end()) {
InputTarget inputTarget;
std::shared_ptr inputChannel =
getInputChannelLocked(windowHandle->getToken());
if (inputChannel == nullptr) {
ALOGW("Window %s already unregistered input channel", windowHandle->getName().c_str());
return;
}
inputTarget.inputChannel = inputChannel;
inputTarget.flags = targetFlags;
inputTarget.globalScaleFactor = windowInfo->globalScaleFactor;
inputTarget.displaySize =
int2(windowHandle->getInfo()->displayWidth, windowHandle->getInfo()->displayHeight);
inputTargets.push_back(inputTarget);
it = inputTargets.end() - 1;
}
ALOG_ASSERT(it->flags == targetFlags);
ALOG_ASSERT(it->globalScaleFactor == windowInfo->globalScaleFactor);
it->addPointers(pointerIds, windowInfo->transform);
}
经过上面的一系列判断后，最终tempTouchState的windows队列保存了所有可以接收当前输入事件的窗口。不管是按键事件还是Motion事件，最终都是调用InputDispatcher.addWindowTargetLocked将这些窗口加入到了inputTargets中：
1)、首先检查当前焦点窗口是否已经加入到inputTargets，避免重复加入。
2)、如果inputTargets里还没有，那么根据焦点窗口的IBinder类型的token找到对应的InputChannel，然后根据该InputWindowHandle创建一个对应的InputTarget对象并添加到inputTargets中。之前有分析过，在为Server端和Client端创建InputChannel对的时候，会创建一个BBinder对象，并且将键值对
另外注意到裁剪的工作是在tempTouchState的结果传给inputTargets之后才做的，那么就说明本次搜索的结果有效，这些被裁剪的窗口在本次事件分发中仍然可以收到事件，要在下一轮分发的时候这些窗口才会被过滤掉。
4 InputDispatcher.dispatchEventLocked
void InputDispatcher::dispatchEventLocked(nsecs_t currentTime,
std::shared_ptr eventEntry,
const std::vector& inputTargets) {
......
for (const InputTarget& inputTarget : inputTargets) {
sp connection =
getConnectionLocked(inputTarget.inputChannel->getConnectionToken());
if (connection != nullptr) {
prepareDispatchCycleLocked(currentTime, connection, eventEntry, inputTarget);
} else {
......
}
}
}
上面无论是Key还是Motion，最后都在寻找完可以接收当前输入事件的窗口后，将寻找结果放到了inputTargets中，然后调用了InputDispatcher.dispatchEventLocked。该函数的主要工作是：
1)、遍历传入的inputTargets，调用InputDispatcher.prepareDispatchCycleLocked函数来分发事件，这里说明了对于一个输入事件来说，会传递给多个窗口进行处理。
2)、之前分析过，对于每一个服务端InputChannel，InputDispatcher都创建了一个Connection对象来保存这个InputChannel对象，这个Connection对象，可以通过IBinder类型的token来检索得到，那么这里便可以通过InputTarget的InputChannel对象中的token来得到持有服务端InputChannel的Connection对象。
5 InputDispatcher.prepareDispatchCycleLocked
void InputDispatcher::prepareDispatchCycleLocked(nsecs_t currentTime,
const sp& connection,
std::shared_ptr eventEntry,
const InputTarget& inputTarget) {
......
// Split a motion event if needed.
if (inputTarget.flags & InputTarget::FLAG_SPLIT) {
......
}
// Not splitting. Enqueue dispatch entries for the event as is.
enqueueDispatchEntriesLocked(currentTime, connection, eventEntry, inputTarget);
}
这个方法主要判断当前输入事件是否支持拆分，如果支持那么把当前事件拆分。
FLAG_SPLIT用来声明当前输入事件是否支持被拆分，分给多个窗口（遇到过一种情况，在平行视界下，同时在两侧的Activity界面下分别使用一根手指进行上下滑动）。
最终调用InputDispatcher.enqueueDispatchEntriesLocked继续进行分发。
6 InputDispatcher.enqueueDispatchEntriesLocked
void InputDispatcher::enqueueDispatchEntriesLocked(nsecs_t currentTime,
const sp& connection,
std::shared_ptr eventEntry,
const InputTarget& inputTarget) {
if (ATRACE_ENABLED()) {
std::string message =
StringPrintf("enqueueDispatchEntriesLocked(inputChannel=%s, id=0x%" PRIx32 ")",
connection->getInputChannelName().c_str(), eventEntry->id);
ATRACE_NAME(message.c_str());
}
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);
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);
}
}
1)、enqueueDispatchEntryLocked函数内容不再详细分析，大概的作用是，如果目标窗口设置了以下集中flag，表示目标窗口需要处理这类事件，那么就把输入事件封装为相应的DispatchEntry类型，加入到Connection.outBoundQueue队列中：
/* This flag indicates that the event should be sent as is.
* Should always be set unless the event is to be transmuted. */
FLAG_DISPATCH_AS_IS = 1 << 8,
/* This flag indicates that a MotionEvent with AMOTION_EVENT_ACTION_DOWN falls outside
* of the area of this target and so should instead be delivered as an
* AMOTION_EVENT_ACTION_OUTSIDE to this target. */
FLAG_DISPATCH_AS_OUTSIDE = 1 << 9,
/* This flag indicates that a hover sequence is starting in the given window.
* The event is transmuted into ACTION_HOVER_ENTER. */
FLAG_DISPATCH_AS_HOVER_ENTER = 1 << 10,
/* This flag indicates that a hover event happened outside of a window which handled
* previous hover events, signifying the end of the current hover sequence for that
* window.
* The event is transmuted into ACTION_HOVER_ENTER. */
FLAG_DISPATCH_AS_HOVER_EXIT = 1 << 11,
/* This flag indicates that the event should be canceled.
* It is used to transmute ACTION_MOVE into ACTION_CANCEL when a touch slips
* outside of a window. */
FLAG_DISPATCH_AS_SLIPPERY_EXIT = 1 << 12,
/* This flag indicates that the event should be dispatched as an initial down.
* It is used to transmute ACTION_MOVE into ACTION_DOWN when a touch slips
* into a new window. */
FLAG_DISPATCH_AS_SLIPPERY_ENTER = 1 << 13,
2)、如果Coonection.outBoundQueue队列之前为空，但是经过enqueueDispatchEntryLocked后不为空，那么调用InputDispatcher.startDispatchCycleLocked开始分发事件。
7 InputDispatcher.startDispatchCycleLocked
void InputDispatcher::startDispatchCycleLocked(nsecs_t currentTime,
const sp& connection) {
......
while (connection->status == Connection::STATUS_NORMAL && !connection->outboundQueue.empty()) {
......
switch (eventEntry.type) {
case EventEntry::Type::KEY: {
// 7.1 分发Key事件
const KeyEntry& keyEntry = static_cast(eventEntry);
std::array hmac = getSignature(keyEntry, *dispatchEntry);
// Publish the key event.
status = connection->inputPublisher
.publishKeyEvent(dispatchEntry->seq,
dispatchEntry->resolvedEventId, keyEntry.deviceId,
keyEntry.source, keyEntry.displayId,
std::move(hmac), dispatchEntry->resolvedAction,
dispatchEntry->resolvedFlags, keyEntry.keyCode,
keyEntry.scanCode, keyEntry.metaState,
keyEntry.repeatCount, keyEntry.downTime,
keyEntry.eventTime);
break;
}
case EventEntry::Type::MOTION: {
// 7.2 分发Motion事件
......
// 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,
dispatchEntry->transform,
motionEntry.xPrecision, motionEntry.yPrecision,
motionEntry.xCursorPosition,
motionEntry.yCursorPosition,
dispatchEntry->displaySize.x,
dispatchEntry->displaySize.y,
motionEntry.downTime, motionEntry.eventTime,
motionEntry.pointerCount,
motionEntry.pointerProperties, usingCoords);
break;
}
case EventEntry::Type::FOCUS: {
......
}
case EventEntry::Type::POINTER_CAPTURE_CHANGED: {
......
}
case EventEntry::Type::DRAG: {
......
}
case EventEntry::Type::CONFIGURATION_CHANGED:
case EventEntry::Type::DEVICE_RESET:
case EventEntry::Type::SENSOR: {
......
}
}
// Check the result.
......
}
}
这里循环遍历传入的Connection.outboundQueue，然后针对不同类型的事件，分别走相应的流程去处理，这里我们只关心KEY和MOTION两种类型。
7.1 分发Key事件
status_t InputPublisher::publishKeyEvent(uint32_t seq, int32_t eventId, int32_t deviceId,
int32_t source, int32_t displayId,
std::array hmac, int32_t action,
int32_t flags, int32_t keyCode, int32_t scanCode,
int32_t metaState, int32_t repeatCount, nsecs_t downTime,
nsecs_t eventTime) {
......
InputMessage msg;
msg.header.type = InputMessage::Type::KEY;
msg.header.seq = seq;
msg.body.key.eventId = eventId;
msg.body.key.deviceId = deviceId;
msg.body.key.source = source;
msg.body.key.displayId = displayId;
msg.body.key.hmac = std::move(hmac);
msg.body.key.action = action;
msg.body.key.flags = flags;
msg.body.key.keyCode = keyCode;
msg.body.key.scanCode = scanCode;
msg.body.key.metaState = metaState;
msg.body.key.repeatCount = repeatCount;
msg.body.key.downTime = downTime;
msg.body.key.eventTime = eventTime;
return mChannel->sendMessage(&msg);
}
把输入事件的信息重新封装到一个InputMessage类型的结构体中，然后调用InputChannel.sendMessage。
根据InputMessage结构体的注释，这是用于发送输入事件和相关信号的中间表示，用于IPC通信，通过socket发送。
7.2 分发Motion事件
status_t InputPublisher::publishMotionEvent(
uint32_t seq, int32_t eventId, int32_t deviceId, int32_t source, int32_t displayId,
std::array hmac, int32_t action, int32_t actionButton, int32_t flags,
int32_t edgeFlags, int32_t metaState, int32_t buttonState,
MotionClassification classification, const ui::Transform& transform, float xPrecision,
float yPrecision, float xCursorPosition, float yCursorPosition, int32_t displayWidth,
int32_t displayHeight, nsecs_t downTime, nsecs_t eventTime, uint32_t pointerCount,
const PointerProperties* pointerProperties, const PointerCoords* pointerCoords) {
......
InputMessage msg;
msg.header.type = InputMessage::Type::MOTION;
msg.header.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.dsdx = transform.dsdx();
msg.body.motion.dtdx = transform.dtdx();
msg.body.motion.dtdy = transform.dtdy();
msg.body.motion.dsdy = transform.dsdy();
msg.body.motion.tx = transform.tx();
msg.body.motion.ty = transform.ty();
msg.body.motion.xPrecision = xPrecision;
msg.body.motion.yPrecision = yPrecision;
msg.body.motion.xCursorPosition = xCursorPosition;
msg.body.motion.yCursorPosition = yCursorPosition;
msg.body.motion.displayWidth = displayWidth;
msg.body.motion.displayHeight = displayHeight;
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);
}
把输入事件的信息重新封装到一个InputMessage类型的结构体中，然后调用InputChannel.sendMessage。
8 InputChannel.sendMessage
status_t InputChannel::sendMessage(const InputMessage* msg) {
const size_t msgLength = msg->size();
InputMessage cleanMsg;
msg->getSanitizedCopy(&cleanMsg);
ssize_t nWrite;
do {
nWrite = ::send(getFd(), &cleanMsg, msgLength, MSG_DONTWAIT | MSG_NOSIGNAL);
} while (nWrite == -1 && errno == EINTR);
......
}
这里调用socket 的send函数向服务端InputChannel保存的socket文件描述符发送封装好的InputMessage信息。
之前我们分析过了ViewRootImpl#setView中会创建一个WindowInputEventReceiver对象，进而构建一个NativeInputEventReceiver对象，并且在初始化的过程中，会调用：
mMessageQueue->getLooper()->addFd(fd, 0, events, this, nullptr);
来对客户端InputChannel中保存的客户端socket文件描述符进行监听，如果服务端有数据写入那么就调用NativeInputEventReceiver.handleEvent回调，那么现在就是回调触发的时机。
9 NativeInputEventReceiver.handleEvent
int NativeInputEventReceiver::handleEvent(int receiveFd, int events, void* data) {
// Allowed return values of this function as documented in LooperCallback::handleEvent
......
if (events & ALOOPER_EVENT_INPUT) {
JNIEnv* env = AndroidRuntime::getJNIEnv();
status_t status = consumeEvents(env, false /*consumeBatches*/, -1, nullptr);
mMessageQueue->raiseAndClearException(env, "handleReceiveCallback");
return status == OK || status == NO_MEMORY ? KEEP_CALLBACK : REMOVE_CALLBACK;
}
......
}
ALOOPER_EVENT_INPUT表示文件描述符可读，我们在注册NativeInputEventReceiver的时候，这里传入的events类型就是ALOOPER_EVENT_INPUT：
status_t NativeInputEventReceiver::initialize() {
setFdEvents(ALOOPER_EVENT_INPUT);
return OK;
}
因此走ALOOPER_EVENT_INPUT流程，继续调用NativeInputEventReceiver.consumeEvents。
10 NativeInputEventReceiver.consumeEvents
status_t NativeInputEventReceiver::consumeEvents(JNIEnv* env,
bool consumeBatches, nsecs_t frameTime, bool* outConsumedBatch) {
......
for (;;) {
uint32_t seq;
InputEvent* inputEvent;
// 10.1 读取客户端InputChannel发送的事件并转化为InputEvent
status_t status = mInputConsumer.consume(&mInputEventFactory,
consumeBatches, frameTime, &seq, &inputEvent);
......
if (!skipCallbacks) {
// 10.2 获取到Java对象InputEventReceiver
if (!receiverObj.get()) {
receiverObj.reset(jniGetReferent(env, mReceiverWeakGlobal));
......
}
jobject inputEventObj;
switch (inputEvent->getType()) {
case AINPUT_EVENT_TYPE_KEY:
if (kDebugDispatchCycle) {
ALOGD("channel '%s' ~ Received key event.", getInputChannelName().c_str());
}
// 10.3
inputEventObj = android_view_KeyEvent_fromNative(env,
static_cast(inputEvent));
break;
case AINPUT_EVENT_TYPE_MOTION: {
if (kDebugDispatchCycle) {
ALOGD("channel '%s' ~ Received motion event.", getInputChannelName().c_str());
}
// 10.3 将Native层输入事件对象转换为上层输入事件对象
MotionEvent* motionEvent = static_cast(inputEvent);
if ((motionEvent->getAction() & AMOTION_EVENT_ACTION_MOVE) && outConsumedBatch) {
*outConsumedBatch = true;
}
inputEventObj = android_view_MotionEvent_obtainAsCopy(env, motionEvent);
break;
}
case AINPUT_EVENT_TYPE_FOCUS: {
....
}
case AINPUT_EVENT_TYPE_CAPTURE: {
....
}
case AINPUT_EVENT_TYPE_DRAG: {
....
}
default:
assert(false); // InputConsumer should prevent this from ever happening
inputEventObj = nullptr;
}
if (inputEventObj) {
if (kDebugDispatchCycle) {
ALOGD("channel '%s' ~ Dispatching input event.", getInputChannelName().c_str());
}
// 10.4 调用Java层对象receiverObj 的dispatchInputEvent方法
env->CallVoidMethod(receiverObj.get(),
gInputEventReceiverClassInfo.dispatchInputEvent, seq, inputEventObj);
....
} else {
......
}
}
....
}
}
10.1 读取客户端InputChannel发送的事件并转化为InputEvent
调用InputConsumer.comsume函数，将输入事件转化为一个InputEvent对象。
status_t InputConsumer::consume(InputEventFactoryInterface* factory, bool consumeBatches,
nsecs_t frameTime, uint32_t* outSeq, InputEvent** outEvent) {
......
*outSeq = 0;
*outEvent = nullptr;
// Fetch the next input message.
// Loop until an event can be returned or no additional events are received.
while (!*outEvent) {
if (mMsgDeferred) {
// mMsg contains a valid input message from the previous call to consume
// that has not yet been processed.
mMsgDeferred = false;
} else {
// 10.1.1 InputChannel读取事件
// Receive a fresh message.
status_t result = mChannel->receiveMessage(&mMsg);
......
}
switch (mMsg.header.type) {
case InputMessage::Type::KEY: {
// 10.1.2 创建和初始化输入事件
KeyEvent* keyEvent = factory->createKeyEvent();
if (!keyEvent) return NO_MEMORY;
initializeKeyEvent(keyEvent, &mMsg);
*outSeq = mMsg.header.seq;
*outEvent = keyEvent;
......
}
case InputMessage::Type::MOTION: {
// 10.1.2 创建和初始化输入事件
......
MotionEvent* motionEvent = factory->createMotionEvent();
if (!motionEvent) return NO_MEMORY;
updateTouchState(mMsg);
initializeMotionEvent(motionEvent, &mMsg);
*outSeq = mMsg.header.seq;
*outEvent = motionEvent;
......
}
case InputMessage::Type::FINISHED:
case InputMessage::Type::TIMELINE: {
......
}
case InputMessage::Type::FOCUS: {
......
}
case InputMessage::Type::CAPTURE: {
......
}
case InputMessage::Type::DRAG: {
......
}
}
}
return OK;
}
10.1.1 InputChannel读取事件
这里的mChannel即是客户端对应的InputChannel对象，是在客户端创建InputEventReceiver的时候传入的。
回看第8步中，服务端InputChannel调用InputChannel.sendMessage，将输入事件写入服务端InputChannel对应的文件描述符发送缓冲区：
status_t InputChannel::sendMessage(const InputMessage* msg) {
const size_t msgLength = msg->size();
InputMessage cleanMsg;
msg->getSanitizedCopy(&cleanMsg);
ssize_t nWrite;
do {
nWrite = ::send(getFd(), &cleanMsg, msgLength, MSG_DONTWAIT | MSG_NOSIGNAL);
} while (nWrite == -1 && errno == EINTR);
......
}
那么我们在这里就可以通过InputChannel.receiverMessage，将输入信息从客户端InputChannel对应的文件描述符的接收缓冲区中读取出来：
status_t InputChannel::receiveMessage(InputMessage* msg) {
ssize_t nRead;
do {
nRead = ::recv(getFd(), msg, sizeof(InputMessage), MSG_DONTWAIT);
} while (nRead == -1 && errno == EINTR);
......
}
最终输入事件被存入InputMessage类型的msg中。
10.1.2 创建和初始化输入事件
针对不同的事件类型创建不同的事件对象，比如KEY事件为KeyEvent，MOTION事件为MotionEvent等，然后将上一步中msg的信息取出传给这些新创建的对象，最后将传入的outEvent指向新创建的事件对象。
10.2 获取到Java对象InputEventReceiver
receiverObj会被重置为mReceiverWeakGlobal：
receiverObj.reset(jniGetReferent(env, mReceiverWeakGlobal));
我们之前在ViewRootImpl创建WindowInputEventReceiver的时候，会把Java层的InputEventReceiver对象的弱引用作为初始化NativeInputEventReceiver的参数，即：
mReceiverPtr = nativeInit(new WeakReference(this),
inputChannel, mMessageQueue);
后续NativeInputEventReceiver的全局变量mReceiverWeakGlobal便会持有这个引用：
NativeInputEventReceiver::NativeInputEventReceiver(
JNIEnv* env, jobject receiverWeak, const std::shared_ptr& inputChannel,
const sp& messageQueue)
: mReceiverWeakGlobal(env->NewGlobalRef(receiverWeak)),
那么这里receiverObj指向的便是Java层的InputEventReceiver。
10.3 将Native层输入事件对象转换为上层输入事件对象
按键事件：
inputEventObj = android_view_KeyEvent_fromNative(env,
static_cast(inputEvent));
Motion事件：
MotionEvent* motionEvent = static_cast(inputEvent);
......
// 10.3
inputEventObj = android_view_MotionEvent_obtainAsCopy(env, motionEvent);
最终将经过InputConsumer.comsume填充的InputEvent事件转化为上层Java对象。
10.4 调用Java层对象receiverObj 的dispatchInputEvent方法
env->CallVoidMethod(receiverObj.get(),
gInputEventReceiverClassInfo.dispatchInputEvent, seq, inputEventObj);
最终receiverObj是上层InputEventReceiver对象，inputEventObj也已经转化为上层对应的输入事件，那么调用InputEventReceiver.dispatchInputEvent将输入事件传递给上层。
11 InputEventReceiver.dispatchInputEvent
// Called from native code.
@SuppressWarnings("unused")
@UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
private void dispatchInputEvent(int seq, InputEvent event) {
mSeqMap.put(event.getSequenceNumber(), seq);
onInputEvent(event);
}
因为我们分析的是ViewRootImpl#setView中的监听输入事件注册流程，因此这里的InputEventReceiver实际上是一个WindowInputEventReceiver对象。
12 ViewRootImpl.WindowInputEventReceiver.onInputEvent
final class WindowInputEventReceiver extends InputEventReceiver {
public WindowInputEventReceiver(InputChannel inputChannel, Looper looper) {
super(inputChannel, looper);
}
@Override
public void onInputEvent(InputEvent event) {
/// M: record current key event and motion event to dump input event info for
/// ANR analysis. {
ViewDebugManager.getInstance().debugInputEventStart(event);
/// }
Trace.traceBegin(Trace.TRACE_TAG_VIEW, "processInputEventForCompatibility");
List<InputEvent> processedEvents;
try {
processedEvents =
mInputCompatProcessor.processInputEventForCompatibility(event);
} finally {
Trace.traceEnd(Trace.TRACE_TAG_VIEW);
}
if (processedEvents != null) {
if (processedEvents.isEmpty()) {
// InputEvent consumed by mInputCompatProcessor
finishInputEvent(event, true);
} else {
for (int i = 0; i < processedEvents.size(); i++) {
enqueueInputEvent(
processedEvents.get(i), this,
QueuedInputEvent.FLAG_MODIFIED_FOR_COMPATIBILITY, true);
}
}
} else {
enqueueInputEvent(event, this, 0, true);
}
}
......
}
private WindowInputEventReceiver mInputEventReceiver;
后续会调用ViewRootImpl#enqueueInputEvent进行一系列处理。
13 总结
1)、InputDispatcher分发线程首先根据事件类型，寻找所有可以接收当前输入事件的窗口，构建一个InputTarget队列。
2)、遍历InputTarget队列，队列中的所有窗口都需要处理本次输入事件。
3)、将输入事件信息封装成InputMessage对象，服务端InputChannel调用socket的send函数将InputMessage写入服务端socket的发送缓冲区。
4)、服务端InputChannel发送事件后，客户端这边注册的NativeInputEventReceiver的Looper监听到客户端socket的接收缓冲区有数据写入，回调NativeInputEventReceiver.handleEvent函数，收集服务端传过来的InputMessage信息，最终将输入事件封装为Java层的KeyEvent或者MotionEvent等类型，然后调用Java层InputEventReceiver#DispatchInputEvent完成输入事件从Native层到Java上层的传递。