Surface創(chuàng)建
在ViewRootImpl，創(chuàng)建一個(gè)final的Surface對(duì)象沟娱，任何線(xiàn)程可訪(fǎng)問(wèn)它嗡官，內(nèi)部mLock鎖。ViewRootImpl類(lèi)中的Surface定義膀篮。
final Surface mSurface = new Surface();
第一次performTraversals方法或窗體發(fā)生改變時(shí)嘹狞，Surface的#isValid方法判斷是否有效，relayoutWindow方法誓竿，初始化Surface磅网。
之前無(wú)效，現(xiàn)在有效
1：設(shè)置newSurface標(biāo)志筷屡，下次再繪制涧偷。
2：初始化硬件渲染，mHardwareRenderer#initinitialize方法之前有效毙死，現(xiàn)在無(wú)效
各種destroy停止一直有效
硬件渲染更新燎潮，mHardwareRenderer#updateSurface方法
Surface的#isValid方法。
public boolean isValid() {
synchronized (mLock) {
if (mNativeObject == 0) return false;
return nativeIsValid(mNativeObject);
}
}
當(dāng)Surface內(nèi)部底層指針mNativeObject不空扼倘，且底層JNI方法#nativeIsValid判斷有效時(shí)确封，認(rèn)定Java層Surface有效。
通過(guò)IWindowSession的#relayout方法訪(fǎng)問(wèn)Wms服務(wù)。
public int relayout(IWindow window, int seq, ...,Surface outSurface) {
int res = mService.relayoutWindow(this, window, ..., outSurface);
return res;
}
Wms服務(wù)的#relayoutWindow方法爪喘，初始化App進(jìn)程傳過(guò)來(lái)的Surface颜曾。
public int relayoutWindow(Session session, IWindow client, ...,Surface outSurface) {
..
if (viewVisibility == View.VISIBLE &&
(win.mAppToken == null || !win.mAppToken.clientHidden)) {
try {
...
SurfaceControl surfaceControl = winAnimator.createSurfaceLocked();
//創(chuàng)建surfaceControl
if (surfaceControl != null) {
outSurface.copyFrom(surfaceControl);
} else {
outSurface.release();
}
} catch (Exception e) {
}
}
...
}
創(chuàng)建一個(gè)SurfaceControl對(duì)象，調(diào)用它的copyFrom方法腥放，初始化底層Surface泛啸，該對(duì)象是Surface控制類(lèi)绿语。
創(chuàng)建SurfaceControl
SurfaceControl底層結(jié)構(gòu)圖秃症。
WindowStateAnimator的createSurfaceLocked方法。
SurfaceControl createSurfaceLocked() {
if (mSurfaceControl == null) {
mDrawState = DRAW_PENDING;//狀態(tài)變更為待繪制
...
try {
mSurfaceW = width;//設(shè)置surface的寬高
mSurfaceH = height;
...
mSurfaceFormat = format;//設(shè)置surface格式
mSurfaceControl = new SurfaceControl(
mSession.mSurfaceSession,
attrs.getTitle().toString(),
width, height, format, flags);
w.mHasSurface = true;//winstate有了surface
try {
mSurfaceX = left;
mSurfaceY = top;
try {
mSurfaceControl.setPosition(left, top);
mSurfaceLayer = mAnimLayer;
...
mSurfaceControl.setLayer(mAnimLayer);
mSurfaceControl.setAlpha(0);
mSurfaceShown = false;
} catch (RuntimeException e) {
...
}
mLastHidden = true;//剛創(chuàng)建的設(shè)為隱藏
}
}
}
在Java層吕粹，SurfaceControl#構(gòu)造方法种柑，JNI#方法，創(chuàng)建底層SurfaceControl匹耕，參數(shù)是SurfaceSession聚请、寬高、格式等稳其，返回指針驶赏。
static jlong nativeCreate(JNIEnv* env, jclass clazz, jobject sessionObj,
jstring nameStr, jint w, jint h, jint format, jint flags) {
sp<SurfaceComposerClient> client(android_view_SurfaceSession_getClient(env, sessionObj));
//創(chuàng)建底層surfaceControl。
sp<SurfaceControl> surface = client->createSurface(
String8(name.c_str()), w, h, format, flags);
...
surface->incStrong((void *)nativeCreate);
return reinterpret_cast<jlong>(surface.get());
}
底層SurfaceComposerClient既鞠，它在SurfaceSession構(gòu)造方法創(chuàng)建煤傍。創(chuàng)建底層SurfaceControl。
sp<SurfaceControl> SurfaceComposerClient::createSurface(
const String8& name,
uint32_t w,
uint32_t h,
PixelFormat format,
uint32_t flags) {
sp<SurfaceControl> sur;
if (mStatus == NO_ERROR) {
sp<IBinder> handle;
sp<IGraphicBufferProducer> gbp;
status_t err = mClient->createSurface(name, w, h, format, flags,
&handle, &gbp);
if (err == NO_ERROR) {
sur = new SurfaceControl(this, handle, gbp);
}
}
return sur;
}
在Wms服務(wù)進(jìn)程嘱蛋，此方法本質(zhì)是調(diào)用Client#createSurface實(shí)現(xiàn)與SF進(jìn)程通信蚯姆，SF進(jìn)程初始化handle與gbp，最后洒敏，構(gòu)建一個(gè)底層SurfaceControl用于封裝關(guān)鍵的handle與gdp龄恋。
ISurfaceComposerClient是Wms服務(wù)進(jìn)程與SF進(jìn)程通信業(yè)務(wù)接口，SurfaceComposerClient#onFirstRef方法在構(gòu)造方法前調(diào)用凶伙。
void SurfaceComposerClient::onFirstRef() {
sp<ISurfaceComposer> sm(ComposerService::getComposerService());
if (sm != 0) {
sp<ISurfaceComposerClient> conn = sm->createConnection();
if (conn != 0) {
mClient = conn;//初始化mClient郭毕。
mStatus = NO_ERROR;
}
}
}
通過(guò)createConnection方法，調(diào)用端得到的業(yè)務(wù)接口的實(shí)現(xiàn)BpSurfaceComposerClient函荣。SF進(jìn)程服務(wù)端創(chuàng)建Client對(duì)象铣卡，繼承BnSurfaceComposerClient。
SF進(jìn)程createSurface方法
Wms進(jìn)程發(fā)起訪(fǎng)問(wèn)后偏竟，SF進(jìn)程啟動(dòng)binder線(xiàn)程處理業(yè)務(wù)煮落，向SF主線(xiàn)程發(fā)送一個(gè)MessageCreateLayer消息。
Client#createSurface方法踊谋。
status_t Client::createSurface(...) {
//先定義一個(gè)消息類(lèi)MessageCreateLayer
class MessageCreateLayer : public MessageBase {
SurfaceFlinger* flinger;
Client* client;
sp<IBinder>* handle;
sp<IGraphicBufferProducer>* gbp;
status_t result;
..
public:
MessageCreateLayer(SurfaceFlinger* flinger,
const String8& name, Client* client,
uint32_t w, uint32_t h, PixelFormat format, uint32_t flags,
sp<IBinder>* handle,
sp<IGraphicBufferProducer>* gbp)
: flinger(flinger), client(client),
handle(handle), gbp(gbp),
name(name), w(w), h(h), format(format), flags(flags) {
}
status_t getResult() const { return result; }
virtual bool handler() {
result = flinger->createLayer(name, client, w, h, format, flags,
handle, gbp);//
return true;
}
};
sp<MessageBase> msg = new MessageCreateLayer(mFlinger.get(),
name, this, w, h, format, flags, handle, gbp);
mFlinger->postMessageSync(msg);
return static_cast<MessageCreateLayer*>( msg.get() )->getResult();
}
創(chuàng)建一個(gè)MessageCreateLayer消息蝉仇，postMessageSync發(fā)送給SF主線(xiàn)程。
status_t SurfaceFlinger::postMessageSync(const sp<MessageBase>& msg,
nsecs_t reltime, uint32_t /* flags */) {
status_t res = mEventQueue.postMessage(msg, reltime);
if (res == NO_ERROR) {
msg->wait();//柵欄等待
}
return res;
}
向EventQueue消息隊(duì)列發(fā)送同步消息，然后通過(guò)柵欄使binder線(xiàn)程陷入wait轿衔，最后由主線(xiàn)程喚醒沉迹。MessageCreateLayer繼承MessageBase，當(dāng)主線(xiàn)程handleMessage方法處理時(shí)害驹，觸發(fā)子類(lèi)MessageCreateLayer重寫(xiě)的handler方法鞭呕，最后打開(kāi)柵欄，喚醒等待的binder線(xiàn)程宛官。
void MessageBase::handleMessage(const Message&) {
//走到MessageCreateLayer重寫(xiě)的handler方法
this->handler();
barrier.open();
};
//MessageCreateLayer重寫(xiě)的handler方法
virtual bool handler() {
result = flinger->createLayer(name, client, w, h, format, flags,handle, gbp);
return true;
}
handler處理時(shí)葫松，觸發(fā)主線(xiàn)程SF#createLayer方法，真正初始化handle與gbp底洗，返回result腋么，SF#binder線(xiàn)程被喚醒后，createSurface繼續(xù)執(zhí)行亥揖，此時(shí)珊擂，result已初始化賦值。
總結(jié)
binder線(xiàn)程被柵欄阻擋费变，進(jìn)入等待摧扇，當(dāng)主線(xiàn)程handler方法執(zhí)行后，有了result挚歧，打開(kāi)柵欄扛稽，放行>binder線(xiàn)程，被喚醒拿到result昼激。
SF主線(xiàn)程createLayer方法
status_t SurfaceFlinger::createLayer(
const String8& name,
const sp<Client>& client,
uint32_t w, uint32_t h, PixelFormat format, uint32_t flags,
sp<IBinder>* handle, sp<IGraphicBufferProducer>* gbp) {
sp<Layer> layer;
result = createNormalLayer(client,
name, w, h, flags, format,//format是java層傳過(guò)來(lái)的
handle, gbp, &layer);//創(chuàng)建Layer對(duì)象庇绽，指針在layer中。
...
result = addClientLayer(client, *handle, *gbp, layer);//將layer增加到list中
...
setTransactionFlags(eTransactionNeeded);//0x01 創(chuàng)建Layer橙困，觸發(fā)eTransactionNeeded
return result;
}
SurfaceFlinger#createNormalLayer方法瞧掺。
status_t SurfaceFlinger::createNormalLayer(const sp<Client>& client,//普通Layer
const String8& name, uint32_t w, uint32_t h, uint32_t flags, PixelFormat& format,
sp<IBinder>* handle, sp<IGraphicBufferProducer>* gbp, sp<Layer>* outLayer) {
...
*outLayer = new Layer(this, client, name, w, h, flags);//創(chuàng)建Layer
status_t err = (*outLayer)->setBuffers(w, h, format, flags);
if (err == NO_ERROR) {
*handle = (*outLayer)->getHandle();//初始化handle和gbp
*gbp = (*outLayer)->getProducer();
}
return err;
}
創(chuàng)建普通層級(jí)Layer對(duì)象，Layer#getHandle與Layer#getProducer方法初始化handle凡傅、gbp指針辟狈，將Layer加入到Client中的map保存，
每個(gè)Layer對(duì)應(yīng)一個(gè)handle夏跷。
- Layer#getHandle：handle是IBinder類(lèi)型哼转，創(chuàng)建服務(wù)進(jìn)程端Handle對(duì)象，在內(nèi)核為其創(chuàng)建服務(wù)節(jié)點(diǎn)槽华，客戶(hù)端拿到的handle是BpXxx壹蔓，handle是一個(gè)遠(yuǎn)程進(jìn)程連接到SF進(jìn)程的句柄。
- Layer#getProducer：返回Layer的IGraphicBufferProducer猫态。IGraphicBufferProducer也是跨進(jìn)程通信的業(yè)務(wù)接口佣蓉，遠(yuǎn)程進(jìn)程拿到的是BpGraphicBufferProducer披摄，通過(guò)它操作圖形內(nèi)存區(qū)的。
- SF進(jìn)程通過(guò)reply的writeStrongBinder方法寫(xiě)入勇凭，遠(yuǎn)程進(jìn)程通過(guò)readStrongBinder讀取疚膊。
底層Surface
Surface#copyFrom方法。
public void copyFrom(SurfaceControl other) {
...
//底層SurfaceControl指針
long surfaceControlPtr = other.mNativeObject;
...
long newNativeObject = nativeCreateFromSurfaceControl(surfaceControlPtr);
synchronized (mLock) {
if (mNativeObject != 0) {
nativeRelease(mNativeObject);//釋放原底層Surface指針
}
setNativeObjectLocked(newNativeObject);
}
}
JNI#方法利用底層SurfaceControl創(chuàng)建底層Surface虾标。
底層SurfaceControl#getSurface方法寓盗。
sp<Surface> SurfaceControl::getSurface() const {
Mutex::Autolock _l(mLock);
if (mSurfaceData == 0) {
mSurfaceData = new Surface(mGraphicBufferProducer, false);
}
return mSurfaceData;
}
底層Surface創(chuàng)建，封裝GraphicBufferProducer指針璧函。
Wms服務(wù)初始化Surface傀蚌，App進(jìn)程通過(guò)Surface操作圖形緩沖區(qū)。
GraphicBufferProducer是生產(chǎn)者柳譬。
任重而道遠(yuǎn)
