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。_centralsurfacesimpl

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。
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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.xml
index 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. -->
 <resources>
     <!-- Nav bar button default ordering/layout -->
-    <string name="config_navBarLayout" translatable="false">left[.25W],back[.5WC];home;recent[.5WC],right[.25W]</string>
+    <string name="config_navBarLayout" translatable="false">back;home;recent;volume;comments;whiteboard;collapse</string>
 </resources>

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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.java
index 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 < mButtonDispatchers.size(); i++) {
   
                 final ButtonDispatcher dispatcher = mButtonDispatchers.valueAt(i);
                 dispatcher.setCurrentView(view);
@@ -236,34 +243,64 @@ public class NavigationBarInflaterView extends FrameLayout
         if (newLayout == null) {
   
             newLayout = getDefaultLayout();
         }
-        String[] sets = newLayout.split(GRAVITY_SEPARATOR, 3);
-        if (sets.length != 3) {
   
+
+        //xuhao add 
+        String[] sets = newLayout.split(GRAVITY_SEPARATOR, 7);
+        if (sets.length != 7) {
   
             Log.d(TAG, "Invalid layout.");
             newLayout = 
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