Android6.0 按键流程（五）无线鼠标右键无效 -- hal层

最近在我们的手机上碰到这样一个问题，用otg连接无线鼠标，发现右键没反应。

 

于是先用getEvent命令：查看其扫描码，然后再去kl文件中，结果没找到这个扫描码对应的键盘码。

于是结合之前分析的按键流程，怀疑按键流程最后没走KeyboardInputMapper，就在InputReader中打印log。

最后在InputDevice::process函数中遍历InputMapper调用器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 {
            }
        } 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];
                mapper->process(rawEvent);
            }
        }
    }
}

最后发现只调用了CursorInputMapper::process函数。

 

一、CursorInputMapper的process函数

下面我们开始分析CusorInputMapper的process函数。

void CursorInputMapper::process(const RawEvent* rawEvent) {
    mCursorButtonAccumulator.process(rawEvent);//按键
    mCursorMotionAccumulator.process(rawEvent);//移动
    mCursorScrollAccumulator.process(rawEvent);//滚动

    if (rawEvent->type == EV_SYN && rawEvent->code == SYN_REPORT) {
        sync(rawEvent->when);
    }
}

先来看CursorButtonAccumulator::process函数，根据按键事件传来的值，赋值各个成员变量

void CursorButtonAccumulator::process(const RawEvent* rawEvent) {
    if (rawEvent->type == EV_KEY) {
        switch (rawEvent->code) {
        case BTN_LEFT:
            mBtnLeft = rawEvent->value;//鼠标左键
            break;
        case BTN_RIGHT:
            mBtnRight = rawEvent->value;//鼠标右键
            break;
        case BTN_MIDDLE:
            mBtnMiddle = rawEvent->value;
            break;
        case BTN_BACK:
            mBtnBack = rawEvent->value;
            break;
        case BTN_SIDE:
            mBtnSide = rawEvent->value;
            break;
        case BTN_FORWARD:
            mBtnForward = rawEvent->value;
            break;
        case BTN_EXTRA:
            mBtnExtra = rawEvent->value;
            break;
        case BTN_TASK:
            mBtnTask = rawEvent->value;
            break;
        }
    }
}

剩下的鼠标移动和滚动事件我们就不分析了。

下面我们再分析下CursorInputMapper::sync函数，我们分析部分代码：

void CursorInputMapper::sync(nsecs_t when) {
    int32_t lastButtonState = mButtonState;
    int32_t currentButtonState = mCursorButtonAccumulator.getButtonState();
    mButtonState = currentButtonState;

    bool wasDown = isPointerDown(lastButtonState);
    bool down = isPointerDown(currentButtonState);

我们先看看CursorButtonAccumulator.getButtonState函数：

uint32_t CursorButtonAccumulator::getButtonState() const {
    uint32_t result = 0;
    if (mBtnLeft) {
        result |= AMOTION_EVENT_BUTTON_PRIMARY;
    }
    if (mBtnRight) {
        //result |= AMOTION_EVENT_BUTTON_SECONDARY;
        result |= AMOTION_EVENT_BUTTON_BACK;//修改成返回键
    }
    if (mBtnMiddle) {
        result |= AMOTION_EVENT_BUTTON_TERTIARY;
    }
    if (mBtnBack || mBtnSide) {
        result |= AMOTION_EVENT_BUTTON_BACK;
    }
    if (mBtnForward || mBtnExtra) {
        result |= AMOTION_EVENT_BUTTON_FORWARD;
    }
    return result;
}

这个函数根据之前赋值的成员变量，返回结果或上不同的flag，我们右键的处理只需将result 或上AMOTION_EVENT_BUTTON_BACK就可以使右键变成返回键了。

继续分析CursorInputMapper::sync函数，把ButtonState保存下来，

sync主要我们分析两个函数一个getListener()->notifyMotion，另一个是synthesizeButtonKeys函数，我们先来看synthesizeButtonKeys函数

static void synthesizeButtonKeys(InputReaderContext* context, int32_t action,
        nsecs_t when, int32_t deviceId, uint32_t source,
        uint32_t policyFlags, int32_t lastButtonState, int32_t currentButtonState) {
    synthesizeButtonKey(context, action, when, deviceId, source, policyFlags,
            lastButtonState, currentButtonState,
            AMOTION_EVENT_BUTTON_BACK, AKEYCODE_BACK);//返回键
    synthesizeButtonKey(context, action, when, deviceId, source, policyFlags,
            lastButtonState, currentButtonState,
            AMOTION_EVENT_BUTTON_FORWARD, AKEYCODE_FORWARD);
}

再来看看synthesizeButtonKey，

static void synthesizeButtonKey(InputReaderContext* context, int32_t action,
        nsecs_t when, int32_t deviceId, uint32_t source,
        uint32_t policyFlags, int32_t lastButtonState, int32_t currentButtonState,
        int32_t buttonState, int32_t keyCode) {
    if (
            (action == AKEY_EVENT_ACTION_DOWN//按下键
                    && !(lastButtonState & buttonState)
                    && (currentButtonState & buttonState))//如果是返回键那么该条件成立
            || (action == AKEY_EVENT_ACTION_UP
                    && (lastButtonState & buttonState)
                    && !(currentButtonState & buttonState))) {
        NotifyKeyArgs args(when, deviceId, source, policyFlags,
                action, 0, keyCode, 0, context->getGlobalMetaState(), when);
        context->getListener()->notifyKey(&args);
    }
}

反正这么说，如果我们按键有AMOTION_EVENT_BUTTON_BACK这个flag，那么最后调用了listener的notifyKey函数，这个我们就不分析了。

上几篇博客分析过了notifyKey，最终有InputDispatcher那块处理，然后最后由应用进程在上层的ViewRootImpl处理按键消息。

我们接下来主要分析下getListener()->notifyMotion函数

 

二、notifyMotion函数

 

我们下面看下notifyMotion函数

void InputDispatcher::notifyMotion(const NotifyMotionArgs* args) {
    if (!validateMotionEvent(args->action, args->actionButton,
                args->pointerCount, args->pointerProperties)) {
        return;
    }

    uint32_t policyFlags = args->policyFlags;
    policyFlags |= POLICY_FLAG_TRUSTED;
    mPolicy->interceptMotionBeforeQueueing(args->eventTime, /*byref*/ policyFlags);

    bool needWake;
    { // acquire lock
        mLock.lock();

        if (shouldSendMotionToInputFilterLocked(args)) {
            mLock.unlock();

            MotionEvent event;
            event.initialize(args->deviceId, args->source, args->action, args->actionButton,
                    args->flags, args->edgeFlags, args->metaState, args->buttonState,
                    0, 0, args->xPrecision, args->yPrecision,
                    args->downTime, args->eventTime,
                    args->pointerCount, args->pointerProperties, args->pointerCoords);

            policyFlags |= POLICY_FLAG_FILTERED;
            if (!mPolicy->filterInputEvent(&event, policyFlags)) {
                return; // event was consumed by the filter
            }

            mLock.lock();
        }

        // Just enqueue a new motion event.
        MotionEntry* newEntry = new MotionEntry(args->eventTime,
                args->deviceId, args->source, policyFlags,
                args->action, args->actionButton, args->flags,
                args->metaState, args->buttonState,
                args->edgeFlags, args->xPrecision, args->yPrecision, args->downTime,
                args->displayId,
                args->pointerCount, args->pointerProperties, args->pointerCoords, 0, 0);

        needWake = enqueueInboundEventLocked(newEntry);
        mLock.unlock();
    } // release lock

    if (needWake) {
        mLooper->wake();
    }
}

这个和之前分析notifyKey一样，然后调用了enqueueInboundEventLocked放入了mInboundQueue队列中。

 

bool InputDispatcher::enqueueInboundEventLocked(EventEntry* entry) {
    bool needWake = mInboundQueue.isEmpty();
    mInboundQueue.enqueueAtTail(entry);
    traceInboundQueueLengthLocked();

    switch (entry->type) {
    case EventEntry::TYPE_KEY: {
        // Optimize app switch latency.
        // If the application takes too long to catch up then we drop all events preceding
        // the app switch key.
        KeyEntry* keyEntry = static_cast(entry);
        if (isAppSwitchKeyEventLocked(keyEntry)) {
            if (keyEntry->action == AKEY_EVENT_ACTION_DOWN) {
                mAppSwitchSawKeyDown = true;
            } else if (keyEntry->action == AKEY_EVENT_ACTION_UP) {
                if (mAppSwitchSawKeyDown) {
                    mAppSwitchDueTime = keyEntry->eventTime + APP_SWITCH_TIMEOUT;
                    mAppSwitchSawKeyDown = false;
                    needWake = true;
                }
            }
        }
        break;
    }

    case EventEntry::TYPE_MOTION: {
        // Optimize case where the current application is unresponsive and the user
        // decides to touch a window in a different application.
        // If the application takes too long to catch up then we drop all events preceding
        // the touch into the other window.
        MotionEntry* motionEntry = static_cast(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));
            sp touchedWindowHandle = findTouchedWindowAtLocked(displayId, x, y);
            if (touchedWindowHandle != NULL
                    && touchedWindowHandle->inputApplicationHandle
                            != mInputTargetWaitApplicationHandle) {
                // User touched a different application than the one we are waiting on.
                // Flag the event, and start pruning the input queue.
                mNextUnblockedEvent = motionEntry;
                needWake = true;
            }
        }
        break;
    }
    }

    return needWake;
}

然后调用了InputDispatcher的dispatchOnce函数

 

 

 

 

 

void InputDispatcher::dispatchOnce() {
    nsecs_t nextWakeupTime = LONG_LONG_MAX;
    { // acquire lock
        AutoMutex _l(mLock);
        mDispatcherIsAliveCondition.broadcast();

        // Run a dispatch loop if there are no pending commands.
        // The dispatch loop might enqueue commands to run afterwards.
        if (!haveCommandsLocked()) {
            dispatchOnceInnerLocked(&nextWakeupTime);
        }

        // Run all pending commands if there are any.
        // If any commands were run then force the next poll to wake up immediately.
        if (runCommandsLockedInterruptible()) {
            nextWakeupTime = LONG_LONG_MIN;
        }
    } // release lock

    // Wait for callback or timeout or wake.  (make sure we round up, not down)
    nsecs_t currentTime = now();
    int timeoutMillis = toMillisecondTimeoutDelay(currentTime, nextWakeupTime);
    mLooper->pollOnce(timeoutMillis);
}

这个函数中又调用了dispatchOnceInnerLocked函数，下面是一段代码，我们看到在这个函数中type_key和type_motion调用了不同的函数处理

 

 

 

 

    case EventEntry::TYPE_KEY: {
        KeyEntry* typedEntry = static_cast(mPendingEvent);
        if (isAppSwitchDue) {
            if (isAppSwitchKeyEventLocked(typedEntry)) {
                resetPendingAppSwitchLocked(true);
                isAppSwitchDue = false;
            } else if (dropReason == DROP_REASON_NOT_DROPPED) {
                dropReason = DROP_REASON_APP_SWITCH;
            }
        }
        if (dropReason == DROP_REASON_NOT_DROPPED
                && isStaleEventLocked(currentTime, typedEntry)) {
            dropReason = DROP_REASON_STALE;
        }
        if (dropReason == DROP_REASON_NOT_DROPPED && mNextUnblockedEvent) {
            dropReason = DROP_REASON_BLOCKED;
        }
        done = dispatchKeyLocked(currentTime, typedEntry, &dropReason, nextWakeupTime);
        break;
    }

    case EventEntry::TYPE_MOTION: {
        MotionEntry* typedEntry = static_cast(mPendingEvent);
        if (dropReason == DROP_REASON_NOT_DROPPED && isAppSwitchDue) {
            dropReason = DROP_REASON_APP_SWITCH;
        }
        if (dropReason == DROP_REASON_NOT_DROPPED
                && isStaleEventLocked(currentTime, typedEntry)) {
            dropReason = DROP_REASON_STALE;
        }
        if (dropReason == DROP_REASON_NOT_DROPPED && mNextUnblockedEvent) {
            dropReason = DROP_REASON_BLOCKED;
        }
        done = dispatchMotionLocked(currentTime, typedEntry,
                &dropReason, nextWakeupTime);
        break;
    }

在dispatchMotionLocked也是调用了dispatchEventLocked，知道最后的startDispatchCycleLocked函数：我们节选了一段对type_motion的处理

 

        case EventEntry::TYPE_MOTION: {
            MotionEntry* motionEntry = static_cast(eventEntry);

            PointerCoords scaledCoords[MAX_POINTERS];
            const PointerCoords* usingCoords = motionEntry->pointerCoords;

            // Set the X and Y offset depending on the input source.
            float xOffset, yOffset, scaleFactor;
            if ((motionEntry->source & AINPUT_SOURCE_CLASS_POINTER)
                    && !(dispatchEntry->targetFlags & InputTarget::FLAG_ZERO_COORDS)) {
                scaleFactor = dispatchEntry->scaleFactor;
                xOffset = dispatchEntry->xOffset * scaleFactor;
                yOffset = dispatchEntry->yOffset * scaleFactor;
                if (scaleFactor != 1.0f) {
                    for (uint32_t i = 0; i < motionEntry->pointerCount; i++) {
                        scaledCoords[i] = motionEntry->pointerCoords[i];
                        scaledCoords[i].scale(scaleFactor);
                    }
                    usingCoords = scaledCoords;
                }
            } else {
                xOffset = 0.0f;
                yOffset = 0.0f;
                scaleFactor = 1.0f;

                // We don't want the dispatch target to know.
                if (dispatchEntry->targetFlags & InputTarget::FLAG_ZERO_COORDS) {
                    for (uint32_t i = 0; i < motionEntry->pointerCount; i++) {
                        scaledCoords[i].clear();
                    }
                    usingCoords = scaledCoords;
                }
            }

            // Publish the motion event.
            status = connection->inputPublisher.publishMotionEvent(dispatchEntry->seq,
                    motionEntry->deviceId, motionEntry->source,
                    dispatchEntry->resolvedAction, motionEntry->actionButton,
                    dispatchEntry->resolvedFlags, motionEntry->edgeFlags,
                    motionEntry->metaState, motionEntry->buttonState,
                    xOffset, yOffset, motionEntry->xPrecision, motionEntry->yPrecision,
                    motionEntry->downTime, motionEntry->eventTime,
                    motionEntry->pointerCount, motionEntry->pointerProperties,
                    usingCoords);
            break;
        }

最后调用了connection->inputPublisher.publishMotionEvent函数：

status_t InputPublisher::publishMotionEvent(
        uint32_t seq,
        int32_t deviceId,
        int32_t source,
        int32_t action,
        int32_t actionButton,
        int32_t flags,
        int32_t edgeFlags,
        int32_t metaState,
        int32_t buttonState,
        float xOffset,
        float yOffset,
        float xPrecision,
        float yPrecision,
        nsecs_t downTime,
        nsecs_t eventTime,
        uint32_t pointerCount,
        const PointerProperties* pointerProperties,
        const PointerCoords* pointerCoords) {
    if (!seq) {
        ALOGE("Attempted to publish a motion event with sequence number 0.");
        return BAD_VALUE;
    }

    if (pointerCount > MAX_POINTERS || pointerCount < 1) {
        ALOGE("channel '%s' publisher ~ Invalid number of pointers provided: %" PRIu32 ".",
                mChannel->getName().string(), pointerCount);
        return BAD_VALUE;
    }

    InputMessage msg;
    msg.header.type = InputMessage::TYPE_MOTION;
    msg.body.motion.seq = seq;
    msg.body.motion.deviceId = deviceId;
    msg.body.motion.source = source;
    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.xOffset = xOffset;
    msg.body.motion.yOffset = yOffset;
    msg.body.motion.xPrecision = xPrecision;
    msg.body.motion.yPrecision = yPrecision;
    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);
}

最后还是调用了mChannel的sendMessage函数，和之前的流程就一样了。
 

 

 

 

 

 

因此总结下所有的流程和正常的按键差不多，只是没有扫描码转化成键盘码的流程等。