SystemUI与StatusBar - 安卓R

SystemUI包含状态栏、导航栏等，是一个系统级app。

SystemUI启动流程

在frameworks/base/services/java/com/android/server/SystemServer.java的startOtherServices方法中：

    /**
     * Starts a miscellaneous grab bag of stuff that has yet to be refactored and organized.
     */
    private void startOtherServices(@NonNull TimingsTraceAndSlog t) {
		......
		// We now tell the activity manager it is okay to run third party
        // code.  It will call back into us once it has gotten to the state
        // where third party code can really run (but before it has actually
        // started launching the initial applications), for us to complete our
        // initialization.
        mActivityManagerService.systemReady(() -> {
			......
			try {
                startSystemUi(context, windowManagerF);
            } catch (Throwable e) {
                reportWtf("starting System UI", e);
            }
			......
		}, t);
		......
	}

调用了startSystemUi方法：

    private static void startSystemUi(Context context, WindowManagerService windowManager) {
        PackageManagerInternal pm = LocalServices.getService(PackageManagerInternal.class);
        Intent intent = new Intent();
        intent.setComponent(pm.getSystemUiServiceComponent());
        intent.addFlags(Intent.FLAG_DEBUG_TRIAGED_MISSING);
        //Slog.d(TAG, "Starting service: " + intent);
        context.startServiceAsUser(intent, UserHandle.SYSTEM);
        windowManager.onSystemUiStarted();
    }

启动了frameworks/base/packages/SystemUI/src/com/android/systemui/SystemUIService.java，其onCreate方法：

    @Override
    public void onCreate() {
        super.onCreate();

        // Start all of SystemUI
        ((SystemUIApplication) getApplication()).startServicesIfNeeded();

        ......
    }

调用了frameworks/base/packages/SystemUI/src/com/android/systemui/SystemUIApplication.java的startServicesIfNeeded方法：

    /**
     * Makes sure that all the SystemUI services are running. If they are already running, this is a
     * no-op. This is needed to conditinally start all the services, as we only need to have it in
     * the main process.
     * <p>This method must only be called from the main thread.</p>
     */

    public void startServicesIfNeeded() {
        String[] names = SystemUIFactory.getInstance().getSystemUIServiceComponents(getResources());
        startServicesIfNeeded(/* metricsPrefix= */ "StartServices", names);
    }

    /**
     * Ensures that all the Secondary user SystemUI services are running. If they are already
     * running, this is a no-op. This is needed to conditionally start all the services, as we only
     * need to have it in the main process.
     * <p>This method must only be called from the main thread.</p>
     */
    void startSecondaryUserServicesIfNeeded() {
        String[] names = SystemUIFactory.getInstance().getSystemUIServiceComponentsPerUser(
                getResources());
        startServicesIfNeeded(/* metricsPrefix= */ "StartSecondaryServices", names);
    }

    private void startServicesIfNeeded(String metricsPrefix, String[] services) {
        if (mServicesStarted) {
            return;
        }
        mServices = new SystemUI[services.length];

        if (!mBootCompleteCache.isBootComplete()) {
            // check to see if maybe it was already completed long before we began
            // see ActivityManagerService.finishBooting()
            if ("1".equals(SystemProperties.get("sys.boot_completed"))) {
                mBootCompleteCache.setBootComplete();
                if (DEBUG) {
                    Log.v(TAG, "BOOT_COMPLETED was already sent");
                }
            }
        }

        final DumpManager dumpManager = mRootComponent.createDumpManager();

        Log.v(TAG, "Starting SystemUI services for user " +
                Process.myUserHandle().getIdentifier() + ".");
        TimingsTraceLog log = new TimingsTraceLog("SystemUIBootTiming",
                Trace.TRACE_TAG_APP);
        log.traceBegin(metricsPrefix);
        final int N = services.length;
        for (int i = 0; i < N; i++) {
            String clsName = services[i];
            if (DEBUG) Log.d(TAG, "loading: " + clsName);
            log.traceBegin(metricsPrefix + clsName);
            long ti = System.currentTimeMillis();
            try {
                SystemUI obj = mComponentHelper.resolveSystemUI(clsName);
                if (obj == null) {
                    Constructor constructor = Class.forName(clsName).getConstructor(Context.class);
                    obj = (SystemUI) constructor.newInstance(this);
                }
                mServices[i] = obj;
            } catch (ClassNotFoundException
                    | NoSuchMethodException
                    | IllegalAccessException
                    | InstantiationException
                    | InvocationTargetException ex) {
                throw new RuntimeException(ex);
            }

            if (DEBUG) Log.d(TAG, "running: " + mServices[i]);
            mServices[i].start();
            log.traceEnd();

            // Warn if initialization of component takes too long
            ti = System.currentTimeMillis() - ti;
            if (ti > 1000) {
                Log.w(TAG, "Initialization of " + clsName + " took " + ti + " ms");
            }
            if (mBootCompleteCache.isBootComplete()) {
                mServices[i].onBootCompleted();
            }

            dumpManager.registerDumpable(mServices[i].getClass().getName(), mServices[i]);
        }
        mRootComponent.getInitController().executePostInitTasks();
        log.traceEnd();

        mServicesStarted = true;
    }

mServices是类型为frameworks/base/packages/SystemUI/src/com/android/systemui/SystemUI.java的数组，在这里对每个SystemUI调用start初始化。

状态栏StatusBar

状态栏在frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/StatusBar.java中实现，其start方法：

    @Override
    public void start() {
        ......
		mBarService = IStatusBarService.Stub.asInterface(
                ServiceManager.getService(Context.STATUS_BAR_SERVICE));
		......
        // Connect in to the status bar manager service
        mCommandQueue.addCallback(this);

		RegisterStatusBarResult result = null;
        try {
            result = mBarService.registerStatusBar(mCommandQueue);  // 在StatusBarService里面注册CommandQueue
        } catch (RemoteException ex) {
            ex.rethrowFromSystemServer();
        }

        createAndAddWindows(result);  // 窗口的创建与显示

        ......

        // Set up the initial icon state
        int numIcons = result.mIcons.size();
        for (int i = 0; i < numIcons; i++) {
            mCommandQueue.setIcon(result.mIcons.keyAt(i), result.mIcons.valueAt(i));
        }
		
		......
    }

在frameworks/base/services/java/com/android/server/SystemServer.java的startOtherServices方法中：

    /**
     * Starts a miscellaneous grab bag of stuff that has yet to be refactored and organized.
     */
    private void startOtherServices(@NonNull TimingsTraceAndSlog t) {
		......
                try {
                    statusBar = new StatusBarManagerService(context);
                    ServiceManager.addService(Context.STATUS_BAR_SERVICE, statusBar);
                } catch (Throwable e) {
                    reportWtf("starting StatusBarManagerService", e);
                }
		......
	}

frameworks/base/services/core/java/com/android/server/statusbar/StatusBarManagerService.java的构造方法：

    /**
     * Construct the service
     */
    public StatusBarManagerService(Context context) {
        mContext = context;

        LocalServices.addService(StatusBarManagerInternal.class, mInternalService);
        LocalServices.addService(GlobalActionsProvider.class, mGlobalActionsProvider);

        // We always have a default display.
        final UiState state = new UiState();
        mDisplayUiState.put(DEFAULT_DISPLAY, state);

        final DisplayManager displayManager =
                (DisplayManager) context.getSystemService(Context.DISPLAY_SERVICE);
        displayManager.registerDisplayListener(this, mHandler);
    }

其registerStatusBar方法：

    // ================================================================================
    // Callbacks from the status bar service.
    // ================================================================================
    // TODO(b/118592525): refactor it as an IStatusBar API.
    @Override
    public RegisterStatusBarResult registerStatusBar(IStatusBar bar) {
        enforceStatusBarService();

        Slog.i(TAG, "registerStatusBar bar=" + bar);
        mBar = bar;
        mDeathRecipient.linkToDeath();
        notifyBarAttachChanged();
        final ArrayMap<String, StatusBarIcon> icons;
        synchronized (mIcons) {
            icons = new ArrayMap<>(mIcons);
        }
        synchronized (mLock) {
            // TODO(b/118592525): Currently, status bar only works on the default display.
            // Make it aware of multi-display if needed.
            final UiState state = mDisplayUiState.get(DEFAULT_DISPLAY);
            final int[] transientBarTypes = new int[state.mTransientBarTypes.size()];
            for (int i = 0; i < transientBarTypes.length; i++) {
                transientBarTypes[i] = state.mTransientBarTypes.valueAt(i);
            }
            return new RegisterStatusBarResult(icons, gatherDisableActionsLocked(mCurrentUserId, 1),
                    state.mAppearance, state.mAppearanceRegions, state.mImeWindowVis,
                    state.mImeBackDisposition, state.mShowImeSwitcher,
                    gatherDisableActionsLocked(mCurrentUserId, 2), state.mImeToken,
                    state.mNavbarColorManagedByIme, state.mFullscreen, state.mImmersive,
                    transientBarTypes);
        }
    }

类型为CommandQueue的bar赋值给了mBar，用来与StatusBar进行binder通信。

例如setIcon方法：

    @Override
    public void setIcon(String slot, String iconPackage, int iconId, int iconLevel,
            String contentDescription) {
        enforceStatusBar();

        synchronized (mIcons) {
            StatusBarIcon icon = new StatusBarIcon(iconPackage, UserHandle.SYSTEM, iconId,
                    iconLevel, 0, contentDescription);
            //Slog.d(TAG, "setIcon slot=" + slot + " index=" + index + " icon=" + icon);
            mIcons.put(slot, icon);

            if (mBar != null) {
                try {
                    mBar.setIcon(slot, icon);
                } catch (RemoteException ex) {
                }
            }
        }
    }

在mIcons里面保存一份副本，然后调用mBar的setIcon方法通过CommandQueue交给StatusBar去处理。

在StatusBar.start方法中还调用了createAndAddWindows方法：

    public void createAndAddWindows(@Nullable RegisterStatusBarResult result) {
        makeStatusBarView(result);
        mNotificationShadeWindowController.attach();
        mStatusBarWindowController.attach();
    }

其中mStatusBarWindowController是frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/StatusBarWindowController.java，其attach方法：

    /**
     * Adds the status bar view to the window manager.
     */
    public void attach() {
        // Now that the status bar window encompasses the sliding panel and its
        // translucent backdrop, the entire thing is made TRANSLUCENT and is
        // hardware-accelerated.
        mLp = new WindowManager.LayoutParams(
                ViewGroup.LayoutParams.MATCH_PARENT,
                mBarHeight,
                WindowManager.LayoutParams.TYPE_STATUS_BAR,
                WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
                        | WindowManager.LayoutParams.FLAG_SPLIT_TOUCH
                        | WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS,
                PixelFormat.TRANSLUCENT);
        mLp.privateFlags |= PRIVATE_FLAG_COLOR_SPACE_AGNOSTIC;
        mLp.token = new Binder();
        mLp.gravity = Gravity.TOP;
        mLp.setFitInsetsTypes(0 /* types */);
        mLp.setTitle("StatusBar");
        mLp.packageName = mContext.getPackageName();
        mLp.layoutInDisplayCutoutMode = LAYOUT_IN_DISPLAY_CUTOUT_MODE_ALWAYS;

        mWindowManager.addView(mStatusBarView, mLp);
        mLpChanged.copyFrom(mLp);
    }