Android_Surface_创建流程

本文主要是基于Android10.0.0分析Surface的创建流程

1：概况

Surface本质上是一个绘图表面，Window是用来承载视图View的，View的绘制是在绘图表面上完成的，我们先从窗口的创建流程开始
应用程序端的surface

    // These can be accessed by any thread, must be protected with a lock.
    // Surface can never be reassigned or cleared (use Surface.clear()).
    @UnsupportedAppUsage
    public final Surface mSurface = new Surface();

2：WindowManager.java::addView

   try {
          mOrigWindowType = mWindowAttributes.type;
          mAttachInfo.mRecomputeGlobalAttributes = true;
          collectViewAttributes();
           res = mWindowSession.addToDisplay(mWindow, mSeq, mWindowAttributes,
                            getHostVisibility(), mDisplay.getDisplayId(), mTmpFrame,
                            mAttachInfo.mContentInsets, mAttachInfo.mStableInsets,
                            mAttachInfo.mOutsets, mAttachInfo.mDisplayCutout, mInputChannel,
                            mTempInsets);
                    setFrame(mTmpFrame);
                } catch (RemoteException e) {

    @Override
    public int addToDisplay(IWindow window, int seq, WindowManager.LayoutParams attrs,
            int viewVisibility, int displayId, Rect outFrame, Rect outContentInsets,
            Rect outStableInsets, Rect outOutsets,
            DisplayCutout.ParcelableWrapper outDisplayCutout, InputChannel outInputChannel,
            InsetsState outInsetsState) {
        return mService.addWindow(this, window, seq, attrs, viewVisibility, displayId, outFrame,
                outContentInsets, outStableInsets, outOutsets, outDisplayCutout, outInputChannel,
                outInsetsState);
    }

最终是调用WMS的addWindow方法

2.1:WindowManagerService.java::addWindow

.............................................
 final WindowState win = new WindowState(this, session, client, token, parentWindow,
                    appOp[0], seq, attrs, viewVisibility, session.mUid,
                    session.mCanAddInternalSystemWindow);
 win.attach();//调用WindowState::attch方法
 mWindowMap.put(client.asBinder(), win);//将win存放在map中
....................................................
 void attach() {
        if (localLOGV) Slog.v(TAG, "Attaching " + this + " token=" + mToken);
        mSession.windowAddedLocked(mAttrs.packageName);
 }
...................................................

2.2:Session.java::windowAddedLocked

    void windowAddedLocked(String packageName) {
        mPackageName = packageName;
        mRelayoutTag = "relayoutWindow: " + mPackageName;
        if (mSurfaceSession == null) {
            mSurfaceSession = new SurfaceSession();
            mService.mSessions.add(this);
            if (mLastReportedAnimatorScale != mService.getCurrentAnimatorScale()) {
                mService.dispatchNewAnimatorScaleLocked(this);
            }
        }
        mNumWindow++;
    }

创建一个SurfaceSession对象，然后将其添加到mSessions中

2.3:SurfaceSession::java

   public SurfaceSession() {
        mNativeClient = nativeCreate();
    }

对应的找到c/c++的实现

2.4:android_view_SurfaceSession.cpp::nativeCreate

static jlong nativeCreate(JNIEnv* env, jclass clazz) {
    SurfaceComposerClient* client = new SurfaceComposerClient();
    client->incStrong((void*)nativeCreate);
    return reinterpret_cast<jlong>(client);
}

创建一个SurfaceComposerClient对象，然后返回它的指针，一个应用程序就有一个该对象，我们在前面知道WindowSession是单利的

2.5:SurfaceComposerClient.cpp::onFirstRef

void SurfaceComposerClient::onFirstRef() {
    sp<ISurfaceComposer> sf(ComposerService::getComposerService());
    if (sf != nullptr && mStatus == NO_INIT) {
        sp<ISurfaceComposerClient> conn;
        conn = sf->createConnection();//sf 就是SurfaceFlinger
        if (conn != nullptr) {
            mClient = conn;
            mStatus = NO_ERROR;
        }
    }
}

2.6:SurfaceFlinger.cpp::createConnection

static sp<ISurfaceComposerClient> initClient(const sp<Client>& client) {
    status_t err = client->initCheck();
    if (err == NO_ERROR) {
        return client;
    }
    return nullptr;
}
sp<ISurfaceComposerClient> SurfaceFlinger::createConnection() {
    return initClient(new Client(this));
}

构造了一个Client对象，Client实现了ISurfaceComposerClient接口。是一个可以跨进程通信的aidl对象。除此之外它还可以创建Surface，并且维护一个应用程序的所有Layer

3:应用程序端Surface的创建

    // These can be accessed by any thread, must be protected with a lock.
    // Surface can never be reassigned or cleared (use Surface.clear()).
    @UnsupportedAppUsage
    public final Surface mSurface = new Surface();

3.1:ViewRootImpl.java::relayoutWindow

int relayoutResult = mWindowSession.relayout(mWindow, mSeq, params,
                (int) (mView.getMeasuredWidth() * appScale + 0.5f),
                (int) (mView.getMeasuredHeight() * appScale + 0.5f), viewVisibility,
                insetsPending ? WindowManagerGlobal.RELAYOUT_INSETS_PENDING : 0, frameNumber,
                mTmpFrame, mPendingOverscanInsets, mPendingContentInsets, mPendingVisibleInsets,
                mPendingStableInsets, mPendingOutsets, mPendingBackDropFrame, mPendingDisplayCutout,
                mPendingMergedConfiguration, mSurfaceControl, mTempInsets);

3.2:WindowManagerService.java::relayoutWindow

 if (shouldRelayout) {
                .........................................
                result = win.relayoutVisibleWindow(result, attrChanges);
                try {
                    result = createSurfaceControl(outSurfaceControl, result, win, winAnimator);
                } catch (Exception e) {
                    displayContent.getInputMonitor().updateInputWindowsLw(true /*force*/);
                    Binder.restoreCallingIdentity(origId);
                    return 0;
                }
                if ((result & WindowManagerGlobal.RELAYOUT_RES_FIRST_TIME) != 0) {
                    focusMayChange = true;
                }

3.3:WindowSurfaceController.java

   final SurfaceControl.Builder b = win.makeSurface()
                .setParent(win.getSurfaceControl())
                .setName(name)
                .setBufferSize(w, h)
                .setFormat(format)
                .setFlags(flags)
                .setMetadata(METADATA_WINDOW_TYPE, windowType)
                .setMetadata(METADATA_OWNER_UID, ownerUid);
        mSurfaceControl = b.build();
............................................
try {
            if (metadata != null && metadata.size() > 0) {
                metaParcel.writeInt(metadata.size());
                for (int i = 0; i < metadata.size(); ++i) {
                    metaParcel.writeInt(metadata.keyAt(i));
                    metaParcel.writeByteArray(
                            ByteBuffer.allocate(4).order(ByteOrder.nativeOrder())
                                    .putInt(metadata.valueAt(i)).array());
                }
                metaParcel.setDataPosition(0);
            }
            mNativeObject = nativeCreate(session, name, w, h, format, flags,
                    parent != null ? parent.mNativeObject : 0, metaParcel);
        } finally {
            metaParcel.recycle();
        }
..................................................

3.4:android_view_SurfaceControl.cpp::nativeCreate

static jlong nativeCreate(JNIEnv* env, jclass clazz, jobject sessionObj,
        jstring nameStr, jint w, jint h, jint format, jint flags, jlong parentObject,
        jobject metadataParcel) {
    ScopedUtfChars name(env, nameStr);
    sp<SurfaceComposerClient> client;
    if (sessionObj != NULL) {
        client = android_view_SurfaceSession_getClient(env, sessionObj);
    } else {
        client = SurfaceComposerClient::getDefault();
    }
    SurfaceControl *parent = reinterpret_cast<SurfaceControl*>(parentObject);
    sp<SurfaceControl> surface;
    LayerMetadata metadata;
    Parcel* parcel = parcelForJavaObject(env, metadataParcel);
    if (parcel && !parcel->objectsCount()) {
        status_t err = metadata.readFromParcel(parcel);
        if (err != NO_ERROR) {
          jniThrowException(env, "java/lang/IllegalArgumentException",
                            "Metadata parcel has wrong format");
        }
    }
    status_t err = client->createSurfaceChecked(
            String8(name.c_str()), w, h, format, &surface, flags, parent, std::move(metadata));
    if (err == NAME_NOT_FOUND) {
        jniThrowException(env, "java/lang/IllegalArgumentException", NULL);
        return 0;
    } else if (err != NO_ERROR) {
        jniThrowException(env, OutOfResourcesException, NULL);
        return 0;
    }
    surface->incStrong((void *)nativeCreate);
    return reinterpret_cast<jlong>(surface.get());
}

主要是调用SurfaceComposerClient的createSurfaceChecked方法

3.5:SurfaceComposerClient.cpp::createSurfaceChecked

  if (mStatus == NO_ERROR) {
        sp<IBinder> handle;
        sp<IBinder> parentHandle;
        sp<IGraphicBufferProducer> gbp;
        if (parent != nullptr) {
            parentHandle = parent->getHandle();
        }
        err = mClient->createSurface(name, w, h, format, flags, parentHandle, std::move(metadata),
                                     &handle, &gbp);
       //继续调用SurfaceComposerClient的createSurface
        ALOGE_IF(err, "SurfaceComposerClient::createSurface error %s", strerror(-err));
        if (err == NO_ERROR) {
            *outSurface = new SurfaceControl(this, handle, gbp, true /* owned */);
        }
    }

3.6:Client.cpp::createSurface

status_t Client::createSurface(const String8& name, uint32_t w, uint32_t h, PixelFormat format,
                               uint32_t flags, const sp<IBinder>& parentHandle,
                               LayerMetadata metadata, sp<IBinder>* handle,
                               sp<IGraphicBufferProducer>* gbp) {
    // We rely on createLayer to check permissions.
    return mFlinger->createLayer(name, this, w, h, format, flags, std::move(metadata), handle, gbp,
                                 parentHandle);//mFlinger就是SurfaceFligner
}

3.7:SurfaceFlinger.cpp::createLayer

status_t SurfaceFlinger::createLayer(const String8& name, const sp<Client>& client, uint32_t w,
                                     uint32_t h, PixelFormat format, uint32_t flags,
                                     LayerMetadata metadata, sp<IBinder>* handle,
                                     sp<IGraphicBufferProducer>* gbp,
                                     const sp<IBinder>& parentHandle,
                                     const sp<Layer>& parentLayer) {
    if (int32_t(w|h) < 0) {
        return BAD_VALUE;//判断宽高参数是否合法
    }
    status_t result = NO_ERROR;
    sp<Layer> layer;//申明待创建的layer
    String8 uniqueName = getUniqueLayerName(name);
    bool primaryDisplayOnly = false;
    // window type is WINDOW_TYPE_DONT_SCREENSHOT from SurfaceControl.java
    // TODO b/64227542
    if (metadata.has(METADATA_WINDOW_TYPE)) {
        int32_t windowType = metadata.getInt32(METADATA_WINDOW_TYPE, 0);
        if (windowType == 441731) {//处理窗口类型
            metadata.setInt32(METADATA_WINDOW_TYPE, InputWindowInfo::TYPE_NAVIGATION_BAR_PANEL);
            primaryDisplayOnly = true;
        }
    }
   //flag是根据不同的flag创建不同类型的图层，Layer用来标识一个图层
    switch (flags & ISurfaceComposerClient::eFXSurfaceMask) {
        case ISurfaceComposerClient::eFXSurfaceBufferQueue:
            result = createBufferQueueLayer(client, uniqueName, w, h, flags, std::move(metadata),
                                            format, handle, gbp, &layer);
            break;
        case ISurfaceComposerClient::eFXSurfaceBufferState:
            result = createBufferStateLayer(client, uniqueName, w, h, flags, std::move(metadata),
                                            handle, &layer);
            break;
        case ISurfaceComposerClient::eFXSurfaceColor:
            // check if buffer size is set for color layer.
            if (w > 0 || h > 0) {
                return BAD_VALUE;
            }
            result = createColorLayer(client, uniqueName, w, h, flags, std::move(metadata), handle,
                                      &layer);
            break;
        case ISurfaceComposerClient::eFXSurfaceContainer:
            // check if buffer size is set for container layer.
            if (w > 0 || h > 0) {
                return BAD_VALUE;
            }
            result = createContainerLayer(client, uniqueName, w, h, flags, std::move(metadata),
                                          handle, &layer);
            break;
        default:
            result = BAD_VALUE;
            break;
    }
    if (result != NO_ERROR) {
        return result;
    }
    if (primaryDisplayOnly) {
        layer->setPrimaryDisplayOnly();
    }
    bool addToCurrentState = callingThreadHasUnscopedSurfaceFlingerAccess();
    result = addClientLayer(client, *handle, *gbp, layer, parentHandle, parentLayer,
                            addToCurrentState);//将layer添加到client集合去中统一管理
    if (result != NO_ERROR) {
        return result;
    }
    mInterceptor->saveSurfaceCreation(layer);
    setTransactionFlags(eTransactionNeeded);
    return result;
}

3.8:createBufferQueueLayer

status_t SurfaceFlinger::createBufferQueueLayer(const sp<Client>& client, const String8& name,
                                                uint32_t w, uint32_t h, uint32_t flags,
                                                LayerMetadata metadata, PixelFormat& format,
                                                sp<IBinder>* handle,
                                                sp<IGraphicBufferProducer>* gbp,
                                                sp<Layer>* outLayer) {
    // initialize the surfaces
    switch (format) {//format是格式，这个格式是windowManager.LayoutParms传递
    case PIXEL_FORMAT_TRANSPARENT:
    case PIXEL_FORMAT_TRANSLUCENT:
        format = PIXEL_FORMAT_RGBA_8888;
        break;
    case PIXEL_FORMAT_OPAQUE:
        format = PIXEL_FORMAT_RGBX_8888;
        break;
    }
   //通过工厂创建
    sp<BufferQueueLayer> layer = getFactory().createBufferQueueLayer(
            LayerCreationArgs(this, client, name, w, h, flags, std::move(metadata)));
    status_t err = layer->setDefaultBufferProperties(w, h, format);//设置默认的属性
    if (err == NO_ERROR) {
        *handle = layer->getHandle();
        *gbp = layer->getProducer();
        *outLayer = layer;
    }
    return err;
}

3.9:SurfaceFlignerFactory.cpp::createGraphicBufferLayer

            sp<BufferQueueLayer> createBufferQueueLayer(const LayerCreationArgs& args) override {
            return new BufferQueueLayer(args);
        }

3.10:BufferQueueLayer.cpp

void BufferQueueLayer::onFirstRef() {
    BufferLayer::onFirstRef();
    // Creates a custom BufferQueue for SurfaceFlingerConsumer to use
    sp<IGraphicBufferProducer> producer;
    sp<IGraphicBufferConsumer> consumer;
    BufferQueue::createBufferQueue(&producer, &consumer, true);
    mProducer = new MonitoredProducer(producer, mFlinger, this);
    {
        // Grab the SF state lock during this since it's the only safe way to access RenderEngine
        Mutex::Autolock lock(mFlinger->mStateLock);
        mConsumer =
                new BufferLayerConsumer(consumer, mFlinger->getRenderEngine(), mTextureName, this);
    }
    mConsumer->setConsumerUsageBits(getEffectiveUsage(0));
    mConsumer->setContentsChangedListener(this);
    mConsumer->setName(mName);
    // BufferQueueCore::mMaxDequeuedBufferCount is default to 1
    if (!mFlinger->isLayerTripleBufferingDisabled()) {
        mProducer->setMaxDequeuedBufferCount(2);
    }
    if (const auto display = mFlinger->getDefaultDisplayDevice()) {
        updateTransformHint(display);
    }
}

3.11:BufferQueue::createBufferQueue

void BufferQueue::createBufferQueue(sp<IGraphicBufferProducer>* outProducer,
        sp<IGraphicBufferConsumer>* outConsumer,
        bool consumerIsSurfaceFlinger) {
    sp<BufferQueueCore> core(new BufferQueueCore());//创建一个BufferQueueCore
    sp<IGraphicBufferProducer> producer(new BufferQueueProducer(core, consumerIsSurfaceFlinger));
    sp<IGraphicBufferConsumer> consumer(new BufferQueueConsumer(core));
    *outProducer = producer;
    *outConsumer = consumer;
}