イベントの最下位処理フローの入力

Android描画メカニズムのソースコード解析では,入力イベントの上位レベルでの伝達関係を紹介した.
本稿では、入力プロセス全体が最下位から上位にどのように伝達されるかについて説明します.
まず私たちの出発点は前の編です:Viewの描画プロセスの中のSetViewが始まり、Activityの最下層のView:mDecorがSetViewの中で最初に行われたことを知っています.では、私たちのviewの受信者も、ここでやったはずです.
ここから始めましょう
ここで私达はやはり以前の习惯に従って、私达の本章の関心の内容を残して、その他はすべてすでに取り除いて、ここで私达はいくつかのよく知らないものを见ました
1.InputChannel
2.addToDisplay
3.WindowInputEventReceiver
ここでは、それぞれが今回の入力で紹介するポイントですが、彼らの役割が何なのかを順に見てみましょう.
Step 1:ViewRootImpl.java

    public void setView(View view, WindowManager.LayoutParams attrs, View panelParentView) {
        synchronized (this) {
            if (mView == null) {

                if ((mWindowAttributes.inputFeatures
                        & WindowManager.LayoutParams.INPUT_FEATURE_NO_INPUT_CHANNEL) == 0) {
                    mInputChannel = new InputChannel();                               //  Step 2
                }
                try {
                    res = mWindowSession.addToDisplay(mWindow, mSeq, mWindowAttributes,
                            getHostVisibility(), mDisplay.getDisplayId(),
                            mAttachInfo.mContentInsets, mAttachInfo.mStableInsets, mInputChannel);     //  Step 3            ，   client channel，       
                } catch (RemoteException e) {
                }
                if (view instanceof RootViewSurfaceTaker) {
                    mInputQueueCallback =
                        ((RootViewSurfaceTaker)view).willYouTakeTheInputQueue();
                }
                if (mInputChannel != null) {
                    if (mInputQueueCallback != null) {                                               //      android     c     ，     ，     java         ，     NativeActivity.java
                        mInputQueue = new InputQueue();
                        mInputQueueCallback.onInputQueueCreated(mInputQueue);
                    }
                    mInputEventReceiver = new WindowInputEventReceiver(mInputChannel,
                            Looper.myLooper());                                                        //   client  channel     。Step 23
                }

                // Set up the input pipeline.
                CharSequence counterSuffix = attrs.getTitle();
                mSyntheticInputStage = new SyntheticInputStage();
                InputStage viewPostImeStage = new ViewPostImeInputStage(mSyntheticInputStage);
                InputStage nativePostImeStage = new NativePostImeInputStage(viewPostImeStage,
                        "aq:native-post-ime:" + counterSuffix);
                InputStage earlyPostImeStage = new EarlyPostImeInputStage(nativePostImeStage);
                InputStage imeStage = new ImeInputStage(earlyPostImeStage,
                        "aq:ime:" + counterSuffix);
                InputStage viewPreImeStage = new ViewPreImeInputStage(imeStage);
                InputStage nativePreImeStage = new NativePreImeInputStage(viewPreImeStage,
                        "aq:native-pre-ime:" + counterSuffix);

                mFirstInputStage = nativePreImeStage;
                mFirstPostImeInputStage = earlyPostImeStage;
                mPendingInputEventQueueLengthCounterName = "aq:pending:" + counterSuffix;
            }
        }
    }

Step 2:InputChannel.java

    public InputChannel() {
    }

この構造は空です.つまり、本当のことは私たちが取得した対象であることを示しています.mInputChannel、これはaddToDisplayに伝わります.
ここではまずStep 3に入って具体的に何をしたかを見てみましょう.
Step 3 : WindowManagerService.java
過程はとても簡単で、みんなは自分で見てみましょう、ここは最終的にそのままここに転勤します

    public int addWindow(Session session, IWindow client, int seq,
            WindowManager.LayoutParams attrs, int viewVisibility, int displayId,
            Rect outContentInsets, Rect outStableInsets, InputChannel outInputChannel) {

        synchronized(mWindowMap) {
		
            win = new WindowState(this, session, client, token,
                    attachedWindow, appOp[0], seq, attrs, viewVisibility, displayContent);              //  window   。

            if (outInputChannel != null && (attrs.inputFeatures
                    & WindowManager.LayoutParams.INPUT_FEATURE_NO_INPUT_CHANNEL) == 0) {
                String name = win.makeInputChannelName();                                              //      ，         InputChannel ，            log   ，
                InputChannel[] inputChannels = InputChannel.openInputChannelPair(name);                //  Step 4，           Step8    ，0  Server ，1  client 。
                win.setInputChannel(inputChannels[0]);                                                 //       Server  channel   WindowState ，          window  。
                inputChannels[1].transferTo(outInputChannel);                                          //  outInputChannel  ViewRootImpl     ，      view 。

                mInputManager.registerInputChannel(win.mInputChannel, win.mInputWindowHandle);         //   server     InputManagerService ，  
            }

            // From now on, no exceptions or errors allowed!

            res = WindowManagerGlobal.ADD_OKAY;

            origId = Binder.clearCallingIdentity();

            if (addToken) {
                mTokenMap.put(attrs.token, token);
            }
            win.attach();
            mWindowMap.put(client.asBinder(), win);
            if (win.mAppOp != AppOpsManager.OP_NONE) {
                if (mAppOps.startOpNoThrow(win.mAppOp, win.getOwningUid(), win.getOwningPackage())
                        != AppOpsManager.MODE_ALLOWED) {
                    win.setAppOpVisibilityLw(false);
                }
            }

            if (type == TYPE_APPLICATION_STARTING && token.appWindowToken != null) {
                token.appWindowToken.startingWindow = win;
                if (DEBUG_STARTING_WINDOW) Slog.v (TAG, "addWindow: " + token.appWindowToken
                        + " startingWindow=" + win);
            }

            boolean imMayMove = true;

            if (type == TYPE_INPUT_METHOD) {
                win.mGivenInsetsPending = true;
                mInputMethodWindow = win;
                addInputMethodWindowToListLocked(win);
                imMayMove = false;
            } else if (type == TYPE_INPUT_METHOD_DIALOG) {
                mInputMethodDialogs.add(win);
                addWindowToListInOrderLocked(win, true);
                moveInputMethodDialogsLocked(findDesiredInputMethodWindowIndexLocked(true));
                imMayMove = false;
            } else {
                addWindowToListInOrderLocked(win, true);
                if (type == TYPE_WALLPAPER) {
                    mLastWallpaperTimeoutTime = 0;
                    displayContent.pendingLayoutChanges |= FINISH_LAYOUT_REDO_WALLPAPER;
                } else if ((attrs.flags&FLAG_SHOW_WALLPAPER) != 0) {
                    displayContent.pendingLayoutChanges |= FINISH_LAYOUT_REDO_WALLPAPER;
                } else if (mWallpaperTarget != null
                        && mWallpaperTarget.mLayer >= win.mBaseLayer) {
                    // If there is currently a wallpaper being shown, and
                    // the base layer of the new window is below the current
                    // layer of the target window, then adjust the wallpaper.
                    // This is to avoid a new window being placed between the
                    // wallpaper and its target.
                    displayContent.pendingLayoutChanges |= FINISH_LAYOUT_REDO_WALLPAPER;
                }
            }

            final WindowStateAnimator winAnimator = win.mWinAnimator;
            winAnimator.mEnterAnimationPending = true;
            winAnimator.mEnteringAnimation = true;

            if (displayContent.isDefaultDisplay) {
                mPolicy.getInsetHintLw(win.mAttrs, outContentInsets, outStableInsets);
            } else {
                outContentInsets.setEmpty();
                outStableInsets.setEmpty();
            }

            if (mInTouchMode) {
                res |= WindowManagerGlobal.ADD_FLAG_IN_TOUCH_MODE;
            }
            if (win.mAppToken == null || !win.mAppToken.clientHidden) {
                res |= WindowManagerGlobal.ADD_FLAG_APP_VISIBLE;
            }

            mInputMonitor.setUpdateInputWindowsNeededLw();

            boolean focusChanged = false;
            if (win.canReceiveKeys()) {
                focusChanged = updateFocusedWindowLocked(UPDATE_FOCUS_WILL_ASSIGN_LAYERS,
                        false /*updateInputWindows*/);
                if (focusChanged) {
                    imMayMove = false;
                }
            }

            if (imMayMove) {
                moveInputMethodWindowsIfNeededLocked(false);
            }

            assignLayersLocked(displayContent.getWindowList());
            // Don't do layout here, the window must call
            // relayout to be displayed, so we'll do it there.

            if (focusChanged) {
                mInputMonitor.setInputFocusLw(mCurrentFocus, false /*updateInputWindows*/);
            }
            mInputMonitor.updateInputWindowsLw(false /*force*/);

            if (localLOGV || DEBUG_ADD_REMOVE) Slog.v(TAG, "addWindow: New client "
                    + client.asBinder() + ": window=" + win + " Callers=" + Debug.getCallers(5));

            if (win.isVisibleOrAdding() && updateOrientationFromAppTokensLocked(false)) {
                reportNewConfig = true;
            }
        }

        if (reportNewConfig) {
            sendNewConfiguration();
        }

        Binder.restoreCallingIdentity(origId);

        return res;
    }

Step 4 : InputChannel.java

    public static InputChannel[] openInputChannelPair(String name) {
        return nativeOpenInputChannelPair(name);                   //    native  ，  Step 5
    }

Step 5 :android_view_InputChannel.cppはここが重要で、全部持ってきました.
PSここではNativeとjavaのインタラクションの方法がたくさん使われていますが、慣れていない場合は参考にしてください.
http://game.ceeger.com/Script/AndroidJNI/AndroidJNI.html

static jobjectArray android_view_InputChannel_nativeOpenInputChannelPair(JNIEnv* env,
        jclass clazz, jstring nameObj) {
    const char* nameChars = env->GetStringUTFChars(nameObj, NULL);
    String8 name(nameChars);                     //   name     java       
    env->ReleaseStringUTFChars(nameObj, nameChars);

    sp serverChannel;
    sp clientChannel;
    status_t result = InputChannel::openInputChannelPair(name, serverChannel, clientChannel);                     //  Step 6:          serverChannel clientChannel   Step 6    ，        ，             。

    if (result) {
        String8 message;
        message.appendFormat("Could not open input channel pair.  status=%d", result);
        jniThrowRuntimeException(env, message.string());
        return NULL;
    }

    jobjectArray channelPair = env->NewObjectArray(2, gInputChannelClassInfo.clazz, NULL);                     //       2   ，     java  InputChannel         ，     java 
    if (env->ExceptionCheck()) {
        return NULL;
    }

    jobject serverChannelObj = android_view_InputChannel_createInputChannel(env,
            new NativeInputChannel(serverChannel));                                                         //  Step 8 
    if (env->ExceptionCheck()) {
        return NULL;
    }

    jobject clientChannelObj = android_view_InputChannel_createInputChannel(env,
            new NativeInputChannel(clientChannel));
    if (env->ExceptionCheck()) {
        return NULL;
    }

    env->SetObjectArrayElement(channelPair, 0, serverChannelObj);
    env->SetObjectArrayElement(channelPair, 1, clientChannelObj);
    return channelPair;                                                            //     0  server ， 1     ，     java     。
}

Step 6 :InputTransport.cpp
ここではまずいくつかのlinuxの関数の使い方を紹介しますが、実は4.0以前のバージョンで、ここでは匿名共有メモリと匿名パイプで実現されています.
現在の長所については、それは明らかに違いない.コードは一方で、IBMの前の紹介を参照してください.http://www.ibm.com/developerworks/cn/linux/l-pipebid/
1.socketpair:
Linuxの公式解釈:

The socketpair() call creates an unnamed pair of connected sockets in
the specified domain, of the specified type, and using the optionally
specified protocol.
The descriptors used in referencing the new sockets are returned in
sv[0] and sv[1].  The two sockets are indistinguishable.

私の説明:パイプと似ていますが、これは双方向通信で、パイプは一方向通信です.最後のパラメータは、通信の両端を返します.
2.setsockopt:
Linuxの公式解釈:

getsockopt() and setsockopt() manipulate options for the socket
referred to by the file descriptor sockfd.  Options may exist at
multiple protocol levels; they are always present at the uppermost
socket level.
When manipulating socket options, the level at which the option
resides and the name of the option must be specified.  To manipulate
options at the sockets API level, level is specified as SOL_SOCKET.
To manipulate options at any other level the protocol number of the
appropriate protocol controlling the option is supplied.  For
example, to indicate that an option is to be interpreted by the TCP
protocol

私の説明:入出力端子を設定する

 
  
status_t InputChannel::openInputChannelPair(const String8& name,
        sp& outServerChannel, sp& outClientChannel) {
    int sockets[2];
    if (socketpair(AF_UNIX, SOCK_SEQPACKET, 0, sockets)) {
        status_t result = -errno;
        ALOGE("channel '%s' ~ Could not create socket pair.  errno=%d",
                name.string(), errno);
        outServerChannel.clear();
        outClientChannel.clear();
        return result;
    }

    int bufferSize = SOCKET_BUFFER_SIZE;
    setsockopt(sockets[0], SOL_SOCKET, SO_SNDBUF, &bufferSize, sizeof(bufferSize));
    setsockopt(sockets[0], SOL_SOCKET, SO_RCVBUF, &bufferSize, sizeof(bufferSize));
    setsockopt(sockets[1], SOL_SOCKET, SO_SNDBUF, &bufferSize, sizeof(bufferSize));
    setsockopt(sockets[1], SOL_SOCKET, SO_RCVBUF, &bufferSize, sizeof(bufferSize));

    String8 serverChannelName = name;
    serverChannelName.append(" (server)");
    outServerChannel = new InputChannel(serverChannelName, sockets[0]);               //Step 7

    String8 clientChannelName = name;
    clientChannelName.append(" (client)");
    outClientChannel = new InputChannel(clientChannelName, sockets[1]);
    return OK;
}
  
Step 7:InputTransport.cpp 
 
  
 
  
InputChannel::InputChannel(const String8& name, int fd) :
        mName(name), mFd(fd) {

    int result = fcntl(mFd, F_SETFL, O_NONBLOCK);  //           。
    LOG_ALWAYS_FATAL_IF(result != 0, "channel '%s' ~ Could not make socket "
            "non-blocking.  errno=%d", mName.string(), errno);
}
  
Step 8 :android_view_InputChannel.cpp 
 
  
static jobject android_view_InputChannel_createInputChannel(JNIEnv* env,
        NativeInputChannel* nativeInputChannel) {
    jobject inputChannelObj = env->NewObject(gInputChannelClassInfo.clazz,
            gInputChannelClassInfo.ctor);           //        InputChannel     ，jni     。
    if (inputChannelObj) {
        android_view_InputChannel_setNativeInputChannel(env, inputChannelObj, nativeInputChannel);   //Step 9
    }
    return inputChannelObj;           //               java 。
}
  
 
  
 
  Step 9 ：android_view_InputChannel.cpp 
  
 
  
static void android_view_InputChannel_setNativeInputChannel(JNIEnv* env, jobject inputChannelObj,
        NativeInputChannel* nativeInputChannel) {
    env->SetLongField(inputChannelObj, gInputChannelClassInfo.mPtr,
             reinterpret_cast(nativeInputChannel));            //  java   mPtr  ,reinterpret_cast        ，         long 
}
  
Step 10 :InputManagerService.java 
 
  
    public void registerInputChannel(InputChannel inputChannel,
            InputWindowHandle inputWindowHandle) {
        if (inputChannel == null) {
            throw new IllegalArgumentException("inputChannel must not be null.");
        }

        nativeRegisterInputChannel(mPtr, inputChannel, inputWindowHandle, false);   //Step 11
    }
  
Step 11 :com_android_server_input_InputManagerService.cpp 
static void nativeRegisterInputChannel(JNIEnv* env, jclass clazz,
        jlong ptr, jobject inputChannelObj, jobject inputWindowHandleObj, jboolean monitor) {
    NativeInputManager* im = reinterpret_cast(ptr);                     //             

    sp inputChannel = android_view_InputChannel_getInputChannel(env,
            inputChannelObj);                         //       ，      Server  ，
    if (inputChannel == NULL) {
        throwInputChannelNotInitialized(env);
        return;
    }

    sp inputWindowHandle =
            android_server_InputWindowHandle_getHandle(env, inputWindowHandleObj);                 //       Native    Handle

    status_t status = im->registerInputChannel(
            env, inputChannel, inputWindowHandle, monitor);                                        //Step 14:
    if (status) {
        String8 message;
        message.appendFormat("Failed to register input channel.  status=%d", status);
        jniThrowRuntimeException(env, message.string());
        return;
    }

    if (! monitor) {
        android_view_InputChannel_setDisposeCallback(env, inputChannelObj,
                handleInputChannelDisposed, im);
    }
}
  
Step 12 :android_view_InputChannel.cpp 
sp android_view_InputChannel_getInputChannel(JNIEnv* env, jobject inputChannelObj) {
    NativeInputChannel* nativeInputChannel =
            android_view_InputChannel_getNativeInputChannel(env, inputChannelObj);           //  Step 13.
    return nativeInputChannel != NULL ? nativeInputChannel->getInputChannel() : NULL;       //                 ，
}
  
Step 13 : android_view_InputChannel.cpp 
static NativeInputChannel* android_view_InputChannel_getNativeInputChannel(JNIEnv* env,
        jobject inputChannelObj) {
    jlong longPtr = env->GetLongField(inputChannelObj, gInputChannelClassInfo.mPtr);//            Step 8         ，         ，             。
    return reinterpret_cast(longPtr);   //        
}
  
Step 14 : com_android_server_input_InputManagerService.cpp 
status_t NativeInputManager::registerInputChannel(JNIEnv* env,
        const sp& inputChannel,
        const sp& inputWindowHandle, bool monitor) {
    return mInputManager->getDispatcher()->registerInputChannel(
            inputChannel, inputWindowHandle, monitor);                                  //Step 15
}
  
Step 15 : InputDispatcher.cpp 
status_t InputDispatcher::registerInputChannel(const sp& inputChannel,
        const sp& inputWindowHandle, bool monitor) {

    { // acquire lock
        AutoMutex _l(mLock);

        if (getConnectionIndexLocked(inputChannel) >= 0) {
            ALOGW("Attempted to register already registered input channel '%s'",
                    inputChannel->getName().string());
            return BAD_VALUE;
        }

        sp connection = new Connection(inputChannel, inputWindowHandle, monitor);                   //moditor   false，          。    connection  ，        。

        int fd = inputChannel->getFd();                   //  server      Fd+
        mConnectionsByFd.add(fd, connection);             // connnect    ，

        if (monitor) {
            mMonitoringChannels.push(inputChannel);       //        
        }

        mLooper->addFd(fd, 0, ALOOPER_EVENT_INPUT, handleReceiveCallback, this);                 //         server      ，     ，       ，Looper             ，         
    } // release lock

    // Wake the looper because some connections have changed.
    mLooper->wake();
    return OK;
}
  
Step 16 :InputDispatcher.cpp 
ここまで通信全体が確立されています.server側がこのchannel側にデータを書けば、client側は受け入れられるはずです.次に、ここでどのようにデータを書くかを見てみましょう.
イベント書き込みがコールバックする方法があることを知っています.これはどのようにchannel側にデータを書くかを見てみましょう.
PS:ここで使用しているconnectionでStep 15に入れました.
int InputDispatcher::handleReceiveCallback(int fd, int events, void* data) {
    InputDispatcher* d = static_cast(data);

    { // acquire lock
        AutoMutex _l(d->mLock);

        ssize_t connectionIndex = d->mConnectionsByFd.indexOfKey(fd);
        if (connectionIndex < 0) {
            ALOGE("Received spurious receive callback for unknown input channel.  "
                    "fd=%d, events=0x%x", fd, events);
            return 0; // remove the callback
        }

        bool notify;
        sp connection = d->mConnectionsByFd.valueAt(connectionIndex);
        if (!(events & (ALOOPER_EVENT_ERROR | ALOOPER_EVENT_HANGUP))) {
            if (!(events & ALOOPER_EVENT_INPUT)) {
                ALOGW("channel '%s' ~ Received spurious callback for unhandled poll event.  "
                        "events=0x%x", connection->getInputChannelName(), events);
                return 1;
            }

            nsecs_t currentTime = now();
            bool gotOne = false;
            status_t status;
            for (;;) {
                uint32_t seq;
                bool handled;
                status = connection->inputPublisher.receiveFinishedSignal(&seq, &handled);                 //            ，     client     ，  client     ，      
                if (status) {
                    break;
                }
                d->finishDispatchCycleLocked(currentTime, connection, seq, handled);                        //Step 17
                gotOne = true;
            }
            if (gotOne) {
                d->runCommandsLockedInterruptible();
                if (status == WOULD_BLOCK) {
                    return 1;
                }
            }

            notify = status != DEAD_OBJECT || !connection->monitor;
            if (notify) {
                ALOGE("channel '%s' ~ Failed to receive finished signal.  status=%d",
                        connection->getInputChannelName(), status);
            }
        } else {
            // Monitor channels are never explicitly unregistered.
            // We do it automatically when the remote endpoint is closed so don't warn
            // about them.
            notify = !connection->monitor;
            if (notify) {
                ALOGW("channel '%s' ~ Consumer closed input channel or an error occurred.  "
                        "events=0x%x", connection->getInputChannelName(), events);
            }
        }

        // Unregister the channel.
        d->unregisterInputChannelLocked(connection->inputChannel, notify);
        return 0; // remove the callback
    } // release lock
}
  
Step 17:InputDispatcher.cpp 
void InputDispatcher::finishDispatchCycleLocked(nsecs_t currentTime,
        const sp& connection, uint32_t seq, bool handled) {
#if DEBUG_DISPATCH_CYCLE
    ALOGD("channel '%s' ~ finishDispatchCycle - seq=%u, handled=%s",
            connection->getInputChannelName(), seq, toString(handled));
#endif

    connection->inputPublisherBlocked = false;

    if (connection->status == Connection::STATUS_BROKEN
            || connection->status == Connection::STATUS_ZOMBIE) {
        return;
    }

    // Notify other system components and prepare to start the next dispatch cycle.
    onDispatchCycleFinishedLocked(currentTime, connection, seq, handled);                  //Step 18 
}
  
Step 18:InputDispatcher.cpp 
void InputDispatcher::onDispatchCycleFinishedLocked(
        nsecs_t currentTime, const sp& connection, uint32_t seq, bool handled) {
    CommandEntry* commandEntry = postCommandLocked(
            & InputDispatcher::doDispatchCycleFinishedLockedInterruptible);              //Step 19            ，      ，   Step 20          。
    commandEntry->connection = connection;
    commandEntry->eventTime = currentTime;
    commandEntry->seq = seq;
    commandEntry->handled = handled;
}
  
Step 19:InputDispatcher.cpp 
InputDispatcher::CommandEntry* InputDispatcher::postCommandLocked(Command command) {
    CommandEntry* commandEntry = new CommandEntry(command);
    mCommandQueue.enqueueAtTail(commandEntry);                    //             mCommandQueue ，
    return commandEntry;
}
  
Step 20:InputDispatcher.cpp 
void InputDispatcher::doDispatchCycleFinishedLockedInterruptible(
        CommandEntry* commandEntry) {
    sp connection = commandEntry->connection;
    nsecs_t finishTime = commandEntry->eventTime;
    uint32_t seq = commandEntry->seq;
    bool handled = commandEntry->handled;

    // Handle post-event policy actions.
    DispatchEntry* dispatchEntry = connection->findWaitQueueEntry(seq);
    if (dispatchEntry) {
        nsecs_t eventDuration = finishTime - dispatchEntry->deliveryTime;
        if (eventDuration > SLOW_EVENT_PROCESSING_WARNING_TIMEOUT) {
            String8 msg;
            msg.appendFormat("Window '%s' spent %0.1fms processing the last input event: ",
                    connection->getWindowName(), eventDuration * 0.000001f);
            dispatchEntry->eventEntry->appendDescription(msg);
            ALOGI("%s", msg.string());
        }

        bool restartEvent;
        if (dispatchEntry->eventEntry->type == EventEntry::TYPE_KEY) {
            KeyEntry* keyEntry = static_cast(dispatchEntry->eventEntry);
            restartEvent = afterKeyEventLockedInterruptible(connection,
                    dispatchEntry, keyEntry, handled);
        } else if (dispatchEntry->eventEntry->type == EventEntry::TYPE_MOTION) {
            MotionEntry* motionEntry = static_cast(dispatchEntry->eventEntry);
            restartEvent = afterMotionEventLockedInterruptible(connection,
                    dispatchEntry, motionEntry, handled);
        } else {
            restartEvent = false;
        }

        // Dequeue the event and start the next cycle.
        // Note that because the lock might have been released, it is possible that the
        // contents of the wait queue to have been drained, so we need to double-check
        // a few things.
        if (dispatchEntry == connection->findWaitQueueEntry(seq)) {
            connection->waitQueue.dequeue(dispatchEntry);
            traceWaitQueueLengthLocked(connection);
            if (restartEvent && connection->status == Connection::STATUS_NORMAL) {
                connection->outboundQueue.enqueueAtHead(dispatchEntry);
                traceOutboundQueueLengthLocked(connection);
            } else {
                releaseDispatchEntryLocked(dispatchEntry);
            }
        }

        // Start the next dispatch cycle for this connection.
        startDispatchCycleLocked(now(), connection);               //Step 21
    }
}
  
Step 21:InputDispatcher.cpp 
void InputDispatcher::startDispatchCycleLocked(nsecs_t currentTime,
        const sp& connection) {

    while (connection->status == Connection::STATUS_NORMAL
            && !connection->outboundQueue.isEmpty()) {
        DispatchEntry* dispatchEntry = connection->outboundQueue.head;
        dispatchEntry->deliveryTime = currentTime;

        // Publish the event.
        status_t status;
        EventEntry* eventEntry = dispatchEntry->eventEntry;
        switch (eventEntry->type) {
        case EventEntry::TYPE_KEY: {
            KeyEntry* keyEntry = static_cast(eventEntry);

            // Publish the key event.
            status = connection->inputPublisher.publishKeyEvent(dispatchEntry->seq,
                    keyEntry->deviceId, keyEntry->source,
                    dispatchEntry->resolvedAction, dispatchEntry->resolvedFlags,
                    keyEntry->keyCode, keyEntry->scanCode,
                    keyEntry->metaState, keyEntry->repeatCount, keyEntry->downTime,
                    keyEntry->eventTime);
            break;
        }

        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, dispatchEntry->resolvedFlags,
                    motionEntry->edgeFlags, motionEntry->metaState, motionEntry->buttonState,
                    xOffset, yOffset,
                    motionEntry->xPrecision, motionEntry->yPrecision,
                    motionEntry->downTime, motionEntry->eventTime,
                    motionEntry->pointerCount, motionEntry->pointerProperties,
                    usingCoords);
            break;
        }

        default:
            ALOG_ASSERT(false);
            return;
        }

        // Check the result.
        if (status) {
            if (status == WOULD_BLOCK) {
                if (connection->waitQueue.isEmpty()) {
                    ALOGE("channel '%s' ~ Could not publish event because the pipe is full. "
                            "This is unexpected because the wait queue is empty, so the pipe "
                            "should be empty and we shouldn't have any problems writing an "
                            "event to it, status=%d", connection->getInputChannelName(), status);
                    abortBrokenDispatchCycleLocked(currentTime, connection, true /*notify*/);
                } else {
                    // Pipe is full and we are waiting for the app to finish process some events
                    // before sending more events to it.
                    connection->inputPublisherBlocked = true;
                }
            } else {
                ALOGE("channel '%s' ~ Could not publish event due to an unexpected error, "
                        "status=%d", connection->getInputChannelName(), status);
                abortBrokenDispatchCycleLocked(currentTime, connection, true /*notify*/);
            }
            return;
        }

        // Re-enqueue the event on the wait queue.
        connection->outboundQueue.dequeue(dispatchEntry);
        traceOutboundQueueLengthLocked(connection);
        connection->waitQueue.enqueueAtTail(dispatchEntry);
        traceWaitQueueLengthLocked(connection);
    }
}
  
Step 22: InputDispatcher.cpp 
status_t InputPublisher::publishKeyEvent(
        uint32_t seq,
        int32_t deviceId,
        int32_t source,
        int32_t action,
        int32_t flags,
        int32_t keyCode,
        int32_t scanCode,
        int32_t metaState,
        int32_t repeatCount,
        nsecs_t downTime,
        nsecs_t eventTime) {

    if (!seq) {
        ALOGE("Attempted to publish a key event with sequence number 0.");
        return BAD_VALUE;
    }

    InputMessage msg;
    msg.header.type = InputMessage::TYPE_KEY;
    msg.body.key.seq = seq;
    msg.body.key.deviceId = deviceId;
    msg.body.key.source = source;
    msg.body.key.action = action;
    msg.body.key.flags = flags;
    msg.body.key.keyCode = keyCode;
    msg.body.key.scanCode = scanCode;
    msg.body.key.metaState = metaState;
    msg.body.key.repeatCount = repeatCount;
    msg.body.key.downTime = downTime;
    msg.body.key.eventTime = eventTime;
    return mChannel->sendMessage(&msg);               //         send  ，     。   client        

}
  
Step 23 :InputEventReceiver.java 
 
  
    public InputEventReceiver(InputChannel inputChannel, Looper looper) {
        mInputChannel = inputChannel;
        mMessageQueue = looper.getQueue();
        mReceiverPtr = nativeInit(new WeakReference(this),
                inputChannel, mMessageQueue);

        mCloseGuard.open("dispose");
    }
  
Step 24 : android_view_InputEventReceiver.cpp 
 
  
static jlong nativeInit(JNIEnv* env, jclass clazz, jobject receiverWeak,
        jobject inputChannelObj, jobject messageQueueObj) {
    sp inputChannel = android_view_InputChannel_getInputChannel(env,
            inputChannelObj);
    if (inputChannel == NULL) {
        jniThrowRuntimeException(env, "InputChannel is not initialized.");
        return 0;
    }

    sp messageQueue = android_os_MessageQueue_getMessageQueue(env, messageQueueObj);
    if (messageQueue == NULL) {
        jniThrowRuntimeException(env, "MessageQueue is not initialized.");
        return 0;
    }

    sp receiver = new NativeInputEventReceiver(env,
            receiverWeak, inputChannel, messageQueue);                      
    status_t status = receiver->initialize();                               //  Step 25 
    if (status) {
        String8 message;
        message.appendFormat("Failed to initialize input event receiver.  status=%d", status);
        jniThrowRuntimeException(env, message.string());
        return 0;
    }

    receiver->incStrong(gInputEventReceiverClassInfo.clazz); // retain a reference for the object
    return reinterpret_cast(receiver.get());
}
  
Step 25 :android_view_InputEventReceiver.cpp 
                ，   request     ， Server         ，      PollInner  wait  ，         ，
  
  Looper     ，   Looper        。
  
 
  
status_t NativeInputEventReceiver::initialize() {
    setFdEvents(ALOOPER_EVENT_INPUT);
    return OK;
}
  
void NativeInputEventReceiver::setFdEvents(int events) {
    if (mFdEvents != events) {
        mFdEvents = events;
        int fd = mInputConsumer.getChannel()->getFd();
        if (events) {
            mMessageQueue->getLooper()->addFd(fd, 0, events, this, NULL);
        } else {
            mMessageQueue->getLooper()->removeFd(fd);
        }
    }
}
  
Step 26 ： Looper.cpp
  
Looper        ，            ，           。
  
 
  
int Looper::pollInner(int timeoutMillis) {
	......
    int callbackResult = response.request.callback->handleEvent(fd, events, data);//         callback android_view_InputEventReceiver  this，      Step 27
	......
}
  
Step 27 : android_view_InputEventReceiver.cpp 
 
  
int NativeInputEventReceiver::handleEvent(int receiveFd, int events, void* data) {
    if (events & (ALOOPER_EVENT_ERROR | ALOOPER_EVENT_HANGUP)) {               //         ，
        return 0; // remove the callback
    }

    if (events & ALOOPER_EVENT_INPUT) {                                       //      event ALOOPER_EVENT_INPUT       ，
        JNIEnv* env = AndroidRuntime::getJNIEnv();
        status_t status = consumeEvents(env, false /*consumeBatches*/, -1, NULL);
        mMessageQueue->raiseAndClearException(env, "handleReceiveCallback");
        return status == OK || status == NO_MEMORY ? 1 : 0;
    }

    if (events & ALOOPER_EVENT_OUTPUT) {
        for (size_t i = 0; i < mFinishQueue.size(); i++) {
            const Finish& finish = mFinishQueue.itemAt(i);
            status_t status = mInputConsumer.sendFinishedSignal(finish.seq, finish.handled);
            if (status) {
                mFinishQueue.removeItemsAt(0, i);

                if (status == WOULD_BLOCK) {
                    return 1; // keep the callback, try again later
                }

                ALOGW("Failed to send finished signal on channel '%s'.  status=%d",
                        getInputChannelName(), status);
                if (status != DEAD_OBJECT) {
                    JNIEnv* env = AndroidRuntime::getJNIEnv();
                    String8 message;
                    message.appendFormat("Failed to finish input event.  status=%d", status);
                    jniThrowRuntimeException(env, message.string());
                    mMessageQueue->raiseAndClearException(env, "finishInputEvent");
                }
                return 0; // remove the callback
            }
        }

        mFinishQueue.clear();
        setFdEvents(ALOOPER_EVENT_INPUT);
        return 1;
    }

    ALOGW("channel '%s' ~ Received spurious callback for unhandled poll event.  "
            "events=0x%x", getInputChannelName(), events);
    return 1;
}
  
Step 28 ：android_view_InputEventReceiver.cpp
  
 
  
 
  
status_t NativeInputEventReceiver::consumeEvents(JNIEnv* env,
        bool consumeBatches, nsecs_t frameTime, bool* outConsumedBatch) {

    if (consumeBatches) {
        mBatchedInputEventPending = false;
    }
    if (outConsumedBatch) {
        *outConsumedBatch = false;
    }

    ScopedLocalRef receiverObj(env, NULL);
    bool skipCallbacks = false;
    for (;;) {
        uint32_t seq;
        InputEvent* inputEvent;
        status_t status = mInputConsumer.consume(&mInputEventFactory,
                consumeBatches, frameTime, &seq, &inputEvent);                         //         Step 29
        if (status) {
            if (status == WOULD_BLOCK) {
                if (!skipCallbacks && !mBatchedInputEventPending
                        && mInputConsumer.hasPendingBatch()) {
                    // There is a pending batch.  Come back later.
                    if (!receiverObj.get()) {
                        receiverObj.reset(jniGetReferent(env, mReceiverWeakGlobal));
                        if (!receiverObj.get()) {
                            ALOGW("channel '%s' ~ Receiver object was finalized "
                                    "without being disposed.", getInputChannelName());
                            return DEAD_OBJECT;
                        }
                    }

                    mBatchedInputEventPending = true;
                    env->CallVoidMethod(receiverObj.get(),
                            gInputEventReceiverClassInfo.dispatchBatchedInputEventPending);
                    if (env->ExceptionCheck()) {
                        ALOGE("Exception dispatching batched input events.");
                        mBatchedInputEventPending = false; // try again later
                    }
                }
                return OK;
            }
            ALOGE("channel '%s' ~ Failed to consume input event.  status=%d",
                    getInputChannelName(), status);
            return status;
        }
        assert(inputEvent);

        if (!skipCallbacks) {
            if (!receiverObj.get()) {
                receiverObj.reset(jniGetReferent(env, mReceiverWeakGlobal));
                if (!receiverObj.get()) {
                    ALOGW("channel '%s' ~ Receiver object was finalized "
                            "without being disposed.", getInputChannelName());
                    return DEAD_OBJECT;
                }
            }

            jobject inputEventObj;
            switch (inputEvent->getType()) {
            case AINPUT_EVENT_TYPE_KEY:
                inputEventObj = android_view_KeyEvent_fromNative(env,
                        static_cast(inputEvent));
                break;

            case AINPUT_EVENT_TYPE_MOTION: {
                MotionEvent* motionEvent = static_cast(inputEvent);
                if ((motionEvent->getAction() & AMOTION_EVENT_ACTION_MOVE) && outConsumedBatch) {
                    *outConsumedBatch = true;
                }
                inputEventObj = android_view_MotionEvent_obtainAsCopy(env, motionEvent);
                break;
            }

            default:
                assert(false); // InputConsumer should prevent this from ever happening
                inputEventObj = NULL;
            }

            if (inputEventObj) {
                env->CallVoidMethod(receiverObj.get(),
                        gInputEventReceiverClassInfo.dispatchInputEvent, seq, inputEventObj);                            //         ，     java ，  Step 30
                if (env->ExceptionCheck()) {
                    ALOGE("Exception dispatching input event.");
                    skipCallbacks = true;
                }
                env->DeleteLocalRef(inputEventObj);
            } else {
                ALOGW("channel '%s' ~ Failed to obtain event object.", getInputChannelName());
                skipCallbacks = true;
            }
        }

        if (skipCallbacks) {
            mInputConsumer.sendFinishedSignal(seq, false);
        }
    }
}
  
Step 29 :InputTransport.cpp 
status_t InputConsumer::consume(InputEventFactoryInterface* factory,
        bool consumeBatches, nsecs_t frameTime, uint32_t* outSeq, InputEvent** outEvent) {

    *outSeq = 0;
    *outEvent = NULL;

    // Fetch the next input message.
    // Loop until an event can be returned or no additional events are received.
    while (!*outEvent) {
        if (mMsgDeferred) {
            mMsgDeferred = false;
        } else {
            // Receive a fresh message.
            status_t result = mChannel->receiveMessage(&mMsg);
            if (result) {
                // Consume the next batched event unless batches are being held for later.
                if (consumeBatches || result != WOULD_BLOCK) {
                    result = consumeBatch(factory, frameTime, outSeq, outEvent);
                    if (*outEvent) {
                        break;
                    }
                }
                return result;
            }
        }

        switch (mMsg.header.type) {
        case InputMessage::TYPE_KEY: {
            KeyEvent* keyEvent = factory->createKeyEvent();
            if (!keyEvent) return NO_MEMORY;

            initializeKeyEvent(keyEvent, &mMsg);
            *outSeq = mMsg.body.key.seq;
            *outEvent = keyEvent;
            break;
        }

        case AINPUT_EVENT_TYPE_MOTION: {
            ssize_t batchIndex = findBatch(mMsg.body.motion.deviceId, mMsg.body.motion.source);
            if (batchIndex >= 0) {
                Batch& batch = mBatches.editItemAt(batchIndex);
                if (canAddSample(batch, &mMsg)) {
                    batch.samples.push(mMsg);
                    break;
                } else {
                    // We cannot append to the batch in progress, so we need to consume
                    // the previous batch right now and defer the new message until later.
                    mMsgDeferred = true;
                    status_t result = consumeSamples(factory,
                            batch, batch.samples.size(), outSeq, outEvent);
                    mBatches.removeAt(batchIndex);
                    if (result) {
                        return result;
                    }
                    break;
                }
            }

            // Start a new batch if needed.
            if (mMsg.body.motion.action == AMOTION_EVENT_ACTION_MOVE
                    || mMsg.body.motion.action == AMOTION_EVENT_ACTION_HOVER_MOVE) {
                mBatches.push();
                Batch& batch = mBatches.editTop();
                batch.samples.push(mMsg);
                break;
            }

            MotionEvent* motionEvent = factory->createMotionEvent();
            if (! motionEvent) return NO_MEMORY;

            updateTouchState(&mMsg);
            initializeMotionEvent(motionEvent, &mMsg);
            *outSeq = mMsg.body.motion.seq;
            *outEvent = motionEvent;
            break;
        }

        default:
            return UNKNOWN_ERROR;
        }
    }
    return OK;
}
  
Step 30 :InputEventReceiver.java 
    @SuppressWarnings("unused")
    private void dispatchInputEvent(int seq, InputEvent event) {
        mSeqMap.put(event.getSequenceNumber(), seq);
        onInputEvent(event);               //         Step 31
    }
  
Step 31 :ViewRootImpl.java$ 
WindowInputEventReceiver
  
        @Override
        public void onInputEvent(InputEvent event) {
            enqueueInputEvent(event, this, 0, true);
        }
  
Step 32 :ViewRootImpl.java 
 
  
    void enqueueInputEvent(InputEvent event,
            InputEventReceiver receiver, int flags, boolean processImmediately) {
        QueuedInputEvent q = obtainQueuedInputEvent(event, receiver, flags);                      //                 ，   ，             ，    10 ，

        // Always enqueue the input event in order, regardless of its time stamp.
        // We do this because the application or the IME may inject key events
        // in response to touch events and we want to ensure that the injected keys
        // are processed in the order they were received and we cannot trust that
        // the time stamp of injected events are monotonic.
        QueuedInputEvent last = mPendingInputEventTail;
        if (last == null) {
            mPendingInputEventHead = q;
            mPendingInputEventTail = q;
        } else {
            last.mNext = q;
            mPendingInputEventTail = q;
        }
        mPendingInputEventCount += 1;
        Trace.traceCounter(Trace.TRACE_TAG_INPUT, mPendingInputEventQueueLengthCounterName,
                mPendingInputEventCount);

        if (processImmediately) {
            doProcessInputEvents();                          //Step 33
        } else {
            scheduleProcessInputEvents();
        }
    }
  
Step 33 : 
ViewRootImpl.java
  
    ，   ，            ，        ，
  
 
  
    void doProcessInputEvents() {
        // Deliver all pending input events in the queue.
        while (mPendingInputEventHead != null) {
            QueuedInputEvent q = mPendingInputEventHead;
            mPendingInputEventHead = q.mNext;
            if (mPendingInputEventHead == null) {
                mPendingInputEventTail = null;
            }
            q.mNext = null;

            mPendingInputEventCount -= 1;
            Trace.traceCounter(Trace.TRACE_TAG_INPUT, mPendingInputEventQueueLengthCounterName,
                    mPendingInputEventCount);

            deliverInputEvent(q);
        }

        // We are done processing all input events that we can process right now
        // so we can clear the pending flag immediately.
        if (mProcessInputEventsScheduled) {
            mProcessInputEventsScheduled = false;
            mHandler.removeMessages(MSG_PROCESS_INPUT_EVENTS);
        }
    }
  
Step 34 :ViewRootImpl.java 
    private void deliverInputEvent(QueuedInputEvent q) {
        Trace.asyncTraceBegin(Trace.TRACE_TAG_VIEW, "deliverInputEvent",
                q.mEvent.getSequenceNumber());
        if (mInputEventConsistencyVerifier != null) {
            mInputEventConsistencyVerifier.onInputEvent(q.mEvent, 0);
        }

        InputStage stage;
        if (q.shouldSendToSynthesizer()) {
            stage = mSyntheticInputStage;
        } else {
            stage = q.shouldSkipIme() ? mFirstPostImeInputStage : mFirstInputStage;
        }

        if (stage != null) {
            stage.deliver(q);
        } else {
            finishInputEvent(q);
        }
    }
がここに来てから、実はすでに柳暗花明になった.私たちは前の文章の中でandroid描画メカニズムのソースコード分析のStep 7で後の流れを分析したことがあるので、ここでは疲れない.
      ，      ，  touch            mDecor。