第8章 ?深入理解Surface系統(tǒng)

說明：為書寫方便起見，后文將SurfaceFlinger簡寫為SF。

private final voidhandleLaunchActivity(ActivityRecord r, Intent customIntent) {

????? ?//①performLaunchActivity返回一個Activity

?????? Activitya = performLaunchActivity(r, customIntent);

?

??????? if(a != null) {

???????????r.createdConfig = new Configuration(mConfiguration);

???????????Bundle oldState = r.state;

??????????//②調(diào)用handleResumeActivity

???????????handleResumeActivity(r.token, false, r.isForward);

?? }

??????......

}

private final ActivityperformLaunchActivity(ActivityRecord r,

Intent customIntent) {

??? ????

???????ActivityInfo aInfo = r.activityInfo;

??????? ......//完成一些準(zhǔn)備工作

??????//Activity定義在Activity.java中

???????Activity activity = null;

???????try {

???????????java.lang.ClassLoader cl = r.packageInfo.getClassLoader();

???? /*

???? mInstrumentation為Instrumentation類型，源文件為Instrumentation.java。

???? 它在newActivity函數(shù)中根據(jù)Activity的類名通過Java反射機制來創(chuàng)建對應(yīng)的Activity，

???? 這個函數(shù)比較復(fù)雜，待會我們再分析它。

???? */

???????????activity = mInstrumentation.newActivity(

??????????????????? cl,component.getClassName(), r.intent);

?? ?????????r.intent.setExtrasClassLoader(cl);

???????????if (r.state != null) {

???????????????r.state.setClassLoader(cl);

???????????}

??????? }catch (Exception e) {

????????????......

??????? }

?

???????try {

???????????Application app =

?????????????r.packageInfo.makeApplication(false,mInstrumentation);

?

????????????if (activity != null) {

???????????????//在Activity中g(shù)etContext函數(shù)返回的就是這個ContextImpl類型的對象

???????????????ContextImpl appContext = new ContextImpl();

???????????????......

??????????????//下面這個函數(shù)會調(diào)用Activity的onCreate函數(shù)

???????????????mInstrumentation.callActivityOnCreate(activity, r.state);

?????? ?????????......

???????return activity;

?}

final void handleResumeActivity(IBinder token,boolean clearHide,

boolean isForward) {

boolean willBeVisible = !a.mStartedActivity;

??????????

if (r.window == null && !a.mFinished&& willBeVisible) {

????? r.window= r.activity.getWindow();

????? //①獲得一個View對象

????? Viewdecor = r.window.getDecorView();

?????decor.setVisibility(View.INVISIBLE);

????? //②獲得ViewManager對象

????? ViewManagerwm = a.getWindowManager();

??????......

????? //③把剛才的decor對象加入到ViewManager中

?????? wm.addView(decor,l);

?? }

?????????......//其他處理

}

public void setContentView(View view) {

//getWindow返回的是什么呢？一起來看看。

?getWindow().setContentView(view);

}

?

public Window getWindow() {

? returnmWindow; //返回一個類型為Window的mWindow，它是什么？

}

activity = mInstrumentation.newActivity(

??????????????????? cl,component.getClassName(), r.intent);

public Activity newActivity(Class<?>clazz, Context context,

???????????IBinder token, Application application, Intent intent,

??????????? ActivityInfo info, CharSequencetitle, Activity parent,

String id,Object lastNonConfigurationInstance)

throws InstantiationException, IllegalAccessException{

???????

Activity activity = (Activity)clazz.newInstance();

???????ActivityThread aThread = null;

??????? //關(guān)鍵函數(shù)attach!!

???????activity.attach(context, aThread, this, token, application, intent,

info, title,parent, id, lastNonConfigurationInstance,

new Configuration());

???????return activity;

??? }

final void attach(Context context,ActivityThread aThread,

???????????Instrumentation instr, IBinder token, int ident,

???????????Application application, Intent intent, ActivityInfo info,

???????????CharSequence title, Activity parent, String id,

???????????Object lastNonConfigurationInstance,

???????????HashMap<String,Object> lastNonConfigurationChildInstances,

???????????Configuration config) {

??????? ......

??????? //利用PolicyManager來創(chuàng)建Window對象

???????mWindow = PolicyManager.makeNewWindow(this);

???????mWindow.setCallback(this);

??????? ......

??????? //創(chuàng)建WindowManager對象

???????mWindow.setWindowManager(null, mToken, mComponent.flattenToString());

??????? if(mParent != null) {

???????????mWindow.setContainer(mParent.getWindow());

??????? }

?????? //保存這個WindowManager對象

???????mWindowManager = mWindow.getWindowManager();

???????mCurrentConfig = config;

}

注意，上面路徑中的灰色目錄phone是針對智能手機這種小屏幕的；另外還有一個平級的目錄叫mid，是針對Mid設(shè)備的。mid目錄的代碼比較少，可能目前還沒有開發(fā)完畢。

public final class PolicyManager {

???private static final String POLICY_IMPL_CLASS_NAME =

???????"com.android.internal.policy.impl.Policy";

?

???private static final IPolicy sPolicy;

?

??? static{

??????? //

???????try {

???????????Class policyClass = Class.forName(POLICY_IMPL_CLASS_NAME);

???????????//創(chuàng)建Policy對象

???????????sPolicy = (IPolicy)policyClass.newInstance();

??????? }catch (ClassNotFoundException ex) {

????????????......

??? ???}

?

????private PolicyManager() {}

?

??? //通過Policy對象的makeNewWindow創(chuàng)建一個Window

??? publicstatic Window makeNewWindow(Context context) {

???????return sPolicy.makeNewWindow(context);

??? }

?? ......

}

public class Policy implements IPolicy {

???private static final String TAG = "PhonePolicy";

?

???private static final String[] preload_classes = {

???????"com.android.internal.policy.impl.PhoneLayoutInflater",

???????"com.android.internal.policy.impl.PhoneWindow",

???????"com.android.internal.policy.impl.PhoneWindow$1",

???????"com.android.internal.policy.impl.PhoneWindow$ContextMenuCallback",

???????"com.android.internal.policy.impl.PhoneWindow$DecorView",

???????"com.android.internal.policy.impl.PhoneWindow$PanelFeatureState",

"com.android.internal.policy.impl.PhoneWindow$PanelFeatureState$SavedState",

??? };

?

??? static{

??????? //加載所有的類

???????for (String s : preload_classes) {

???????????try {

???????????????Class.forName(s);

???????????} catch (ClassNotFoundException ex) {

???????????????......

???????????}

??????? }

??? }

?

public PhoneWindow makeNewWindow(Contextcontext) {

?? ?????//makeNewWindow返回的是PhoneWindow對象

???????return new PhoneWindow(context);

??? }

?

??? ......

}

mWindow = PolicyManager.makeNewWindow(this);

??......//創(chuàng)建mWindow對象

?? //調(diào)用mWindow的setWindowManager函數(shù)

mWindow.setWindowManager(null, mToken,mComponent.flattenToString());

?? .....

public class PhoneWindow extends Windowimplements MenuBuilder.Callback

public void setWindowManager(WindowManagerwm,IBinder appToken, String appName) {?????//注意，傳入的wm值為null

???????mAppToken = appToken;

???????mAppName = appName;

??????? if(wm == null) {

??????????//如果wm為空的話，則創(chuàng)建WindowManagerImpl對象

???????????wm = WindowManagerImpl.getDefault();

??????? }

?????? //mWindowManager是一個LocalWindowManager

???????mWindowManager = new LocalWindowManager(wm);

??? }

private class LocalWindowManager implementsWindowManager {

???????LocalWindowManager(WindowManager wm) {

???????????mWindowManager = wm;//還好，只是簡單地保存了傳入的wm參數(shù)

???????????mDefaultDisplay = mContext.getResources().getDefaultDisplay(

???????????????????mWindowManager.getDefaultDisplay());

??????? }

??? ......

public class WindowManagerImpl implementsWindowManager {

......

?

public static WindowManagerImpl getDefault()

{

?? ??return mWindowManager; //返回的就是WindowManagerImpl對象

}

private static WindowManagerImpl mWindowManager= new WindowManagerImpl();

}

public void setContentView(View view) {

???????getWindow().setContentView(view);//getWindow返回的是PhoneWindow

}

public void setContentView(View view) {

?? //調(diào)用另一個setContentView

?? setContentView(view,

new ViewGroup.LayoutParams(MATCH_PARENT,MATCH_PARENT));

}

?

public void setContentView(View view,ViewGroup.LayoutParams params) {

?? //mContentParent為ViewGroup類型，它的初值為null

???? if(mContentParent == null) {

???????????installDecor();

???? }else {

???????????mContentParent.removeAllViews();

???? }

??? //把view加入到ViewGroup中

????mContentParent.addView(view, params);

???? ......

}

這里采用的是23種設(shè)計模式中的Composite模式，它是UI編程中常用的模式之一。

private void installDecor() {

?? ?if (mDecor == null) {

???? //創(chuàng)建mDecor，它為DecorView類型，從FrameLayout派生

???? mDecor= generateDecor();

? ??????????......

?? }

? if(mContentParent == null) {

???? //得到這個mContentParent

mContentParent = generateLayout(mDecor);

//創(chuàng)建標(biāo)題欄

??? mTitleView= (TextView)findViewById(com.android.internal.R.id.title);

......

}

protected ViewGroup generateLayout(DecorViewdecor){

? ......

? intlayoutResource;

? intfeatures = getLocalFeatures();

? if((features & ((1 << FEATURE_LEFT_ICON) |(1 <<FEATURE_RIGHT_ICON))) != 0) {

????? if(mIsFloating) {

????? //根據(jù)情況取得對應(yīng)標(biāo)題欄的資源id

?????layoutResource = ?com.android.internal.R.layout.dialog_title_icons;

???? }

???????......

}

?

? mDecor.startChanging();

?

?View in =mLayoutInflater.inflate(layoutResource, null);

?//加入標(biāo)題欄

?decor.addView(in,new ViewGroup.LayoutParams(MATCH_PARENT, MATCH_PARENT));

?? /*

ID_ANDROID_CONTENT的值為”com.android.internal.R.id.content”

?? ??這個contentParent由findViewById返回，實際上就是mDecorView的一部分。

?? */

?? ViewGroupcontentParent = (ViewGroup)findViewById(ID_ANDROID_CONTENT);

? ?......

?? mDecor.finishChanging();

?? returncontentParent;

}

public View findViewById(int id) {

??//getDecorView將返回mDecorView,所以contentParent確實是DecorView的一部分

?? returngetDecorView().findViewById(id);

?}

注意，這里使用了設(shè)計模式中的Decorator（裝飾）模式，它也是UI編程中常用的模式之一。

final void handleResumeActivity(IBinder token,boolean clearHide,

boolean isForward) {

?booleanwillBeVisible = !a.mStartedActivity;

......

if (r.window == null && !a.mFinished&& willBeVisible) {

???? r.window= r.activity.getWindow();

??? //①獲得一個View對象?，F(xiàn)在知道這個view就是DecorView

?? Viewdecor = r.window.getDecorView();

?? decor.setVisibility(View.INVISIBLE);

? //②獲得ViewManager對象,這個wm就是LocalWindowManager

? ViewManagerwm = a.getWindowManager();

? WindowManager.LayoutParamsl = r.window.getAttributes();

? a.mDecor= decor;

? l.type =WindowManager.LayoutParams.TYPE_BASE_APPLICATION;

? if(a.mVisibleFromClient) {

?????? a.mWindowAdded= true;

?????? //③把剛才的decor對象加入到ViewManager中

????? wm.addView(decor,l);

?? }

......//其他處理

}

由于代碼比較長，跳轉(zhuǎn)關(guān)系也很多，在分析代碼時，請讀者把握流程，在大腦中建立一個代碼分析的堆棧。

wm.addView(decor, l);//wm類型實際是LocalWindowManager

public final void addView(View view,ViewGroup.LayoutParams params) {

??

?WindowManager.LayoutParams wp =(WindowManager.LayoutParams)params;

?CharSequence curTitle = wp.getTitle();

?...... //做一些操作，可以不管它

//還記得前面提到過的Proxy模式嗎？mWindowManager對象實際上是WindowManagerImpl類型

mWindowManager.addView(view, params);

}

private void addView(View view,ViewGroup.LayoutParams params, boolean nest)

{

? ViewRootroot; //ViewRoot，幕后的主角終于登場了！

? synchronized(this) {

? //①創(chuàng)建ViewRoot

? root =new ViewRoot(view.getContext());

??root.mAddNesting = 1;

? view.setLayoutParams(wparams);

???????????

? if(mViews == null) {

?? ???index = 1;

???? ?mViews = new View[1];

????? mRoots= new ViewRoot[1];

?????mParams = new WindowManager.LayoutParams[1];

?? } else{

?????......

??? }

?? index--;

?? mViews[index]= view;

?? mRoots[index]= root;//保存這個root

?? mParams[index]= wparams;

?

//②setView,其中view是剛才我們介紹的DecorView

? root.setView(view,wparams, panelParentView);//

}

public final class ViewRoot extends Handlerimplements ViewParent,

???????View.AttachInfo.Callbacks //從Handler類派生

{

private final Surface mSurface = new Surface();//這里創(chuàng)建了一個Surface對象

final W mWindow;?//這個是什么？

View mView;

}

static class W extends IWindow.Stub

public ViewRoot(Context context) {

???????super();

??????....

?????? // getWindowSession？我們進去看看

??????getWindowSession(context.getMainLooper());

?????......//ViewRoot的mWindow是一個W類型，注意它不是Window類型，而是IWindow類型

?????? mWindow= new W(this, context);

}

ublic static IWindowSessiongetWindowSession(Looper mainLooper) {

synchronized (mStaticInit) {

? if(!mInitialized) {

?? try {

????? InputMethodManagerimm =

???????? InputMethodManager.getInstance(mainLooper);

????? //下面這個函數(shù)先得到WindowManagerService的Binder代理，然后調(diào)用它的openSession

sWindowSession = IWindowManager.Stub.asInterface(

?????????????????? ServiceManager.getService("window"))

?????????????????.openSession(imm.getClient(), imm.getInputContext());

??????????????????? mInitialized = true;

???????????????} catch (RemoteException e) {

???????????????}

???????????}

???????????return sWindowSession;

??????? }

??? }

openSession的操作是一個使用Binder通信的跨進程調(diào)用，暫且記住這個函數(shù)，在精簡流程之后再來分析。

public void setView(View view, WindowManager.LayoutParamsattrs,

????????????????????????View panelParentView){//第一個參數(shù)view是DecorView

??????......

?????? mView= view;//保存這個view

???????synchronized (this) {

???????????requestLayout(); //待會先看看這個。

???????????????try {

??????????????????? //調(diào)用IWindowSession的add函數(shù)，第一個參數(shù)是mWindow

??????????????????? res =sWindowSession.add(mWindow, mWindowAttributes,

???????????????????????????getHostVisibility(), mAttachInfo.mContentInsets);

???????????????}

??? ??????......

}

public void requestLayout() {

???????checkThread();

???????mLayoutRequested = true;

???????scheduleTraversals();

}

public void scheduleTraversals() {

??????? if(!mTraversalScheduled) {

???????????mTraversalScheduled = true;

???????????sendEmptyMessage(DO_TRAVERSAL); //發(fā)送DO_TRAVERSAL消息

??????? }

}

public IWindowSessionopenSession(IInputMethodClient client,

????????????????????????????????????????IInputContextinputContext) {

?????? ......

return new Session(client, inputContext);

}

public int add(IWindow window,WindowManager.LayoutParams attrs,

???????????????int viewVisibility, Rect outContentInsets) {

??? //調(diào)用外部類對象的addWindow,也就是WMS的addWindow

??? returnaddWindow(this, window, attrs, viewVisibility,

??????????????????????????????? outContentInsets);

}

public int addWindow(Session session, IWindowclient,

???????????WindowManager.LayoutParams attrs, int viewVisibility,

???????????Rect outContentInsets) {

???????????......

??????????//創(chuàng)建一個WindowState

??????????win = new WindowState(session, client, token,

??????????????????? attachedWindow, attrs,viewVisibility);

?????? ???......

?????????//調(diào)用attach函數(shù)

??????????win.attach();

??????????......

??????????return res;

}

void attach() {

????? //mSession就是Session對象，調(diào)用它的windowAddedLocked函數(shù)

?????mSession.windowAddedLocked();

}

void windowAddedLocked() {

? if(mSurfaceSession == null) {

??????? ......

?????? //創(chuàng)建一個SurfaceSession對象

?????? mSurfaceSession= new SurfaceSession();

?????? ......

???? }

???? ?mNumWindow++;

}