Quick Settings行內人簡稱qs，是SystemUI必不可少的一部分。它主要負責開啟關閉各個系統的功能模組，如wifi、藍芽、手電筒等。

從圖中可以看出，每一個系統功能都對應這一個按鈕，而這個按鈕的學名就是Tile。

正文

單個Tile的載入流程

SystemUI是如何載入每個Tile的呢？在Statusbar初始化的時候，在makeStatusbarBarView()中對QsTile進行了初始化：

protected void makeStatusBarView() {
        ......

        // Set up the quick settings tile panel
        View container = mStatusBarWindow.findViewById(R.id.qs_frame);
        if (container != null) {
            FragmentHostManager fragmentHostManager = FragmentHostManager.get(container);
            ExtensionFragmentListener.attachExtensonToFragment(container, QS.TAG, R.id.qs_frame,
                    Dependency.get(ExtensionController.class)
                            .newExtension(QS.class)
                            .withPlugin(QS.class)
                            .withFeature(PackageManager.FEATURE_AUTOMOTIVE, CarQSFragment::new)
                            .withDefault(QSFragment::new)
                            .build());
            final QSTileHost qsh = SystemUIFactory.getInstance().createQSTileHost(mContext, this,
                    mIconController);
            mBrightnessMirrorController = new BrightnessMirrorController(mStatusBarWindow,
                    (visible) -> {
                        mBrightnessMirrorVisible = visible;
                        updateScrimController();
                    });
            fragmentHostManager.addTagListener(QS.TAG, (tag, f) -> {
                QS qs = (QS) f;
                if (qs instanceof QSFragment) {
                    ((QSFragment) qs).setHost(qsh);
                    mQSPanel = ((QSFragment) qs).getQsPanel();
                    mQSPanel.setBrightnessMirror(mBrightnessMirrorController);
                    mKeyguardStatusBar.setQSPanel(mQSPanel);
                }
            });
        }
        ......
    }
 

通過初始化QsTileHost，進行QsTile的載入。在QsTileHost初始化的時候，增加Tunable監聽：

public QSTileHost(Context context, StatusBar statusBar,
            StatusBarIconController iconController) {
        mIconController = iconController;
        mContext = context;
        mStatusBar = statusBar;

        mServices = new TileServices(this, Dependency.get(Dependency.BG_LOOPER));

        mQsFactories.add(new QSFactoryImpl(this));
        Dependency.get(PluginManager.class).addPluginListener(this, QSFactory.class, true);

        Dependency.get(TunerService.class).addTunable(this, TILES_SETTING);
        // AutoTileManager can modify mTiles so make sure mTiles has already been initialized.
        mAutoTiles = new AutoTileManager(context, this);
    }
 

這裡的TunerSerivce的作用是註冊對欄位"sysui_qs_tiles"的系統資料庫監聽：

private void addTunable(Tunable tunable, String key) {
        if (!mTunableLookup.containsKey(key)) {
            mTunableLookup.put(key, new ArraySet<Tunable>());
        }
        mTunableLookup.get(key).add(tunable);
        if (LeakDetector.ENABLED) {
            mTunables.add(tunable);
            Dependency.get(LeakDetector.class).trackCollection(mTunables, "TunerService.mTunables");
        }
        Uri uri = Settings.Secure.getUriFor(key);
        if (!mListeningUris.containsKey(uri)) {
            mListeningUris.put(uri, key);
            mContentResolver.registerContentObserver(uri, false, mObserver, mCurrentUser);
        }
        // Send the first state.
        String value = Settings.Secure.getStringForUser(mContentResolver, key, mCurrentUser);
        tunable.onTuningChanged(key, value);
    }
 

通過addTunable觸發QsTileHost中onTuningChanged：

@Override
    public void onTuningChanged(String key, String newValue) {
        if (!TILES_SETTING.equals(key)) {
            return;
        }
        if (DEBUG) Log.d(TAG, "Recreating tiles");
        if (newValue == null && UserManager.isDeviceInDemoMode(mContext)) {
            newValue = mContext.getResources().getString(R.string.quick_settings_tiles_retail_mode);
        }
        final List<String> tileSpecs = loadTileSpecs(mContext, newValue);
        int currentUser = ActivityManager.getCurrentUser();
        if (tileSpecs.equals(mTileSpecs) && currentUser == mCurrentUser) return;
        mTiles.entrySet().stream().filter(tile -> !tileSpecs.contains(tile.getKey())).forEach(
                tile -> {
                    if (DEBUG) Log.d(TAG, "Destroying tile: " + tile.getKey());
                    tile.getValue().destroy();
                });
        final LinkedHashMap<String, QSTile> newTiles = new LinkedHashMap<>();
        for (String tileSpec : tileSpecs) {
            QSTile tile = mTiles.get(tileSpec);
            if (tile != null && (!(tile instanceof CustomTile)
                    || ((CustomTile) tile).getUser() == currentUser)) {
                if (tile.isAvailable()) {
                    if (DEBUG) Log.d(TAG, "Adding " + tile);
                    tile.removeCallbacks();
                    if (!(tile instanceof CustomTile) && mCurrentUser != currentUser) {
                        tile.userSwitch(currentUser);
                    }
                    newTiles.put(tileSpec, tile);
                } else {
                    tile.destroy();
                }
            } else {
                if (DEBUG) Log.d(TAG, "Creating tile: " + tileSpec);
                try {
                    tile = createTile(tileSpec);
                    if (tile != null) {
                        if (tile.isAvailable()) {
                            tile.setTileSpec(tileSpec);
                            newTiles.put(tileSpec, tile);
                        } else {
                            tile.destroy();
                        }
                    }
                } catch (Throwable t) {
                    Log.w(TAG, "Error creating tile for spec: " + tileSpec, t);
                }
            }
        }
        mCurrentUser = currentUser;
        mTileSpecs.clear();
        mTileSpecs.addAll(tileSpecs);
        mTiles.clear();
        mTiles.putAll(newTiles);
        for (int i = 0; i < mCallbacks.size(); i++) {
            mCallbacks.get(i).onTilesChanged();
        }
    }

以上步驟進行了讀取配置，並creatTile的操作。通過loadTileSpecs()獲取到需要createTile的list：

protected List<String> loadTileSpecs(Context context, String tileList) {
        final Resources res = context.getResources();
        String defaultTileList = res.getString(R.string.quick_settings_tiles_default);
        if (tileList == null) {
            tileList = res.getString(R.string.quick_settings_tiles);
            if (DEBUG) Log.d(TAG, "Loaded tile specs from config: " + tileList);
        } else {
            if (DEBUG) Log.d(TAG, "Loaded tile specs from setting: " + tileList);
        }
        final ArrayList<String> tiles = new ArrayList<String>();
        boolean addedDefault = false;
        for (String tile : tileList.split(",")) {
            tile = tile.trim();
            if (tile.isEmpty()) continue;
            if (tile.equals("default")) {
                if (!addedDefault) {
                    tiles.addAll(Arrays.asList(defaultTileList.split(",")));
                    addedDefault = true;
                }
            } else {
                tiles.add(tile);
            }
        }
        return tiles;
    }

通過"quick_settings_tiles_default"進入預設tile的配置，這裡的tile list不包括可編輯的。獲取到list之後，通過creatTile()進行建立：

public QSTile createTile(String tileSpec) {
        for (int i = 0; i < mQsFactories.size(); i++) {
            QSTile t = mQsFactories.get(i).createTile(tileSpec);
            if (t != null) {
                return t;
            }
        }
        return null;
    }

這裡通過迴圈，在QsFactoryImpl中進行tile的建立：

public QSTile createTile(String tileSpec) {
        QSTileImpl tile = createTileInternal(tileSpec);
        if (tile != null) {
            tile.handleStale(); // Tile was just created, must be stale.
        }
        return tile;
    }

private QSTileImpl createTileInternal(String tileSpec) {
        switch (tileSpec) {
            case "wifi":
                return new WifiTile(mHost);
            case "bt":
                return new BluetoothTile(mHost);
            case "cell":
                return new CellularTile(mHost);
            case "dnd":
                return new DndTile(mHost);
            case "inversion":
                return new ColorInversionTile(mHost);
            case "airplane":
                return new AirplaneModeTile(mHost);
            case "work":
                return new WorkModeTile(mHost);
            case "rotation":
                return new RotationLockTile(mHost);
            case "flashlight":
                return new FlashlightTile(mHost);
            case "location":
                return new LocationTile(mHost);
            case "cast":
                return new CastTile(mHost);
            case "hotspot":
                return new HotspotTile(mHost);
            case "user":
                return new UserTile(mHost);
            case "battery":
                return new BatterySaverTile(mHost);
            case "saver":
                return new DataSaverTile(mHost);
            case "night":
                return new NightDisplayTile(mHost);
            case "nfc":
                return new NfcTile(mHost);
        }

        // Intent tiles.
        if (tileSpec.startsWith(IntentTile.PREFIX)) return IntentTile.create(mHost, tileSpec);
        if (tileSpec.startsWith(CustomTile.PREFIX)) return CustomTile.create(mHost, tileSpec);

        // Debug tiles.
        if (Build.IS_DEBUGGABLE) {
            if (tileSpec.equals(GarbageMonitor.MemoryTile.TILE_SPEC)) {
                return new GarbageMonitor.MemoryTile(mHost);
            }
        }

        // Broken tiles.
        Log.w(TAG, "Bad tile spec: " + tileSpec);
        return null;
    }

根據tileSpec進行對應tile的初始化。

編輯區Tile載入流程

當用戶點選qs區域的編輯按鈕時，可以看到一個這樣的介面：

從圖中可以看出，進入qs編輯模式之後，會出現更多tile，並且可以拖動到上方供使用者平時下拉後直接使用，或者將不常用的放到待選區域。這裡從UI上可以看出待選區域由兩部分組成，一部分是SystemUI內部的Tile，而類似google Nearby這種Tile則是第三應用自己註冊的Tile。接下來，就分析一下這些Tile是如何載入的？
當進入編輯模式之後，QsCustomer會對tile有一個query操作，由TileQueryHelper實現：

public void queryTiles(QSTileHost host) {
        mTiles.clear();
        mSpecs.clear();
        mFinished = false;
        // Enqueue jobs to fetch every system tile and then ever package tile.
        addStockTiles(host);
        addPackageTiles(host);
    }

從程式碼中也可以看出，載入Tile分成了StockTiles和PackageTiles，分別代表SystemUI內建Tile和第三註冊Tile，先來看下內建Tile：

private void addStockTiles(QSTileHost host) {
        String possible = mContext.getString(R.string.quick_settings_tiles_stock);
        final ArrayList<String> possibleTiles = new ArrayList<>();
        possibleTiles.addAll(Arrays.asList(possible.split(",")));
        if (Build.IS_DEBUGGABLE) {
            possibleTiles.add(GarbageMonitor.MemoryTile.TILE_SPEC);
        }
        final ArrayList<QSTile> tilesToAdd = new ArrayList<>();
        for (String spec : possibleTiles) {
            final QSTile tile = host.createTile(spec);
            if (tile == null) {
                continue;
            } else if (!tile.isAvailable()) {
                tile.destroy();
                continue;
            }
            tile.setListening(this, true);
            tile.clearState();
            tile.refreshState();
            tile.setListening(this, false);
            tile.setTileSpec(spec);
            tilesToAdd.add(tile);
        }

        mBgHandler.post(() -> {
            for (QSTile tile : tilesToAdd) {
                final QSTile.State state = tile.getState().copy();
                // Ignore the current state and get the generic label instead.
                state.label = tile.getTileLabel();
                tile.destroy();
                addTile(tile.getTileSpec(), null, state, true);
            }
            notifyTilesChanged(false);
        });
    }

"quick_settings_tiles_stock"對應的就是SystemUI中可載入的所有Tile，如果希望客製化也可以在此處進行修改。接下來，再看一下如何載入第三方Tile（如Nearby）：

private void addPackageTiles(final QSTileHost host) {
        mBgHandler.post(() -> {
            Collection<QSTile> params = host.getTiles();
            PackageManager pm = mContext.getPackageManager();
            List<ResolveInfo> services = pm.queryIntentServicesAsUser(
                    new Intent(TileService.ACTION_QS_TILE), 0, ActivityManager.getCurrentUser());
            String stockTiles = mContext.getString(R.string.quick_settings_tiles_stock);

            for (ResolveInfo info : services) {
                String packageName = info.serviceInfo.packageName;
                ComponentName componentName = new ComponentName(packageName, info.serviceInfo.name);

                // Don't include apps that are a part of the default tile set.
                if (stockTiles.contains(componentName.flattenToString())) {
                    continue;
                }

                final CharSequence appLabel = info.serviceInfo.applicationInfo.loadLabel(pm);
                String spec = CustomTile.toSpec(componentName);
                State state = getState(params, spec);
                if (state != null) {
                    addTile(spec, appLabel, state, false);
                    continue;
                }
                if (info.serviceInfo.icon == 0 && info.serviceInfo.applicationInfo.icon == 0) {
                    continue;
                }
                Drawable icon = info.serviceInfo.loadIcon(pm);
                if (!permission.BIND_QUICK_SETTINGS_TILE.equals(info.serviceInfo.permission)) {
                    continue;
                }
                if (icon == null) {
                    continue;
                }
                icon.mutate();
                icon.setTint(mContext.getColor(android.R.color.white));
                CharSequence label = info.serviceInfo.loadLabel(pm);
                addTile(spec, icon, label != null ? label.toString() : "null", appLabel);
            }

            notifyTilesChanged(true);
        });
    }

從程式碼中不難看出，通過PackageManager來query帶有“TileService.ACTION_QS_TILE”的Intent的應用，獲取到它們的resolveinfo獲取第三方註冊的Tile的資訊，如Tile的名稱、icon、應用名稱等。

到這裡，Qs Tile載入的資料流程已經講完，後面有時間再講一下UI的載入流程。如有什麼問題歡迎指