ViewRootImpl管理著整個(gè)view tree。 對(duì)于ViewRootImpl.setView()，我們可以簡(jiǎn)單的把它當(dāng)做一個(gè)UI渲染操作的入口。

http://androidxref.com/6.0.1_r10/xref/frameworks/base/core/java/android/view/WindowManagerImpl.java

public void setView(View view, WindowManager.LayoutParams attrs, View panelParentView) {
    ...
    //mWindowSession是一個(gè)aidl，ViewRootImpl利用它來(lái)和WindowManagerService交互
    //mWindow是一個(gè)aidl，WindowManagerService可以利用這個(gè)對(duì)象與服務(wù)端交互
    //mAttachInfo可以理解為是一個(gè)data bean，可以跨進(jìn)程傳遞
    res = mWindowSession.addToDisplay(mWindow, mSeq, mWindowAttributes,
            getHostVisibility(), mDisplay.getDisplayId(), mWinFrame,
            mAttachInfo.mContentInsets, mAttachInfo.mStableInsets,
            mAttachInfo.mOutsets, mAttachInfo.mDisplayCutout, mInputChannel);
    ...
}

ViewRootImpl.setView()方法會(huì)向WindowManagerService請(qǐng)求添加一個(gè)Window,mWindowSession.addToDisplay()跨進(jìn)程最終調(diào)用到了WindowManagerService.addWindow():
http://androidxref.com/6.0.1_r10/xref/frameworks/base/services/core/java/com/android/server/wm/WindowManagerService.java

public int addWindow(Session session, IWindow client...) {
    ...
    //WindowState用來(lái)描述一個(gè)Window
    final WindowState win = new WindowState(this, session, client, token, parentWindow,
                appOp[0], seq, attrs, viewVisibility, session.mUid,
                session.mCanAddInternalSystemWindow);
    ...
    win.attach();  //會(huì)創(chuàng)建一個(gè)SurfaceSession

    mWindowMap.put(client.asBinder(), win); //mWindowMap是WindowManagerService用來(lái)保存當(dāng)前所有Window新的的集合
    ...
    win.mToken.addWindow(win); //一個(gè)token下會(huì)有多個(gè)win state。 其實(shí)token與PhoneWindow是一一對(duì)應(yīng)的。
    ...
}

http://androidxref.com/6.0.1_r10/xref/frameworks/base/services/core/java/com/android/server/wm/WindowState.java

 void attach() {
       if (WindowManagerService.localLOGV) Slog.v(
            TAG, "Attaching " + this + " token=" + mToken
            + ", list=" + mToken.windows);
        mSession.windowAddedLocked();
   }

WindowState是WindowManagerService用來(lái)描述應(yīng)用程序的一個(gè)Window的對(duì)象。上面注釋我標(biāo)注了win.attach(),這個(gè)方法可以說(shuō)是Window與SurfaceFlinger鏈接的起點(diǎn),它最終會(huì)調(diào)用到Session.windowAddedLocked():
http://androidxref.com/6.0.1_r10/xref/frameworks/base/services/core/java/com/android/server/wm/Session.java

void windowAddedLocked(String packageName) {
    ...
    if (mSurfaceSession == null) { 
        ...
        mSurfaceSession = new SurfaceSession();
        ...
    }
}

http://androidxref.com/6.0.1_r10/xref/frameworks/base/core/java/android/view/SurfaceSession.java

//SurfaceSession類的構(gòu)造方法
public final class SurfaceSession {
    private long mNativeClient; // SurfaceComposerClient*

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

這里調(diào)用了native方法nativeCreate()，這個(gè)方法其實(shí)是返回了一個(gè)SurfaceComposerClient指針。那這個(gè)對(duì)象是怎么創(chuàng)建的呢？

SurfaceComposerClient的創(chuàng)建

http://androidxref.com/6.0.1_r10/xref/frameworks/base/core/jni/android_view_SurfaceSession.cpp

static jlong nativeCreate(JNIEnv* env, jclass clazz) {
    SurfaceComposerClient* client = new SurfaceComposerClient(); //構(gòu)造函數(shù)其實(shí)并沒有做什么
    client->incStrong((void*)nativeCreate);
    return reinterpret_cast<jlong>(client);
}

即構(gòu)造了一個(gè)SurfaceComposerClient對(duì)象。并返回它的指針。這個(gè)對(duì)象一個(gè)應(yīng)用程序就有一個(gè)，它是應(yīng)用程序與SurfaceFlinger溝通的橋梁，為什么這么說(shuō)呢？在SurfaceComposerClient指針第一次使用時(shí)會(huì)調(diào)用下面這個(gè)方法:

//這個(gè)方法在第一次使用SurfaceComposerClient的指針的時(shí)候會(huì)調(diào)用
void SurfaceComposerClient::onFirstRef() {
    ....
    sp<ISurfaceComposerClient> conn;
    //sf 就是SurfaceFlinger
    conn = (rootProducer != nullptr) ? sf->createScopedConnection(rootProducer) :
            sf->createConnection();
    ...
}

即通過(guò)SurfaceFlinger(它本身具有跨進(jìn)程通信的能力)創(chuàng)建了一個(gè)ISurfaceComposerClient對(duì)象:

http://androidxref.com/6.0.1_r10/xref/frameworks/native/services/surfaceflinger/SurfaceFlinger.cpp

sp<ISurfaceComposerClient> SurfaceFlinger::createConnection() {
    return initClient(new Client(this)); //initClient這個(gè)方法其實(shí)并沒有做什么，
}

即構(gòu)造了一個(gè)Client對(duì)象，Client實(shí)現(xiàn)了ISurfaceComposerClient接口。是一個(gè)可以跨進(jìn)程通信的aidl對(duì)象。即SurfaceComposerClient可以通過(guò)它來(lái)和SurfaceFlinger通信。除此之外它還可以創(chuàng)建Surface，并且維護(hù)一個(gè)應(yīng)用程序的所有Layer(下文會(huì)分析到它是什么)。它是一個(gè)十分重要的對(duì)象，我們先來(lái)看一下它的組成,它所涉及的其他東西在下文分析中都會(huì)講到:
http://androidxref.com/6.0.1_r10/xref/frameworks/native/services/surfaceflinger/Client.h

class Client : public BnSurfaceComposerClient
{
public:
    ...
    void attachLayer(const sp<IBinder>& handle, const sp<Layer>& layer);
    void detachLayer(const Layer* layer);
    ...
private:
    // ISurfaceComposerClient interface。   gbp很重要，它維護(hù)這一個(gè)應(yīng)用程序的渲染 Buffer隊(duì)列
    virtual status_t createSurface(...sp<IBinder>* handle, sp<IGraphicBufferProducer>* gbp);

    virtual status_t destroySurface(const sp<IBinder>& handle); 

    //跨進(jìn)程通信方法
    virtual status_t onTransact(uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags);
    ...

    // constant
    sp<SurfaceFlinger> mFlinger;

    // protected by mLock
    DefaultKeyedVector< wp<IBinder>, wp<Layer> > mLayers; // 一個(gè)應(yīng)用程序的所有Layer
    ...
};

經(jīng)過(guò)上面這一頓源碼分析，我們大概知道了ViewRootImpl.setView()所引發(fā)的主要操作:

WindowManagerService創(chuàng)建了一個(gè)WindowState。用來(lái)表示客戶端的一個(gè)Window
WindowManagerService創(chuàng)建了一個(gè)SurfaceSession,SurfaceSession會(huì)與SurfaceFlinger構(gòu)建鏈接，創(chuàng)建了一個(gè)SurfaceComposerClient對(duì)象，一個(gè)應(yīng)用程序只具有一個(gè)這個(gè)對(duì)象。
SurfaceComposerClient創(chuàng)建了一個(gè)Client, 這個(gè)對(duì)象十分重要，它維護(hù)這應(yīng)用程序的渲染核心數(shù)據(jù)，并負(fù)責(zé)與SurfaceFlinger通信。

經(jīng)過(guò)上面的步驟，應(yīng)用程序的ViewRootImpl已經(jīng)被WindowManagerService識(shí)別，并且應(yīng)用程序已經(jīng)與SurfaceFlinger建立連接。即創(chuàng)建了SurfaceComposerClient和Client對(duì)象

文章開始就已經(jīng)說(shuō)了Surface是Window(ViewRootImpl)的UI載體，那Surface是在哪里創(chuàng)建的呢？

Surface的創(chuàng)建

其實(shí)一個(gè)ViewRootImpl就對(duì)應(yīng)一個(gè)Surface。

http://androidxref.com/6.0.1_r10/xref/frameworks/base/core/java/android/view/Surface.java

這點(diǎn)可以通過(guò)ViewRootImpl的源碼看出:

即ViewRootImpl在構(gòu)造的時(shí)候就new 了一個(gè) Surface。但其實(shí)這個(gè)新new的Surface并沒有什么邏輯，它的構(gòu)造函數(shù)是空的。

http://androidxref.com/6.0.1_r10/xref/frameworks/base/core/java/android/view/ViewRootImpl.java

public final class ViewRootImpl implements ViewParent,
        View.AttachInfo.Callbacks, HardwareRenderer.HardwareDrawCallbacks {
//...
public final Surface mSurface = new Surface();
//...
public void setView(View view, WindowManager.LayoutParams attrs, View panelParentView) {
    ...
    requestLayout(); //susion 請(qǐng)求layout。先添加到待渲染隊(duì)列中  
    ...
    res = mWindowSession.addToDisplay(mWindow, ...); //WindowManagerService會(huì)創(chuàng)建mWindow對(duì)應(yīng)的WindowState
    ...
}
 @Override
 public void requestLayout() {
        if (!mHandlingLayoutInLayoutRequest) {
            checkThread();
            mLayoutRequested = true;
            scheduleTraversals();
        }
    }

}

即在向WindowManagerService請(qǐng)求創(chuàng)建WindowState之前，調(diào)用了requestLayout(),這個(gè)方法會(huì)引起ViewRootImpl所管理的整個(gè)view tree的重新渲染。它最終會(huì)調(diào)用到scheduleTraversals():

http://androidxref.com/6.0.1_r10/xref/frameworks/base/core/java/android/view/ViewRootImpl.java

void scheduleTraversals() {
    ...
    mChoreographer.postCallback(Choreographer.CALLBACK_TRAVERSAL, mTraversalRunnable, null);
    ...
}

scheduleTraversals()會(huì)通過(guò)Choreographer來(lái)post一個(gè)mTraversalRunnable，Choreographer接收顯示系統(tǒng)的時(shí)間脈沖(垂直同步信號(hào)-VSync信號(hào)，16ms發(fā)出一次)，在下一個(gè)frame渲染時(shí)控制執(zhí)行這個(gè)mTraversalRunnable。

但是mTraversalRunnable的執(zhí)行至少要在應(yīng)用程序與SurfaceFlinger建立連接之后。這是因?yàn)殇秩静僮魇怯?code>SurfaceFlinger負(fù)責(zé)調(diào)度了，如果應(yīng)用程序還沒有與SurfaceFlinger創(chuàng)建連接，那SurfaceFlinger當(dāng)然不會(huì)渲染這個(gè)應(yīng)用程序。所以在執(zhí)行完mWindowSession.addToDisplay(mWindow, ...)之后，才會(huì)執(zhí)行mTraversalRunnable:

final class TraversalRunnable implements Runnable {
    @Override
    public void run() {
        doTraversal();
    }
}

doTraversal()會(huì)調(diào)用到ViewRootImpl.performTraversals(),大部分同學(xué)可能知道這個(gè)方法是一個(gè)view tree的measure/layout/draw的控制方法:

private void performTraversals() {
    finalView host = mView; //mView是一個(gè)Window的根View，對(duì)于Activity來(lái)說(shuō)就是DecorView
    ...
    relayoutWindow(params, viewVisibility, insetsPending);
    ...
    performMeasure(childWidthMeasureSpec, childHeightMeasureSpec);
    ...         
    performLayout(lp, mWidth, mHeight);
    ...
    performDraw();
    ...
}

Surface的具體創(chuàng)建就由relayoutWindow(params, viewVisibility, insetsPending)這個(gè)方法來(lái)完成的。這個(gè)方法會(huì)通過(guò)IPC調(diào)用到WindowManagerService.relayoutWindow():

http://androidxref.com/6.0.1_r10/xref/frameworks/base/core/java/android/view/ViewRootImpl.java

private int relayoutWindow(WindowManager.LayoutParams params, ...) throws RemoteException {
    ...
    int relayoutResult = mWindowSession.relayout(mWindow,..., mSurface);
    ...
}

mWindowSession.relayout()方法的很多參數(shù)，不過(guò)有一個(gè)十分重要的參數(shù)我沒有省略，就是mSurface。前面已經(jīng)分析了它就是一個(gè)空的Surface對(duì)象。其實(shí):

真正的Surface創(chuàng)建是由SurfaceControl完成的，應(yīng)用程序ViewRootImpl的Surface只是一個(gè)指針，指向這個(gè)Surface

下面就來(lái)看一下SurfaceControl是如何創(chuàng)建Surface的:

mWindowSession.relayout()會(huì)調(diào)用到WindowManagerService.relayoutWindow():

http://androidxref.com/6.0.1_r10/xref/frameworks/base/services/core/java/com/android/server/wm/WindowManagerService.java

 //這里的outSurface其實(shí)就是ViewRootImpl中的那個(gè)Surface
public int relayoutWindow(Session session, IWindow client....Surface outSurface){ 
    ...
    result = createSurfaceControl(outSurface, result, win, winAnimator);  
    ...
}

private int createSurfaceControl(Surface outSurface, int result, WindowState win,WindowStateAnimator winAnimator) {
    ...
    surfaceController = winAnimator.createSurfaceLocked(win.mAttrs.type, win.mOwnerUid);
    ...
    surfaceController.getSurface(outSurface);
}

winAnimator.createSurfaceLocked實(shí)際上是創(chuàng)建了一個(gè)SurfaceControl。即上面是先構(gòu)造SurfaceControl，然后在構(gòu)造Surface。

http://androidxref.com/6.0.1_r10/xref/frameworks/base/services/core/java/com/android/server/wm/WindowStateAnimator.java

 SurfaceControl createSurfaceLocked() {
        final WindowState w = mWin;
        if (mSurfaceControl == null) {
           //...
             mSurfaceFormat = format;
                if (DEBUG_SURFACE_TRACE) {
                    mSurfaceControl = new SurfaceTrace(
                            mSession.mSurfaceSession,
                            attrs.getTitle().toString(),
                            width, height, format, flags);
                } else {
                    mSurfaceControl = new SurfaceControl(
                        mSession.mSurfaceSession,
                        attrs.getTitle().toString(),
                        width, height, format, flags);
                }
             //...
        }
        return mSurfaceControl;
    }        

SurfaceControl的創(chuàng)建

winAnimator.createSurfaceLocked其實(shí)是通過(guò)SurfaceControl的構(gòu)造函數(shù)創(chuàng)建了一個(gè)SurfaceControl對(duì)象,這個(gè)對(duì)象的作用其實(shí)就是負(fù)責(zé)維護(hù)Surface,Surface其實(shí)也是由這個(gè)對(duì)象負(fù)責(zé)創(chuàng)建的，我們看一下這個(gè)對(duì)象的構(gòu)造方法:

http://androidxref.com/6.0.1_r10/xref/frameworks/base/core/java/android/view/SurfaceControl.java

long mNativeObject; //成員指針變量，指向native創(chuàng)建的SurfaceControl

private SurfaceControl(SurfaceSession session, String name, int w, int h, int format, int flags,
            SurfaceControl parent, int windowType, int ownerUid){
    ...
    mNativeObject = nativeCreate(session, name, w, h, format, flags,
        parent != null ? parent.mNativeObject : 0, windowType, ownerUid);
    ...
}

即調(diào)用了nativeCreate()并返回一個(gè)SurfaceControl指針:

http://androidxref.com/6.0.1_r10/xref/frameworks/native/libs/gui/SurfaceControl.cpp

static jlong nativeCreate(JNIEnv* env, ...) {
    //這個(gè)client其實(shí)就是前面創(chuàng)建的SurfaceComposerClinent
    sp<SurfaceComposerClient> client(android_view_SurfaceSession_getClient(env, sessionObj)); 
    sp<SurfaceControl> surface; //創(chuàng)建成功之后，這個(gè)指針會(huì)指向新創(chuàng)建的SurfaceControl
    status_t err = client->createSurfaceChecked(String8(name.c_str()), w, h, format, &surface, flags, parent, windowType, ownerUid);
    ...
    return reinterpret_cast<jlong>(surface.get()); //返回這個(gè)SurfaceControl的地址
}

即調(diào)用到SurfaceComposerClient.createSurfaceChecked():

http://androidxref.com/6.0.1_r10/xref/frameworks/native/libs/gui/SurfaceComposerClient.cpp

//outSurface會(huì)指向新創(chuàng)建的SurfaceControl
status_t SurfaceComposerClient::createSurfaceChecked(...sp<SurfaceControl>* outSurface..) 
{
    sp<IGraphicBufferProducer> gbp; //這個(gè)對(duì)象很重要
    ...
    err = mClient->createSurface(name, w, h, format, flags, parentHandle, windowType, ownerUid, &handle, &gbp);
    if (err == NO_ERROR) {
        //SurfaceControl創(chuàng)建成功, 指針賦值
        *outSurface = new SurfaceControl(this, handle, gbp, true);
    }
    return err;
}

上面這個(gè)方法實(shí)際上是調(diào)用Client.createSurface()來(lái)創(chuàng)建一個(gè)Surface。在創(chuàng)建時(shí)有一個(gè)很重要的參數(shù)sp<IGraphicBufferProducer> gbp,在下面源碼分析中我們也要重點(diǎn)注意它。這是因?yàn)閼?yīng)用所渲染的每一幀，實(shí)際上都會(huì)添加到IGraphicBufferProducer中，來(lái)等待SurfaceFlinger的渲染。
http://androidxref.com/6.0.1_r10/xref/frameworks/native/services/surfaceflinger/Client.cpp

status_t Client::createSurface(...)
{
    ...
    //gbp 直接透?jìng)鞯搅薙urfaceFlinger
    return mFlinger->createLayer(name, this, w, h, format, flags, windowType, ownerUid, handle, gbp, &parent);
}

Surface在SurfaceFlinger中對(duì)應(yīng)的實(shí)體其實(shí)是Layer

我們繼續(xù)看一下mFlinger->createLayer()

http://androidxref.com/6.0.1_r10/xref/frameworks/native/services/surfaceflinger/SurfaceFlinger.cpp

status_t SurfaceFlinger::createLayer(const String8& name,const sp<Client>& client...)
{
    status_t result = NO_ERROR;
    sp<Layer> layer; //將要?jiǎng)?chuàng)建的layer
    switch (flags & ISurfaceComposerClient::eFXSurfaceMask) {
        case ISurfaceComposerClient::eFXSurfaceNormal:
            result = createBufferLayer(client,
                    uniqueName, w, h, flags, format,
                    handle, gbp, &layer); // 注意gbp，這時(shí)候還沒有構(gòu)造呢！
            break;
            ... //Layer 分為好幾種，這里不全部列出
    }
    ...
    result = addClientLayer(client, *handle, *gbp, layer, *parent);  //這個(gè)layer和client相關(guān)聯(lián), 添加到Client的mLayers集合中。
    ...
    return result;
}

從SurfaceFlinger.createLayer()方法可以看出Layer分為好幾種。我們這里只對(duì)普通的BufferLayer的創(chuàng)建做一下分析，看createBufferLayer():

http://androidxref.com/6.0.1_r10/xref/frameworks/native/services/surfaceflinger/SurfaceFlinger.cpp

status_t SurfaceFlinger::createBufferLayer(const sp<Client>& client... sp<Layer>* outLayer)
{
    ...
    sp<BufferLayer> layer = new BufferLayer(this, client, name, w, h, flags);
    status_t err = layer->setBuffers(w, h, format, flags);  //設(shè)置layer的寬高
    if (err == NO_ERROR) {
        *handle = layer->getHandle(); //創(chuàng)建handle
        *gbp = layer->getProducer(); //創(chuàng)建 gbp IGraphicBufferProducer
        *outLayer = layer; //把新建的layer的指針拷貝給outLayer,這樣outLayer就指向了新建的BufferLayer
    }
    return err;
}

前面我說(shuō)過(guò)IGraphicBufferProducer(gbp)是一個(gè)很重要的對(duì)象，它涉及到SurfaceFlinger的渲染邏輯，下面我們就看一下這個(gè)對(duì)象的創(chuàng)建邏輯:

IGraphicBufferProducer(gbp)的創(chuàng)建

sp<IGraphicBufferProducer> BufferLayer::getProducer() const {
    return mProducer;
}

即mProducer其實(shí)是Layer的成員變量，它的創(chuàng)建時(shí)機(jī)是Layer第一次被使用時(shí):

void BufferLayer::onFirstRef() {
    ...
    BufferQueue::createBufferQueue(&producer, &consumer, true); 
    mProducer = new MonitoredProducer(producer, mFlinger, this);
    ...
}

所以mProducer的實(shí)例是MonitoredProducer,但其實(shí)它只是一個(gè)裝飾類，它實(shí)際功能都委托給構(gòu)造它的參數(shù)producer:

BufferQueue.cpp

void BufferQueue::createBufferQueue(sp<IGraphicBufferProducer>* outProducer,
    ...
    sp<IGraphicBufferProducer> producer(new BufferQueueProducer(core, consumerIsSurfaceFlinger));
    sp<IGraphicBufferConsumer> consumer(new BufferQueueConsumer(core)); //注意這個(gè)consumer
    ...
    *outProducer = producer;
    *outConsumer = consumer;
}

所以實(shí)際實(shí)現(xiàn)mProducer的工作的queueProducer是BufferQueueProducer。

所以構(gòu)造一個(gè)SurfaceControl所做的工作就是創(chuàng)建了一個(gè)SurfaceControl,并讓SurfaceFlinger創(chuàng)建了一個(gè)對(duì)應(yīng)的Layer，Layer中有一個(gè)IGraphicBufferProducer,它的實(shí)例是BufferQueueProducer。

可以用下面這個(gè)圖來(lái)描述SurfaceControl的創(chuàng)建過(guò)程:

從SurfaceControl中獲取Surface

我們回看WindowManagerService.createSurfaceControl()， 來(lái)看一下java層的Surface對(duì)象到底是個(gè)什么:

http://androidxref.com/6.0.1_r10/xref/frameworks/base/services/core/java/com/android/server/wm/WindowManagerService.java

private int createSurfaceControl(Surface outSurface, int result, WindowState win,WindowStateAnimator winAnimator) {
    ...
    surfaceController = winAnimator.createSurfaceLocked(win.mAttrs.type, win.mOwnerUid);
    ...
    surfaceController.getSurface(outSurface);
}

上面我們已經(jīng)了解了winAnimator.createSurfaceLocked的整個(gè)過(guò)程，我們看一下surfaceController.getSurface(outSurface), surfaceController是WindowSurfaceController的實(shí)例:

//WindowSurfaceController.java
void getSurface(Surface outSurface) {
    outSurface.copyFrom(mSurfaceControl);
}

//Surface.java
public void copyFrom(SurfaceControl other) {
    ...
    long surfaceControlPtr = other.mNativeObject;
    ...
    long newNativeObject = nativeGetFromSurfaceControl(surfaceControlPtr);
    ...
    mNativeObject = ptr; // mNativeObject指向native創(chuàng)建的Surface
}

即Surface.copyFrom()方法調(diào)用nativeGetFromSurfaceControl()來(lái)獲取一個(gè)指針，這個(gè)指針是根據(jù)前面創(chuàng)建的SurfaceControl的指針來(lái)尋找的，即傳入的參數(shù)surfaceControlPtr:

android_view_Surface.cpp

static jlong nativeGetFromSurfaceControl(JNIEnv* env, jclass clazz, jlong surfaceControlNativeObj) {
    sp<SurfaceControl> ctrl(reinterpret_cast<SurfaceControl *>(surfaceControlNativeObj)); //把java指針轉(zhuǎn)化內(nèi)native指針
    sp<Surface> surface(ctrl->getSurface()); //直接構(gòu)造一個(gè)Surface，指向 ctrl->getSurface()
    if (surface != NULL) {
        surface->incStrong(&sRefBaseOwner); //強(qiáng)引用
    }
    return reinterpret_cast<jlong>(surface.get());
}

這里的ctrl指向前面創(chuàng)建的SurfaceControl，繼續(xù)追溯ctrl->getSurface():

sp<Surface> SurfaceControl::getSurface() const
{
    Mutex::Autolock _l(mLock);
    if (mSurfaceData == 0) {
        return generateSurfaceLocked();
    }
    return mSurfaceData;
}

sp<Surface> SurfaceControl::generateSurfaceLocked() const
{
    //這個(gè)mGraphicBufferProducer其實(shí)就是上面分析的BufferQueueProducer
    mSurfaceData = new Surface(mGraphicBufferProducer, false); 
    return mSurfaceData;
}

即直接new了一個(gè)nativie的Surface返回給java層，java層的Surface指向的就是native層的Surface。

所以Surface的實(shí)際創(chuàng)建可以用下圖表示:

經(jīng)過(guò)上面這個(gè)圖，也可以理解SurfaceControl為什么叫SurfaceControl了。

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