基于Android 6.0源码， 分析InputManagerService的启动过程
一. InputReader起点
上一篇文章Input系统—启动篇，介绍IMS服务的启动过程会创建两个native线程，分别是InputReader,InputDispatcher. 接下来从InputReader线程的执行过程从threadLoop为起点开始分析。
1.1 threadLoop
[-> InputReader.cpp]
bool InputReaderThread::threadLoop() {
mReader->loopOnce(); //【见小节1.2】
return true;
}
threadLoop返回值true代表的是会不断地循环调用loopOnce()。另外，如果当返回值为false则会 退出循环。整个过程是不断循环的地调用InputReader的loopOnce()方法，先来回顾一下InputReader对象构造方法。
1.2 loopOnce
[-> InputReader.cpp]
void InputReader::loopOnce() {
...
{
AutoMutex _l(mLock);
uint32_t changes = mConfigurationChangesToRefresh;
if (changes) {
timeoutMillis = 0;
...
} else if (mNextTimeout != LLONG_MAX) {
nsecs_t now = systemTime(SYSTEM_TIME_MONOTONIC);
timeoutMillis = toMillisecondTimeoutDelay(now, mNextTimeout);
}
}
//从EventHub读取事件，其中EVENT_BUFFER_SIZE = 256【见小节2.1】
size_t count = mEventHub->getEvents(timeoutMillis, mEventBuffer, EVENT_BUFFER_SIZE);
{ // acquire lock
AutoMutex _l(mLock);
mReaderIsAliveCondition.broadcast();
if (count) { //处理事件【见小节3.1】
processEventsLocked(mEventBuffer, count);
}
if (oldGeneration != mGeneration) {
inputDevicesChanged = true;
getInputDevicesLocked(inputDevices);
}
...
} // release lock
if (inputDevicesChanged) { //输入设备发生改变
mPolicy->notifyInputDevicesChanged(inputDevices);
}
//发送事件到nputDispatcher【见小节4.1】
mQueuedListener->flush();
}
二. EventHub
2.1 getEvents
[-> EventHub.cpp]
size_t EventHub::getEvents(int timeoutMillis, RawEvent* buffer, size_t bufferSize) {
AutoMutex _l(mLock); //加锁
struct input_event readBuffer[bufferSize];
RawEvent* event = buffer; //原始事件
size_t capacity = bufferSize; //容量大小为256
bool awoken = false;
for (;;) {
nsecs_t now = systemTime(SYSTEM_TIME_MONOTONIC);
...
if (mNeedToScanDevices) {
mNeedToScanDevices = false;
scanDevicesLocked(); //扫描设备【见小节2.2】
mNeedToSendFinishedDeviceScan = true;
}
while (mOpeningDevices != NULL) {
Device* device = mOpeningDevices;
mOpeningDevices = device->next;
event->when = now;
event->deviceId = device->id == mBuiltInKeyboardId ? 0 : device->id;
event->type = DEVICE_ADDED; //添加设备的事件
event += 1;
mNeedToSendFinishedDeviceScan = true;
if (--capacity == 0) {
break;
}
}
...
bool deviceChanged = false;
while (mPendingEventIndex < mPendingEventCount) {
//从mPendingEventItems读取事件项
const struct epoll_event& eventItem = mPendingEventItems[mPendingEventIndex++];
...
//获取设备ID所对应的device
ssize_t deviceIndex = mDevices.indexOfKey(eventItem.data.u32);
Device* device = mDevices.valueAt(deviceIndex);
if (eventItem.events & EPOLLIN) {
//从设备不断读取事件，放入到readBuffer
int32_t readSize = read(device->fd, readBuffer,
sizeof(struct input_event) * capacity);
if (readSize == 0 || (readSize < 0 && errno == ENODEV)) {
deviceChanged = true;
closeDeviceLocked(device);//设备已被移除则执行关闭操作
} else if (readSize < 0) {
...
} else if ((readSize % sizeof(struct input_event)) != 0) {
...
} else {
int32_t deviceId = device->id == mBuiltInKeyboardId ? 0 : device->id;
size_t count = size_t(readSize) / sizeof(struct input_event);
for (size_t i = 0; i < count; i++) {
//获取readBuffer的数据
struct input_event& iev = readBuffer[i];
//将input_event信息, 封装成RawEvent
event->when = nsecs_t(iev.time.tv_sec) * 1000000000LL
+ nsecs_t(iev.time.tv_usec) * 1000LL;
event->deviceId = deviceId;
event->type = iev.type;
event->code = iev.code;
event->value = iev.value;
event += 1;
capacity -= 1;
}
if (capacity == 0) {
mPendingEventIndex -= 1;
break;
}
}
}
...
}
...
mLock.unlock(); //poll之前先释放锁
//等待input事件的到来
int pollResult = epoll_wait(mEpollFd, mPendingEventItems, EPOLL_MAX_EVENTS, timeoutMillis);
...
mLock.lock(); //poll之后再次请求锁
if (pollResult < 0) { //出现错误
mPendingEventCount = 0;
if (errno != EINTR) {
usleep(100000); //系统发生错误则休眠1s
}
} else {
mPendingEventCount = size_t(pollResult);
}
}
return event - buffer; //返回所读取的事件个数
}
EventHub采用INotify + epoll机制实现监听目录/dev/input下的设备节点，经过EventHub将input_event结构体 + deviceId 转换成RawEvent结构体，如下：
2.1.1 RawEvent
[-> InputEventReader.h]
struct input_event {
struct timeval time; //事件发生的时间点
__u16 type;
__u16 code;
__s32 value;
};
struct RawEvent {
nsecs_t when; //事件发生的时间店
int32_t deviceId; //产生事件的设备Id
int32_t type; // 事件类型
int32_t code;
int32_t value;
};
此处事件类型:
- DEVICE_ADDED(添加)
- DEVICE_REMOVED(删除)
- FINISHED_DEVICE_SCAN(扫描完成)
- type<FIRST_SYNTHETIC_EVENT(其他事件)
getEvents()已完成转换事件转换工作, 接下来,顺便看看设备扫描过程.
2.2 设备扫描
2.2.1 scanDevicesLocked
void EventHub::scanDevicesLocked() {
//此处DEVICE_PATH="/dev/input"【见小节2.3】
status_t res = scanDirLocked(DEVICE_PATH);
...
}
2.2.2 scanDirLocked
status_t EventHub::scanDirLocked(const char *dirname)
{
char devname[PATH_MAX];
char *filename;
DIR *dir;
struct dirent *de;
dir = opendir(dirname);
strcpy(devname, dirname);
filename = devname + strlen(devname);
*filename++ = '/';
//读取/dev/input/目录下所有的设备节点
while((de = readdir(dir))) {
if(de->d_name[0] == '.' &&
(de->d_name[1] == '\0' ||
(de->d_name[1] == '.' && de->d_name[2] == '\0')))
continue;
strcpy(filename, de->d_name);
//打开相应的设备节点【2.2.3】
openDeviceLocked(devname);
}
closedir(dir);
return 0;
}
2.2.3 openDeviceLocked
status_t EventHub::openDeviceLocked(const char *devicePath) {
char buffer[80];
//打开设备文件
int fd = open(devicePath, O_RDWR | O_CLOEXEC);
InputDeviceIdentifier identifier;
//获取设备名
if(ioctl(fd, EVIOCGNAME(sizeof(buffer) - 1), &buffer) < 1){
} else {
buffer[sizeof(buffer) - 1] = '\0';
identifier.name.setTo(buffer);
}
identifier.bus = inputId.bustype;
identifier.product = inputId.product;
identifier.vendor = inputId.vendor;
identifier.version = inputId.version;
//获取设备物理地址
if(ioctl(fd, EVIOCGPHYS(sizeof(buffer) - 1), &buffer) < 1) {
} else {
buffer[sizeof(buffer) - 1] = '\0';
identifier.location.setTo(buffer);
}
//获取设备唯一ID
if(ioctl(fd, EVIOCGUNIQ(sizeof(buffer) - 1), &buffer) < 1) {
} else {
buffer[sizeof(buffer) - 1] = '\0';
identifier.uniqueId.setTo(buffer);
}
//将identifier信息填充到fd
assignDescriptorLocked(identifier);
//设置fd为非阻塞方式
fcntl(fd, F_SETFL, O_NONBLOCK);
//获取设备ID，分配设备对象内存
int32_t deviceId = mNextDeviceId++;
Device* device = new Device(fd, deviceId, String8(devicePath), identifier);
...
//注册epoll
struct epoll_event eventItem;
memset(&eventItem, 0, sizeof(eventItem));
eventItem.events = EPOLLIN;
if (mUsingEpollWakeup) {
eventItem.events |= EPOLLWAKEUP;
}
eventItem.data.u32 = deviceId;
if (epoll_ctl(mEpollFd, EPOLL_CTL_ADD, fd, &eventItem)) {
delete device; //添加失败则删除该设备
return -1;
}
...
//【见小节2.2.4】
addDeviceLocked(device);
}
2.2.4 addDeviceLocked
void EventHub::addDeviceLocked(Device* device) {
mDevices.add(device->id, device); //添加到mDevices队列
device->next = mOpeningDevices;
mOpeningDevices = device;
}
介绍了EventHub从设备节点获取事件的流程，当收到事件后接下里便开始处理事件。
三. InputReader
3.1 processEventsLocked
[-> InputReader.cpp]
void InputReader::processEventsLocked(const RawEvent* rawEvents, size_t count) {
for (const RawEvent* rawEvent = rawEvents; count;) {
int32_t type = rawEvent->type;
size_t batchSize = 1;
if (type < EventHubInterface::FIRST_SYNTHETIC_EVENT) {
int32_t deviceId = rawEvent->deviceId;
while (batchSize < count) {
if (rawEvent[batchSize].type >= EventHubInterface::FIRST_SYNTHETIC_EVENT
|| rawEvent[batchSize].deviceId != deviceId) {
break;
}
batchSize += 1; //同一设备的事件打包处理
}
//数据事件的处理【见小节3.3】
processEventsForDeviceLocked(deviceId, rawEvent, batchSize);
} else {
switch (rawEvent->type) {
case EventHubInterface::DEVICE_ADDED:
//设备添加【见小节3.2】
addDeviceLocked(rawEvent->when, rawEvent->deviceId);
break;
case EventHubInterface::DEVICE_REMOVED:
//设备移除
removeDeviceLocked(rawEvent->when, rawEvent->deviceId);
break;
case EventHubInterface::FINISHED_DEVICE_SCAN:
//设备扫描完成
handleConfigurationChangedLocked(rawEvent->when);
break;
default:
ALOG_ASSERT(false);//不会发生
break;
}
}
count -= batchSize;
rawEvent += batchSize;
}
}
事件处理总共有下几类类型：
- DEVICE_ADDED(设备增加), [见小节3.2]
- DEVICE_REMOVED(设备移除)
- FINISHED_DEVICE_SCAN(设备扫描完成)
- 数据事件[见小节3.4]
先来说说DEVICE_ADDED设备增加的过程。
3.2 设备增加
3.2.1 addDeviceLocked
void InputReader::addDeviceLocked(nsecs_t when, int32_t deviceId) {
ssize_t deviceIndex = mDevices.indexOfKey(deviceId);
if (deviceIndex >= 0) {
return; //已添加的相同设备则不再添加
}
InputDeviceIdentifier identifier = mEventHub->getDeviceIdentifier(deviceId);
uint32_t classes = mEventHub->getDeviceClasses(deviceId);
int32_t controllerNumber = mEventHub->getDeviceControllerNumber(deviceId);
//【见小节3.2.2】
InputDevice* device = createDeviceLocked(deviceId, controllerNumber, identifier, classes);
device->configure(when, &mConfig, 0);
device->reset(when);
mDevices.add(deviceId, device); //添加设备到mDevices
...
}
3.2.2 createDeviceLocked
InputDevice* InputReader::createDeviceLocked(int32_t deviceId, int32_t controllerNumber,
const InputDeviceIdentifier& identifier, uint32_t classes) {
//创建InputDevice对象
InputDevice* device = new InputDevice(&mContext, deviceId, bumpGenerationLocked(),
controllerNumber, identifier, classes);
...
//获取键盘源类型
uint32_t keyboardSource = 0;
int32_t keyboardType = AINPUT_KEYBOARD_TYPE_NON_ALPHABETIC;
if (classes & INPUT_DEVICE_CLASS_KEYBOARD) {
keyboardSource |= AINPUT_SOURCE_KEYBOARD;
}
if (classes & INPUT_DEVICE_CLASS_ALPHAKEY) {
keyboardType = AINPUT_KEYBOARD_TYPE_ALPHABETIC;
}
if (classes & INPUT_DEVICE_CLASS_DPAD) {
keyboardSource |= AINPUT_SOURCE_DPAD;
}
if (classes & INPUT_DEVICE_CLASS_GAMEPAD) {
keyboardSource |= AINPUT_SOURCE_GAMEPAD;
}
//添加键盘类设备InputMapper
if (keyboardSource != 0) {
device->addMapper(new KeyboardInputMapper(device, keyboardSource, keyboardType));
}
//添加鼠标类设备InputMapper
if (classes & INPUT_DEVICE_CLASS_CURSOR) {
device->addMapper(new CursorInputMapper(device));
}
//添加触摸屏设备InputMapper
if (classes & INPUT_DEVICE_CLASS_TOUCH_MT) {
device->addMapper(new MultiTouchInputMapper(device));
} else if (classes & INPUT_DEVICE_CLASS_TOUCH) {
device->addMapper(new SingleTouchInputMapper(device));
}
...
return device;
}
该方法主要功能：
- 创建InputDevice对象，将InputReader的mContext赋给InputDevice对象所对应的变量
- 根据设备类型来创建并添加相对应的InputMapper，同时设置mContext.
input设备类型有很多种，以上代码只列举部分常见的设备以及相应的InputMapper：
- 键盘类设备：KeyboardInputMapper
- 触摸屏设备：MultiTouchInputMapper或SingleTouchInputMapper
- 鼠标类设备：CursorInputMapper
介绍完设备增加过程，继续回到[小节3.1]除了设备的增删，更常见事件便是数据事件，那么接下来介绍数据事件的 处理过程。
3.3 事件处理
3.3.1 processEventsForDeviceLocked
void InputReader::processEventsForDeviceLocked(int32_t deviceId,
const RawEvent* rawEvents, size_t count) {
ssize_t deviceIndex = mDevices.indexOfKey(deviceId);
...
InputDevice* device = mDevices.valueAt(deviceIndex);
if (device->isIgnored()) {
return; //可忽略则直接返回
}
//【见小节3.3.2】
device->process(rawEvents, count);
}
3.3.2 InputDevice.process
void InputDevice::process(const RawEvent* rawEvents, size_t count) {
size_t numMappers = mMappers.size();
for (const RawEvent* rawEvent = rawEvents; count--; rawEvent++) {
if (mDropUntilNextSync) {
if (rawEvent->type == EV_SYN && rawEvent->code == SYN_REPORT) {
mDropUntilNextSync = false;
}
} else if (rawEvent->type == EV_SYN && rawEvent->code == SYN_DROPPED) {
mDropUntilNextSync = true;
reset(rawEvent->when);
} else {
for (size_t i = 0; i < numMappers; i++) {
InputMapper* mapper = mMappers[i];
//调用具体mapper来处理【见小节3.4】
mapper->process(rawEvent);
}
}
}
}
小节[3.2]createDeviceLocked创建设备并添加InputMapper，提到会有多种InputMapper。 这里以KeyboardInputMapper(按键事件)为例来展开说明
3.4 按键事件处理
3.4.1 KeyboardInputMapper.process
[-> InputReader.cpp ::KeyboardInputMapper]
void KeyboardInputMapper::process(const RawEvent* rawEvent) {
switch (rawEvent->type) {
case EV_KEY: {
int32_t scanCode = rawEvent->code;
int32_t usageCode = mCurrentHidUsage;
mCurrentHidUsage = 0;
if (isKeyboardOrGamepadKey(scanCode)) {
int32_t keyCode;
//获取所对应的KeyCode【见小节3.4.2】
if (getEventHub()->mapKey(getDeviceId(), scanCode, usageCode, &keyCode, &flags)) {
keyCode = AKEYCODE_UNKNOWN;
flags = 0;
}
//【见小节3.4.4】
processKey(rawEvent->when, rawEvent->value != 0, keyCode, scanCode, flags);
}
break;
}
case EV_MSC: ...
case EV_SYN: ...
}
}
3.4.2 EventHub::mapKey
[-> EventHub.cpp]
status_t EventHub::mapKey(int32_t deviceId,
int32_t scanCode, int32_t usageCode, int32_t metaState,
int32_t* outKeycode, int32_t* outMetaState, uint32_t* outFlags) const {
AutoMutex _l(mLock);
Device* device = getDeviceLocked(deviceId); //获取设备对象
status_t status = NAME_NOT_FOUND;
if (device) {
sp<KeyCharacterMap> kcm = device->getKeyCharacterMap();
if (kcm != NULL) {
//根据scanCode找到keyCode【见小节3.4.3】
if (!kcm->mapKey(scanCode, usageCode, outKeycode)) {
*outFlags = 0;
status = NO_ERROR;
}
}
}
...
return status;
}
将事件的扫描码(scanCode)转换成键盘码(Keycode)
3.4.3 KeyCharacterMap::mapKey
[-> KeyCharacterMap.cpp]
status_t KeyCharacterMap::mapKey(int32_t scanCode, int32_t usageCode, int32_t* outKeyCode) const {
...
if (scanCode) {
ssize_t index = mKeysByScanCode.indexOfKey(scanCode);
if (index >= 0) {
//根据scanCode找到keyCode
*outKeyCode = mKeysByScanCode.valueAt(index);
return OK;
}
}
*outKeyCode = AKEYCODE_UNKNOWN;
return NAME_NOT_FOUND;
}
再回到[3.4.1],接下来进入如下过程:
3.4.4 InputMapper.processKey
[-> InputReader.cpp]
void KeyboardInputMapper::processKey(nsecs_t when, bool down, int32_t keyCode,
int32_t scanCode, uint32_t policyFlags) {
if (down) {
if (mParameters.orientationAware && mParameters.hasAssociatedDisplay) {
keyCode = rotateKeyCode(keyCode, mOrientation);
}
ssize_t keyDownIndex = findKeyDown(scanCode);
if (keyDownIndex >= 0) {
//mKeyDowns记录着所有按下的键
keyCode = mKeyDowns.itemAt(keyDownIndex).keyCode;
} else {
...
mKeyDowns.push(); //压入栈顶
KeyDown& keyDown = mKeyDowns.editTop();
keyDown.keyCode = keyCode;
keyDown.scanCode = scanCode;
}
mDownTime = when; //记录按下时间点
} else {
ssize_t keyDownIndex = findKeyDown(scanCode);
if (keyDownIndex >= 0) {
//键抬起操作，则移除按下事件
keyCode = mKeyDowns.itemAt(keyDownIndex).keyCode;
mKeyDowns.removeAt(size_t(keyDownIndex));
} else {
return; //键盘没有按下操作，则直接忽略抬起操作
}
}
nsecs_t downTime = mDownTime;
...
//创建NotifyKeyArgs对象, when记录eventTime, downTime记录按下时间；
NotifyKeyArgs args(when, getDeviceId(), mSource, policyFlags,
down ? AKEY_EVENT_ACTION_DOWN : AKEY_EVENT_ACTION_UP,
AKEY_EVENT_FLAG_FROM_SYSTEM, keyCode, scanCode, newMetaState, downTime);
//通知key事件【见小节3.4.5】
getListener()->notifyKey(&args);
}
参数说明：
- mKeyDowns记录着所有按下的键;
- mDownTime记录按下时间点;
- 此处KeyboardInputMapper的mContext指向InputReader，getListener()获取的便是mQueuedListener。 接下来调用该对象的notifyKey.
3.4.5 QueuedInputListener.notifyKey
[-> InputListener.cpp]
void QueuedInputListener::notifyKey(const NotifyKeyArgs* args) {
mArgsQueue.push(new NotifyKeyArgs(*args));
}
mArgsQueue的数据类型为Vector<NotifyArgs*>，将该key事件压人该栈顶。 到此,整个事件加工完成, 再然后就是将事件发送给InputDispatcher线程.
接下来,再回调小节[1.2] InputReader的loopOnce过程, 可知当执行完processEventsLocked()过程, 然后便开始执行mQueuedListener->flush()过程, 如下文.
四. QueuedListener
4.1 QueuedInputListener.flush
[-> InputListener.cpp]
void QueuedInputListener::flush() {
size_t count = mArgsQueue.size();
for (size_t i = 0; i < count; i++) {
NotifyArgs* args = mArgsQueue[i];
//【见小节4.2】
args->notify(mInnerListener);
delete args;
}
mArgsQueue.clear();
}
遍历整个mArgsQueue数组, 在input架构中NotifyArgs的实现子类主要有以下几类:
- NotifyConfigurationChangedArgs
- NotifyKeyArgs
- NotifyMotionArgs
- NotifySwitchArgs
- NotifyDeviceResetArgs
紧接着上述的小节[3.4.5], 可知此处是NotifyKeyArgs对象.
从InputManager对象初始化的过程可知，mInnerListener便是InputDispatcher对象。
4.2 NotifyKeyArgs.notify
[-> InputListener.cpp]
void NotifyKeyArgs::notify(const sp<InputListenerInterface>& listener) const {
listener->notifyKey(this); // this是指NotifyKeyArgs【见小节4.3】
}
4.3 InputDispatcher.notifyKey
[-> InputDispatcher.cpp]
void InputDispatcher::notifyKey(const NotifyKeyArgs* args) {
if (!validateKeyEvent(args->action)) {
return;
}
...
int32_t keyCode = args->keyCode;
if (keyCode == AKEYCODE_HOME) {
if (args->action == AKEY_EVENT_ACTION_DOWN) {
property_set("sys.domekey.down", "1");
} else if (args->action == AKEY_EVENT_ACTION_UP) {
property_set("sys.domekey.down", "0");
}
}
if (metaState & AMETA_META_ON && args->action == AKEY_EVENT_ACTION_DOWN) {
...
} else if (args->action == AKEY_EVENT_ACTION_UP) {
...
}
KeyEvent event; //初始化KeyEvent对象
event.initialize(args->deviceId, args->source, args->action,
flags, keyCode, args->scanCode, metaState, 0,
args->downTime, args->eventTime);
//mPolicy是指NativeInputManager对象。【小节4.3.1】
mPolicy->interceptKeyBeforeQueueing(&event, /*byref*/ policyFlags);
bool needWake;
{
mLock.lock();
if (shouldSendKeyToInputFilterLocked(args)) {
mLock.unlock();
policyFlags |= POLICY_FLAG_FILTERED;
//当inputEventObj不为空, 则事件被filter所拦截【见小节4.3.2】
if (!mPolicy->filterInputEvent(&event, policyFlags)) {
return;
}
mLock.lock();
}
int32_t repeatCount = 0;
//创建KeyEntry对象
KeyEntry* newEntry = new KeyEntry(args->eventTime,
args->deviceId, args->source, policyFlags,
args->action, flags, keyCode, args->scanCode,
metaState, repeatCount, args->downTime);
//将KeyEntry放入队列【见小节4.3.3】
needWake = enqueueInboundEventLocked(newEntry);
mLock.unlock();
}
if (needWake) {
//唤醒InputDispatcher线程【见小节4.3.5】
mLooper->wake();
}
}
该方法的主要功能：
- 调用NativeInputManager.interceptKeyBeforeQueueing，加入队列前执行拦截动作，但并不改变流程，调用链：
- IMS.interceptKeyBeforeQueueing
- InputMonitor.interceptKeyBeforeQueueing (继承IMS.WindowManagerCallbacks)
- PhoneWindowManager.interceptKeyBeforeQueueing (继承WindowManagerPolicy)
- 当mInputFilterEnabled=true(该值默认为false,可通过setInputFilterEnabled设置),则调用NativeInputManager.filterInputEvent过滤输入事件；
- 当返回值为false则过滤该事件，不再往下分发；
- 生成KeyEvent，并调用enqueueInboundEventLocked，将该事件加入到InputDispatcherd的成员变量mInboundQueue。
4.3.1 interceptKeyBeforeQueueing
void NativeInputManager::interceptKeyBeforeQueueing(const KeyEvent* keyEvent,
uint32_t& policyFlags) {
...
if ((policyFlags & POLICY_FLAG_TRUSTED)) {
nsecs_t when = keyEvent->getEventTime(); //时间
JNIEnv* env = jniEnv();
jobject keyEventObj = android_view_KeyEvent_fromNative(env, keyEvent);
if (keyEventObj) {
// 调用Java层的IMS.interceptKeyBeforeQueueing
wmActions = env->CallIntMethod(mServiceObj,
gServiceClassInfo.interceptKeyBeforeQueueing,
keyEventObj, policyFlags);
...
} else {
...
}
handleInterceptActions(wmActions, when, /*byref*/ policyFlags);
} else {
...
}
}
该方法会调用Java层的InputManagerService的interceptKeyBeforeQueueing()方法。
4.3.2 filterInputEvent
bool NativeInputManager::filterInputEvent(const InputEvent* inputEvent, uint32_t policyFlags) {
jobject inputEventObj;
JNIEnv* env = jniEnv();
switch (inputEvent->getType()) {
case AINPUT_EVENT_TYPE_KEY:
inputEventObj = android_view_KeyEvent_fromNative(env,
static_cast<const KeyEvent*>(inputEvent));
break;
case AINPUT_EVENT_TYPE_MOTION:
inputEventObj = android_view_MotionEvent_obtainAsCopy(env,
static_cast<const MotionEvent*>(inputEvent));
break;
default:
return true; // 走事件正常的分发流程
}
if (!inputEventObj) {
return true; // 当inputEventObj为空, 则走事件正常的分发流程
}
//当inputEventObj不为空,则调用Java层的IMS.filterInputEvent()
jboolean pass = env->CallBooleanMethod(mServiceObj, gServiceClassInfo.filterInputEvent,
inputEventObj, policyFlags);
if (checkAndClearExceptionFromCallback(env, "filterInputEvent")) {
pass = true; //出现Exception，则走事件正常的分发流程
}
env->DeleteLocalRef(inputEventObj);
return pass;
}
当inputEventObj不为空,则调用Java层的IMS.filterInputEvent(). 经过层层调用后, 最终会再调用InputDispatcher.injectInputEvent(),该基本等效于该方法的后半段:
- enqueueInboundEventLocked
- wakeup
4.3.3 enqueueInboundEventLocked
bool InputDispatcher::enqueueInboundEventLocked(EventEntry* entry) {
bool needWake = mInboundQueue.isEmpty();
mInboundQueue.enqueueAtTail(entry); //将该事件放入mInboundQueue队列尾部
switch (entry->type) {
case EventEntry::TYPE_KEY: {
KeyEntry* keyEntry = static_cast<KeyEntry*>(entry);
if (isAppSwitchKeyEventLocked(keyEntry)) {
if (keyEntry->action == AKEY_EVENT_ACTION_DOWN) {
mAppSwitchSawKeyDown = true; //按下事件
} else if (keyEntry->action == AKEY_EVENT_ACTION_UP) {
if (mAppSwitchSawKeyDown) {
//其中APP_SWITCH_TIMEOUT=500ms
mAppSwitchDueTime = keyEntry->eventTime + APP_SWITCH_TIMEOUT;
mAppSwitchSawKeyDown = false;
needWake = true;
}
}
}
break;
}
case EventEntry::TYPE_MOTION: {
//当前App无响应且用户希望切换到其他应用窗口，则drop该窗口事件，并处理其他窗口事件
MotionEntry* motionEntry = static_cast<MotionEntry*>(entry);
if (motionEntry->action == AMOTION_EVENT_ACTION_DOWN
&& (motionEntry->source & AINPUT_SOURCE_CLASS_POINTER)
&& mInputTargetWaitCause == INPUT_TARGET_WAIT_CAUSE_APPLICATION_NOT_READY
&& mInputTargetWaitApplicationHandle != NULL) {
int32_t displayId = motionEntry->displayId;
int32_t x = int32_t(motionEntry->pointerCoords[0].
getAxisValue(AMOTION_EVENT_AXIS_X));
int32_t y = int32_t(motionEntry->pointerCoords[0].
getAxisValue(AMOTION_EVENT_AXIS_Y));
//查询可触摸的窗口【见小节4.3.4】
sp<InputWindowHandle> touchedWindowHandle = findTouchedWindowAtLocked(displayId, x, y);
if (touchedWindowHandle != NULL
&& touchedWindowHandle->inputApplicationHandle
!= mInputTargetWaitApplicationHandle) {
mNextUnblockedEvent = motionEntry;
needWake = true;
}
}
break;
}
}
return needWake;
}
AppSwitchKeyEvent是指keyCode等于以下值：
- AKEYCODE_HOME
- AKEYCODE_ENDCALL
- AKEYCODE_APP_SWITCH
4.3.4 findTouchedWindowAtLocked
[-> InputDispatcher.cpp]
sp<InputWindowHandle> InputDispatcher::findTouchedWindowAtLocked(int32_t displayId,
int32_t x, int32_t y) {
//从前台到后台来遍历查询可触摸的窗口
size_t numWindows = mWindowHandles.size();
for (size_t i = 0; i < numWindows; i++) {
sp<InputWindowHandle> windowHandle = mWindowHandles.itemAt(i);
const 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)) {
return windowHandle; //找到目标窗口
}
}
}
}
}
return NULL;
}
此处mWindowHandles的赋值过程是由Java层的InputMonitor.setInputWindows(),经过JNI调用后进入InputDispatcher::setInputWindows()方法完成. 进一步说, 就是WMS执行addWindow()过程或许UI改变等场景,都会触发该方法的修改.
4.3.5 Looper.wake
[-> system/core/libutils/Looper.cpp]
void Looper::wake() {
uint64_t inc = 1;
ssize_t nWrite = TEMP_FAILURE_RETRY(write(mWakeEventFd, &inc, sizeof(uint64_t)));
if (nWrite != sizeof(uint64_t)) {
if (errno != EAGAIN) {
ALOGW("Could not write wake signal, errno=%d", errno);
}
}
}
[小节4.3]的过程会调用enqueueInboundEventLocked()方法来决定是否需要将数字1写入句柄mWakeEventFd来唤醒InputDispatcher线程. 满足唤醒的条件:
- 执行enqueueInboundEventLocked方法前,mInboundQueue队列为空,执行完必然不再为空,则需要唤醒分发线程;
- 当事件类型为key事件,且发生一对按下和抬起操作,则需要唤醒;
- 当事件类型为motion事件,且当前可触摸的窗口属于另一个应用,则需要唤醒.
五. 总结
5.1 核心工作
InputReader整个过程涉及多次事件封装转换，其主要工作核心是以下三大步骤:
- getEvents：通过EventHub(监听目录/dev/input)读取事件放入mEventBuffer,而mEventBuffer是一个大小为256的数组, 再将事件input_event转换为RawEvent; [见小节2.1]
- processEventsLocked: 对事件进行加工, 转换RawEvent -> NotifyKeyArgs(NotifyArgs) [见小节3.1]
- QueuedListener->flush：将事件发送到InputDispatcher线程, 转换NotifyKeyArgs -> KeyEntry(EventEntry) [见小节4.1]
InputReader线程不断循环地执行InputReader.loopOnce(), 每次处理完生成的是EventEntry(比如KeyEntry, MotionEntry), 接下来的工作就交给InputDispatcher线程。
5.2 流程图
点击查看大图:
InputReader的核心工作就是从EventHub获取数据后生成EventEntry事件，加入到InputDispatcher的mInboundQueue队列，再唤醒InputDispatcher线程。
说明:
- IMS.filterInputEvent可以过滤无需上报的事件，当该方法返回值为false则代表是需要被过滤掉的事件，无机会交给InputDispatcher来分发。
- 节点/dev/input的event事件所对应的输入设备信息位于
/proc/bus/input/devices，也可以通过getevent来获取事件. 不同的input事件所对应的物理input节点，比如常见的情形：- 屏幕触摸和(MENU,HOME,BACK)3按键：对应同一个input设备节点；
- POWER和音量(下)键：对应同一个input设备节点；
- 音量(上)键：对应同一个input设备节点；
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