Android 14 平板Taskbar加载流程解析
2024-02-12 / 龙之叶   

前言

从 Android 12开始，如果是大屏底下导航栏会变成显示一个任务栏，从 NavigationBar 变成 Taskbar 。

注：CentralSurfacesImpl.java 与 原来的 statusbar.java 的作用一样。

CentralSurfacesImpl 的启动流程前面有说过，这里不在说明。

frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/CentralSurfacesImpl.java

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public class CentralSurfacesImpl extends CoreStartable implements
        CentralSurfaces {

     //省略其他代码....
    protected void makeStatusBarView(@Nullable RegisterStatusBarResult result) {
        //省略其他代码....
        createNavigationBar(result);
       //省略其他代码....
  
    }

    protected void createNavigationBar(@Nullable RegisterStatusBarResult result) {
        // 调用 NavigationBarController 的 createNavigationBars()方法创建 NavigationBar
        mNavigationBarController.createNavigationBars(true /* includeDefaultDisplay */, result);
    }

}

接着往下看：
NavigationBarController#createNavigationBars()
frameworks/base/packages/SystemUI/src/com/android/systemui/navigationbar/NavigationBarController.java

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public void createNavigationBars(final boolean includeDefaultDisplay,
        RegisterStatusBarResult result) {
    // 如果需要，更新辅助功能按钮模式
    updateAccessibilityButtonModeIfNeeded();
    // 这里是重点，Android 12 之前版本的，没有这个判断。可以看下 initializeTaskbarIfNecessary() 方法。
    // 如果我们初始化TaskBar，则不需要在默认显示上创建导航栏
    final boolean shouldCreateDefaultNavbar = includeDefaultDisplay
            && !initializeTaskbarIfNecessary();
    Display[] displays = mDisplayManager.getDisplays();
    for (Display display : displays) {
        if (shouldCreateDefaultNavbar || display.getDisplayId() != DEFAULT_DISPLAY) {
            createNavigationBar(display, null /* savedState */, result);
        }
    }
}

/** @return {@code true} if taskbar is enabled, false otherwise */
private boolean initializeTaskbarIfNecessary() {
    // 这里会判断是否是平板。
    // 跟踪代码发现，如果屏幕的（最小边长度*160/dpi值）< 600，就会判断为设备是平板设备
    // system/vendor/mediatek/proprietary/packages/apps/SystemUI/shared/src/com/android/systemui/shared/recents/utilities/Utilities.java
    // Enable for large screens or (phone AND flag is set); assuming phone = !mIsLargeScreen
    boolean taskbarEnabled = (mIsLargeScreen || mFeatureFlags.isEnabled(
            Flags.HIDE_NAVBAR_WINDOW)) && shouldCreateNavBarAndTaskBar(mContext.getDisplayId());

    if (taskbarEnabled) {
        Trace.beginSection("NavigationBarController#initializeTaskbarIfNecessary");
        final int displayId = mContext.getDisplayId();
        // Hint to NavBarHelper if we are replacing an existing bar to skip extra work
        mNavBarHelper.setTogglingNavbarTaskbar(mNavigationBars.contains(displayId));
        // Remove navigation bar when taskbar is showing
        // 移除导航栏
        removeNavigationBar(displayId);
        // 加载任务栏
        mTaskbarDelegate.init(displayId);
        mNavBarHelper.setTogglingNavbarTaskbar(false);
        Trace.endSection();

    } else {
        mTaskbarDelegate.destroy();
    }
    return taskbarEnabled;
}

我们分析平板，所以这里直接看 mTaskbarDelegate.init(mContext.getDisplayId()) 方法；
TaskbarDelegate#init()
frameworks/base/packages/SystemUI/src/com/android/systemui/navigationbar/TaskbarDelegate.java

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public void init(int displayId) {
    if (mInitialized) {
        return;
    }
    //省略其他代码....
    // 注册监听，切换导航模式时接收回调。
    mEdgeBackGestureHandler.onNavigationModeChanged(
            mNavigationModeController.addListener(this));
    // 边缘手势处理，注意：这里只加载、处理手势。
    // 手势中左右两返回图标由这里加载，底部黑色小横条不在这里加载。
    mEdgeBackGestureHandler.onNavBarAttached();
    //省略其他代码....
}

// 导航模式改变回调，进行处理
@Override
public void onNavigationModeChanged(int mode) {
    mNavigationMode = mode;
    mEdgeBackGestureHandler.onNavigationModeChanged(mode);
}

1. 手势加载

EdgeBackGestureHandler#onNavBarAttached()
frameworks/base/packages/SystemUI/src/com/android/systemui/navigationbar/gestural/EdgeBackGestureHandler.java

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/**
 * @see NavigationBarView#onAttachedToWindow()
 */
public void onNavBarAttached() {
    mIsAttached = true;
    mProtoTracer.add(this);
    mOverviewProxyService.addCallback(mQuickSwitchListener);
    mSysUiState.addCallback(mSysUiStateCallback);
    // 重点关注这里，更新视图
    updateIsEnabled();
    startTracking();
}

private void updateIsEnabled() {
    // mIsAttached 是否已经添加上了，mIsGesturalModeEnabled 是否启用手势模式
    boolean isEnabled = mIsAttached && mIsGesturalModeEnabled;
    if (isEnabled == mIsEnabled) {
        return;
    }
    mIsEnabled = isEnabled;
    // 如果无效的话结束监听 Input
    disposeInputChannel();
    if (mEdgeBackPlugin != null) {
        // 边缘导航栏销毁
        mEdgeBackPlugin.onDestroy();
        mEdgeBackPlugin = null;
    }
    // 是否启用手势模式
    if (!mIsEnabled) {
            // 注销监听返回手势参数的设置变化
        mGestureNavigationSettingsObserver.unregister();
        if (DEBUG_MISSING_GESTURE) {
            Log.d(DEBUG_MISSING_GESTURE_TAG, "Unregister display listener");
        }
        mPluginManager.removePluginListener(this);
        TaskStackChangeListeners.getInstance().unregisterTaskStackListener(mTaskStackListener);
        DeviceConfig.removeOnPropertiesChangedListener(mOnPropertiesChangedListener);
        try {
                // 注销 WMS 里保存的除外区域监听
            mWindowManagerService.unregisterSystemGestureExclusionListener(
                    mGestureExclusionListener, mDisplayId);
        } catch (RemoteException | IllegalArgumentException e) {
            Log.e(TAG, "Failed to unregister window manager callbacks", e);
        }
    } else {
        // 监听返回手势参数的设置变化
        mGestureNavigationSettingsObserver.register();
        updateDisplaySize();
        if (DEBUG_MISSING_GESTURE) {
            Log.d(DEBUG_MISSING_GESTURE_TAG, "Register display listener");
        }
        TaskStackChangeListeners.getInstance().registerTaskStackListener(mTaskStackListener);
        DeviceConfig.addOnPropertiesChangedListener(DeviceConfig.NAMESPACE_SYSTEMUI,
                mMainExecutor::execute, mOnPropertiesChangedListener);
        try {
            // 监听 WMS 里保存的除外区域
            mWindowManagerService.registerSystemGestureExclusionListener(
                    mGestureExclusionListener, mDisplayId);
        } catch (RemoteException | IllegalArgumentException e) {
            Log.e(TAG, "Failed to register window manager callbacks", e);
        }
        //  注册名为 edge-swipe 的InputMonitor
        mInputMonitor = InputManager.getInstance().monitorGestureInput(
                "edge-swipe", mDisplayId);
        mInputEventReceiver = new InputChannelCompat.InputEventReceiver(
                mInputMonitor.getInputChannel(), Looper.getMainLooper(),
                Choreographer.getInstance(), this::onInputEvent);
        // 添加 NavigationBarEdgePanel 为 Edge Back 事件的处理实现
        setEdgeBackPlugin(
                new NavigationBarEdgePanel(mContext, mBackAnimation, mLatencyTracker));
        mPluginManager.addPluginListener(
                this, NavigationEdgeBackPlugin.class, /*allowMultiple=*/ false);
    }
    // 更新 ML 模型资源.
    updateMLModelState();
}

// 创建返回手势视图
private void setEdgeBackPlugin(NavigationEdgeBackPlugin edgeBackPlugin) {
    try {
        Trace.beginSection("setEdgeBackPlugin");
        // 缓存 NavigationEdgeBackPlugin 实现
        mEdgeBackPlugin = edgeBackPlugin;
        // 向 NavigationEdgeBackPlugin 注册 Back 手势的触发回调
        mEdgeBackPlugin.setBackCallback(mBackCallback);
        // 准备好手势视图的 Window 参数
        mEdgeBackPlugin.setLayoutParams(createLayoutParams());
        updateDisplaySize();
    } finally {
        Trace.endSection();
    }
}

// 配置返回手势 Window 的参数
// 包括 flag、type、title 等属性
private WindowManager.LayoutParams createLayoutParams() {
    Resources resources = mContext.getResources();
    WindowManager.LayoutParams layoutParams = new WindowManager.LayoutParams(
            resources.getDimensionPixelSize(R.dimen.navigation_edge_panel_width),
            resources.getDimensionPixelSize(R.dimen.navigation_edge_panel_height),
            WindowManager.LayoutParams.TYPE_NAVIGATION_BAR_PANEL,
            WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
                    | WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE
                    | WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN,
            PixelFormat.TRANSLUCENT);
    ...
    layoutParams.setTitle(TAG + mContext.getDisplayId());
    layoutParams.setFitInsetsTypes(0 /* types */);
    layoutParams.setTrustedOverlay();
    return layoutParams;
}

到此手势导航创建完成。

注意：此时 View 还是不可见的，后续事件产生的时候会进行展示和刷新

下面粗略的看下手势相关的事件：
frameworks/base/packages/SystemUI/src/com/android/systemui/navigationbar/gestural/EdgeBackGestureHandler.java

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private void onMotionEvent(MotionEvent ev) {
    int action = ev.getActionMasked();
    if (action == MotionEvent.ACTION_DOWN) {
        mInputEventReceiver.setBatchingEnabled(false);
        mIsOnLeftEdge = ev.getX() <= mEdgeWidthLeft + mLeftInset;
        mMLResults = 0;
        mLogGesture = false;
        mInRejectedExclusion = false;
        boolean isWithinInsets = isWithinInsets((int) ev.getX(), (int) ev.getY());
        // 根据返回手势是否有效、
        // 点击区域是否是停用区域等条件
        // 得到当前是否允许视图处理该手势
        mAllowGesture = !mDisabledForQuickstep && mIsBackGestureAllowed && isWithinInsets
                && !mGestureBlockingActivityRunning
                && !QuickStepContract.isBackGestureDisabled(mSysUiFlags)
                && isWithinTouchRegion((int) ev.getX(), (int) ev.getY());
        if (mAllowGesture) {
            // 更新当前是屏幕左侧还是右侧
            mEdgeBackPlugin.setIsLeftPanel(mIsOnLeftEdge);
            // 发射事件给视图
            mEdgeBackPlugin.onMotionEvent(ev);
        }
    } else if (mAllowGesture || mLogGesture) {
        if (!mThresholdCrossed) {
            mEndPoint.x = (int) ev.getX();
            mEndPoint.y = (int) ev.getY();
            // 多个手指按下的话取消事件处理
            if (action == MotionEvent.ACTION_POINTER_DOWN) {
                if (mAllowGesture) {
                    logGesture(SysUiStatsLog.BACK_GESTURE__TYPE__INCOMPLETE_MULTI_TOUCH);
                    cancelGesture(ev);
                }
                mLogGesture = false;
                return;
            } else if (action == MotionEvent.ACTION_MOVE) {
                // 手指移动超过长按阈值的话
                // 也要取消事件处理
                if ((ev.getEventTime() - ev.getDownTime()) > mLongPressTimeout) {
                    if (mAllowGesture) {
                        logGesture(SysUiStatsLog.BACK_GESTURE__TYPE__INCOMPLETE_LONG_PRESS);
                        cancelGesture(ev);
                    }
                    mLogGesture = false;
                    return;
                }
                ...
            }
        }
        // 通过上述检查的话
        // 将 MOVE、UP 交给视图
        if (mAllowGesture) {
            // forward touch
            mEdgeBackPlugin.onMotionEvent(ev);
        }
    }
    mProtoTracer.scheduleFrameUpdate();
}

事件间传递到 NavigationBarEdgePanel ，进行展示返回手势和触发返回。
NavigationBarEdgePanel 继续进行后面的工作：手势的判断、视图的刷新、动画的展示。
onMotionEvent() 的逻辑：

  • DOWN 的时候先让视图变为可见 VISIBLE
  • MOVE 的处理通过 handleMoveEvent() 判断距离，决定是否要更新赋予 mTriggerBack
  • UP 的时候将检查该变量决定是否触发返回动作即 triggerBack()

frameworks/base/packages/SystemUI/src/com/android/systemui/navigationbar/gestural/NavigationBarEdgePanel.java

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public void onMotionEvent(MotionEvent event) {
    if (mVelocityTracker == null) {
        mVelocityTracker = VelocityTracker.obtain();
    }
    mVelocityTracker.addMovement(event);
    switch (event.getActionMasked()) {
        case MotionEvent.ACTION_DOWN:
            mDragSlopPassed = false;
            resetOnDown();
            mStartX = event.getX();
            mStartY = event.getY();
            setVisibility(VISIBLE);
            updatePosition(event.getY());
            mRegionSamplingHelper.start(mSamplingRect);
            mWindowManager.updateViewLayout(this, mLayoutParams);
            break;
        case MotionEvent.ACTION_MOVE:
            handleMoveEvent(event);
            break;
        case MotionEvent.ACTION_UP:
            if (mTriggerBack) {
                triggerBack();
            } else {
                cancelBack();
            }
            ...
    }
}

手势相关的事件流程到此打住了。

2. 按钮导航

按钮导航是在 TouchInteractionService.java 中的 onCreate() 方法开始的。
packages/apps/Launcher3/quickstep/src/com/android/quickstep/TouchInteractionService.java

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@Override
public void onCreate() {
    super.onCreate();
    //省略其他代码....
    
    mTaskbarManager = new TaskbarManager(this);
    //省略其他代码....
}

用户配置完成后，根据配置，是否加载按钮导航。如果加载则会调用 TaskbarManager.java 中的 recreateTaskbar() 方法。
TaskbarManager#recreateTaskbar()
packages/apps/Launcher3/quickstep/src/com/android/launcher3/taskbar/TaskbarManager.java

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private void recreateTaskbar() {
    // 销毁现有任务栏
    destroyExistingTaskbar();
    // 获取设备配置文件的
    DeviceProfile dp =
            mUserUnlocked ? LauncherAppState.getIDP(mContext).getDeviceProfile(mContext) : null;
    // 任务栏是否启用
    boolean isTaskBarEnabled = dp != null && dp.isTaskbarPresent;
    if(dp != null){
        Log.d("longzhiye","longzhiye"+(dp != null)+"----"+(dp.isTaskbarPresent));
    }
    if (!isTaskBarEnabled) {
        SystemUiProxy.INSTANCE.get(mContext)
                .notifyTaskbarStatus(/* visible */ false, /* stashed */ false);
        return;
    }
    // TaskbarActivityContext 按钮导航的视图在里面加载，包括那个底部横线也在里面。
    mTaskbarActivityContext = new TaskbarActivityContext(mContext, dp, mNavButtonController,
            mUnfoldProgressProvider);
    // 初始化
    mTaskbarActivityContext.init(mSharedState);
    if (mActivity != null) {
        // 设置相关控制器
        mTaskbarActivityContext.setUIController(
                createTaskbarUIControllerForActivity(mActivity));
    }
}

在 TaskbarManager 类中有个 mDispInfoChangeListener 的监听，当导航模式切换时，会在 DisplayController 类中 去回调这里来。
接着往下看TaskbarActivityContext的构造方法：

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public TaskbarActivityContext(Context windowContext, DeviceProfile dp,
        TaskbarNavButtonController buttonController, ScopedUnfoldTransitionProgressProvider
        unfoldTransitionProgressProvider) {
    super(windowContext);
    mDeviceProfile = dp.copy(this);
    final Resources resources = getResources();
    mNavMode = DisplayController.getNavigationMode(windowContext);
    mImeDrawsImeNavBar = getBoolByName(IME_DRAWS_IME_NAV_BAR_RES_NAME, resources, false);
    mIsSafeModeEnabled = TraceHelper.allowIpcs("isSafeMode",
            () -> getPackageManager().isSafeMode());
    mIsUserSetupComplete = SettingsCache.INSTANCE.get(this).getValue(
            Settings.Secure.getUriFor(Settings.Secure.USER_SETUP_COMPLETE), 0);
    mIsNavBarForceVisible = SettingsCache.INSTANCE.get(this).getValue(
            Settings.Secure.getUriFor(Settings.Secure.NAV_BAR_KIDS_MODE), 0);
    mIsNavBarKidsMode = SettingsCache.INSTANCE.get(this).getValue(
            Settings.Secure.getUriFor(Settings.Secure.NAV_BAR_KIDS_MODE), 0);
    updateIconSize(resources);
    // 首先获取显示和焦点，因为视图可能会在构造函数中使用它们。
    Display display = windowContext.getDisplay();
    Context c = display.getDisplayId() == Display.DEFAULT_DISPLAY
            ? windowContext.getApplicationContext()
            : windowContext.getApplicationContext().createDisplayContext(display);
    mWindowManager = c.getSystemService(WindowManager.class);
    mLeftCorner = display.getRoundedCorner(RoundedCorner.POSITION_BOTTOM_LEFT);
    mRightCorner = display.getRoundedCorner(RoundedCorner.POSITION_BOTTOM_RIGHT);
    // 初始化 views.
    mDragLayer = (TaskbarDragLayer) mLayoutInflater.inflate(
            R.layout.taskbar, null, false);
    TaskbarView taskbarView = mDragLayer.findViewById(R.id.taskbar_view);
    TaskbarScrimView taskbarScrimView = mDragLayer.findViewById(R.id.taskbar_scrim);
    FrameLayout navButtonsView = mDragLayer.findViewById(R.id.navbuttons_view);
    StashedHandleView stashedHandleView = mDragLayer.findViewById(R.id.stashed_handle);
    mAccessibilityDelegate = new TaskbarShortcutMenuAccessibilityDelegate(this);
    // 构造控制器 controllers，将会在对应的控制添加对应的图标，以控制逻辑
    mControllers = new TaskbarControllers(this,
            new TaskbarDragController(this),
            buttonController,
            getPackageManager().hasSystemFeature(FEATURE_PC)
                    ? new DesktopNavbarButtonsViewController(this, navButtonsView) :     
                    new NavbarButtonsViewController(this, navButtonsView),
            new RotationButtonController(this,
                    c.getColor(R.color.taskbar_nav_icon_light_color),
                    c.getColor(R.color.taskbar_nav_icon_dark_color),
                    R.drawable.ic_sysbar_rotate_button_ccw_start_0,
                    R.drawable.ic_sysbar_rotate_button_ccw_start_90,
                    R.drawable.ic_sysbar_rotate_button_cw_start_0,
                    R.drawable.ic_sysbar_rotate_button_cw_start_90,
                    () -> getDisplay().getRotation()),
            new TaskbarDragLayerController(this, mDragLayer),
            new TaskbarViewController(this, taskbarView),
            new TaskbarScrimViewController(this, taskbarScrimView),
            new TaskbarUnfoldAnimationController(this, unfoldTransitionProgressProvider,
                    mWindowManager, WindowManagerGlobal.getWindowManagerService()),
            new TaskbarKeyguardController(this),
            new StashedHandleViewController(this, stashedHandleView),
            new TaskbarStashController(this),
            new TaskbarEduController(this),
            new TaskbarAutohideSuspendController(this),
            new TaskbarPopupController(this),
            new TaskbarForceVisibleImmersiveController(this),
            new TaskbarAllAppsController(this, dp),
            new TaskbarInsetsController(this));
}
public void init(@NonNull TaskbarSharedState sharedState) {
    mLastRequestedNonFullscreenHeight = getDefaultTaskbarWindowHeight();
    mWindowLayoutParams = createDefaultWindowLayoutParams();
    //  在 TaskbarControllers控制器里，初始化前面构造方法中添加的各种控制器。
    mControllers.init(sharedState);
    updateSysuiStateFlags(sharedState.sysuiStateFlags, true /* fromInit */);
    // 生成 LayoutParams 用于将视图作为新窗口直接添加到 WindowManager
    mWindowManager.addView(mDragLayer, mWindowLayoutParams);
}

这里以 NavbarButtonsViewController 为例子分析：
packages/apps/Launcher3/quickstep/src/com/android/launcher3/taskbar/NavbarButtonsViewController.java

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/**
 * Initializes the controller
 */
public void init(TaskbarControllers controllers) {
        // 省略部分代码......
    // 强制导航按钮（特别是后退按钮）在设置向导期间可见。
    boolean isInSetup = !mContext.isUserSetupComplete();
    boolean isInKidsMode = mContext.isNavBarKidsModeActive();
    boolean alwaysShowButtons = isThreeButtonNav || isInSetup;
    // 省略部分代码......
        
    if (alwaysShowButtons) {
        // 初始化按钮
        initButtons(mNavButtonContainer, mEndContextualContainer,
                mControllers.navButtonController);
    } else {
        
    }
    // 省略部分代码......
    mSeparateWindowParent.recreateControllers();
}
private void initButtons(ViewGroup navContainer, ViewGroup endContainer,
        TaskbarNavButtonController navButtonController) {
    // back Button
    mBackButton = addButton(R.drawable.ic_sysbar_back, BUTTON_BACK,
            mNavButtonContainer, mControllers.navButtonController, R.id.back);
    mBackButtonAlpha = new MultiValueAlpha(mBackButton, NUM_ALPHA_CHANNELS);
    mBackButtonAlpha.setUpdateVisibility(true);
    mPropertyHolders.add(new StatePropertyHolder(
            mBackButtonAlpha.getProperty(ALPHA_INDEX_KEYGUARD_OR_DISABLE),
            flags -> {
                // Show only if not disabled, and if not on the keyguard or otherwise only when
                // the bouncer or a lockscreen app is showing above the keyguard
                boolean showingOnKeyguard = (flags & FLAG_KEYGUARD_VISIBLE) == 0 ||
                        (flags & FLAG_ONLY_BACK_FOR_BOUNCER_VISIBLE) != 0 ||
                        (flags & FLAG_KEYGUARD_OCCLUDED) != 0;
                return (flags & FLAG_DISABLE_BACK) == 0
                        && ((flags & FLAG_KEYGUARD_VISIBLE) == 0 || showingOnKeyguard);
            }));
    boolean isRtl = Utilities.isRtl(mContext.getResources());
    mPropertyHolders.add(new StatePropertyHolder(mBackButton,
            flags -> (flags & FLAG_IME_VISIBLE) != 0 && !mContext.isNavBarKidsModeActive(),
            View.ROTATION, isRtl ? 90 : -90, 0));
    // Translate back button to be at end/start of other buttons for keyguard
    int navButtonSize = mContext.getResources().getDimensionPixelSize(
            R.dimen.taskbar_nav_buttons_size);
    mPropertyHolders.add(new StatePropertyHolder(
            mBackButton, flags -> (flags & FLAG_ONLY_BACK_FOR_BOUNCER_VISIBLE) != 0
                    || (flags & FLAG_KEYGUARD_VISIBLE) != 0,
            VIEW_TRANSLATE_X, navButtonSize * (isRtl ? -2 : 2), 0));
    // home button
    mHomeButton = addButton(R.drawable.ic_sysbar_home, BUTTON_HOME, navContainer,
            navButtonController, R.id.home);
    mHomeButtonAlpha = new MultiValueAlpha(mHomeButton, NUM_ALPHA_CHANNELS);
    mHomeButtonAlpha.setUpdateVisibility(true);
    mPropertyHolders.add(
            new StatePropertyHolder(mHomeButtonAlpha.getProperty(
                    ALPHA_INDEX_KEYGUARD_OR_DISABLE),
            flags -> (flags & FLAG_KEYGUARD_VISIBLE) == 0 &&
                    (flags & FLAG_DISABLE_HOME) == 0));
    // Recents button
    View recentsButton = addButton(R.drawable.ic_sysbar_recent, BUTTON_RECENTS,
            navContainer, navButtonController, R.id.recent_apps);
    mHitboxExtender.init(recentsButton, mNavButtonsView, mContext.getDeviceProfile(),
            () -> {
                float[] recentsCoords = new float[2];
                getDescendantCoordRelativeToAncestor(recentsButton, mNavButtonsView,
                        recentsCoords, false);
                return recentsCoords;
            }, new Handler());
    recentsButton.setOnClickListener(v -> {
        navButtonController.onButtonClick(BUTTON_RECENTS);
        mHitboxExtender.onRecentsButtonClicked();
    });
    mPropertyHolders.add(new StatePropertyHolder(recentsButton,
            flags -> (flags & FLAG_KEYGUARD_VISIBLE) == 0 && (flags & FLAG_DISABLE_RECENTS) == 0
                    && !mContext.isNavBarKidsModeActive()));
    // A11y button
    mA11yButton =  (R.drawable.ic_sysbar_accessibility_button, BUTTON_A11Y,
            endContainer, navButtonController, R.id.accessibility_button,
            R.layout.taskbar_contextual_button);
    mPropertyHolders.add(new StatePropertyHolder(mA11yButton,
            flags -> (flags & FLAG_A11Y_VISIBLE) != 0
                    && (flags & FLAG_ROTATION_BUTTON_VISIBLE) == 0));
}

事件的在 addButton() 的时候直接设置了，而且有特殊需求的，会单独设置。

本文链接：
http://longzhiye.top/2024/02/12/2024-02-12/