Android 8.1 中Systemui中的常见修改（六）NavigationBar加载流程

本文主要分为两个部分

一.NavigationBar的加载流程

二.Android P上如何去除NavigationBar

 

一 NavigationBar的加载流程

NavigationBar就是我们常说的导航栏，今天我们来探究一下NavigationBar的加载流程。

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

首先在makeStatusBarView中进行判断是否有navigationBar

protected void makeStatusBarView() {

        try {
            //判断是否有navigationbar
            boolean showNav = mWindowManagerService.hasNavigationBar();
            if (DEBUG) Log.v(TAG, "hasNavigationBar=" + showNav);
            if (showNav) {
                createNavigationBar();
            }
        } catch (RemoteException ex) {
            // no window manager? good luck with that
        }

}

    protected void createNavigationBar() {
        mNavigationBarView = NavigationBarFragment.create(mContext, (tag, fragment) -> {
            mNavigationBar = (NavigationBarFragment) fragment;
            if (mLightBarController != null) {
                mNavigationBar.setLightBarController(mLightBarController);
            }
            mNavigationBar.setCurrentSysuiVisibility(mSystemUiVisibility);
        });
    }

通过上面的方法我们可以看见调用NavigationBarFragment去进行初始化的，我们继续看这个方法。

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

先构造一个继承于Fragment的NavigationBarFragment，然后inflate了一个FrameLayout布局"R.layout.navigation_bar_window"，然后通过FragmentManager把NavigationBarFragment对象给替换进去，触发Fragment生命周期里的onCreateView()，再inflate布局"R.layout.navigation_bar"加载真正需要显示的NavigationBarView。

    public static View create(Context context, FragmentListener listener) {
        WindowManager.LayoutParams lp = new WindowManager.LayoutParams(
                LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT,
                WindowManager.LayoutParams.TYPE_NAVIGATION_BAR,
                WindowManager.LayoutParams.FLAG_TOUCHABLE_WHEN_WAKING
                        | WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
                        | WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL
                        | WindowManager.LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH
                        | WindowManager.LayoutParams.FLAG_SPLIT_TOUCH
                        | WindowManager.LayoutParams.FLAG_SLIPPERY,
                PixelFormat.TRANSLUCENT);
        lp.token = new Binder();
        lp.setTitle("NavigationBar");
        lp.windowAnimations = 0;
        //加载布局文件
        View navigationBarView = LayoutInflater.from(context).inflate(
                R.layout.navigation_bar_window, null);

        if (DEBUG) Log.v(TAG, "addNavigationBar: about to add " + navigationBarView);
        if (navigationBarView == null) return null;

        context.getSystemService(WindowManager.class).addView(navigationBarView, lp);
        FragmentHostManager fragmentHost = FragmentHostManager.get(navigationBarView);
        NavigationBarFragment fragment = new NavigationBarFragment();
        fragmentHost.getFragmentManager().beginTransaction()
                .replace(R.id.navigation_bar_frame, fragment, TAG)
                .commit();
        fragmentHost.addTagListener(TAG, listener);
        return navigationBarView;
    }
}

    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container,
            Bundle savedInstanceState) {
        return inflater.inflate(R.layout.navigation_bar, container, false);
    }

这里面我们看一下navigation_bar.xml

我们进入frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarInflaterView.java中去查看

    public NavigationBarInflaterView(Context context, AttributeSet attrs) {
        super(context, attrs);
        createInflaters();
        Display display = ((WindowManager)
                context.getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();
        Mode displayMode = display.getMode();
        isRot0Landscape = displayMode.getPhysicalWidth() > displayMode.getPhysicalHeight();
    }

    private void createInflaters() {
       //根据屏幕旋转角度去写子view
        mLayoutInflater = LayoutInflater.from(mContext);
        Configuration landscape = new Configuration();
        landscape.setTo(mContext.getResources().getConfiguration());
        landscape.orientation = Configuration.ORIENTATION_LANDSCAPE;
        mLandscapeInflater = LayoutInflater.from(mContext.createConfigurationContext(landscape));
    }

    @Override
    protected void onFinishInflate() {
        //该方法是view的生命周期，每一个view被inflate后都会加载调用该方法
        super.onFinishInflate();
        inflateChildren();
        clearViews();
        inflateLayout(getDefaultLayout());//加载了三个按钮的关键方法
    }

    private void inflateChildren() {
        removeAllViews();
        mRot0 = (FrameLayout) mLayoutInflater.inflate(R.layout.navigation_layout, this, false);
        mRot0.setId(R.id.rot0);
        addView(mRot0);
        mRot90 = (FrameLayout) mLayoutInflater.inflate(R.layout.navigation_layout_rot90, this,
                false);
        mRot90.setId(R.id.rot90);
        addView(mRot90);
        updateAlternativeOrder();
    }

关键添加方法

   protected String getDefaultLayout() {
        return mContext.getString(R.string.config_navBarLayout);
    }

.//res/values-sw372dp/config.xml:   
 left[.25W],back[.5WC];home;recent[.5WC],right[.25W]

 

解析xml文件中的string

 protected void inflateLayout(String newLayout) {
        mCurrentLayout = newLayout;
        if (newLayout == null) {
            newLayout = getDefaultLayout();
        }
        String[] sets = newLayout.split(GRAVITY_SEPARATOR, 3);//根据分号区分，变成3个数组
        String[] start = sets[0].split(BUTTON_SEPARATOR);//根据逗号区分，包含 left[.25W]和back[.5WC]
        String[] center = sets[1].split(BUTTON_SEPARATOR);//包含home
        String[] end = sets[2].split(BUTTON_SEPARATOR);//包含recent[.5WC]和right[.25W]
        // Inflate these in start to end order or accessibility traversal will be messed up.
        inflateButtons(start, mRot0.findViewById(R.id.ends_group), isRot0Landscape, true);
        inflateButtons(start, mRot90.findViewById(R.id.ends_group), !isRot0Landscape, true);

        inflateButtons(center, mRot0.findViewById(R.id.center_group), isRot0Landscape, false);
        inflateButtons(center, mRot90.findViewById(R.id.center_group), !isRot0Landscape, false);

        addGravitySpacer(mRot0.findViewById(R.id.ends_group));
        addGravitySpacer(mRot90.findViewById(R.id.ends_group));

        inflateButtons(end, mRot0.findViewById(R.id.ends_group), isRot0Landscape, false);
        inflateButtons(end, mRot90.findViewById(R.id.ends_group), !isRot0Landscape, false);
    }

我们接着看inflateButtons的方法

    private void inflateButtons(String[] buttons, ViewGroup parent, boolean landscape,
            boolean start) {
        for (int i = 0; i < buttons.length; i++) {
            inflateButton(buttons[i], parent, landscape, start);//调用inflateButton方法
        }
    }

调用inflatebutton方法

 @Nullable
    protected View inflateButton(String buttonSpec, ViewGroup parent, boolean landscape,
            boolean start) {
        LayoutInflater inflater = landscape ? mLandscapeInflater : mLayoutInflater;
        View v = createView(buttonSpec, parent, inflater); //创建view
        if (v == null) return null;

        v = applySize(v, buttonSpec, landscape, start);
        parent.addView(v);
        addToDispatchers(v);
        View lastView = landscape ? mLastLandscape : mLastPortrait;
        View accessibilityView = v;
        if (v instanceof ReverseFrameLayout) {
            accessibilityView = ((ReverseFrameLayout) v).getChildAt(0);
        }
        if (lastView != null) {
            accessibilityView.setAccessibilityTraversalAfter(lastView.getId());
        }
        if (landscape) {
            mLastLandscape = accessibilityView;
        } else {
            mLastPortrait = accessibilityView;
        }
        return v;
    }

到这里我们基本就介绍完了NavigationBar的基本加载流程了。

我们在多说一下上面的createView方法：

这里我们可以看见会根据String去加载对应layout

 private View createView(String buttonSpec, ViewGroup parent, LayoutInflater inflater) {
        View v = null;
        String button = extractButton(buttonSpec);
        if (LEFT.equals(button)) {
            String s = Dependency.get(TunerService.class).getValue(NAV_BAR_LEFT, NAVSPACE);
            button = extractButton(s);
        } else if (RIGHT.equals(button)) {
            String s = Dependency.get(TunerService.class).getValue(NAV_BAR_RIGHT, MENU_IME);
            button = extractButton(s);
        }
        // Let plugins go first so they can override a standard view if they want.
        for (NavBarButtonProvider provider : mPlugins) {
            v = provider.createView(buttonSpec, parent);
            if (v != null) return v;
        }
        if (HOME.equals(button)) {
            v = inflater.inflate(R.layout.home, parent, false);
        } else if (BACK.equals(button)) {
            v = inflater.inflate(R.layout.back, parent, false);
        } else if (RECENT.equals(button)) {
            v = inflater.inflate(R.layout.recent_apps, parent, false);
        } else if (MENU_IME.equals(button)) {
            v = inflater.inflate(R.layout.menu_ime, parent, false);
        } else if (NAVSPACE.equals(button)) {
            v = inflater.inflate(R.layout.nav_key_space, parent, false);
        } else if (CLIPBOARD.equals(button)) {
            v = inflater.inflate(R.layout.clipboard, parent, false);
        } else if (button.startsWith(KEY)) {
            String uri = extractImage(button);
            int code = extractKeycode(button);
            v = inflater.inflate(R.layout.custom_key, parent, false);
            ((KeyButtonView) v).setCode(code);
            if (uri != null) {
                if (uri.contains(":")) {
                    ((KeyButtonView) v).loadAsync(Icon.createWithContentUri(uri));
                } else if (uri.contains("/")) {
                    int index = uri.indexOf('/');
                    String pkg = uri.substring(0, index);
                    int id = Integer.parseInt(uri.substring(index + 1));
                    ((KeyButtonView) v).loadAsync(Icon.createWithResource(pkg, id));
                }
            }
        }
        return v;
    }

这里面我们以home.xml来探究

这里面的KeyButtonView 包含这个按钮的点击事件等

public boolean onTouchEvent(MotionEvent ev) {
        final int action = ev.getAction();
        int x, y;
        if (action == MotionEvent.ACTION_DOWN) {
            mGestureAborted = false;
        }
        if (mGestureAborted) {
            return false;
        }

        switch (action) {
            case MotionEvent.ACTION_DOWN:
                mDownTime = SystemClock.uptimeMillis();
                mLongClicked = false;
                setPressed(true);
                if (mCode != 0) {
                    sendEvent(KeyEvent.ACTION_DOWN, 0, mDownTime);
                } else {
                    // Provide the same haptic feedback that the system offers for virtual keys.
                    performHapticFeedback(HapticFeedbackConstants.VIRTUAL_KEY);
                }
                playSoundEffect(SoundEffectConstants.CLICK);
                removeCallbacks(mCheckLongPress);
                postDelayed(mCheckLongPress, ViewConfiguration.getLongPressTimeout());
                break;
            case MotionEvent.ACTION_MOVE:
                x = (int)ev.getX();
                y = (int)ev.getY();
                setPressed(x >= -mTouchSlop
                        && x < getWidth() + mTouchSlop
                        && y >= -mTouchSlop
                        && y < getHeight() + mTouchSlop);
                break;
            case MotionEvent.ACTION_CANCEL:
                setPressed(false);
                if (mCode != 0) {
                    sendEvent(KeyEvent.ACTION_UP, KeyEvent.FLAG_CANCELED);
                }
                removeCallbacks(mCheckLongPress);
                break;
            case MotionEvent.ACTION_UP:
                final boolean doIt = isPressed() && !mLongClicked;
                setPressed(false);
                // Always send a release ourselves because it doesn't seem to be sent elsewhere
                // and it feels weird to sometimes get a release haptic and other times not.
                if ((SystemClock.uptimeMillis() - mDownTime) > 150 && !mLongClicked) {
                    performHapticFeedback(HapticFeedbackConstants.VIRTUAL_KEY_RELEASE);
                }
                if (mCode != 0) {
                    if (doIt) {
                        sendEvent(KeyEvent.ACTION_UP, 0);
                        sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_CLICKED);
                    } else {
                        sendEvent(KeyEvent.ACTION_UP, KeyEvent.FLAG_CANCELED);
                    }
                } else {
                    // no key code, just a regular ImageView
                    if (doIt && mOnClickListener != null) {
                        mOnClickListener.onClick(this);
                        sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_CLICKED);
                    }
                }
                removeCallbacks(mCheckLongPress);
                break;
        }

        return true;
    }

上面有一个很重要的方法就是sendEvent()方法，实质是调用InputManager的injectInputEvent模拟发送来实现与物理按键相同的功能。

    public void sendEvent(int action, int flags) {
        sendEvent(action, flags, SystemClock.uptimeMillis());
    }

    void sendEvent(int action, int flags, long when) {
        mMetricsLogger.write(new LogMaker(MetricsEvent.ACTION_NAV_BUTTON_EVENT)
                .setType(MetricsEvent.TYPE_ACTION)
                .setSubtype(mCode)
                .addTaggedData(MetricsEvent.FIELD_NAV_ACTION, action)
                .addTaggedData(MetricsEvent.FIELD_FLAGS, flags));
        final int repeatCount = (flags & KeyEvent.FLAG_LONG_PRESS) != 0 ? 1 : 0;
        final KeyEvent ev = new KeyEvent(mDownTime, when, action, mCode, repeatCount,
                0, KeyCharacterMap.VIRTUAL_KEYBOARD, 0,
                flags | KeyEvent.FLAG_FROM_SYSTEM | KeyEvent.FLAG_VIRTUAL_HARD_KEY,
                InputDevice.SOURCE_KEYBOARD);
        //模拟物理按键的方法去实现的
        InputManager.getInstance().injectInputEvent(ev,
                InputManager.INJECT_INPUT_EVENT_MODE_ASYNC);
    }

这里面最后在补充一下，对于icon的加载是通过NavigationBarView.java这个方法来实现的。

二、Android P上如何去除NavigationBar

/** 
    *  NavigationBarFragment.java 新增方法
    *  用于StatusBar里删除导航栏时调用 
    */
    public static void removeFragment(Context context, NavigationBarFragment fragment, View view) {
        if (fragment != null && view != null) {
            ((WindowManager)context.getSystemService(Context.WINDOW_SERVICE)).removeView(view);
            FragmentHostManager fragmentHost = FragmentHostManager.get(view);
            fragmentHost.getFragmentManager().beginTransaction()
                    .remove(fragment)
                    .commit();
        }
    }