Android input系统原理二

1.inputmanager启动源码分析

在SystemServer.java中构造了 inputmanagerservice的对象,在其构造函数中,最重要的是这个nativeInit函数。 下面是核心代码

inputManager = new InputManagerService(context);

public InputManagerService(Context context) {
.........
    mPtr = nativeInit(this, mContext, mHandler.getLooper().getQueue());
.........
    LocalServices.addService(InputManagerInternal.class, new LocalService());
}

nativeinit函数

对应的jni函数文件名:com_android_server_input_InputManagerService.cpp

nativeInit 构造了一个NativeInputManager,核心代码中构造了一个EventHub和一个InputManager,并且将EventHub传递给了InputManager。那么InputManager就持有了EventHub类。后续可以看到这个EventHub是读取驱动节点数据的核心类。有用到epoll来监听节点

EventHub::EventHub(void) :
    mEpollFd = epoll_create(EPOLL_SIZE_HINT);

}

在InputManager的构造函数中可以看到接收了InputReaderPolicyInterface 和  InputDispatcherPolicyInterface 虚基类的两个子类对象,因为外部传入的两个this,说明NativeInputManager是继承了这两个虚基类的,这里就不放代码了。

NativeInputManager::NativeInputManager(jobject contextObj,
        jobject serviceObj, const sp<Looper>& looper) :
        mLooper(looper), mInteractive(true) {
...........

    sp<EventHub> eventHub = new EventHub();
    mInputManager = new InputManager(eventHub, this, this);
}


InputManager::InputManager(
        const sp<EventHubInterface>& eventHub,
        const sp<InputReaderPolicyInterface>& readerPolicy,
        const sp<InputDispatcherPolicyInterface>& dispatcherPolicy) {
    mDispatcher = new InputDispatcher(dispatcherPolicy);
    mReader = new InputReader(eventHub, readerPolicy, mDispatcher);
    initialize();
}

然后去创建了继承了线程的对象

void InputManager::initialize() {
    mReaderThread = new InputReaderThread(mReader);
    mDispatcherThread = new InputDispatcherThread(mDispatcher);
}

线程的启动是在nativeStart,最后走到InputManager.cpp中的start函数启动线程

status_t InputManager::start() {
    status_t result = mDispatcherThread->run("InputDispatcher", PRIORITY_URGENT_DISPLAY);
    if (result) {
        ALOGE("Could not start InputDispatcher thread due to error %d.", result);
        return result;
    }

    result = mReaderThread->run("InputReader", PRIORITY_URGENT_DISPLAY);
    if (result) {
        ALOGE("Could not start InputReader thread due to error %d.", result);

        mDispatcherThread->requestExit();
        return result;
    }

    return OK;
}

2.inputReader源码

启动后调用到InputReader.cpp的loopOnce,

void InputReader::loopOnce() {
.........
    size_t count = mEventHub->getEvents(timeoutMillis, mEventBuffer, EVENT_BUFFER_SIZE);
.........
}

在InputReader.h中可以看到mEventBuffer的声明和定义,相当于给getEvents传递了一个长度为256 类型为RawEvent的数组
// The event queue.
static const int EVENT_BUFFER_SIZE = 256;
RawEvent mEventBuffer[EVENT_BUFFER_SIZE];

在EventHub.h可以看到RawEvent的声明,结构体中的这些变量和getevent命令看到的数据非常类似。
/*
 * A raw event as retrieved from the EventHub.
 */
struct RawEvent {
    nsecs_t when;
    int32_t deviceId;
    int32_t type;
    int32_t code;
    int32_t value;
};

在getEvents 函数中,代码量过大,因此贴核心代码

size_t EventHub::getEvents(int timeoutMillis, RawEvent* buffer, size_t bufferSize) {

    struct input_event readBuffer[bufferSize];//创建了input_event 的数组,结构体中的数据和RawEvent实际上大差不差
    RawEvent* event = buffer;//event 指向数组头
    size_t capacity = bufferSize;
    bool awoken = false;

    for (;;) {

        if (mNeedToScanDevices) {//默认第一次进来需要扫描设备
            mNeedToScanDevices = false;
            scanDevicesLocked();
            mNeedToSendFinishedDeviceScan = true;
        }
.........
//看后面代码继续分析
}

scanDevicesLocked函数的详细解释 

static const char *DEVICE_PATH = "/dev/input";

void EventHub::scanDevicesLocked() {
    status_t res = scanDirLocked(DEVICE_PATH);
    if(res < 0) {
        ALOGE("scan dir failed for %s\n", DEVICE_PATH);
    }
    if (mDevices.indexOfKey(VIRTUAL_KEYBOARD_ID) < 0) {
        createVirtualKeyboardLocked();
    }
}

//打开文件夹/dev/input,读取文件夹下面所有节点,然后在分别打开对应的文件openDeviceLocked
//有了这些信息之后,可以通过这些信息去创建Device对象, 对对应设备加载配置文件或者配置属性
status_t EventHub::scanDirLocked(const char *dirname)
{
    char devname[PATH_MAX];
    char *filename;
    DIR *dir;
    struct dirent *de;
    dir = opendir(dirname);
    if(dir == NULL)
        return -1;
    strcpy(devname, dirname);
    filename = devname + strlen(devname);
    *filename++ = '/';
    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);
        openDeviceLocked(devname);
    }
    closedir(dir);
    return 0;
}


//这个函数很长,核心就是通过ioctl获取一些device 的信息,
status_t EventHub::openDeviceLocked(const char *devicePath) {
    // Get device driver version.
    int driverVersion;
    if(ioctl(fd, EVIOCGVERSION, &driverVersion)) {
        ALOGE("could not get driver version for %s, %s\n", devicePath, strerror(errno));
        close(fd);
        return -1;
    }

    // Get device identifier.
    struct input_id inputId;
    if(ioctl(fd, EVIOCGID, &inputId)) {
        ALOGE("could not get device input id for %s, %s\n", devicePath, strerror(errno));
        close(fd);
        return -1;
    }


    // Allocate device.  (The device object takes ownership of the fd at this point.)
    int32_t deviceId = mNextDeviceId++;
    Device* device = new Device(fd, deviceId, String8(devicePath), identifier);

    // Load the configuration file for the device.
    loadConfigurationLocked(device);//加载配置文件



    // See if this is a touch pad.//对触摸屏配置属性  判断是不是多指触摸
    // Is this a new modern multi-touch driver?
    if (test_bit(ABS_MT_POSITION_X, device->absBitmask)
            && test_bit(ABS_MT_POSITION_Y, device->absBitmask)) {
        // Some joysticks such as the PS3 controller report axes that conflict
        // with the ABS_MT range.  Try to confirm that the device really is
        // a touch screen.
        if (test_bit(BTN_TOUCH, device->keyBitmask) || !haveGamepadButtons) {
            device->classes |= INPUT_DEVICE_CLASS_TOUCH | INPUT_DEVICE_CLASS_TOUCH_MT;
        }
    // Is this an old style single-touch driver?
    } else if (test_bit(BTN_TOUCH, device->keyBitmask)
            && test_bit(ABS_X, device->absBitmask)
            && test_bit(ABS_Y, device->absBitmask)) {
        device->classes |= INPUT_DEVICE_CLASS_TOUCH;
    // Is this a BT stylus?
    } else if ((test_bit(ABS_PRESSURE, device->absBitmask) ||
                test_bit(BTN_TOUCH, device->keyBitmask))
            && !test_bit(ABS_X, device->absBitmask)
            && !test_bit(ABS_Y, device->absBitmask)) {
        device->classes |= INPUT_DEVICE_CLASS_EXTERNAL_STYLUS;
        // Keyboard will try to claim some of the buttons but we really want to reserve those so we
        // can fuse it with the touch screen data, so just take them back. Note this means an
        // external stylus cannot also be a keyboard device.
        device->classes &= ~INPUT_DEVICE_CLASS_KEYBOARD;
    }

    // Load the key map.//加载按键的配置文件
    // We need to do this for joysticks too because the key layout may specify axes.
    status_t keyMapStatus = NAME_NOT_FOUND;
    if (device->classes & (INPUT_DEVICE_CLASS_KEYBOARD | INPUT_DEVICE_CLASS_JOYSTICK)) {
        // Load the keymap for the device.
        keyMapStatus = loadKeyMapLocked(device);
    }


    if (registerDeviceForEpollLocked(device) != OK) {
        delete device;
        return -1;
    }

    configureFd(device);
    addDeviceLocked(device);添加device  将所有扫描到的device通过头插的方式用链表链接起来


}

注册监听fd
status_t EventHub::registerDeviceForEpollLocked(Device* device) {
    struct epoll_event eventItem;
    memset(&eventItem, 0, sizeof(eventItem));
    eventItem.events = EPOLLIN;
    if (mUsingEpollWakeup) {
        eventItem.events |= EPOLLWAKEUP;
    }
    eventItem.data.u32 = device->id;
    if (epoll_ctl(mEpollFd, EPOLL_CTL_ADD, device->fd, &eventItem)) {
        ALOGE("Could not add device fd to epoll instance.  errno=%d", errno);
        return -errno;
    }
    return OK;
}


//这一段检查输入设备是否为键盘(INPUT_DEVICE_CLASS_KEYBOARD),然后通过 ioctl 调用 EVIOCSREP //来禁用内核的键盘按键重复功能,因为用户态代码会自己处理按键重复逻辑

void EventHub::configureFd(Device* device) {
    // Set fd parameters with ioctl, such as key repeat, suspend block, and clock type
    if (device->classes & INPUT_DEVICE_CLASS_KEYBOARD) {
        // Disable kernel key repeat since we handle it ourselves
        unsigned int repeatRate[] = {0, 0};
        if (ioctl(device->fd, EVIOCSREP, repeatRate)) {
            ALOGW("Unable to disable kernel key repeat for %s: %s",
                  device->path.string(), strerror(errno));
        }
    }

    String8 wakeMechanism("EPOLLWAKEUP");
//这里是为设备配置挂起阻止机制。当 mUsingEpollWakeup 未被启用时,它会尝试通过 ioctl 调用 //EVIOCSSUSPENDBLOCK 来阻止设备进入挂起状态。这个机制用于保证当设备处于挂起状态时,仍然能够唤醒//系统处理输入事件
    if (!mUsingEpollWakeup) {
#ifndef EVIOCSSUSPENDBLOCK
        // uapi headers don't include EVIOCSSUSPENDBLOCK, and future kernels
        // will use an epoll flag instead, so as long as we want to support
        // this feature, we need to be prepared to define the ioctl ourselves.
#define EVIOCSSUSPENDBLOCK _IOW('E', 0x91, int)
#endif
        if (ioctl(device->fd, EVIOCSSUSPENDBLOCK, 1)) {
            wakeMechanism = "<none>";
        } else {
            wakeMechanism = "EVIOCSSUSPENDBLOCK";
        }
    }
//设置输入设备使用单调时钟(CLOCK_MONOTONIC)来记录事件的时间戳。单调时钟保证时间总是向前移动,//避免系统时钟调整(如夏令时变化)对输入事件的时间戳产生影响
    // Tell the kernel that we want to use the monotonic clock for reporting timestamps
    // associated with input events.  This is important because the input system
    // uses the timestamps extensively and assumes they were recorded using the monotonic
    // clock.
    int clockId = CLOCK_MONOTONIC;
    bool usingClockIoctl = !ioctl(device->fd, EVIOCSCLOCKID, &clockId);
    ALOGI("wakeMechanism=%s, usingClockIoctl=%s", wakeMechanism.string(),
          toString(usingClockIoctl));
}


void EventHub::addDeviceLocked(Device* device) {
    mDevices.add(device->id, device);
    device->next = mOpeningDevices;
    mOpeningDevices = device;
}

scanDevicesLocked 总结就是扫描监听文件,通过ioctl去驱动中获取不同设备的信息,不同输入设陪配置流程不同,加载配置文件,创建Device,最后将Device存起来。

//这段代码就是将刚才形成链表的device分别遍历将id取出来,赋值给event存起来。
while (mOpeningDevices != NULL) {
    Device* device = mOpeningDevices;
    ALOGV("Reporting device opened: id=%d, name=%s\n",
            device->id, device->path.string());
    mOpeningDevices = device->next;
    event->when = now;
    event->deviceId = device->id == mBuiltInKeyboardId ? 0 : device->id;
    event->type = DEVICE_ADDED;
    event += 1;
    mNeedToSendFinishedDeviceScan = true;
    if (--capacity == 0) {
        break;
    }
}
//这里为true,如果有5个device的话,这里在添加一个,那么就总共有6个了。
if (mNeedToSendFinishedDeviceScan) {
    mNeedToSendFinishedDeviceScan = false;
    event->when = now;
    event->type = FINISHED_DEVICE_SCAN;
    event += 1;
    if (--capacity == 0) {
        break;
    }
}

接下来就会执行这里,因为第一次扫描设备,其它代码都不会执行

// Return now if we have collected any events or if we were explicitly awoken.
if (event != buffer || awoken) {
    break;
}

//break之后,返回扫描到的设备数
// All done, return the number of events we read.
return event - buffer;

在InputReader.cpp中,在getEvents函数之后会返回设备数,如果扫描到了5个设备,那么这里会返回6,具体可以看上面getEvents的函数源码解析

void InputReader::loopOnce() {
    int32_t oldGeneration;
    int32_t timeoutMillis;
    bool inputDevicesChanged = false;
..........
    size_t count = mEventHub->getEvents(timeoutMillis, mEventBuffer, EVENT_BUFFER_SIZE);

    { // acquire lock
        AutoMutex _l(mLock);
        mReaderIsAliveCondition.broadcast();

        if (count) {
            processEventsLocked(mEventBuffer, count);
        }

        if (mNextTimeout != LLONG_MAX) {
            nsecs_t now = systemTime(SYSTEM_TIME_MONOTONIC);
            if (now >= mNextTimeout) {
#if DEBUG_RAW_EVENTS
                ALOGD("Timeout expired, latency=%0.3fms", (now - mNextTimeout) * 0.000001f);
#endif
                mNextTimeout = LLONG_MAX;
                timeoutExpiredLocked(now);
            }
        }

        if (oldGeneration != mGeneration) {
            inputDevicesChanged = true;
            getInputDevicesLocked(inputDevices);
        }
    } // release lock

    // Send out a message that the describes the changed input devices.
    if (inputDevicesChanged) {
        mPolicy->notifyInputDevicesChanged(inputDevices);
    }

    // Flush queued events out to the listener.
    // This must happen outside of the lock because the listener could potentially call
    // back into the InputReader's methods, such as getScanCodeState, or become blocked
    // on another thread similarly waiting to acquire the InputReader lock thereby
    // resulting in a deadlock.  This situation is actually quite plausible because the
    // listener is actually the input dispatcher, which calls into the window manager,
    // which occasionally calls into the input reader.
    mQueuedListener->flush();
}

就下来会进入到processEventsLocked对device进行处理,很明显,根据device type,这里将会进入addDeviceLocked

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;
            }
#if DEBUG_RAW_EVENTS
            ALOGD("BatchSize: %zu Count: %zu", batchSize, count);
#endif
            processEventsForDeviceLocked(deviceId, rawEvent, batchSize);
        } else {
            switch (rawEvent->type) {
            case EventHubInterface::DEVICE_ADDED:
                addDeviceLocked(rawEvent->when, rawEvent->deviceId);
                break;
            case EventHubInterface::DEVICE_REMOVED:
                removeDeviceLocked(rawEvent->when, rawEvent->deviceId);
                break;
            case EventHubInterface::FINISHED_DEVICE_SCAN:
                handleConfigurationChangedLocked(rawEvent->when);
                break;
            default:
                ALOG_ASSERT(false); // can't happen
                break;
            }
        }
        count -= batchSize;
        rawEvent += batchSize;
    }
}

void InputReader::addDeviceLocked(nsecs_t when, int32_t deviceId) {
//这里验证deviceId是否在mDevices中存在,如果存在,就不需要再添加一遍了
    ssize_t deviceIndex = mDevices.indexOfKey(deviceId);
    if (deviceIndex >= 0) {
        ALOGW("Ignoring spurious device added event for deviceId %d.", deviceId);
        return;
    }
    //根据deviceId去获取device的相关信息
    InputDeviceIdentifier identifier = mEventHub->getDeviceIdentifier(deviceId);
    uint32_t classes = mEventHub->getDeviceClasses(deviceId);
    int32_t controllerNumber = mEventHub->getDeviceControllerNumber(deviceId);
    //创建InputDevice
    InputDevice* device = createDeviceLocked(deviceId, controllerNumber, identifier, classes);
    device->configure(when, &mConfig, 0);
    device->reset(when);

    if (device->isIgnored()) {
        ALOGI("Device added: id=%d, name='%s' (ignored non-input device)", deviceId,
                identifier.name.string());
    } else {
        ALOGI("Device added: id=%d, name='%s', sources=0x%08x", deviceId,
                identifier.name.string(), device->getSources());
    }

    //将InputDevice放入到mDevices存起来
    mDevices.add(deviceId, device);
    bumpGenerationLocked();

    if (device->getClasses() & INPUT_DEVICE_CLASS_EXTERNAL_STYLUS) {
        notifyExternalStylusPresenceChanged();
    }
}

//这里是给每个InputDevice都添加了一个Mapper,由Mapper将原始数据转换为真正的触摸数据
InputDevice* InputReader::createDeviceLocked(int32_t deviceId, int32_t controllerNumber,
        const InputDeviceIdentifier& identifier, uint32_t classes) {
    InputDevice* device = new InputDevice(&mContext, deviceId, bumpGenerationLocked(),
            controllerNumber, identifier, classes);

    // External devices.
    if (classes & INPUT_DEVICE_CLASS_EXTERNAL) {
        device->setExternal(true);
    }

    // Devices with mics.
    if (classes & INPUT_DEVICE_CLASS_MIC) {
        device->setMic(true);
    }

    // Switch-like devices.
    if (classes & INPUT_DEVICE_CLASS_SWITCH) {
        device->addMapper(new SwitchInputMapper(device));
    }

    // Scroll wheel-like devices.
    if (classes & INPUT_DEVICE_CLASS_ROTARY_ENCODER) {
        device->addMapper(new RotaryEncoderInputMapper(device));
    }

    // Vibrator-like devices.
    if (classes & INPUT_DEVICE_CLASS_VIBRATOR) {
        device->addMapper(new VibratorInputMapper(device));
    }

    // Keyboard-like devices.
    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;
    }

    if (keyboardSource != 0) {
        device->addMapper(new KeyboardInputMapper(device, keyboardSource, keyboardType));
    }

    // Cursor-like devices.
    if (classes & INPUT_DEVICE_CLASS_CURSOR) {
        device->addMapper(new CursorInputMapper(device));
    }

    // Touchscreens and touchpad devices.
    if (classes & INPUT_DEVICE_CLASS_TOUCH_MT) {
        device->addMapper(new MultiTouchInputMapper(device));
    } else if (classes & INPUT_DEVICE_CLASS_TOUCH) {
        device->addMapper(new SingleTouchInputMapper(device));
    }

    // Joystick-like devices.
    if (classes & INPUT_DEVICE_CLASS_JOYSTICK) {
        device->addMapper(new JoystickInputMapper(device));
    }

    // External stylus-like devices.
    if (classes & INPUT_DEVICE_CLASS_EXTERNAL_STYLUS) {
        device->addMapper(new ExternalStylusInputMapper(device));
    }

    return device;
}

在processEventsLocked中,会循环处理每个device。

然后循环第二次进入getevent,前面的流程都不会执行,在这里会等待事件的发生,如果有事件发生,那么mPendingEventItems中将会存储eventItem

mPendingEventIndex = 0;

release_wake_lock(WAKE_LOCK_ID);

int pollResult = epoll_wait(mEpollFd, mPendingEventItems, EPOLL_MAX_EVENTS, timeoutMillis);

 如果有事件发生,那么mPendingEventIndex将会为0,mPendingEventCount至少也是1.就会进入这个while循环中。

while (mPendingEventIndex < mPendingEventCount) {
    const struct epoll_event& eventItem = mPendingEventItems[mPendingEventIndex++];
    //判断是否有新的节点添加或删除
    if (eventItem.data.u32 == EPOLL_ID_INOTIFY) {
        if (eventItem.events & EPOLLIN) {
            mPendingINotify = true;
        } else {
            ALOGW("Received unexpected epoll event 0x%08x for INotify.", eventItem.events);
        }
        continue;
    }

........

    //获取对应device,通过device来读取event,最多读取256个inputevent
    ssize_t deviceIndex = mDevices.indexOfKey(eventItem.data.u32);
    if (deviceIndex < 0) {
        ALOGW("Received unexpected epoll event 0x%08x for unknown device id %d.",
                eventItem.events, eventItem.data.u32);
        continue;
    }

    Device* device = mDevices.valueAt(deviceIndex);
    if (eventItem.events & EPOLLIN) {
        int32_t readSize = read(device->fd, readBuffer,
                sizeof(struct input_event) * capacity);
    if (readSize == 0 || (readSize < 0 && errno == ENODEV)) {
..........
    } else if (readSize < 0) {
..........
    } else if ((readSize % sizeof(struct input_event)) != 0) {
..........
    } else {
        int32_t deviceId = device->id == mBuiltInKeyboardId ? 0 : device->id;
        //计算读取到了多少个input_event
        size_t count = size_t(readSize) / sizeof(struct input_event);
        for (size_t i = 0; i < count; i++) {
            struct input_event& iev = readBuffer[i];
            ALOGV("%s got: time=%d.%06d, type=%d, code=%d, value=%d",
                    device->path.string(),
                    (int) iev.time.tv_sec, (int) iev.time.tv_usec,
                    iev.type, iev.code, iev.value);

            // Some input devices may have a better concept of the time
            // when an input event was actually generated than the kernel
            // which simply timestamps all events on entry to evdev.
            // This is a custom Android extension of the input protocol
            // mainly intended for use with uinput based device drivers.
            if (iev.type == EV_MSC) {
                if (iev.code == MSC_ANDROID_TIME_SEC) {
                    device->timestampOverrideSec = iev.value;
                    continue;
                } else if (iev.code == MSC_ANDROID_TIME_USEC) {
                    device->timestampOverrideUsec = iev.value;
                    continue;
                }
            }
            if (device->timestampOverrideSec || device->timestampOverrideUsec) {
                iev.time.tv_sec = device->timestampOverrideSec;
                iev.time.tv_usec = device->timestampOverrideUsec;
                if (iev.type == EV_SYN && iev.code == SYN_REPORT) {
                    device->timestampOverrideSec = 0;
                    device->timestampOverrideUsec = 0;
                }
                ALOGV("applied override time %d.%06d",
                        int(iev.time.tv_sec), int(iev.time.tv_usec));
            }

            // Use the time specified in the event instead of the current time
            // so that downstream code can get more accurate estimates of
            // event dispatch latency from the time the event is enqueued onto
            // the evdev client buffer.
            //
            // The event's timestamp fortuitously uses the same monotonic clock
            // time base as the rest of Android.  The kernel event device driver
            // (drivers/input/evdev.c) obtains timestamps using ktime_get_ts().
            // The systemTime(SYSTEM_TIME_MONOTONIC) function we use everywhere
            // calls clock_gettime(CLOCK_MONOTONIC) which is implemented as a
            // system call that also queries ktime_get_ts().
            event->when = nsecs_t(iev.time.tv_sec) * 1000000000LL
                    + nsecs_t(iev.time.tv_usec) * 1000LL;
            ALOGV("event time %" PRId64 ", now %" PRId64, event->when, now);

            // Bug 7291243: Add a guard in case the kernel generates timestamps
            // that appear to be far into the future because they were generated
            // using the wrong clock source.
            //
            // This can happen because when the input device is initially opened
            // it has a default clock source of CLOCK_REALTIME.  Any input events
            // enqueued right after the device is opened will have timestamps
            // generated using CLOCK_REALTIME.  We later set the clock source
            // to CLOCK_MONOTONIC but it is already too late.
            //
            // Invalid input event timestamps can result in ANRs, crashes and
            // and other issues that are hard to track down.  We must not let them
            // propagate through the system.
            //
            // Log a warning so that we notice the problem and recover gracefully.
            if (event->when >= now + 10 * 1000000000LL) {
                // Double-check.  Time may have moved on.
                nsecs_t time = systemTime(SYSTEM_TIME_MONOTONIC);
                if (event->when > time) {
                    ALOGW("An input event from %s has a timestamp that appears to "
                            "have been generated using the wrong clock source "
                            "(expected CLOCK_MONOTONIC): "
                            "event time %" PRId64 ", current time %" PRId64
                            ", call time %" PRId64 ".  "
                            "Using current time instead.",
                            device->path.string(), event->when, time, now);
                    event->when = time;
                } else {
                    ALOGV("Event time is ok but failed the fast path and required "
                            "an extra call to systemTime: "
                            "event time %" PRId64 ", current time %" PRId64
                            ", call time %" PRId64 ".",
                            event->when, time, now);
                }
            }
            //在将inputevent转化为RawEvent
            event->deviceId = deviceId;
            event->type = iev.type;
            event->code = iev.code;
            event->value = iev.value;
            event += 1;
            capacity -= 1;
        }
        if (capacity == 0) {
            // The result buffer is full.  Reset the pending event index
            // so we will try to read the device again on the next iteration.
            mPendingEventIndex -= 1;
            break;
        }
    }

}

到这里又因为event != buffer退出循环了,后续去处理RawEvent
// Return now if we have collected any events or if we were explicitly awoken.
if (event != buffer || awoken) {
    break;
}

 调用processEventsLocked对数据进行处理,这里本质上是找出同一个设备产生的一些了device进行处理

void InputReader::processEventsLocked(const RawEvent* rawEvents, size_t count) {
    for (const RawEvent* rawEvent = rawEvents; count;) {
        int32_t type = rawEvent->type;
        size_t batchSize = 1;
        //使用这个逻辑对具体时间进行处理
        //1.如果某个设备产生了10个数据,预期是把这10个数据同时处理掉,但是如果这10个数据之间
        //有其它设备产生的数据,那么就会退出下面这个while循环。先处理同一个设备产生的数据。
        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;
            }
#if DEBUG_RAW_EVENTS
            ALOGD("BatchSize: %zu Count: %zu", batchSize, count);
#endif
            //在这里处理由同一个device产生的一连串的数据
            processEventsForDeviceLocked(deviceId, rawEvent, batchSize);
        } else {
....
....
        }
        count -= batchSize;
        rawEvent += batchSize;
    }
}

 processEventsForDeviceLocked中找出id对应的InputDevice调用process进行处理

void InputReader::processEventsForDeviceLocked(int32_t deviceId,
        const RawEvent* rawEvents, size_t count) {
    ssize_t deviceIndex = mDevices.indexOfKey(deviceId);
    if (deviceIndex < 0) {
        ALOGW("Discarding event for unknown deviceId %d.", deviceId);
        return;
    }

    InputDevice* device = mDevices.valueAt(deviceIndex);
    if (device->isIgnored()) {
        //ALOGD("Discarding event for ignored deviceId %d.", deviceId);
        return;
    }

    device->process(rawEvents, count);
}

 在InputDevice::process函数中,默认mDropUntilNextSync为false,所以调用mapper->process进行处理

void InputDevice::process(const RawEvent* rawEvents, size_t count) {
    // Process all of the events in order for each mapper.
    // We cannot simply ask each mapper to process them in bulk because mappers may
    // have side-effects that must be interleaved.  For example, joystick movement events and
    // gamepad button presses are handled by different mappers but they should be dispatched
    // in the order received.
    size_t numMappers = mMappers.size();
    for (const RawEvent* rawEvent = rawEvents; count != 0; rawEvent++) {
#if DEBUG_RAW_EVENTS
        ALOGD("Input event: device=%d type=0x%04x code=0x%04x value=0x%08x when=%" PRId64,
                rawEvent->deviceId, rawEvent->type, rawEvent->code, rawEvent->value,
                rawEvent->when);
#endif

        if (mDropUntilNextSync) {
            if (rawEvent->type == EV_SYN && rawEvent->code == SYN_REPORT) {
                mDropUntilNextSync = false;
#if DEBUG_RAW_EVENTS
                ALOGD("Recovered from input event buffer overrun.");
#endif
            } else {
#if DEBUG_RAW_EVENTS
                ALOGD("Dropped input event while waiting for next input sync.");
#endif
            }
        } else if (rawEvent->type == EV_SYN && rawEvent->code == SYN_DROPPED) {
            //是一种异常情况,不具体分析
            ALOGI("Detected input event buffer overrun for device %s.", getName().string());
            mDropUntilNextSync = true;
            reset(rawEvent->when);
        } else {
            for (size_t i = 0; i < numMappers; i++) {
                InputMapper* mapper = mMappers[i];
                mapper->process(rawEvent);
            }
        }
        --count;
    }
}

如果设备是触摸屏,那么会调用MultiTouchInputMapper的process进行处理,对照数据进行分析

void MultiTouchInputMapper::process(const RawEvent* rawEvent) {
    TouchInputMapper::process(rawEvent);

    mMultiTouchMotionAccumulator.process(rawEvent);
}

void MultiTouchMotionAccumulator::process(const RawEvent* rawEvent) {
    if (rawEvent->type == EV_ABS) {
        //最开始数据是ABS类型
        bool newSlot = false;
        //是不是用的slot协议,一般都是这种协议
        if (mUsingSlotsProtocol) {
            //code最开始是ABS_MT_SLOT
            if (rawEvent->code == ABS_MT_SLOT) {
                //将触点id保存
                mCurrentSlot = rawEvent->value;
                //表示有新的slot
                newSlot = true;
            }
        } else if (mCurrentSlot < 0) {
            mCurrentSlot = 0;
        }
        
        //mCurrentSlot 到这里不会小于0,触点大于等于16时将会报错不支持。  第一次slot判断到此结束
        if (mCurrentSlot < 0 || size_t(mCurrentSlot) >= mSlotCount) {
#if DEBUG_POINTERS
            if (newSlot) {
                ALOGW("MultiTouch device emitted invalid slot index %d but it "
                        "should be between 0 and %zd; ignoring this slot.",
                        mCurrentSlot, mSlotCount - 1);
            }
#endif
        } else {
            //当mCurrentSlot为0时
            Slot* slot = &mSlots[mCurrentSlot];

            switch (rawEvent->code) {
            case ABS_MT_POSITION_X:
                slot->mInUse = true;
                slot->mAbsMTPositionX = rawEvent->value;
                break;
            case ABS_MT_POSITION_Y:
                slot->mInUse = true;
                slot->mAbsMTPositionY = rawEvent->value;
                break;
            case ABS_MT_TOUCH_MAJOR:
                slot->mInUse = true;
                slot->mAbsMTTouchMajor = rawEvent->value;
                break;
            case ABS_MT_TOUCH_MINOR:
                slot->mInUse = true;
                slot->mAbsMTTouchMinor = rawEvent->value;
                slot->mHaveAbsMTTouchMinor = true;
                break;
            case ABS_MT_WIDTH_MAJOR:
                slot->mInUse = true;
                slot->mAbsMTWidthMajor = rawEvent->value;
                break;
            case ABS_MT_WIDTH_MINOR:
                slot->mInUse = true;
                slot->mAbsMTWidthMinor = rawEvent->value;
                slot->mHaveAbsMTWidthMinor = true;
                break;
            case ABS_MT_ORIENTATION:
                slot->mInUse = true;
                slot->mAbsMTOrientation = rawEvent->value;
                break;
            //abs 数据第二次处理,value不为0,表示触点没松开,触点松开时value为1

            case ABS_MT_TRACKING_ID:
                if (mUsingSlotsProtocol && rawEvent->value < 0) {
                    // The slot is no longer in use but it retains its previous contents,
                    // which may be reused for subsequent touches.
                    slot->mInUse = false;
                } else {
                    slot->mInUse = true;
                    slot->mAbsMTTrackingId = rawEvent->value;
                }
                break;
            case ABS_MT_PRESSURE:
                slot->mInUse = true;
                slot->mAbsMTPressure = rawEvent->value;
                break;
            case ABS_MT_DISTANCE:
                slot->mInUse = true;
                slot->mAbsMTDistance = rawEvent->value;
                break;
            case ABS_MT_TOOL_TYPE:
                slot->mInUse = true;
                slot->mAbsMTToolType = rawEvent->value;
                slot->mHaveAbsMTToolType = true;
                break;
            }
        }
    } else if (rawEvent->type == EV_SYN && rawEvent->code == SYN_MT_REPORT) {
        // MultiTouch Sync: The driver has returned all data for *one* of the pointers.
        mCurrentSlot += 1;
    } else if (rawEvent->type == EV_MSC && rawEvent->code == MSC_TIMESTAMP) {
        mDeviceTimestamp = rawEvent->value;
    }
}



void TouchInputMapper::process(const RawEvent* rawEvent) {
    mCursorButtonAccumulator.process(rawEvent);
    mCursorScrollAccumulator.process(rawEvent);
    mTouchButtonAccumulator.process(rawEvent);
    //同步尾
    if (rawEvent->type == EV_SYN && rawEvent->code == SYN_REPORT) {
        sync(rawEvent->when);
    }
}


void TouchInputMapper::sync(nsecs_t when) {
    const RawState* last = mRawStatesPending.isEmpty() ?
            &mCurrentRawState : &mRawStatesPending.top();

    // Push a new state.
    mRawStatesPending.push();
    RawState* next = &mRawStatesPending.editTop();
    next->clear();
    next->when = when;

    // Sync button state.
    next->buttonState = mTouchButtonAccumulator.getButtonState()
            | mCursorButtonAccumulator.getButtonState();

    // Sync scroll
    next->rawVScroll = mCursorScrollAccumulator.getRelativeVWheel();
    next->rawHScroll = mCursorScrollAccumulator.getRelativeHWheel();
    mCursorScrollAccumulator.finishSync();

    // Sync touch
    syncTouch(when, next);

    // Assign pointer ids.
    if (!mHavePointerIds) {
        assignPointerIds(last, next);
    }

#if DEBUG_RAW_EVENTS
    ALOGD("syncTouch: pointerCount %d -> %d, touching ids 0x%08x -> 0x%08x, "
            "hovering ids 0x%08x -> 0x%08x",
            last->rawPointerData.pointerCount,
            next->rawPointerData.pointerCount,
            last->rawPointerData.touchingIdBits.value,
            next->rawPointerData.touchingIdBits.value,
            last->rawPointerData.hoveringIdBits.value,
            next->rawPointerData.hoveringIdBits.value);
#endif

    processRawTouches(false /*timeout*/);
}


void MultiTouchInputMapper::syncTouch(nsecs_t when, RawState* outState) {
    //获取slotcount  值为16
    size_t inCount = mMultiTouchMotionAccumulator.getSlotCount();
    size_t outCount = 0;
    BitSet32 newPointerIdBits;
    mHavePointerIds = true;
    //这里遍历每个slot  判断触点是不是还在,如果触点不在,直接略过
    for (size_t inIndex = 0; inIndex < inCount; inIndex++) {
        const MultiTouchMotionAccumulator::Slot* inSlot =
                mMultiTouchMotionAccumulator.getSlot(inIndex);
        if (!inSlot->isInUse()) {
            continue;
        }

        if (outCount >= MAX_POINTERS) {
#if DEBUG_POINTERS
            ALOGD("MultiTouch device %s emitted more than maximum of %d pointers; "
                    "ignoring the rest.",
                    getDeviceName().string(), MAX_POINTERS);
#endif
            break; // too many fingers!
        }

        //构建一个触点对象,数据来自slot
        RawPointerData::Pointer& outPointer = outState->rawPointerData.pointers[outCount];
        outPointer.x = inSlot->getX();
        outPointer.y = inSlot->getY();
        outPointer.pressure = inSlot->getPressure();
        outPointer.touchMajor = inSlot->getTouchMajor();
        outPointer.touchMinor = inSlot->getTouchMinor();
        outPointer.toolMajor = inSlot->getToolMajor();
        outPointer.toolMinor = inSlot->getToolMinor();
        outPointer.orientation = inSlot->getOrientation();
        outPointer.distance = inSlot->getDistance();
        outPointer.tiltX = 0;
        outPointer.tiltY = 0;

        outPointer.toolType = inSlot->getToolType();
        if (outPointer.toolType == AMOTION_EVENT_TOOL_TYPE_UNKNOWN) {
            outPointer.toolType = mTouchButtonAccumulator.getToolType();
            if (outPointer.toolType == AMOTION_EVENT_TOOL_TYPE_UNKNOWN) {
                outPointer.toolType = AMOTION_EVENT_TOOL_TYPE_FINGER;
            }
        }

        bool isHovering = mTouchButtonAccumulator.getToolType() != AMOTION_EVENT_TOOL_TYPE_MOUSE
                && (mTouchButtonAccumulator.isHovering()
                        || (mRawPointerAxes.pressure.valid && inSlot->getPressure() <= 0));
        outPointer.isHovering = isHovering;

        // Assign pointer id using tracking id if available.
        if (mHavePointerIds) {
            int32_t trackingId = inSlot->getTrackingId();
            int32_t id = -1;
            if (trackingId >= 0) {
                for (BitSet32 idBits(mPointerIdBits); !idBits.isEmpty(); ) {
                    //查找并清除第一个被标记的位(即值为 1 的位),然后返回该位的索引
                    uint32_t n = idBits.clearFirstMarkedBit();
                    if (mPointerTrackingIdMap[n] == trackingId) {
                        id = n;
                    }
                }
                //第一次在这里id小于0,并且mPointerIdBits没有满
                if (id < 0 && !mPointerIdBits.isFull()) {
                    id = mPointerIdBits.markFirstUnmarkedBit();//第一次这里返回0,标记第一个没有被标记过的下标,并返回索引
                    //保存trackingId
                    mPointerTrackingIdMap[id] = trackingId;
                }
            }
            if (id < 0) {
                mHavePointerIds = false;
                outState->rawPointerData.clearIdBits();
                newPointerIdBits.clear();
            } else {
                //记录id
                outPointer.id = id;
                //第一个触点
                outState->rawPointerData.idToIndex[id] = outCount;
                outState->rawPointerData.markIdBit(id, isHovering);
                newPointerIdBits.markBit(id);
            }
        }
        outCount += 1;
    }

    outState->deviceTimestamp = mMultiTouchMotionAccumulator.getDeviceTimestamp();
    outState->rawPointerData.pointerCount = outCount;
    mPointerIdBits = newPointerIdBits;

    mMultiTouchMotionAccumulator.finishSync();
}


void TouchInputMapper::processRawTouches(bool timeout) {
    //这里判断是不是某个状态抛弃所有触摸数据
    if (mDeviceMode == DEVICE_MODE_DISABLED) {
        // Drop all input if the device is disabled.
        mCurrentRawState.clear();
        mRawStatesPending.clear();
        return;
    }

    // Drain any pending touch states. The invariant here is that the mCurrentRawState is always
    // valid and must go through the full cook and dispatch cycle. This ensures that anything
    // touching the current state will only observe the events that have been dispatched to the
    // rest of the pipeline.
    const size_t N = mRawStatesPending.size();
    size_t count;
    for(count = 0; count < N; count++) {
        //取出RawState对象的数据,数据在syncTouch时填入
        const RawState& next = mRawStatesPending[count];

        // A failure to assign the stylus id means that we're waiting on stylus data
        // and so should defer the rest of the pipeline.
        if (assignExternalStylusId(next, timeout)) {
            break;
        }

        // All ready to go.
        clearStylusDataPendingFlags();
        //拷贝一份数据
        mCurrentRawState.copyFrom(next);
        if (mCurrentRawState.when < mLastRawState.when) {
            mCurrentRawState.when = mLastRawState.when;
        }
        //关键方法
        cookAndDispatch(mCurrentRawState.when);
    }
    if (count != 0) {
        mRawStatesPending.removeItemsAt(0, count);
    }

    if (mExternalStylusDataPending) {
        if (timeout) {
            nsecs_t when = mExternalStylusFusionTimeout - STYLUS_DATA_LATENCY;
            clearStylusDataPendingFlags();
            mCurrentRawState.copyFrom(mLastRawState);
#if DEBUG_STYLUS_FUSION
            ALOGD("Timeout expired, synthesizing event with new stylus data");
#endif
            cookAndDispatch(when);
        } else if (mExternalStylusFusionTimeout == LLONG_MAX) {
            mExternalStylusFusionTimeout = mExternalStylusState.when + TOUCH_DATA_TIMEOUT;
            getContext()->requestTimeoutAtTime(mExternalStylusFusionTimeout);
        }
    }
}

分析cookAndDispatch

void TouchInputMapper::cookAndDispatch(nsecs_t when) {
    // Always start with a clean state.
    //初始化变量
    mCurrentCookedState.clear();

    // Apply stylus buttons to current raw state.
    applyExternalStylusButtonState(when);

    // Handle policy on initial down or hover events.
    bool initialDown = mLastRawState.rawPointerData.pointerCount == 0
            && mCurrentRawState.rawPointerData.pointerCount != 0;

    uint32_t policyFlags = 0;
    bool buttonsPressed = mCurrentRawState.buttonState & ~mLastRawState.buttonState;
    if (initialDown || buttonsPressed) {
        // If this is a touch screen, hide the pointer on an initial down.
        if (mDeviceMode == DEVICE_MODE_DIRECT) {
            getContext()->fadePointer();
        }

        if (mParameters.wake) {
            policyFlags |= POLICY_FLAG_WAKE;
        }
    }

    // Consume raw off-screen touches before cooking pointer data.
    // If touches are consumed, subsequent code will not receive any pointer data.
    if (consumeRawTouches(when, policyFlags)) {
        //
        mCurrentRawState.rawPointerData.clear();
    }

    // Cook pointer data.  This call populates the mCurrentCookedState.cookedPointerData structure
    // with cooked pointer data that has the same ids and indices as the raw data.
    // The following code can use either the raw or cooked data, as needed.
    //关键方法
    cookPointerData();

    // Apply stylus pressure to current cooked state.
    applyExternalStylusTouchState(when);

    // Synthesize key down from raw buttons if needed.
    synthesizeButtonKeys(getContext(), AKEY_EVENT_ACTION_DOWN, when, getDeviceId(), mSource,
            policyFlags, mLastCookedState.buttonState, mCurrentCookedState.buttonState);

    // Dispatch the touches either directly or by translation through a pointer on screen.
    if (mDeviceMode == DEVICE_MODE_POINTER) {
        for (BitSet32 idBits(mCurrentRawState.rawPointerData.touchingIdBits);
                !idBits.isEmpty(); ) {
            uint32_t id = idBits.clearFirstMarkedBit();
            const RawPointerData::Pointer& pointer =
                    mCurrentRawState.rawPointerData.pointerForId(id);
            if (pointer.toolType == AMOTION_EVENT_TOOL_TYPE_STYLUS
                    || pointer.toolType == AMOTION_EVENT_TOOL_TYPE_ERASER) {
                mCurrentCookedState.stylusIdBits.markBit(id);
            } else if (pointer.toolType == AMOTION_EVENT_TOOL_TYPE_FINGER
                    || pointer.toolType == AMOTION_EVENT_TOOL_TYPE_UNKNOWN) {
                mCurrentCookedState.fingerIdBits.markBit(id);
            } else if (pointer.toolType == AMOTION_EVENT_TOOL_TYPE_MOUSE) {
                mCurrentCookedState.mouseIdBits.markBit(id);
            }
        }
        for (BitSet32 idBits(mCurrentRawState.rawPointerData.hoveringIdBits);
                !idBits.isEmpty(); ) {
            uint32_t id = idBits.clearFirstMarkedBit();
            const RawPointerData::Pointer& pointer =
                    mCurrentRawState.rawPointerData.pointerForId(id);
            if (pointer.toolType == AMOTION_EVENT_TOOL_TYPE_STYLUS
                    || pointer.toolType == AMOTION_EVENT_TOOL_TYPE_ERASER) {
                mCurrentCookedState.stylusIdBits.markBit(id);
            }
        }

        // Stylus takes precedence over all tools, then mouse, then finger.
        PointerUsage pointerUsage = mPointerUsage;
        if (!mCurrentCookedState.stylusIdBits.isEmpty()) {
            mCurrentCookedState.mouseIdBits.clear();
            mCurrentCookedState.fingerIdBits.clear();
            pointerUsage = POINTER_USAGE_STYLUS;
        } else if (!mCurrentCookedState.mouseIdBits.isEmpty()) {
            mCurrentCookedState.fingerIdBits.clear();
            pointerUsage = POINTER_USAGE_MOUSE;
        } else if (!mCurrentCookedState.fingerIdBits.isEmpty() ||
                isPointerDown(mCurrentRawState.buttonState)) {
            pointerUsage = POINTER_USAGE_GESTURES;
        }

        dispatchPointerUsage(when, policyFlags, pointerUsage);
    } else {
        if (mDeviceMode == DEVICE_MODE_DIRECT
                && mConfig.showTouches && mPointerController != NULL) {
            mPointerController->setPresentation(PointerControllerInterface::PRESENTATION_SPOT);
            mPointerController->fade(PointerControllerInterface::TRANSITION_GRADUAL);

            mPointerController->setButtonState(mCurrentRawState.buttonState);
            mPointerController->setSpots(mCurrentCookedState.cookedPointerData.pointerCoords,
                    mCurrentCookedState.cookedPointerData.idToIndex,
                    mCurrentCookedState.cookedPointerData.touchingIdBits);
        }

        if (!mCurrentMotionAborted) {
            dispatchButtonRelease(when, policyFlags);
            dispatchHoverExit(when, policyFlags);
            //触摸点派发
            dispatchTouches(when, policyFlags);
            dispatchHoverEnterAndMove(when, policyFlags);
            dispatchButtonPress(when, policyFlags);
        }

        if (mCurrentCookedState.cookedPointerData.pointerCount == 0) {
            mCurrentMotionAborted = false;
        }
    }

    // Synthesize key up from raw buttons if needed.
    synthesizeButtonKeys(getContext(), AKEY_EVENT_ACTION_UP, when, getDeviceId(), mSource,
            policyFlags, mLastCookedState.buttonState, mCurrentCookedState.buttonState);

    // Clear some transient state.
    mCurrentRawState.rawVScroll = 0;
    mCurrentRawState.rawHScroll = 0;

    // Copy current touch to last touch in preparation for the next cycle.
    mLastRawState.copyFrom(mCurrentRawState);
    mLastCookedState.copyFrom(mCurrentCookedState);
}



void TouchInputMapper::cookPointerData() {
    //获取有多少个触点
    uint32_t currentPointerCount = mCurrentRawState.rawPointerData.pointerCount;

    mCurrentCookedState.cookedPointerData.clear();
    mCurrentCookedState.deviceTimestamp =
            mCurrentRawState.deviceTimestamp;
    //按下点的个数
    mCurrentCookedState.cookedPointerData.pointerCount = currentPointerCount;
    mCurrentCookedState.cookedPointerData.hoveringIdBits =
            mCurrentRawState.rawPointerData.hoveringIdBits;
    //按下id的集合
    mCurrentCookedState.cookedPointerData.touchingIdBits =
            mCurrentRawState.rawPointerData.touchingIdBits;
    //判断按下点的个数是否为0,正常不会为0
    if (mCurrentCookedState.cookedPointerData.pointerCount == 0) {
        mCurrentCookedState.buttonState = 0;
    } else {
        mCurrentCookedState.buttonState = mCurrentRawState.buttonState;
    }

    // Walk through the the active pointers and map device coordinates onto
    // surface coordinates and adjust for display orientation.
        //遍历触点
    for (uint32_t i = 0; i < currentPointerCount; i++) {
        //取出触点数据
        const RawPointerData::Pointer& in = mCurrentRawState.rawPointerData.pointers[i];

        // Size
        float touchMajor, touchMinor, toolMajor, toolMinor, size;
        //size的校准  长轴短轴的校准
        switch (mCalibration.sizeCalibration) {
        case Calibration::SIZE_CALIBRATION_GEOMETRIC:
        case Calibration::SIZE_CALIBRATION_DIAMETER:
        case Calibration::SIZE_CALIBRATION_BOX:
        case Calibration::SIZE_CALIBRATION_AREA:
            if (mRawPointerAxes.touchMajor.valid && mRawPointerAxes.toolMajor.valid) {
                touchMajor = in.touchMajor;
                touchMinor = mRawPointerAxes.touchMinor.valid ? in.touchMinor : in.touchMajor;
                toolMajor = in.toolMajor;
                toolMinor = mRawPointerAxes.toolMinor.valid ? in.toolMinor : in.toolMajor;
                size = mRawPointerAxes.touchMinor.valid
                        ? avg(in.touchMajor, in.touchMinor) : in.touchMajor;
            } else if (mRawPointerAxes.touchMajor.valid) {
                toolMajor = touchMajor = in.touchMajor;
                toolMinor = touchMinor = mRawPointerAxes.touchMinor.valid
                        ? in.touchMinor : in.touchMajor;
                size = mRawPointerAxes.touchMinor.valid
                        ? avg(in.touchMajor, in.touchMinor) : in.touchMajor;
            } else if (mRawPointerAxes.toolMajor.valid) {
                touchMajor = toolMajor = in.toolMajor;
                touchMinor = toolMinor = mRawPointerAxes.toolMinor.valid
                        ? in.toolMinor : in.toolMajor;
                size = mRawPointerAxes.toolMinor.valid
                        ? avg(in.toolMajor, in.toolMinor) : in.toolMajor;
            } else {
                ALOG_ASSERT(false, "No touch or tool axes.  "
                        "Size calibration should have been resolved to NONE.");
                touchMajor = 0;
                touchMinor = 0;
                toolMajor = 0;
                toolMinor = 0;
                size = 0;
            }

            if (mCalibration.haveSizeIsSummed && mCalibration.sizeIsSummed) {
                uint32_t touchingCount =
                        mCurrentRawState.rawPointerData.touchingIdBits.count();
                if (touchingCount > 1) {
                    touchMajor /= touchingCount;
                    touchMinor /= touchingCount;
                    toolMajor /= touchingCount;
                    toolMinor /= touchingCount;
                    size /= touchingCount;
                }
            }

            if (mCalibration.sizeCalibration == Calibration::SIZE_CALIBRATION_GEOMETRIC) {
                touchMajor *= mGeometricScale;
                touchMinor *= mGeometricScale;
                toolMajor *= mGeometricScale;
                toolMinor *= mGeometricScale;
            } else if (mCalibration.sizeCalibration == Calibration::SIZE_CALIBRATION_AREA) {
                touchMajor = touchMajor > 0 ? sqrtf(touchMajor) : 0;
                touchMinor = touchMajor;
                toolMajor = toolMajor > 0 ? sqrtf(toolMajor) : 0;
                toolMinor = toolMajor;
            } else if (mCalibration.sizeCalibration == Calibration::SIZE_CALIBRATION_DIAMETER) {
                touchMinor = touchMajor;
                toolMinor = toolMajor;
            }

            mCalibration.applySizeScaleAndBias(&touchMajor);
            mCalibration.applySizeScaleAndBias(&touchMinor);
            mCalibration.applySizeScaleAndBias(&toolMajor);
            mCalibration.applySizeScaleAndBias(&toolMinor);
            size *= mSizeScale;
            break;
        default:
            touchMajor = 0;
            touchMinor = 0;
            toolMajor = 0;
            toolMinor = 0;
            size = 0;
            break;
        }

        // Pressure
        float pressure;
        switch (mCalibration.pressureCalibration) {
        case Calibration::PRESSURE_CALIBRATION_PHYSICAL:
        case Calibration::PRESSURE_CALIBRATION_AMPLITUDE:
            pressure = in.pressure * mPressureScale;
            break;
        default:
            pressure = in.isHovering ? 0 : 1;
            break;
        }
        //方向校准
        // Tilt and Orientation
        float tilt;
        float orientation;
        if (mHaveTilt) {
            float tiltXAngle = (in.tiltX - mTiltXCenter) * mTiltXScale;
            float tiltYAngle = (in.tiltY - mTiltYCenter) * mTiltYScale;
            orientation = atan2f(-sinf(tiltXAngle), sinf(tiltYAngle));
            tilt = acosf(cosf(tiltXAngle) * cosf(tiltYAngle));
        } else {
            tilt = 0;

            switch (mCalibration.orientationCalibration) {
            case Calibration::ORIENTATION_CALIBRATION_INTERPOLATED:
                orientation = in.orientation * mOrientationScale;
                break;
            case Calibration::ORIENTATION_CALIBRATION_VECTOR: {
                int32_t c1 = signExtendNybble((in.orientation & 0xf0) >> 4);
                int32_t c2 = signExtendNybble(in.orientation & 0x0f);
                if (c1 != 0 || c2 != 0) {
                    orientation = atan2f(c1, c2) * 0.5f;
                    float confidence = hypotf(c1, c2);
                    float scale = 1.0f + confidence / 16.0f;
                    touchMajor *= scale;
                    touchMinor /= scale;
                    toolMajor *= scale;
                    toolMinor /= scale;
                } else {
                    orientation = 0;
                }
                break;
            }
            default:
                orientation = 0;
            }
        }

        // Distance  距离校准
        float distance;
        switch (mCalibration.distanceCalibration) {
        case Calibration::DISTANCE_CALIBRATION_SCALED:
            distance = in.distance * mDistanceScale;
            break;
        default:
            distance = 0;
        }

        // Coverage   覆盖面校准
        int32_t rawLeft, rawTop, rawRight, rawBottom;
        switch (mCalibration.coverageCalibration) {
        case Calibration::COVERAGE_CALIBRATION_BOX:
            rawLeft = (in.toolMinor & 0xffff0000) >> 16;
            rawRight = in.toolMinor & 0x0000ffff;
            rawBottom = in.toolMajor & 0x0000ffff;
            rawTop = (in.toolMajor & 0xffff0000) >> 16;
            break;
        default:
            rawLeft = rawTop = rawRight = rawBottom = 0;
            break;
        }
        //x y 坐标校准
        // Adjust X,Y coords for device calibration
        // TODO: Adjust coverage coords?
        float xTransformed = in.x, yTransformed = in.y;
        mAffineTransform.applyTo(xTransformed, yTransformed);

        // Adjust X, Y, and coverage coords for surface orientation.
        float x, y;
        float left, top, right, bottom;

        switch (mSurfaceOrientation) {
        case DISPLAY_ORIENTATION_90:
            x = float(yTransformed - mRawPointerAxes.y.minValue) * mYScale + mYTranslate;
            y = float(mRawPointerAxes.x.maxValue - xTransformed) * mXScale + mXTranslate;
            left = float(rawTop - mRawPointerAxes.y.minValue) * mYScale + mYTranslate;
            right = float(rawBottom- mRawPointerAxes.y.minValue) * mYScale + mYTranslate;
            bottom = float(mRawPointerAxes.x.maxValue - rawLeft) * mXScale + mXTranslate;
            top = float(mRawPointerAxes.x.maxValue - rawRight) * mXScale + mXTranslate;
            orientation -= M_PI_2;
            if (mOrientedRanges.haveOrientation && orientation < mOrientedRanges.orientation.min) {
                orientation += (mOrientedRanges.orientation.max - mOrientedRanges.orientation.min);
            }
            break;
        case DISPLAY_ORIENTATION_180:
            x = float(mRawPointerAxes.x.maxValue - xTransformed) * mXScale + mXTranslate;
            y = float(mRawPointerAxes.y.maxValue - yTransformed) * mYScale + mYTranslate;
            left = float(mRawPointerAxes.x.maxValue - rawRight) * mXScale + mXTranslate;
            right = float(mRawPointerAxes.x.maxValue - rawLeft) * mXScale + mXTranslate;
            bottom = float(mRawPointerAxes.y.maxValue - rawTop) * mYScale + mYTranslate;
            top = float(mRawPointerAxes.y.maxValue - rawBottom) * mYScale + mYTranslate;
            orientation -= M_PI;
            if (mOrientedRanges.haveOrientation && orientation < mOrientedRanges.orientation.min) {
                orientation += (mOrientedRanges.orientation.max - mOrientedRanges.orientation.min);
            }
            break;
        case DISPLAY_ORIENTATION_270:
            x = float(mRawPointerAxes.y.maxValue - yTransformed) * mYScale + mYTranslate;
            y = float(xTransformed - mRawPointerAxes.x.minValue) * mXScale + mXTranslate;
            left = float(mRawPointerAxes.y.maxValue - rawBottom) * mYScale + mYTranslate;
            right = float(mRawPointerAxes.y.maxValue - rawTop) * mYScale + mYTranslate;
            bottom = float(rawRight - mRawPointerAxes.x.minValue) * mXScale + mXTranslate;
            top = float(rawLeft - mRawPointerAxes.x.minValue) * mXScale + mXTranslate;
            orientation += M_PI_2;
            if (mOrientedRanges.haveOrientation && orientation > mOrientedRanges.orientation.max) {
                orientation -= (mOrientedRanges.orientation.max - mOrientedRanges.orientation.min);
            }
            break;
        default:
            x = float(xTransformed - mRawPointerAxes.x.minValue) * mXScale + mXTranslate;
            y = float(yTransformed - mRawPointerAxes.y.minValue) * mYScale + mYTranslate;
            left = float(rawLeft - mRawPointerAxes.x.minValue) * mXScale + mXTranslate;
            right = float(rawRight - mRawPointerAxes.x.minValue) * mXScale + mXTranslate;
            bottom = float(rawBottom - mRawPointerAxes.y.minValue) * mYScale + mYTranslate;
            top = float(rawTop - mRawPointerAxes.y.minValue) * mYScale + mYTranslate;
            break;
        }

        // Write output coords.
        PointerCoords& out = mCurrentCookedState.cookedPointerData.pointerCoords[i];
        out.clear();
        out.setAxisValue(AMOTION_EVENT_AXIS_X, x);
        out.setAxisValue(AMOTION_EVENT_AXIS_Y, y);
        out.setAxisValue(AMOTION_EVENT_AXIS_PRESSURE, pressure);
        out.setAxisValue(AMOTION_EVENT_AXIS_SIZE, size);
        out.setAxisValue(AMOTION_EVENT_AXIS_TOUCH_MAJOR, touchMajor);
        out.setAxisValue(AMOTION_EVENT_AXIS_TOUCH_MINOR, touchMinor);
        out.setAxisValue(AMOTION_EVENT_AXIS_ORIENTATION, orientation);
        out.setAxisValue(AMOTION_EVENT_AXIS_TILT, tilt);
        out.setAxisValue(AMOTION_EVENT_AXIS_DISTANCE, distance);
        if (mCalibration.coverageCalibration == Calibration::COVERAGE_CALIBRATION_BOX) {
            out.setAxisValue(AMOTION_EVENT_AXIS_GENERIC_1, left);
            out.setAxisValue(AMOTION_EVENT_AXIS_GENERIC_2, top);
            out.setAxisValue(AMOTION_EVENT_AXIS_GENERIC_3, right);
            out.setAxisValue(AMOTION_EVENT_AXIS_GENERIC_4, bottom);
        } else {
            out.setAxisValue(AMOTION_EVENT_AXIS_TOOL_MAJOR, toolMajor);
            out.setAxisValue(AMOTION_EVENT_AXIS_TOOL_MINOR, toolMinor);
        }

        // Write output properties.
        PointerProperties& properties =
                mCurrentCookedState.cookedPointerData.pointerProperties[i];
        uint32_t id = in.id;
        properties.clear();
        properties.id = id;
        properties.toolType = in.toolType;

        // Write id index.
        mCurrentCookedState.cookedPointerData.idToIndex[id] = i;
    }
}



void TouchInputMapper::dispatchTouches(nsecs_t when, uint32_t policyFlags) {
    //触点的个数
    BitSet32 currentIdBits = mCurrentCookedState.cookedPointerData.touchingIdBits;
    //上一次触点
    BitSet32 lastIdBits = mLastCookedState.cookedPointerData.touchingIdBits;
    int32_t metaState = getContext()->getGlobalMetaState();
    int32_t buttonState = mCurrentCookedState.buttonState;
    //本次触点和上一次触点是相等的   没有手指的变化
    if (currentIdBits == lastIdBits) {
        if (!currentIdBits.isEmpty()) { // 当前这次不为空
            // No pointer id changes so this is a move event.
            // The listener takes care of batching moves so we don't have to deal with that here.
            //没有触点的变化并且不为null,还有事件的变化,所以判定为触点的移动
            dispatchMotion(when, policyFlags, mSource,
                    AMOTION_EVENT_ACTION_MOVE, 0, 0, metaState, buttonState,
                    AMOTION_EVENT_EDGE_FLAG_NONE,
                    mCurrentCookedState.deviceTimestamp,
                    mCurrentCookedState.cookedPointerData.pointerProperties,
                    mCurrentCookedState.cookedPointerData.pointerCoords,
                    mCurrentCookedState.cookedPointerData.idToIndex,
                    currentIdBits, -1,
                    mOrientedXPrecision, mOrientedYPrecision, mDownTime);
        }
    } else {
        // There may be pointers going up and pointers going down and pointers moving
        // all at the same time.
        //如果有触点的变化,那么判定是否有触点的按下或抬起或者同时有触点的移动
  
上一篇:【C++指南】类和对象(二):类的默认成员函数——全面剖析 :构造函数


下一篇:SpringBoot在线教育系统:架构设计与技术选型