Android 13 SystemUI，底部导航栏新增功能按键、导航栏侧边(左侧，右侧，顶侧)显示。

写在前面： SystemUI 是Android原生系统极重要的系统APP，本文介绍如何根据需要在原生三个按键BACK HOME RECENT的基础上，新增新的自定义按键。SystemUI总共分为三个版本：Phone手机、Tablet平板、TV版本。Android13中，Phone、Tablet是一样的。本教程适用SystemUI版本：Android13——>Phone 、Tablet版SystemUI。
注：SystemUI的启动流程，本篇文章不介绍。

一、底部导航栏新增功能按键。

  首先介绍一下Phone、Tablet版的SystemUI的启动路线，看下图：

  启动流程中的CentralSurfaces，是我们修改的切入点。打开源码找到CentralSurfacesImpl.java文件，下面我沿着CentralSurfacesImpl.java简单描述一下修改思路，然后贴出完整补丁。

1、frameworks\base\packages\SystemUI\src\com\android\systemui\statusbar\phone\CentralSurfacesImpl.java    @Override    public void start() {       . . . . . .    . . . . . .    . . . . . .    createAndAddWindows(result);//这里为入口    . . . . . .    . . . . . .    . . . . . .}    @Override    public void createAndAddWindows(@Nullable RegisterStatusBarResult result) {           makeStatusBarView(result);//从这里进去创建状态栏、导航栏        mNotificationShadeWindowController.attach();        mStatusBarWindowController.attach();    }    // ================================================================================    // Constructing the view    // ================================================================================    protected void makeStatusBarView(@Nullable RegisterStatusBarResult result) {       . . . . . .    . . . . . .    . . . . . .    createNavigationBar(result);//创建导航栏入口    . . . . . .    . . . . . .    . . . . . .}    protected void createNavigationBar(@Nullable RegisterStatusBarResult result) {           mNavigationBarController.createNavigationBars(true /* includeDefaultDisplay */, result);    }2、frameworks\base\packages\SystemUI\src\com\android\systemui\navigationbar\NavigationBarController.java    public void createNavigationBars(final boolean includeDefaultDisplay,            RegisterStatusBarResult result) {           updateAccessibilityButtonModeIfNeeded();        // Don't need to create nav bar on the default display if we initialize TaskBar.        final boolean shouldCreateDefaultNavbar = includeDefaultDisplay                && !initializeTaskbarIfNecessary();        Display[] displays = mDisplayManager.getDisplays();        for (Display display : displays) {               if (shouldCreateDefaultNavbar || display.getDisplayId() != DEFAULT_DISPLAY) {                   createNavigationBar(display, null /* savedState */, result);            }        }    }    /**     * Adds a navigation bar on default display or an external display if the display supports     * system decorations.     *     * @param display the display to add navigation bar on.     */    @VisibleForTesting    void createNavigationBar(Display display, Bundle savedState, RegisterStatusBarResult result) {           . . . . . .    . . . . . .    . . . . . .    //从这里分为两个部分    NavigationBar navBar = component.getNavigationBar();//导航栏实例化        navBar.init();//将导航栏添加到屏幕上        . . . . . .    . . . . . .    . . . . . .    }

注：导航栏实例化会去加载导航栏对应的XML，里面默认只有Back|Home|Recent，想要添加新的功能键，第一步就是去修改这个XML；navBar.init()中则是为按键添加图标、绑定点击事件，并最终通过windowManager的addView方法将导航添加到桌面上显示。

完整补丁：

1、xml中新增按钮

  以我的项目分辨率 = 1920x1080、dpi = 320、density = 2来说，对应修改的xml为——>res\values-sw372dp\config.xml 我这里给出的例子，除了原生Back|Home|Recent之外，新增了其它四个按键。

diff --git a/frameworks/base/packages/SystemUI/res/values-sw372dp/config.xml b/frameworks/base/packages/SystemUI/res/values-sw372dp/config.xmlindex 07b797a324..3b936766c5 100644--- a/frameworks/base/packages/SystemUI/res/values-sw372dp/config.xml+++ b/frameworks/base/packages/SystemUI/res/values-sw372dp/config.xml@@ -21,5 +21,5 @@      for different hardware and product builds. -->      -    left[.25W],back[.5WC];home;recent[.5WC],right[.25W]+    back;home;recent;volume;comments;whiteboard;collapse 

2、NavigationBarInflaterView.java

  inflateLayout函数新增inflateButtons选项、createView函数新增对新按钮描述String的过滤；这个类的功能主要是从上述的xml文件中把所有按键加载进来，并进行过滤操作。

diff --git a/frameworks/base/packages/SystemUI/src/com/android/systemui/navigationbar/NavigationBarInflaterView.java b/frameworks/base/packages/SystemUI/src/com/android/systemui/navigationbar/NavigationBarInflaterView.javaindex 59bb2278ed..5724e09a00 100644--- a/frameworks/base/packages/SystemUI/src/com/android/systemui/navigationbar/NavigationBarInflaterView.java+++ b/frameworks/base/packages/SystemUI/src/com/android/systemui/navigationbar/NavigationBarInflaterView.java@@ -60,6 +60,12 @@ public class NavigationBarInflaterView extends FrameLayout     public static final String BACK = "back";     public static final String HOME = "home";     public static final String RECENT = "recent";+    //xuhao add+    public static final String VOLUME = "volume";+    public static final String COMMENTS = "comments";+    public static final String WHITEBOARD = "whiteboard";+    public static final String COLLAPSE = "collapse";+//     public static final String NAVSPACE = "space";     public static final String CLIPBOARD = "clipboard";     public static final String HOME_HANDLE = "home_handle";@@ -96,7 +102,7 @@ public class NavigationBarInflaterView extends FrameLayout     private View mLastPortrait;     private View mLastLandscape; -    private boolean mIsVertical;+    private boolean mIsVertical ;     private boolean mAlternativeOrder;      private OverviewProxyService mOverviewProxyService;@@ -177,6 +183,7 @@ public class NavigationBarInflaterView extends FrameLayout     void updateButtonDispatchersCurrentView() {            if (mButtonDispatchers != null) {                View view = mIsVertical ? mVertical : mHorizontal;+            Log.d(TAG,"mIsVertical"+mIsVertical);             for (int i = 0; i