1.1 Window窗口管理框架圖

WMS窗口管理

窗口的添加從Activity::makeVisible開始秕硝，由WindowManagerImpl委托給WindowManagerGlobal處理机杜，WindowManagerGlobal內(nèi)部的mViews闰非、mRoots碉咆、mParams骏庸、mDyingViews分別管理窗口的試圖、主線程景东、布局參數(shù)以及死亡過程中的視圖吞琐；ViewRootImpl持有Session的代理端與WMS通信捆探；

2.1 ActivityThread::handleLaunchActivity

private void handleLaunchActivity(ActivityClientRecord r, Intent customIntent, String reason) {
    ...
    // Initialize before creating the activity
    WindowManagerGlobal.initialize(); // WindowManagerGlobal 初始化
    Activity a = performLaunchActivity(r, customIntent); // 2.2 ActivityThread::performLaunchActivity
    handleResumeActivity(r.token, false, r.isForward, !r.activity.mFinished && !r.startsNotResumed, r.lastProcessedSeq, reason); // 2.6 ActivityThread::handleResumeActivity
}

2.2 ActivityThread::performLaunchActivity

private Activity performLaunchActivity(ActivityClientRecord r, Intent customIntent) {
    Activity activity = null;
    ...
    java.lang.ClassLoader cl = r.packageInfo.getClassLoader();
    activity = mInstrumentation.newActivity(
            cl, component.getClassName(), r.intent); //newInstance
    ...
    activity.attach(appContext, this, getInstrumentation(), r.token,
        r.ident, app, r.intent, r.activityInfo, title, r.parent,
        r.embeddedID, r.lastNonConfigurationInstances, config,
        r.referrer, r.voiceInteractor, window); // 2.3 Activity::attach
    ...
    mInstrumentation.callActivityOnCreate(activity, r.state); //OnCreate
    ...
    activity.performStart();//Onstart
    ...
    mInstrumentation.callActivityOnRestoreInstanceState(activity, r.state); // OnRestoreInstanceState
}

2.3 Activity::attach

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,
        NonConfigurationInstances lastNonConfigurationInstances,
        Configuration config, String referrer, IVoiceInteractor voiceInteractor,
        Window window) {
    attachBaseContext(context); // 

    mWindow = new PhoneWindow(this, window); // 新建PhoneWindow
    mWindow.setWindowControllerCallback(this);
    mWindow.setCallback(this); // Window.CallBack的實現(xiàn)類為Activity
    mWindow.setOnWindowDismissedCallback(this);
    ...
    mToken = token; // 添加一個Activity窗口所需要的令牌
    ...
    mWindow.setWindowManager(
            (WindowManager)context.getSystemService(Context.WINDOW_SERVICE), /* 2.4.1 獲取WindowManagerImpl */
            mToken, mComponent.flattenToString(),
            (info.flags & ActivityInfo.FLAG_HARDWARE_ACCELERATED) != 0); // 2.5.1 PhoneWindow::setWindowManager
    if (mParent != null) {
        mWindow.setContainer(mParent.getWindow());
    }
    mWindowManager = mWindow.getWindowManager(); // mWindowManager is WindowManagerImpl
    mCurrentConfig = config;
}

2.4.1 ContextImpl::getSystemService

public Object getSystemService(String name) {
    return SystemServiceRegistry.getSystemService(this, name); // 2.4.2 SystemServiceRegistry::registerService
}

2.4.2 SystemServiceRegistry::registerService

registerService(Context.WINDOW_SERVICE, WindowManager.class,
        new CachedServiceFetcher<WindowManager>() {
    @Override
    public WindowManager createService(ContextImpl ctx) {
        return new WindowManagerImpl(ctx);
}});

2.5.1 PhoneWindow::setWindowManager

public void setWindowManager(WindowManager wm, IBinder appToken, String appName,
        boolean hardwareAccelerated) { // wm is WindowManagerImpl
    mAppToken = appToken;
    mAppName = appName;
    mHardwareAccelerated = hardwareAccelerated
            || SystemProperties.getBoolean(PROPERTY_HARDWARE_UI, false);
    if (wm == null) {
        wm = (WindowManager)mContext.getSystemService(Context.WINDOW_SERVICE);
    }
    mWindowManager = ((WindowManagerImpl)wm).createLocalWindowManager(this);
}

2.5.2 WindowManagerImpl::createLocalWindowManager

public WindowManagerImpl createLocalWindowManager(Window parentWindow) {
    return new WindowManagerImpl(mContext, parentWindow);
}

2.6 ActivityThread::handleResumeActivity

final void handleResumeActivity(IBinder token,
        boolean clearHide, boolean isForward, boolean reallyResume, int seq, String reason) {
    ...
    r = performResumeActivity(token, clearHide, reason);
    // r.activity.performResume() -> Activity::OnResume
    ...
    if (r != null) {
        final Activity a = r.activity;
        ...
        if (r.window == null && !a.mFinished && willBeVisible) {
            r.window = r.activity.getWindow(); // PhoneWindow
            View decor = r.window.getDecorView(); // 2.6.1 PhoneWindow::getDecorView
            decor.setVisibility(View.INVISIBLE); // Activity的窗口在初創(chuàng)時不可見，因為尚不確定是否真的要顯示窗口給用戶
            ViewManager wm = a.getWindowManager(); // WindowManagerImpl
            WindowManager.LayoutParams l = r.window.getAttributes();
            a.mDecor = decor;
            l.type = WindowManager.LayoutParams.TYPE_BASE_APPLICATION; // 類型：屬于Acitivity的窗口
            l.softInputMode |= forwardBit;
            if (r.mPreserveWindow) {
                a.mWindowAdded = true;
                r.mPreserveWindow = false;
                // Normally the ViewRoot sets up callbacks with the Activity
                // in addView->ViewRootImpl#setView. If we are instead reusing
                // the decor view we have to notify the view root that the
                // callbacks may have changed.
                ViewRootImpl impl = decor.getViewRootImpl();
                if (impl != null) {
                    impl.notifyChildRebuilt();
                }
            }
            if (a.mVisibleFromClient && !a.mWindowAdded) {
                a.mWindowAdded = true;
                wm.addView(decor, l); // WM is windowManagerImpl站粟，添加到WMS
            }
        }
        // The window is now visible if it has been added, we are not
        // simply finishing, and we are not starting another activity.
        if (!r.activity.mFinished && willBeVisible
                && r.activity.mDecor != null && !r.hideForNow) {
            ...
            WindowManager.LayoutParams l = r.window.getAttributes();
            ...
            if (r.activity.mVisibleFromClient) {
                ViewManager wm = a.getWindowManager();
                View decor = r.window.getDecorView();
                wm.updateViewLayout(decor, l); // 通知wms更新布局
            }
            ...
                r.activity.makeVisible(); // 2.7 設置可見
            ...
        }
        ...
        if (!r.onlyLocalRequest) {
            r.nextIdle = mNewActivities;
            mNewActivities = r;
            Looper.myQueue().addIdleHandler(new Idler()); // 
        }
        ActivityManagerNative.getDefault().activityResumed(token); // 通知AMS Activity處于Resumed狀態(tài)

    } else {
        // If an exception was thrown when trying to resume, then
        // just end this activity.
        // resume過程發(fā)生異常黍图，則 finishActivity
            ActivityManagerNative.getDefault()
                .finishActivity(token, Activity.RESULT_CANCELED, null,
                        Activity.DONT_FINISH_TASK_WITH_ACTIVITY);
    }
}

2.6.1 PhoneWindow::getDecorView

public final View getDecorView() {
    if (mDecor == null || mForceDecorInstall) {
        installDecor(); //  2.6.2 
    }
    return mDecor;
}

2.6.2 PhoneWindow::installDecor

private void installDecor() {
    mForceDecorInstall = false;
    if (mDecor == null) {
        mDecor = generateDecor(-1); // 2.6.3 
        mDecor.setDescendantFocusability(ViewGroup.FOCUS_AFTER_DESCENDANTS);
        mDecor.setIsRootNamespace(true);
        if (!mInvalidatePanelMenuPosted && mInvalidatePanelMenuFeatures != 0) {
            mDecor.postOnAnimation(mInvalidatePanelMenuRunnable);
        }
    } else {
        mDecor.setWindow(this); // PhoneWindow::mWindow is PhoneWindow
    }
}

2.6.3 PhoneWindow::generateDecor

protected DecorView generateDecor(int featureId) {
    // System process doesn't have application context and in that case we need to directly use
    // the context we have. Otherwise we want the application context, so we don't cling to the
    // activity.
    Context context;
    ...
    context = getContext();
    ...
    return new DecorView(context, featureId, this, getAttributes());
}

2.6.4 ActivityDecorView相關結(jié)構(gòu)圖

ActivityDecorView相關結(jié)構(gòu)圖

2.7 Activity::makeVisible 設置窗口可見

void makeVisible() {
    if (!mWindowAdded) {
        ViewManager wm = getWindowManager();
        wm.addView(mDecor, getWindow().getAttributes()); // 2.9 委托WindowManagerGlobal添加到wms
        mWindowAdded = true;
    }
    mDecor.setVisibility(View.VISIBLE); // 設置DecorView可見
}

2.8 WindowManagerImpl相關框架圖

WindowManagerImpl相關架構(gòu)圖

接口ViewManager定義了view的基本操作增（addView）、刪（removeView）奴烙、更新（updateViewLayout）;
接口WindowManger繼承自ViewManager助被；
WindowManagerImpl實現(xiàn)WindowManager中的方法，并委托給WindowMangerGlobal處理缸沃；
WindowManagerGlobal中的mViews恰起、mRoots修械、mParams趾牧、mDyingViews分別管理窗口的試圖、主線程肯污、布局參數(shù)以及死亡的試圖翘单；

2.9 WindowManagerGlobal::addView

    public void addView(View view, ViewGroup.LayoutParams params,
            Display display, Window parentWindow) {
        // 參數(shù)檢查
        ...
        ViewRootImpl root;
        View panelParentView = null;

        synchronized (mLock) {
            ...
            int index = findViewLocked(view, false);
            if (index >= 0) {
                if (mDyingViews.contains(view)) {
                    // Don't wait for MSG_DIE to make it's way through root's queue.
                    mRoots.get(index).doDie(); // 3.1 如果已經(jīng)包含此view,則先remove
                } 
            }
            ...
            root = new ViewRootImpl(view.getContext(), display); // 2.12 ViewRootImpl構(gòu)造過程獲取WindowSession
            view.setLayoutParams(wparams);
            mViews.add(view);
            mRoots.add(root);
            mParams.add(wparams); // 保存當前window
        }
        try {
            root.setView(view, wparams, panelParentView); // 2.12 更新布局
        } catch (RuntimeException e) {
            synchronized (mLock) {
                final int index = findViewLocked(view, false);
                if (index >= 0) {
                    removeViewLocked(index, true); // remove試圖
                }
            }
        }
    }

2.10 WindowManagerGlobal::addView 相關調(diào)用棧

WindowManagerImpl.addView()
    new ViewRoot
    // 保存到 mViews  mRoots  mParams
    ViewRoot.setView(xx)
        requestLayout // 檢查主線程
            scheduleTraversals
                sendEmptyMessage
                handleMessage
                    performTraversals  // 2.11 測量 布局 繪制
                        ViewRoot.relayoutWindow
                            IWindowSession.relayout // 參考relayout的調(diào)用棧
                        draw
                            View.draw
                        scheduleTralScheduled // try again
        mWindowSession.addToDisplay // 2.15 與requestLayout同級
        // sWindowSession.add
            WMS.addWindow // 2.16
                new WindowState // 
                WindowState.attach // 
                    Session.windowAddedLocked
                        new SurfaceSession // 開辟一塊內(nèi)存吨枉，由SurfaceFlinger進行混合處理

2.11 測量 布局 繪制流程

performTraversals基本流程

2.12 WindowMangerGlobal::getWindowSession

public static IWindowSession getWindowSession() {
    synchronized (WindowManagerGlobal.class) {
        if (sWindowSession == null) {
            try {
                InputMethodManager imm = InputMethodManager.getInstance();
                IWindowManager windowManager = getWindowManagerService(); // wms
                sWindowSession = windowManager.openSession( // 2.13 wms::opensession
                        new IWindowSessionCallback.Stub() {
                            @Override
                            public void onAnimatorScaleChanged(float scale) {
                                ValueAnimator.setDurationScale(scale);
                            }
                        },
                        imm.getClient(), imm.getInputContext());
            } catch (RemoteException e) {
                throw e.rethrowFromSystemServer();
            }
        }
        return sWindowSession;
    }
}

2.13 WindowMangerService::openSession

public IWindowSession openSession(IWindowSessionCallback callback, IInputMethodClient client,
        IInputContext inputContext) {
    if (client == null) throw new IllegalArgumentException("null client");
    if (inputContext == null) throw new IllegalArgumentException("null inputContext");
    Session session = new Session(this, callback, client, inputContext);
    return session;
}

2.14 WMS::Session與ViewRootImpl關系

Session與ViewRootImpl關系

2.15 Session::addToDisplay

public int addToDisplay(IWindow window, int seq, WindowManager.LayoutParams attrs,
        int viewVisibility, int displayId, Rect outContentInsets, Rect outStableInsets,
        Rect outOutsets, InputChannel outInputChannel) {
    return mService.addWindow(this, window, seq, attrs, viewVisibility, displayId,
            outContentInsets, outStableInsets, outOutsets, outInputChannel);
}

2.16 WMS::addWindow

/**
 * All currently active sessions with clients.
 */
final ArraySet<Session> mSessions = new ArraySet<>();

/**
 * Mapping from an IWindow IBinder to the server's Window object.
 * This is also used as the lock for all of our state.
 * NOTE: Never call into methods that lock ActivityManagerService while holding this object.
 */
final HashMap<IBinder, WindowState> mWindowMap = new HashMap<>();

/**
 * Mapping from a token IBinder to a WindowToken object.
 */
final HashMap<IBinder, WindowToken> mTokenMap = new HashMap<>();

public int addWindow(Session session, IWindow client, int seq,
            WindowManager.LayoutParams attrs, int viewVisibility, int displayId,
            Rect outContentInsets, Rect outStableInsets, Rect outOutsets,
            InputChannel outInputChannel) {
        int res = mPolicy.checkAddPermission(attrs, appOp); // PhoneWindowManager進行權限檢查
        // 接下來依然是做一些檢查
        ...
        WindowState win = new WindowState(this, session, client, token,
                attachedWindow, appOp[0], seq, attrs, viewVisibility, displayContent);
        ...
        mPolicy.adjustWindowParamsLw(win.mAttrs);// 調(diào)整window參數(shù)
        ...
        res = mPolicy.prepareAddWindowLw(win, attrs);
        ...
        win.openInputChannel(outInputChannel); // 窗口端IMS管道


        win.attach(); // 2.17
        mWindowMap.put(client.asBinder(), win); // 保存到mWindowMap

        boolean imMayMove = true;

        if (type == TYPE_INPUT_METHOD) {
            addInputMethodWindowToListLocked(win);
        } else if (type == TYPE_INPUT_METHOD_DIALOG) {
            addWindowToListInOrderLocked(win, true);
        } else {
            addWindowToListInOrderLocked(win, true);
        }
        ...
        final WindowStateAnimator winAnimator = win.mWinAnimator;
        winAnimator.mEnterAnimationPending = true;
        winAnimator.mEnteringAnimation = true;
        ...
        boolean focusChanged = false;
        if (win.canReceiveKeys()) {
            focusChanged = updateFocusedWindowLocked(UPDATE_FOCUS_WILL_ASSIGN_LAYERS,
                    false /*updateInputWindows*/); // 更新焦點窗口
        }
        ...
        if (focusChanged) {
            mInputMonitor.setInputFocusLw(mCurrentFocus, false /*updateInputWindows*/);
        }
        mInputMonitor.updateInputWindowsLw(false /*force*/);
    }
}

mTokenMap： 保存所有的顯示令牌, 用于窗口管理;
mWindowMap：保存所有窗口的狀態(tài)信息（windowstate）, 用于窗口管理;
mSession：保存當前所有想向WMS尋求窗口管理服務的客戶端;

2.17 WindowState::attach

void attach() {
    mSession.windowAddedLocked(); // 2.18
}

2.18 WindowState::windowAddedLocked

void windowAddedLocked() {
    if (mSurfaceSession == null) {
        mSurfaceSession = new SurfaceSession(); // 在內(nèi)存中創(chuàng)建一塊空間圃庭，用于SurfaceFlinger
        mService.mSessions.add(this); //記錄當前Session
        if (mLastReportedAnimatorScale != mService.getCurrentAnimatorScale()) {
            mService.dispatchNewAnimatorScaleLocked(this);
        }
    }
    mNumWindow++;
}

3.1 ViewRootImpl::doDie

void doDie() {
    checkThread(); // 檢查主線程
    synchronized (this) {
        mRemoved = true; // 清楚標記
        if (mAdded) {
            dispatchDetachedFromWindow(); // 3.2 清理窗口的入口
        }

        if (mAdded && !mFirst) {
            Trace.traceBegin(Trace.TRACE_TAG_VIEW, "destroyHardwareRenderer");
            destroyHardwareRenderer();
            Trace.traceEnd(Trace.TRACE_TAG_VIEW);

            if (mView != null) {
                int viewVisibility = mView.getVisibility();
                boolean viewVisibilityChanged = mViewVisibility != viewVisibility;
                if (mWindowAttributesChanged || viewVisibilityChanged) {
                    // If layout params have been changed, first give them
                    // to the window manager to make sure it has the correct
                    // animation info.
                    try {
                        if ((relayoutWindow(mWindowAttributes, viewVisibility, false)
                                & WindowManagerGlobal.RELAYOUT_RES_FIRST_TIME) != 0) {
                            mWindowSession.finishDrawing(mWindow);
                        }
                    } catch (RemoteException e) {
                        Log.e(mTag, "RemoteException when finish draw window " + mWindow
                                + " in " + this, e);
                    }
                }

                mSurface.release();
            }
        }
        mAdded = false;
    }
    WindowManagerGlobal.getInstance().doRemoveView(this); //3.3 移除WindowManagerGlobal中的數(shù)據(jù)
}

3.2 ViewRootImpl::dispatchDetachedFromWindow

void dispatchDetachedFromWindow() {
    if (mView != null && mView.mAttachInfo != null) {
        mAttachInfo.mTreeObserver.dispatchOnWindowAttachedChange(false);
        mView.dispatchDetachedFromWindow(); // 
    }
    ...
    mView.assignParent(null);
    mView = null;
    mAttachInfo.mRootView = null;

    mSurface.release(); // surface釋放

    if (mInputQueueCallback != null && mInputQueue != null) {
        mInputQueueCallback.onInputQueueDestroyed(mInputQueue);
        mInputQueue.dispose(); // 事件隊列清理
        mInputQueueCallback = null;
        mInputQueue = null;
    }
    if (mInputEventReceiver != null) {
        mInputEventReceiver.dispose(); // 輸入事件清理
        mInputEventReceiver = null;
    }
    try {
        mWindowSession.remove(mWindow); // 通知wms移除window
    } catch (RemoteException e) {
        Log.e(mTag, "RemoteException remove window " + mWindow + " in " + this, e);
    }

    // Dispose the input channel after removing the window so the Window Manager
    // doesn't interpret the input channel being closed as an abnormal termination.
    if (mInputChannel != null) {
        mInputChannel.dispose(); // IMS管道清理
        mInputChannel = null;
    }

    mDisplayManager.unregisterDisplayListener(mDisplayListener);
    unscheduleTraversals();
}

3.3 ViewRootImpl::doRemoveView

void doRemoveView(ViewRootImpl root) {
    synchronized (mLock) {
        final int index = mRoots.indexOf(root);
        if (index >= 0) {
            mRoots.remove(index);
            mParams.remove(index);
            final View view = mViews.remove(index);
            mDyingViews.remove(view);
        }
    }
}