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导航栏的介绍_navigationbarinflaterview 添加布局

作者：小蓝xlanll | 2024-03-11 13:21:40

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navigationbarinflaterview 添加布局

一、导航栏的创建：

         PhoneStatusBar -->makeStatusBarView();         

  1.  try {
  2.             boolean showNav = mWindowManagerService.hasNavigationBar();//向wms询问是否需要导航栏
  3.             //if (DEBUG) 
  4. 				Log.v(TAG, "hasNavigationBar=" + showNav);
  5.             if (showNav) {
  6.                 createNavigationBarView(context);//创建导航栏
  7.             }
  8.         } catch (RemoteException ex) {
  9.             // no window manager? good luck with that

 

mWindowManagerService.hasNavigationBar向framework 下面的config.xml中获取   com.android.internal.R.bool.config_showNavigationBar。

     createNavigationBarView(context)：

             

  1.  protected void createNavigationBarView(Context context) {
  2.         inflateNavigationBarView(context);//加载导航栏布局文件
  3.         mNavigationBarView.setDisabledFlags(mDisabled1);//禁用某些功能switches[0]
  4.         mNavigationBarView.setComponents(mRecents, getComponent(Divider.class));//添加控制按键。
  5.         mNavigationBarView.setOnVerticalChangedListener(
  6.                 new NavigationBarView.OnVerticalChangedListener() {
  7.             @Override
  8.             public void onVerticalChanged(boolean isVertical) {
  9.                 if (mAssistManager != null) {
  10.                     mAssistManager.onConfigurationChanged();
  11.                 }
  12.                 mNotificationPanel.setQsScrimEnabled(!isVertical);
  13.             }
  14.         });
  15.         mNavigationBarView.setOnTouchListener(new View.OnTouchListener() {
  16.             @Override
  17.             public boolean onTouch(View v, MotionEvent event) {
  18.                 checkUserAutohide(v, event);
  19.                 return false;
  20.             }});
  21.     }

至此导航栏的UI界面是创建完成但是功能还未全部加载完成，比如按近期列表无效，所以还需要在PhoneStatusBar ->start()中加载addNavigationBar()。

           

  1.  protected void addNavigationBar() {
  2.         if (DEBUG) Log.v(TAG, "addNavigationBar: about to add " + mNavigationBarView);
  3.         if (mNavigationBarView == null) return;
  4.  
  5.         prepareNavigationBarView();
  6.  
  7.         mWindowManager.addView(mNavigationBarView, getNavigationBarLayoutParams());//把这个添加到window窗口
  8.     }
  1.  private void prepareNavigationBarView() {
  2.         mNavigationBarView.reorient();//方向的初始化
  3.  
  4.  
  5.         ButtonDispatcher recentsButton = mNavigationBarView.getRecentsButton();
  6. 		//近期列表的监听
  7.         recentsButton.setOnClickListener(mRecentsClickListener);
  8.         recentsButton.setOnTouchListener(mRecentsPreloadOnTouchListener);
  9.         recentsButton.setLongClickable(true);
  10.         recentsButton.setOnLongClickListener(mRecentsLongClickListener);
  11.  
  12.         ButtonDispatcher backButton = mNavigationBarView.getBackButton();
  13.         backButton.setLongClickable(true);
  14.         backButton.setOnLongClickListener(mLongPressBackListener);
  15.    
  16.         ButtonDispatcher homeButton = mNavigationBarView.getHomeButton();
  17.         homeButton.setOnTouchListener(mHomeActionListener);
  18.         homeButton.setOnLongClickListener(mLongPressHomeListener);
  19.  
  20.  
  21.         /// M: BMW  restore button @{
  22.         if (MultiWindowManager.isSupported()) {
  23.             ButtonDispatcher restoreButton = mNavigationBarView.getRestoreButton();
  24.             restoreButton.setOnClickListener(mRestoreClickListener);
  25.  
  26.  
  27.         }
  28.         /// @}
  29.  
  30.  
  31.         mAssistManager.onConfigurationChanged();
  32.     }
       在上述的代码 recentsButton 、backButton、homeButton分别对应的是导航栏中的近期列表、返回键、Home键。如果继续追溯它们所添加的监听，并未发现back 和home的功能实现，只有近期列表的功能实现。那back 和home的功能实现是在哪里呢？后面会讲到。


二、导航栏的UI界面显示：

        导航栏的创建     

  1. protected void inflateNavigationBarView(Context context) {
  2.         mNavigationBarView = (NavigationBarView) View.inflate(
  3.                 context, R.layout.navigation_bar, null);
  4.     }


    navigation_bar.xml: 

  1. <com.android.systemui.statusbar.phone.NavigationBarView
  2.     xmlns:android="http://schemas.android.com/apk/res/android"
  3.     xmlns:systemui="http://schemas.android.com/apk/res-auto"
  4.     android:layout_height="match_parent"
  5.     android:layout_width="match_parent"
  6.     android:background="@drawable/system_bar_background">
  7.  
  8.     <com.android.systemui.statusbar.phone.NavigationBarInflaterView
  9.         android:id="@+id/navigation_inflater"
  10.         android:layout_width="match_parent"
  11.         android:layout_height="match_parent" />
  12.  
  13. </com.android.systemui.statusbar.phone.NavigationBarView>

    注： @drawable/system_bar_background  导航栏的背景控制

  NavigationBarInflaterView

              

  1. public class NavigationBarInflaterView extends FrameLayout implements TunerService.Tunable {
  2.  
  3.     private static final String TAG = "NavBarInflater";
  4.  
  5.     public static final String NAV_BAR_VIEWS = "sysui_nav_bar";
  6.  
  7.     public static final String MENU_IME = "menu_ime";
  8.     public static final String BACK = "back";
  9.     public static final String HOME = "home";
  10.     public static final String RECENT = "recent";
  11.     public static final String NAVSPACE = "space";
  12.     public static final String CLIPBOARD = "clipboard";
  13.     public static final String KEY = "key";
  14.     /// M: BMW @{
  15.     public static final String RESTORE = "restore";
  16.     /// @}
  17.  
  18.     public static final String GRAVITY_SEPARATOR = ";";
  19.     public static final String BUTTON_SEPARATOR = ",";
  20.  
  21.     public static final String SIZE_MOD_START = "[";
  22.     public static final String SIZE_MOD_END = "]";
  23.  
  24.     public static final String KEY_CODE_START = "(";
  25.     public static final String KEY_IMAGE_DELIM = ":";
  26.     public static final String KEY_CODE_END = ")";
  27.  
  28.     protected LayoutInflater mLayoutInflater;
  29.     protected LayoutInflater mLandscapeInflater;
  30.     private int mDensity;
  31.  
  32.     protected FrameLayout mRot0;
  33.     protected FrameLayout mRot90;
  34.  
  35.     private SparseArray<ButtonDispatcher> mButtonDispatchers;
  36.     private String mCurrentLayout;
  37.  
  38.     private View mLastRot0;
  39.     private View mLastRot90;
  40.  
  41.     public NavigationBarInflaterView(Context context, AttributeSet attrs) {
  42.         super(context, attrs);
  43.         mDensity = context.getResources().getConfiguration().densityDpi;//dpi值
  44.         createInflaters();
  45.     }
  46.  
  47.     private void createInflaters() {
  48.         mLayoutInflater = LayoutInflater.from(mContext);
  49.         Configuration landscape = new Configuration();
  50.         landscape.setTo(mContext.getResources().getConfiguration());
  51.         landscape.orientation = Configuration.ORIENTATION_LANDSCAPE;//初始化方法是横向
  52.         mLandscapeInflater = LayoutInflater.from(mContext.createConfigurationContext(landscape));
  53.     }
  54.  
  55.     @Override
  56.     protected void onConfigurationChanged(Configuration newConfig) {
  57.         super.onConfigurationChanged(newConfig);
  58.         if (mDensity != newConfig.densityDpi) {
  59.             mDensity = newConfig.densityDpi;
  60.             createInflaters();
  61.             inflateChildren();
  62.             clearViews();
  63.             inflateLayout(mCurrentLayout);
  64.         }
  65.     }
  66.  
  67.     @Override
  68.     protected void onFinishInflate() {
  69.         super.onFinishInflate();
  70.         inflateChildren();
  71.         clearViews();
  72.         inflateLayout(getDefaultLayout());
  73.     }
  74.  
  75.     private void inflateChildren() {
  76.         removeAllViews();//移除此group上面的所有view
  77.  
  78. 		//加载O度和90度布局
  79.         mRot0 = (FrameLayout) mLayoutInflater.inflate(R.layout.navigation_layout, this, false);
  80.         mRot0.setId(R.id.rot0);
  81.         addView(mRot0);
  82.         mRot90 = (FrameLayout) mLayoutInflater.inflate(R.layout.navigation_layout_rot90, this,
  83.                 false);
  84.         mRot90.setId(R.id.rot90);
  85.         addView(mRot90);
  86.         if (getParent() instanceof NavigationBarView) {
  87.             ((NavigationBarView) getParent()).updateRotatedViews();
  88.         }
  89.     }
  90.  
  91.     protected String getDefaultLayout() {
  92.         /// M: BMW @{
  93.         if (MultiWindowManager.isSupported()) {
  94.             return mContext.getString(R.string.config_navBarLayout_float);
  95.         }
  96.         /// @}
  97.         return mContext.getString(R.string.config_navBarLayout);
  98.     }
  99.  
  100.     @Override
  101.     protected void onAttachedToWindow() {
  102.         super.onAttachedToWindow();
  103.         TunerService.get(getContext()).addTunable(this, NAV_BAR_VIEWS);
  104.     }
  105.  
  106.     @Override
  107.     protected void onDetachedFromWindow() {
  108.         TunerService.get(getContext()).removeTunable(this);
  109.         super.onDetachedFromWindow();
  110.     }
  111.  
  112.     @Override
  113.     public void onTuningChanged(String key, String newValue) {
  114.         if (NAV_BAR_VIEWS.equals(key)) {
  115.             if (!Objects.equals(mCurrentLayout, newValue)) {
  116.                 clearViews();
  117.                 inflateLayout(newValue);
  118.             }
  119.         }
  120.     }
  121.  
  122.     public void setButtonDispatchers(SparseArray<ButtonDispatcher> buttonDisatchers) {
  123.         mButtonDispatchers = buttonDisatchers;
  124.         for (int i = 0; i < buttonDisatchers.size(); i++) {
  125.             initiallyFill(buttonDisatchers.valueAt(i));
  126.         }
  127.     }
  128.  
  129.     private void initiallyFill(ButtonDispatcher buttonDispatcher) {
  130.         addAll(buttonDispatcher, (ViewGroup) mRot0.findViewById(R.id.ends_group));
  131.         addAll(buttonDispatcher, (ViewGroup) mRot0.findViewById(R.id.center_group));
  132.         addAll(buttonDispatcher, (ViewGroup) mRot90.findViewById(R.id.ends_group));
  133.         addAll(buttonDispatcher, (ViewGroup) mRot90.findViewById(R.id.center_group));
  134.     }
  135.  
  136.     private void addAll(ButtonDispatcher buttonDispatcher, ViewGroup parent) {
  137.         for (int i = 0; i < parent.getChildCount(); i++) {
  138.             // Need to manually search for each id, just in case each group has more than one
  139.             // of a single id.  It probably mostly a waste of time, but shouldn't take long
  140.             // and will only happen once.
  141.             if (parent.getChildAt(i).getId() == buttonDispatcher.getId()) {
  142.                 buttonDispatcher.addView(parent.getChildAt(i));
  143.             } else if (parent.getChildAt(i) instanceof ViewGroup) {
  144.                 addAll(buttonDispatcher, (ViewGroup) parent.getChildAt(i));
  145.             }
  146.         }
  147.     }
  148.  
  149.     protected void inflateLayout(String newLayout) {
  150.         mCurrentLayout = newLayout;
  151.         if (newLayout == null) {
  152.             newLayout = getDefaultLayout();
  153.         }
  154.         String[] sets = newLayout.split(GRAVITY_SEPARATOR, 3);
  155.         String[] start = sets[0].split(BUTTON_SEPARATOR);
  156.         String[] center = sets[1].split(BUTTON_SEPARATOR);
  157.         String[] end = sets[2].split(BUTTON_SEPARATOR);
  158.         // Inflate these in start to end order or accessibility traversal will be messed up.
  159.         inflateButtons(start, (ViewGroup) mRot0.findViewById(R.id.ends_group), false);
  160.         inflateButtons(start, (ViewGroup) mRot90.findViewById(R.id.ends_group), true);
  161.  
  162.         inflateButtons(center, (ViewGroup) mRot0.findViewById(R.id.center_group), false);
  163.         inflateButtons(center, (ViewGroup) mRot90.findViewById(R.id.center_group), true);
  164.  
  165.         addGravitySpacer((LinearLayout) mRot0.findViewById(R.id.ends_group));
  166.         addGravitySpacer((LinearLayout) mRot90.findViewById(R.id.ends_group));
  167.  
  168.         inflateButtons(end, (ViewGroup) mRot0.findViewById(R.id.ends_group), false);
  169.         inflateButtons(end, (ViewGroup) mRot90.findViewById(R.id.ends_group), true);
  170.     }
  171.  
  172.     private void addGravitySpacer(LinearLayout layout) {
  173.         layout.addView(new Space(mContext), new LinearLayout.LayoutParams(0, 0, 1));
  174.     }
  175.  
  176.     private void inflateButtons(String[] buttons, ViewGroup parent, boolean landscape) {
  177.         for (int i = 0; i < buttons.length; i++) {
  178.             inflateButton(buttons[i], parent, landscape, i);
  179.         }
  180.     }
  181.  
  182.     private ViewGroup.LayoutParams copy(ViewGroup.LayoutParams layoutParams) {
  183.         if (layoutParams instanceof LinearLayout.LayoutParams) {
  184.             return new LinearLayout.LayoutParams(layoutParams.width, layoutParams.height,
  185.                     ((LinearLayout.LayoutParams) layoutParams).weight);
  186.         }
  187.         return new LayoutParams(layoutParams.width, layoutParams.height);
  188.     }
  189.  
  190.     @Nullable
  191.     protected View inflateButton(String buttonSpec, ViewGroup parent, boolean landscape,
  192.             int indexInParent) {
  193.         LayoutInflater inflater = landscape ? mLandscapeInflater : mLayoutInflater;
  194.         float size = extractSize(buttonSpec);
  195.         String button = extractButton(buttonSpec);
  196.         View v = null;
  197.         if (HOME.equals(button)) {
  198.             v = inflater.inflate(R.layout.home, parent, false);
  199.             if (landscape && isSw600Dp()) {
  200.                 setupLandButton(v);
  201.             }
  202.         } else if (BACK.equals(button)) {
  203.             v = inflater.inflate(R.layout.back, parent, false);
  204.             if (landscape && isSw600Dp()) {
  205.                 setupLandButton(v);
  206.             }
  207.         } else if (RECENT.equals(button)) {
  208.             v = inflater.inflate(R.layout.recent_apps, parent, false);
  209.             if (landscape && isSw600Dp()) {
  210.                 setupLandButton(v);
  211.             }
  212.         } else if (MENU_IME.equals(button)) {
  213.             v = inflater.inflate(R.layout.menu_ime, parent, false);
  214.         } else if (NAVSPACE.equals(button)) {
  215.             v = inflater.inflate(R.layout.nav_key_space, parent, false);
  216.             /// M: BMW @{
  217.             if (MultiWindowManager.isSupported() && landscape && isSw600Dp()) {
  218.                 setupLandButton(v);
  219.             }
  220.             /// @}
  221.         } else if (CLIPBOARD.equals(button)) {
  222.             v = inflater.inflate(R.layout.clipboard, parent, false);
  223.         /// M: BMW @{
  224.         } else if (MultiWindowManager.isSupported() && RESTORE.equals(button)) {
  225.             v = inflater.inflate(R.layout.restore, parent, false);
  226.             if (landscape && isSw600Dp()) {
  227.                 setupLandButton(v);
  228.             }
  229.         /// @}
  230.         } else if (button.startsWith(KEY)) {
  231.             String uri = extractImage(button);
  232.             int code = extractKeycode(button);
  233.             v = inflater.inflate(R.layout.custom_key, parent, false);
  234.             ((KeyButtonView) v).setCode(code);
  235.             if (uri != null) {
  236.                 ((KeyButtonView) v).loadAsync(uri);
  237.             }
  238.         } else {
  239.             return null;
  240.         }
  241.  
  242.         if (size != 0) {
  243.             ViewGroup.LayoutParams params = v.getLayoutParams();
  244.             params.width = (int) (params.width * size);
  245.         }
  246.         parent.addView(v);
  247.         addToDispatchers(v);
  248.         View lastView = landscape ? mLastRot90 : mLastRot0;
  249.         if (lastView != null) {
  250.             v.setAccessibilityTraversalAfter(lastView.getId());
  251.         }
  252.         if (landscape) {
  253.             mLastRot90 = v;
  254.         } else {
  255.             mLastRot0 = v;
  256.         }
  257.         return v;
  258.     }
  259.  
  260.     public static String extractImage(String buttonSpec) {
  261.         if (!buttonSpec.contains(KEY_IMAGE_DELIM)) {
  262.             return null;
  263.         }
  264.         final int start = buttonSpec.indexOf(KEY_IMAGE_DELIM);
  265.         String subStr = buttonSpec.substring(start + 1, buttonSpec.indexOf(KEY_CODE_END));
  266.         return subStr;
  267.     }
  268.  
  269.     public static int extractKeycode(String buttonSpec) {
  270.         if (!buttonSpec.contains(KEY_CODE_START)) {
  271.             return 1;
  272.         }
  273.         final int start = buttonSpec.indexOf(KEY_CODE_START);
  274.         String subStr = buttonSpec.substring(start + 1, buttonSpec.indexOf(KEY_IMAGE_DELIM));
  275.         return Integer.parseInt(subStr);
  276.     }
  277.  
  278.     public static float extractSize(String buttonSpec) {
  279.         if (!buttonSpec.contains(SIZE_MOD_START)) {
  280.             return 1;
  281.         }
  282.         final int sizeStart = buttonSpec.indexOf(SIZE_MOD_START);
  283.         String sizeStr = buttonSpec.substring(sizeStart + 1, buttonSpec.indexOf(SIZE_MOD_END));
  284.         return Float.parseFloat(sizeStr);
  285.     }
  286.  
  287.     public static String extractButton(String buttonSpec) {
  288.         if (!buttonSpec.contains(SIZE_MOD_START)) {
  289.             return buttonSpec;
  290.         }
  291.         return buttonSpec.substring(0, buttonSpec.indexOf(SIZE_MOD_START));
  292.     }
  293.  
  294.     private void addToDispatchers(View v) {
  295.         if (mButtonDispatchers != null) {
  296.             final int indexOfKey = mButtonDispatchers.indexOfKey(v.getId());
  297.             if (indexOfKey >= 0) {
  298.                 mButtonDispatchers.valueAt(indexOfKey).addView(v);
  299.             } else if (v instanceof ViewGroup) {
  300.                 final ViewGroup viewGroup = (ViewGroup)v;
  301.                 final int N = viewGroup.getChildCount();
  302.                 for (int i = 0; i < N; i++) {
  303.                     addToDispatchers(viewGroup.getChildAt(i));
  304.                 }
  305.             }
  306.         }
  307.     }
  308.  
  309.     private boolean isSw600Dp() {
  310.         Configuration configuration = mContext.getResources().getConfiguration();
  311.         return (configuration.smallestScreenWidthDp >= 600);
  312.     }
  313.  
  314.     /**
  315.      * This manually sets the width of sw600dp landscape buttons because despite
  316.      * overriding the configuration from the overridden resources aren't loaded currently.
  317.      */
  318.     private void setupLandButton(View v) {
  319.         Resources res = mContext.getResources();
  320.         v.getLayoutParams().width = res.getDimensionPixelOffset(
  321.                 R.dimen.navigation_key_width_sw600dp_land);
  322.         int padding = res.getDimensionPixelOffset(R.dimen.navigation_key_padding_sw600dp_land);
  323.         v.setPadding(padding, v.getPaddingTop(), padding, v.getPaddingBottom());
  324.     }
  325.  
  326.     private void clearViews() {
  327.         if (mButtonDispatchers != null) {
  328.             for (int i = 0; i < mButtonDispatchers.size(); i++) {
  329.                 mButtonDispatchers.valueAt(i).clear();
  330.             }
  331.         }
  332.         clearAllChildren((ViewGroup) mRot0.findViewById(R.id.nav_buttons));
  333.         clearAllChildren((ViewGroup) mRot90.findViewById(R.id.nav_buttons));
  334.     }
  335.  
  336.     private void clearAllChildren(ViewGroup group) {
  337.         for (int i = 0; i < group.getChildCount(); i++) {
  338.             ((ViewGroup) group.getChildAt(i)).removeAllViews();
  339.         }
  340.     }
  341. }

  分析：

       1. 这段代码比较简单，文中也有做一些注释，主要功能就是把90度和0度的布局同时添加到ViewGroup中，那这个两个布局既然同时添加到ViewGroup，为什么我看到的只有一种布局文件呢？这是通过setVisibility(View.VISIBLE)来实现，这个功能的实现在NavigationBarView中的updateCurrentView()。

     2.导航栏的三个按键的布局文件分别为：back.xml 、home.xml 、recent_apps.xml. 这个三个布局文件都是KeyButtonView ，而KeyButtonView继承ImageView，所以想修改返回键、Home、近期列表这三个键的UI，只需要更换对应的图片。

    back.xml

  1. <com.android.systemui.statusbar.policy.KeyButtonView
  2.     xmlns:android="http://schemas.android.com/apk/res/android"
  3.     xmlns:systemui="http://schemas.android.com/apk/res-auto"
  4.     android:id="@+id/back"
  5.     android:layout_width="@dimen/navigation_key_width"
  6.     android:layout_height="match_parent"
  7.     android:layout_weight="0"
  8.     android:src="@drawable/ic_sysbar_back"
  9.     systemui:keyCode="4"
  10.     android:scaleType="center"
  11.     android:contentDescription="@string/accessibility_back"
  12.     android:paddingStart="@dimen/navigation_key_padding"
  13.     android:paddingEnd="@dimen/navigation_key_padding"
  14.     />

由于三个布局文件很相近就不一 一列举，@drawable/ic_sysbar_back就是系统所使用的返回键图片，而keyCode=4与系统定义的KEY_BACK相同，因此系统才知道你按back键是让它返回上个界面而不是回到主界面。

   KeyButtonView

  1. public class KeyButtonView extends ImageView {
  2.  
  3.     private int mContentDescriptionRes;
  4.     private long mDownTime;
  5.     private int mCode;
  6.     private int mTouchSlop;
  7.     private boolean mSupportsLongpress = true;
  8.     private AudioManager mAudioManager;
  9.     private boolean mGestureAborted;
  10.     private boolean mLongClicked;
  11.  
  12.     private final Runnable mCheckLongPress = new Runnable() {
  13.         public void run() {
  14.             if (isPressed()) {
  15.                 // Log.d("KeyButtonView", "longpressed: " + this);
  16.                 if (isLongClickable()) {
  17.                     // Just an old-fashioned ImageView
  18.                     performLongClick();
  19.                     mLongClicked = true;
  20.                 } else if (mSupportsLongpress) {
  21.                     sendEvent(KeyEvent.ACTION_DOWN, KeyEvent.FLAG_LONG_PRESS);
  22.                     sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_LONG_CLICKED);
  23.                     mLongClicked = true;
  24.                 }
  25.             }
  26.         }
  27.     };
  28.  
  29.     public KeyButtonView(Context context, AttributeSet attrs) {
  30.         this(context, attrs, 0);
  31.     }
  32.  
  33.     public KeyButtonView(Context context, AttributeSet attrs, int defStyle) {
  34.         super(context, attrs);
  35.  
  36.         TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.KeyButtonView,
  37.                 defStyle, 0);
  38.  
  39.         mCode = a.getInteger(R.styleable.KeyButtonView_keyCode, 0);
  40.  
  41.         mSupportsLongpress = a.getBoolean(R.styleable.KeyButtonView_keyRepeat, true);
  42.  
  43.         TypedValue value = new TypedValue();
  44.         if (a.getValue(R.styleable.KeyButtonView_android_contentDescription, value)) {
  45.             mContentDescriptionRes = value.resourceId;
  46.         }
  47.  
  48.         a.recycle();
  49.  
  50.  
  51.         setClickable(true);
  52.         mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
  53.         mAudioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
  54.         setBackground(new KeyButtonRipple(context, this));
  55.     }
  56.  
  57.     public void setCode(int code) {
  58.         mCode = code;
  59.     }
  60.  
  61.     public void loadAsync(String uri) {
  62.         new AsyncTask<String, Void, Drawable>() {
  63.             @Override
  64.             protected Drawable doInBackground(String... params) {
  65.                 return Icon.createWithContentUri(params[0]).loadDrawable(mContext);
  66.             }
  67.  
  68.             @Override
  69.             protected void onPostExecute(Drawable drawable) {
  70.                 setImageDrawable(drawable);
  71.             }
  72.         }.execute(uri);
  73.     }
  74.  
  75.     @Override
  76.     protected void onConfigurationChanged(Configuration newConfig) {
  77.         super.onConfigurationChanged(newConfig);
  78.  
  79.         if (mContentDescriptionRes != 0) {
  80.             setContentDescription(mContext.getString(mContentDescriptionRes));
  81.         }
  82.     }
  83.  
  84.     @Override
  85.     public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
  86.         super.onInitializeAccessibilityNodeInfo(info);
  87.         if (mCode != 0) {
  88.             info.addAction(new AccessibilityNodeInfo.AccessibilityAction(ACTION_CLICK, null));
  89.             if (mSupportsLongpress || isLongClickable()) {
  90.                 info.addAction(
  91.                         new AccessibilityNodeInfo.AccessibilityAction(ACTION_LONG_CLICK, null));
  92.             }
  93.         }
  94.     }
  95.  
  96.     @Override
  97.     protected void onWindowVisibilityChanged(int visibility) {
  98.         super.onWindowVisibilityChanged(visibility);
  99.         if (visibility != View.VISIBLE) {
  100.             jumpDrawablesToCurrentState();
  101.         }
  102.     }
  103.  
  104.     @Override
  105.     public boolean performAccessibilityActionInternal(int action, Bundle arguments) {
  106.         if (action == ACTION_CLICK && mCode != 0) {
  107.             sendEvent(KeyEvent.ACTION_DOWN, 0, SystemClock.uptimeMillis());
  108.             sendEvent(KeyEvent.ACTION_UP, 0);
  109.             sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_CLICKED);
  110.             playSoundEffect(SoundEffectConstants.CLICK);
  111.             return true;
  112.         } else if (action == ACTION_LONG_CLICK && mCode != 0) {
  113.             sendEvent(KeyEvent.ACTION_DOWN, KeyEvent.FLAG_LONG_PRESS);
  114.             sendEvent(KeyEvent.ACTION_UP, 0);
  115.             sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_LONG_CLICKED);
  116.             return true;
  117.         }
  118.         return super.performAccessibilityActionInternal(action, arguments);
  119.     }
  120.  
  121.     public boolean onTouchEvent(MotionEvent ev) {
  122.         final int action = ev.getAction();
  123.         int x, y;
  124.         if (action == MotionEvent.ACTION_DOWN) {
  125.             mGestureAborted = false;
  126.         }
  127.         if (mGestureAborted) {
  128.             return false;
  129.         }
  130.  
  131.         switch (action) {
  132.             case MotionEvent.ACTION_DOWN:
  133.                 mDownTime = SystemClock.uptimeMillis();
  134.                 mLongClicked = false;
  135.                 setPressed(true);
  136.                 if (mCode != 0) {
  137.                     sendEvent(KeyEvent.ACTION_DOWN, 0, mDownTime);//发送事件给inputmanager
  138.                 } else {
  139.                     // Provide the same haptic feedback that the system offers for virtual keys.
  140.                     performHapticFeedback(HapticFeedbackConstants.VIRTUAL_KEY);
  141.                 }
  142.                 removeCallbacks(mCheckLongPress);
  143.                 postDelayed(mCheckLongPress, ViewConfiguration.getLongPressTimeout());//执行长按事件
  144.                 break;
  145.             case MotionEvent.ACTION_MOVE:
  146.                 x = (int)ev.getX();
  147.                 y = (int)ev.getY();
  148.                 setPressed(x >= -mTouchSlop
  149.                         && x < getWidth() + mTouchSlop
  150.                         && y >= -mTouchSlop
  151.                         && y < getHeight() + mTouchSlop);
  152.                 break;
  153.             case MotionEvent.ACTION_CANCEL:
  154.                 setPressed(false);
  155.                 if (mCode != 0) {
  156.                     sendEvent(KeyEvent.ACTION_UP, KeyEvent.FLAG_CANCELED);
  157.                 }
  158.                 removeCallbacks(mCheckLongPress);
  159.                 break;
  160.             case MotionEvent.ACTION_UP:
  161.                 final boolean doIt = isPressed() && !mLongClicked;
  162.                 setPressed(false);
  163.                 if (mCode != 0) {
  164.                     if (doIt) {
  165.                         sendEvent(KeyEvent.ACTION_UP, 0);
  166.                         sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_CLICKED);
  167.                         playSoundEffect(SoundEffectConstants.CLICK);
  168.                     } else {
  169.                         sendEvent(KeyEvent.ACTION_UP, KeyEvent.FLAG_CANCELED);
  170.                     }
  171.                 } else {
  172.                     // no key code, just a regular ImageView
  173.                     if (doIt) {
  174.                         performClick();
  175.                     }
  176.                 }
  177.                 removeCallbacks(mCheckLongPress);
  178.                 break;
  179.         }
  180.  
  181.         return true;
  182.     }
  183.  
  184.     public void playSoundEffect(int soundConstant) {
  185.         mAudioManager.playSoundEffect(soundConstant, ActivityManager.getCurrentUser());
  186.     };
  187.  
  188.     public void sendEvent(int action, int flags) {
  189.         sendEvent(action, flags, SystemClock.uptimeMillis());
  190.     }
  191.  
  192.     void sendEvent(int action, int flags, long when) {
  193.         final int repeatCount = (flags & KeyEvent.FLAG_LONG_PRESS) != 0 ? 1 : 0;
  194.         final KeyEvent ev = new KeyEvent(mDownTime, when, action, mCode, repeatCount,
  195.                 0, KeyCharacterMap.VIRTUAL_KEYBOARD, 0,
  196.                 flags | KeyEvent.FLAG_FROM_SYSTEM | KeyEvent.FLAG_VIRTUAL_HARD_KEY,
  197.                 InputDevice.SOURCE_KEYBOARD);
  198.         InputManager.getInstance().injectInputEvent(ev,
  199.                 InputManager.INJECT_INPUT_EVENT_MODE_ASYNC);
  200.     }
  201.  
  202.     public void abortCurrentGesture() {
  203.         setPressed(false);
  204.         mGestureAborted = true;
  205.     }
  206. }

      分析：

               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);  中的mCode就是我们之前xml中所定义的。这样系统就能识别我们的意思。意义在于实现不同按键的功能

    NavigationBarView

            

  1. public class NavigationBarView extends LinearLayout {
  2.     final static boolean DEBUG = false;
  3.     final static String TAG = "PhoneStatusBar/NavigationBarView";
  4.  
  5.     // slippery nav bar when everything is disabled, e.g. during setup
  6.     final static boolean SLIPPERY_WHEN_DISABLED = true;
  7.  
  8.     final Display mDisplay;
  9.     View mCurrentView = null;
  10.     View[] mRotatedViews = new View[4];
  11.  
  12.     boolean mVertical;
  13.     boolean mScreenOn;
  14.  
  15.     boolean mShowMenu;
  16.     int mDisabledFlags = 0;
  17.     int mNavigationIconHints = 0;
  18.  
  19.     private Drawable mBackIcon, mBackLandIcon, mBackAltIcon, mBackAltLandIcon;
  20.     private Drawable mBackCarModeIcon, mBackLandCarModeIcon;
  21.     private Drawable mBackAltCarModeIcon, mBackAltLandCarModeIcon;
  22.     private Drawable mHomeDefaultIcon, mHomeCarModeIcon;
  23.     private Drawable mRecentIcon;
  24.     private Drawable mDockedIcon;
  25.     private Drawable mImeIcon;
  26.     private Drawable mMenuIcon;
  27.     /// M: BMW @{
  28.     private Drawable mRestoreIcon;
  29.     private boolean mResizeMode;
  30.     private boolean mRestoreShow;
  31.     /// @}
  32.  
  33.     private NavigationBarGestureHelper mGestureHelper;
  34.     private DeadZone mDeadZone;
  35.     private final NavigationBarTransitions mBarTransitions;
  36.  
  37.     // workaround for LayoutTransitions leaving the nav buttons in a weird state (bug 5549288)
  38.     final static boolean WORKAROUND_INVALID_LAYOUT = true;
  39.     final static int MSG_CHECK_INVALID_LAYOUT = 8686;
  40.  
  41.     // performs manual animation in sync with layout transitions
  42.     private final NavTransitionListener mTransitionListener = new NavTransitionListener();
  43.  
  44.     private OnVerticalChangedListener mOnVerticalChangedListener;
  45.     private boolean mLayoutTransitionsEnabled = true;
  46.     private boolean mWakeAndUnlocking;
  47.     private boolean mCarMode = false;
  48.     private boolean mDockedStackExists;
  49.  
  50.     private final SparseArray<ButtonDispatcher> mButtonDisatchers = new SparseArray<>();
  51.     private Configuration mConfiguration;
  52.  
  53.     // MPlugin for Navigation Bar
  54.     private INavigationBarPlugin mNavBarPlugin;
  55.     /// M: BMW @{
  56.     private KeyguardViewMediator mKeyguardViewMediator;
  57.     /// @}
  58.  
  59.     private class NavTransitionListener implements TransitionListener {
  60.         private boolean mBackTransitioning;
  61.         private boolean mHomeAppearing;
  62.         private long mStartDelay;
  63.         private long mDuration;
  64.         private TimeInterpolator mInterpolator;
  65.  
  66.         @Override
  67.         public void startTransition(LayoutTransition transition, ViewGroup container,
  68.                 View view, int transitionType) {
  69.             if (view.getId() == R.id.back) {
  70.                 mBackTransitioning = true;
  71.             } else if (view.getId() == R.id.home && transitionType == LayoutTransition.APPEARING) {
  72.                 mHomeAppearing = true;
  73.                 mStartDelay = transition.getStartDelay(transitionType);
  74.                 mDuration = transition.getDuration(transitionType);
  75.                 mInterpolator = transition.getInterpolator(transitionType);
  76.             }
  77.         }
  78.  
  79.         @Override
  80.         public void endTransition(LayoutTransition transition, ViewGroup container,
  81.                 View view, int transitionType) {
  82.             if (view.getId() == R.id.back) {
  83.                 mBackTransitioning = false;
  84.             } else if (view.getId() == R.id.home && transitionType == LayoutTransition.APPEARING) {
  85.                 mHomeAppearing = false;
  86.             }
  87.         }
  88.  
  89.         public void onBackAltCleared() {
  90.             ButtonDispatcher backButton = getBackButton();
  91.  
  92.             // When dismissing ime during unlock, force the back button to run the same appearance
  93.             // animation as home (if we catch this condition early enough).
  94.             if (!mBackTransitioning && backButton.getVisibility() == VISIBLE
  95.                     && mHomeAppearing && getHomeButton().getAlpha() == 0) {
  96.                 getBackButton().setAlpha(0);
  97.                 ValueAnimator a = ObjectAnimator.ofFloat(backButton, "alpha", 0, 1);
  98.                 a.setStartDelay(mStartDelay);
  99.                 a.setDuration(mDuration);
  100.                 a.setInterpolator(mInterpolator);
  101.                 a.start();
  102.             }
  103.         }
  104.     }
  105.  
  106.     private final OnClickListener mImeSwitcherClickListener = new OnClickListener() {
  107.         @Override
  108.         public void onClick(View view) {
  109.             mContext.getSystemService(InputMethodManager.class)
  110.                     .showInputMethodPicker(true /* showAuxiliarySubtypes */);
  111.         }
  112.     };
  113.  
  114.     private class H extends Handler {
  115.         public void handleMessage(Message m) {
  116.             switch (m.what) {
  117.                 case MSG_CHECK_INVALID_LAYOUT:
  118.                     final String how = "" + m.obj;
  119.                     final int w = getWidth();
  120.                     final int h = getHeight();
  121.                     final int vw = getCurrentView().getWidth();
  122.                     final int vh = getCurrentView().getHeight();
  123.  
  124.                     if (h != vh || w != vw) {
  125.                         Log.w(TAG, String.format(
  126.                             "*** Invalid layout in navigation bar (%s this=%dx%d cur=%dx%d)",
  127.                             how, w, h, vw, vh));
  128.                         if (WORKAROUND_INVALID_LAYOUT) {
  129.                             requestLayout();
  130.                         }
  131.                     }
  132.                     break;
  133.             }
  134.         }
  135.     }
  136.  
  137.     public NavigationBarView(Context context, AttributeSet attrs) {
  138.         super(context, attrs);
  139.  
  140.         mDisplay = ((WindowManager) context.getSystemService(
  141.                 Context.WINDOW_SERVICE)).getDefaultDisplay();
  142.  
  143.         mVertical = false;
  144.         mShowMenu = false;
  145.         mGestureHelper = new NavigationBarGestureHelper(context);//手势管理类
  146.  
  147.         mConfiguration = new Configuration();
  148.         mConfiguration.updateFrom(context.getResources().getConfiguration());
  149.         updateIcons(context, Configuration.EMPTY, mConfiguration);//加载更新图标
  150.  
  151.        // MPlugin Navigation Bar creation and initialization
  152.         try {
  153.             mNavBarPlugin = (INavigationBarPlugin) MPlugin.createInstance(
  154.             INavigationBarPlugin.class.getName(), context);
  155.         } catch (Exception e) {
  156.             Log.e(TAG, "Catch INavigationBarPlugin exception: ", e);
  157.         }
  158.         if (mNavBarPlugin == null) {
  159.             Log.d(TAG, "DefaultNavigationBarPlugin");
  160.             mNavBarPlugin = new DefaultNavigationBarPlugin(context);
  161.         }
  162.  
  163.         mBarTransitions = new NavigationBarTransitions(this);
  164.         //返回键 、主页 、近期列表 三个按键的监听控制。
  165.         mButtonDisatchers.put(R.id.back, new ButtonDispatcher(R.id.back));
  166.         mButtonDisatchers.put(R.id.home, new ButtonDispatcher(R.id.home));
  167.         mButtonDisatchers.put(R.id.recent_apps, new ButtonDispatcher(R.id.recent_apps));
  168.         /// M: BMW @{
  169.         if (MultiWindowManager.isSupported()) {
  170.             mButtonDisatchers.put(R.id.restore, new ButtonDispatcher(R.id.restore));
  171.             mKeyguardViewMediator = ((SystemUIApplication)context)
  172.                 .getComponent(KeyguardViewMediator.class);
  173.         }
  174.         /// @}
  175.         mButtonDisatchers.put(R.id.menu, new ButtonDispatcher(R.id.menu));
  176.         mButtonDisatchers.put(R.id.ime_switcher, new ButtonDispatcher(R.id.ime_switcher));
  177.     }
  178.  
  179.     public BarTransitions getBarTransitions() {
  180.         return mBarTransitions;
  181.     }
  182.  
  183.     public void setComponents(RecentsComponent recentsComponent, Divider divider) {
  184.         mGestureHelper.setComponents(recentsComponent, divider, this);
  185.     }
  186.  
  187.     public void setOnVerticalChangedListener(OnVerticalChangedListener onVerticalChangedListener) {
  188.         mOnVerticalChangedListener = onVerticalChangedListener;
  189.         notifyVerticalChangedListener(mVertical);
  190.     }
  191.  
  192.     @Override
  193.     public boolean onTouchEvent(MotionEvent event) {
  194.         if (mGestureHelper.onTouchEvent(event)) {
  195.             return true;
  196.         }
  197.         if (mDeadZone != null && event.getAction() == MotionEvent.ACTION_OUTSIDE) {
  198.             mDeadZone.poke(event);
  199.         }
  200.         return super.onTouchEvent(event);
  201.     }
  202.  
  203.     @Override
  204.     public boolean onInterceptTouchEvent(MotionEvent event) {
  205.         return mGestureHelper.onInterceptTouchEvent(event);
  206.     }
  207.  
  208.     public void abortCurrentGesture() {
  209.         getHomeButton().abortCurrentGesture();
  210.     }
  211.  
  212.     private H mHandler = new H();
  213.  
  214.     public View getCurrentView() {
  215.         return mCurrentView;
  216.     }
  217.  
  218.     public View[] getAllViews() {
  219.         return mRotatedViews;
  220.     }
  221.     //TODO:: Temp remove plugin for build pass, need to add back
  222.     public ButtonDispatcher getRecentsButton() {
  223.         return mButtonDisatchers.get(R.id.recent_apps);
  224.     }
  225.  
  226.     public ButtonDispatcher getMenuButton() {
  227.         return mButtonDisatchers.get(R.id.menu);
  228.    }
  229.  
  230.     public ButtonDispatcher getBackButton() {
  231.         return mButtonDisatchers.get(R.id.back);
  232.     }
  233.  
  234.     public ButtonDispatcher getHomeButton() {
  235.         return mButtonDisatchers.get(R.id.home);
  236.     }
  237.  
  238.     public ButtonDispatcher getImeSwitchButton() {
  239.         return mButtonDisatchers.get(R.id.ime_switcher);
  240.     }
  241.  
  242.     /// M: BMW @{
  243.     public ButtonDispatcher getRestoreButton() {
  244.         return mButtonDisatchers.get(R.id.restore);
  245.     }
  246.     /// @}
  247.  
  248.     private void updateCarModeIcons(Context ctx) {
  249.         mBackCarModeIcon = ctx.getDrawable(R.drawable.ic_sysbar_back_carmode);
  250.         mBackLandCarModeIcon = mBackCarModeIcon;
  251.         mBackAltCarModeIcon = ctx.getDrawable(R.drawable.ic_sysbar_back_ime_carmode);
  252.         mBackAltLandCarModeIcon = mBackAltCarModeIcon;
  253.         mHomeCarModeIcon = ctx.getDrawable(R.drawable.ic_sysbar_home_carmode);
  254.     }
  255.  
  256.     private void updateIcons(Context ctx, Configuration oldConfig, Configuration newConfig) {
  257.         if (oldConfig.orientation != newConfig.orientation
  258.                 || oldConfig.densityDpi != newConfig.densityDpi) {
  259.             mDockedIcon = ctx.getDrawable(R.drawable.ic_sysbar_docked);
  260.         }
  261.         if (oldConfig.densityDpi != newConfig.densityDpi) {
  262.             mBackIcon = ctx.getDrawable(R.drawable.ic_sysbar_back);
  263.             mBackLandIcon = mBackIcon;
  264.             mBackAltIcon = ctx.getDrawable(R.drawable.ic_sysbar_back_ime);
  265.             mBackAltLandIcon = mBackAltIcon;
  266.  
  267.             mHomeDefaultIcon = ctx.getDrawable(R.drawable.ic_sysbar_home);
  268.             mRecentIcon = ctx.getDrawable(R.drawable.ic_sysbar_recent);
  269.             mMenuIcon = ctx.getDrawable(R.drawable.ic_sysbar_menu);
  270.             mImeIcon = ctx.getDrawable(R.drawable.ic_ime_switcher_default);
  271.             /// M: BMW @{
  272.             if (MultiWindowManager.isSupported()) {
  273.                 mRestoreIcon = ctx.getDrawable(R.drawable.ic_sysbar_restore);
  274.             }
  275.             /// @}
  276.             updateCarModeIcons(ctx);
  277.         }
  278.     }
  279.  
  280.     @Override
  281.     public void setLayoutDirection(int layoutDirection) {
  282.         // Reload all the icons
  283.         updateIcons(getContext(), Configuration.EMPTY, mConfiguration);
  284.  
  285.         super.setLayoutDirection(layoutDirection);
  286.     }
  287.  
  288.     public void notifyScreenOn(boolean screenOn) {
  289.         mScreenOn = screenOn;
  290.         setDisabledFlags(mDisabledFlags, true);
  291.     }
  292.  
  293.     public void setNavigationIconHints(int hints) {
  294.         setNavigationIconHints(hints, false);
  295.     }
  296.  
  297.     private Drawable getBackIconWithAlt(boolean carMode, boolean landscape) {
  298.         return landscape
  299.                 ? carMode ? mBackAltLandCarModeIcon : mBackAltLandIcon
  300.                 : carMode ? mBackAltCarModeIcon : mBackAltIcon;
  301.     }
  302.  
  303.     private Drawable getBackIcon(boolean carMode, boolean landscape) {
  304.         return landscape
  305.                 ? carMode ? mBackLandCarModeIcon : mBackLandIcon
  306.                 : carMode ? mBackCarModeIcon : mBackIcon;
  307.     }
  308.  
  309.     public void setNavigationIconHints(int hints, boolean force) {
  310.         if (!force && hints == mNavigationIconHints) return;
  311.         final boolean backAlt = (hints & StatusBarManager.NAVIGATION_HINT_BACK_ALT) != 0;
  312.         if ((mNavigationIconHints & StatusBarManager.NAVIGATION_HINT_BACK_ALT) != 0 && !backAlt) {
  313.             mTransitionListener.onBackAltCleared();
  314.         }
  315.         if (DEBUG) {
  316.             android.widget.Toast.makeText(getContext(),
  317.                 "Navigation icon hints = " + hints,
  318.                 500).show();
  319.         }
  320.  
  321.         mNavigationIconHints = hints;
  322.  
  323.         // We have to replace or restore the back and home button icons when exiting or entering
  324.         // carmode, respectively. Recents are not available in CarMode in nav bar so change
  325.         // to recent icon is not required.
  326.         Drawable backIcon = (backAlt)
  327.                 ? getBackIconWithAlt(mCarMode, mVertical)
  328.                 : getBackIcon(mCarMode, mVertical);
  329.         /// M: Support plugin customize.
  330.         //getBackButton().setImageDrawable(backIcon);
  331.         getBackButton().setImageDrawable(mNavBarPlugin.getBackImage(backIcon));//设置返回图标
  332.  
  333.         updateRecentsIcon();//最近列表图标
  334.         /// M: BMW @{
  335.         if (MultiWindowManager.isSupported()) {
  336.             updateRestoreIcon();
  337.         }
  338.         /// @}
  339.        //设置home图标
  340.        
  341.         if (mCarMode) {
  342.             getHomeButton().setImageDrawable(mHomeCarModeIcon);
  343.         } else {
  344.             /// M: Support plugin customize.
  345.             //getHomeButton().setImageDrawable(mHomeDefaultIcon);
  346.             getHomeButton().setImageDrawable(mNavBarPlugin.getHomeImage(mHomeDefaultIcon));
  347.         }
  348.  
  349.         final boolean showImeButton = ((hints & StatusBarManager.NAVIGATION_HINT_IME_SHOWN) != 0);
  350.         getImeSwitchButton().setVisibility(showImeButton ? View.VISIBLE : View.INVISIBLE);
  351.         getImeSwitchButton().setImageDrawable(mImeIcon);
  352.  
  353.         // Update menu button in case the IME state has changed.
  354.         setMenuVisibility(mShowMenu, true);
  355.         getMenuButton().setImageDrawable(mMenuIcon);
  356.  
  357.         setDisabledFlags(mDisabledFlags, true);
  358.     }
  359.  
  360.     public void setDisabledFlags(int disabledFlags) {
  361.         setDisabledFlags(disabledFlags, false);
  362.     }
  363.  
  364.     public void setDisabledFlags(int disabledFlags, boolean force) {
  365.         if (!force && mDisabledFlags == disabledFlags) return;
  366.  
  367.         mDisabledFlags = disabledFlags;
  368.  
  369.         final boolean disableHome = ((disabledFlags & View.STATUS_BAR_DISABLE_HOME) != 0);
  370.  
  371.         // Disable recents always in car mode.
  372.         boolean disableRecent = (
  373.                 mCarMode || (disabledFlags & View.STATUS_BAR_DISABLE_RECENT) != 0);
  374.         final boolean disableBack = ((disabledFlags & View.STATUS_BAR_DISABLE_BACK) != 0)
  375.                 && ((mNavigationIconHints & StatusBarManager.NAVIGATION_HINT_BACK_ALT) == 0);
  376.         final boolean disableSearch = ((disabledFlags & View.STATUS_BAR_DISABLE_SEARCH) != 0);
  377.  
  378.         if (SLIPPERY_WHEN_DISABLED) {
  379.             setSlippery(disableHome && disableRecent && disableBack && disableSearch);
  380.         }
  381.  
  382.         ViewGroup navButtons = (ViewGroup) getCurrentView().findViewById(R.id.nav_buttons);
  383.         if (navButtons != null) {
  384.             LayoutTransition lt = navButtons.getLayoutTransition();
  385.             if (lt != null) {
  386.                 if (!lt.getTransitionListeners().contains(mTransitionListener)) {
  387.                     lt.addTransitionListener(mTransitionListener);
  388.                 }
  389.             }
  390.         }
  391.         if (inLockTask() && disableRecent && !disableHome) {
  392.             // Don't hide recents when in lock task, it is used for exiting.
  393.             // Unless home is hidden, then in DPM locked mode and no exit available.
  394.             disableRecent = false;
  395.         }
  396.  
  397.         getBackButton().setVisibility(disableBack      ? View.INVISIBLE : View.VISIBLE);
  398.         getHomeButton().setVisibility(disableHome      ? View.INVISIBLE : View.VISIBLE);
  399.         getRecentsButton().setVisibility(disableRecent ? View.INVISIBLE : View.VISIBLE);
  400.  
  401.         /// M: BMW @{
  402.         //hide restore when keyguard is showing
  403.         if (MultiWindowManager.isSupported() && mKeyguardViewMediator != null) {
  404.             boolean isKeyguardShowing = mKeyguardViewMediator.isShowing();
  405.             mResizeMode = mRestoreShow && !isKeyguardShowing;
  406.             updateRestoreIcon();
  407.         }
  408.         /// @}
  409.    }
  410.  
  411.     private boolean inLockTask() {
  412.         try {
  413.             return ActivityManagerNative.getDefault().isInLockTaskMode();
  414.         } catch (RemoteException e) {
  415.             return false;
  416.         }
  417.     }
  418.  
  419.     public void setLayoutTransitionsEnabled(boolean enabled) {
  420.         mLayoutTransitionsEnabled = enabled;
  421.         updateLayoutTransitionsEnabled();
  422.     }
  423.  
  424.     public void setWakeAndUnlocking(boolean wakeAndUnlocking) {
  425.         setUseFadingAnimations(wakeAndUnlocking);
  426.         mWakeAndUnlocking = wakeAndUnlocking;
  427.         updateLayoutTransitionsEnabled();
  428.     }
  429.  
  430.     private void updateLayoutTransitionsEnabled() {
  431.         boolean enabled = !mWakeAndUnlocking && mLayoutTransitionsEnabled;
  432.         ViewGroup navButtons = (ViewGroup) getCurrentView().findViewById(R.id.nav_buttons);
  433.         LayoutTransition lt = navButtons.getLayoutTransition();
  434.         if (lt != null) {
  435.             if (enabled) {
  436.                 lt.enableTransitionType(LayoutTransition.APPEARING);
  437.                 lt.enableTransitionType(LayoutTransition.DISAPPEARING);
  438.                 lt.enableTransitionType(LayoutTransition.CHANGE_APPEARING);
  439.                 lt.enableTransitionType(LayoutTransition.CHANGE_DISAPPEARING);
  440.             } else {
  441.                 lt.disableTransitionType(LayoutTransition.APPEARING);
  442.                 lt.disableTransitionType(LayoutTransition.DISAPPEARING);
  443.                 lt.disableTransitionType(LayoutTransition.CHANGE_APPEARING);
  444.                 lt.disableTransitionType(LayoutTransition.CHANGE_DISAPPEARING);
  445.             }
  446.         }
  447.     }
  448.  
  449.     private void setUseFadingAnimations(boolean useFadingAnimations) {
  450.         WindowManager.LayoutParams lp = (WindowManager.LayoutParams) getLayoutParams();
  451.         if (lp != null) {
  452.             boolean old = lp.windowAnimations != 0;
  453.             if (!old && useFadingAnimations) {
  454.                 lp.windowAnimations = R.style.Animation_NavigationBarFadeIn;
  455.             } else if (old && !useFadingAnimations) {
  456.                 lp.windowAnimations = 0;
  457.             } else {
  458.                 return;
  459.             }
  460.             WindowManager wm = (WindowManager)getContext().getSystemService(Context.WINDOW_SERVICE);
  461.             wm.updateViewLayout(this, lp);
  462.         }
  463.     }
  464.  
  465.     public void setSlippery(boolean newSlippery) {
  466.         WindowManager.LayoutParams lp = (WindowManager.LayoutParams) getLayoutParams();
  467.         if (lp != null) {
  468.             boolean oldSlippery = (lp.flags & WindowManager.LayoutParams.FLAG_SLIPPERY) != 0;
  469.             if (!oldSlippery && newSlippery) {
  470.                 lp.flags |= WindowManager.LayoutParams.FLAG_SLIPPERY;
  471.             } else if (oldSlippery && !newSlippery) {
  472.                 lp.flags &= ~WindowManager.LayoutParams.FLAG_SLIPPERY;
  473.             } else {
  474.                 return;
  475.             }
  476.             WindowManager wm = (WindowManager)getContext().getSystemService(Context.WINDOW_SERVICE);
  477.             wm.updateViewLayout(this, lp);
  478.         }
  479.     }
  480.  
  481.     public void setMenuVisibility(final boolean show) {
  482.         setMenuVisibility(show, false);
  483.     }
  484.  
  485.     public void setMenuVisibility(final boolean show, final boolean force) {
  486.         if (!force && mShowMenu == show) return;
  487.  
  488.         mShowMenu = show;
  489.  
  490.         // Only show Menu if IME switcher not shown.
  491.         final boolean shouldShow = mShowMenu &&
  492.                 ((mNavigationIconHints & StatusBarManager.NAVIGATION_HINT_IME_SHOWN) == 0);
  493.  
  494.         getMenuButton().setVisibility(shouldShow ? View.VISIBLE : View.INVISIBLE);
  495.     }
  496.  
  497.     @Override
  498.     public void onFinishInflate() {
  499.         updateRotatedViews();
  500.         ((NavigationBarInflaterView) findViewById(R.id.navigation_inflater)).setButtonDispatchers(
  501.                 mButtonDisatchers);
  502.  
  503.         getImeSwitchButton().setOnClickListener(mImeSwitcherClickListener);
  504.  
  505.         try {
  506.             WindowManagerGlobal.getWindowManagerService().registerDockedStackListener(new Stub() {
  507.                 @Override
  508.                 public void onDividerVisibilityChanged(boolean visible) throws RemoteException {
  509.                 }
  510.  
  511.                 @Override
  512.                 public void onDockedStackExistsChanged(final boolean exists) throws RemoteException {
  513.                     mHandler.post(new Runnable() {
  514.                         @Override
  515.                         public void run() {
  516.                             mDockedStackExists = exists;
  517.                             updateRecentsIcon();//最近列表图标变化的更改。
  518.                         }
  519.                     });
  520.                 }
  521.  
  522.                 @Override
  523.                 public void onDockedStackMinimizedChanged(boolean minimized, long animDuration)
  524.                         throws RemoteException {
  525.                 }
  526.  
  527.                 @Override
  528.                 public void onAdjustedForImeChanged(boolean adjustedForIme, long animDuration)
  529.                         throws RemoteException {
  530.                 }
  531.  
  532.                 @Override
  533.                 public void onDockSideChanged(int newDockSide) throws RemoteException {
  534.                 }
  535.             });
  536.         } catch (RemoteException e) {
  537.             Log.e(TAG, "Failed registering docked stack exists listener", e);
  538.         }
  539.  
  540.  
  541.         /// M: BMW restore button @{
  542.         if (MultiWindowManager.isSupported()) {
  543.             try {
  544.                 WindowManagerGlobal.getWindowManagerService()
  545.                     .registerFreeformStackListener(new IFreeformStackListener.Stub() {
  546.                     @Override
  547.                     public void onShowRestoreButtonChanged(final boolean isShown)
  548.                                  throws RemoteException {
  549.                         mHandler.post(new Runnable() {
  550.                             @Override
  551.                             public void run() {
  552.                                 //hide restore when keyguard is showing
  553.                                 boolean isKeyguardShowing = false;
  554.                                 if (mKeyguardViewMediator != null) {
  555.                                     isKeyguardShowing = mKeyguardViewMediator.isShowing();
  556.                                 }
  557.                                 mRestoreShow = isShown;
  558.                                 mResizeMode = isShown && !isKeyguardShowing;
  559.                                 updateRestoreIcon();
  560.                             }
  561.                     });
  562.                     }
  563.                 });
  564.             } catch (RemoteException e) {
  565.                 Log.e(TAG, "Failed registering freeform stack exists listener", e);
  566.             }
  567.  
  568.         }
  569.  
  570.         /// @}
  571.     }
  572.  
  573.     /// M: BMW restore button @{
  574.     private void updateRestoreIcon() {
  575.         if (MultiWindowManager.DEBUG)
  576.             Log.d(TAG, "BMW, updateRestoreIcon, mResizeMode = " + mResizeMode);
  577.         getRestoreButton().setImageDrawable(mRestoreIcon);
  578.         getRestoreButton().setVisibility(mResizeMode ? View.VISIBLE : View.INVISIBLE);
  579.     }
  580.     /// @}
  581.  
  582.     void updateRotatedViews() {
  583.         mRotatedViews[Surface.ROTATION_0] =
  584.                 mRotatedViews[Surface.ROTATION_180] = findViewById(R.id.rot0);
  585.         mRotatedViews[Surface.ROTATION_270] =
  586.                 mRotatedViews[Surface.ROTATION_90] = findViewById(R.id.rot90);
  587.  
  588.         updateCurrentView();
  589.     }
  590.  
  591.     private void updateCurrentView() {
  592.      //获取旋转角度，在控制树之前会对所以的view进行gone
  593.         final int rot = mDisplay.getRotation();
  594.         for (int i=0; i<4; i++) {
  595.             mRotatedViews[i].setVisibility(View.GONE);
  596.         }
  597.         mCurrentView = mRotatedViews[rot];
  598.         mCurrentView.setVisibility(View.VISIBLE);
  599.         for (int i = 0; i < mButtonDisatchers.size(); i++) {
  600.             mButtonDisatchers.valueAt(i).setCurrentView(mCurrentView);
  601.         }
  602. 		//加载时候的动画显示
  603.         updateLayoutTransitionsEnabled();
  604.     }
  605.  
  606.     private void updateRecentsIcon() {
  607.         /// M: Support plugin customize.
  608.         //getRecentsButton().setImageDrawable(mDockedStackExists ? mDockedIcon : mRecentIcon);
  609.         getRecentsButton().setImageDrawable(
  610.                 mNavBarPlugin.getRecentImage(mDockedStackExists ? mDockedIcon : mRecentIcon));
  611.     }
  612.  
  613.     public boolean isVertical() {
  614.         return mVertical;
  615.     }
  616.  
  617.     public void reorient() {
  618.         updateCurrentView();
  619.  
  620.         getImeSwitchButton().setOnClickListener(mImeSwitcherClickListener);
  621.  
  622.         mDeadZone = (DeadZone) mCurrentView.findViewById(R.id.deadzone);//死亡区域
  623.  
  624.         // force the low profile & disabled states into compliance
  625.         mBarTransitions.init();
  626.         setDisabledFlags(mDisabledFlags, true /* force */);//禁用一些功能。
  627.         setMenuVisibility(mShowMenu, true /* force */);//设置菜单的可见性
  628.  
  629.         if (DEBUG) {
  630.             Log.d(TAG, "reorient(): rot=" + mDisplay.getRotation());
  631.         }
  632.  
  633.         updateTaskSwitchHelper();
  634.         setNavigationIconHints(mNavigationIconHints, true);//修改图标
  635.     }
  636.  
  637.     private void updateTaskSwitchHelper() {
  638.         boolean isRtl = (getLayoutDirection() == View.LAYOUT_DIRECTION_RTL);
  639.         mGestureHelper.setBarState(mVertical, isRtl);
  640.     }
  641.  
  642.     @Override
  643.     protected void onSizeChanged(int w, int h, int oldw, int oldh) {
  644.         if (DEBUG) Log.d(TAG, String.format(
  645.                     "onSizeChanged: (%dx%d) old: (%dx%d)", w, h, oldw, oldh));
  646.  
  647.         final boolean newVertical = w > 0 && h > w;//检查当前是水平还是竖直。
  648.        //当方向变化时，
  649. 		if (newVertical != mVertical) {
  650.             mVertical = newVertical;
  651.             //Log.v(TAG, String.format("onSizeChanged: h=%d, w=%d, vert=%s", h, w, mVertical?"y":"n"));
  652.             reorient();
  653.             notifyVerticalChangedListener(newVertical);
  654.         }
  655.  
  656.         postCheckForInvalidLayout("sizeChanged");
  657.         super.onSizeChanged(w, h, oldw, oldh);
  658.     }
  659.  
  660.     private void notifyVerticalChangedListener(boolean newVertical) {
  661.         if (mOnVerticalChangedListener != null) {
  662.             mOnVerticalChangedListener.onVerticalChanged(newVertical);
  663.         }
  664.     }
  665.  
  666.     @Override
  667.     protected void onConfigurationChanged(Configuration newConfig) {
  668.         super.onConfigurationChanged(newConfig);
  669.         boolean uiCarModeChanged = updateCarMode(newConfig);
  670.         updateTaskSwitchHelper();
  671.         updateIcons(getContext(), mConfiguration, newConfig);
  672.         updateRecentsIcon();
  673.         if (uiCarModeChanged || mConfiguration.densityDpi != newConfig.densityDpi) {
  674.             // If car mode or density changes, we need to reset the icons.
  675.             setNavigationIconHints(mNavigationIconHints, true);
  676.         }
  677.         mConfiguration.updateFrom(newConfig);
  678.     }
  679.  
  680.     /**
  681.      * If the configuration changed, update the carmode and return that it was updated.
  682.      */
  683.     private boolean updateCarMode(Configuration newConfig) {
  684.         boolean uiCarModeChanged = false;
  685.         if (newConfig != null) {
  686.             int uiMode = newConfig.uiMode & Configuration.UI_MODE_TYPE_MASK;
  687.             if (mCarMode && uiMode != Configuration.UI_MODE_TYPE_CAR) {
  688.                 mCarMode = false;
  689.                 uiCarModeChanged = true;
  690.             } else if (uiMode == Configuration.UI_MODE_TYPE_CAR) {
  691.                 mCarMode = true;
  692.                 uiCarModeChanged = true;
  693.             }
  694.         }
  695.         return uiCarModeChanged;
  696.     }
  697.  
  698.     /*
  699.     @Override
  700.     protected void onLayout (boolean changed, int left, int top, int right, int bottom) {
  701.         if (DEBUG) Log.d(TAG, String.format(
  702.                     "onLayout: %s (%d,%d,%d,%d)",
  703.                     changed?"changed":"notchanged", left, top, right, bottom));
  704.         super.onLayout(changed, left, top, right, bottom);
  705.     }
  707.     // uncomment this for extra defensiveness in WORKAROUND_INVALID_LAYOUT situations: if all else
  708.     // fails, any touch on the display will fix the layout.
  709.     @Override
  710.     public boolean onInterceptTouchEvent(MotionEvent ev) {
  711.         if (DEBUG) Log.d(TAG, "onInterceptTouchEvent: " + ev.toString());
  712.         if (ev.getAction() == MotionEvent.ACTION_DOWN) {
  713.             postCheckForInvalidLayout("touch");
  714.         }
  715.         return super.onInterceptTouchEvent(ev);
  716.     }
  717.     */
  718.  
  719.  
  720.     private String getResourceName(int resId) {
  721.         if (resId != 0) {
  722.             final android.content.res.Resources res = getContext().getResources();
  723.             try {
  724.                 return res.getResourceName(resId);
  725.             } catch (android.content.res.Resources.NotFoundException ex) {
  726.                 return "(unknown)";
  727.             }
  728.         } else {
  729.             return "(null)";
  730.         }
  731.     }
  732.  
  733.     private void postCheckForInvalidLayout(final String how) {
  734.         mHandler.obtainMessage(MSG_CHECK_INVALID_LAYOUT, 0, 0, how).sendToTarget();
  735.     }
  736.  
  737.     private static String visibilityToString(int vis) {
  738.         switch (vis) {
  739.             case View.INVISIBLE:
  740.                 return "INVISIBLE";
  741.             case View.GONE:
  742.                 return "GONE";
  743.             default:
  744.                 return "VISIBLE";
  745.         }
  746.     }
  747.  
  748.     public void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
  749.         pw.println("NavigationBarView {");
  750.         final Rect r = new Rect();
  751.         final Point size = new Point();
  752.         mDisplay.getRealSize(size);
  753.  
  754.         pw.println(String.format("      this: " + PhoneStatusBar.viewInfo(this)
  755.                         + " " + visibilityToString(getVisibility())));
  756.  
  757.         getWindowVisibleDisplayFrame(r);
  758.         final boolean offscreen = r.right > size.x || r.bottom > size.y;
  759.         pw.println("      window: "
  760.                 + r.toShortString()
  761.                 + " " + visibilityToString(getWindowVisibility())
  762.                 + (offscreen ? " OFFSCREEN!" : ""));
  763.  
  764.         pw.println(String.format("      mCurrentView: id=%s (%dx%d) %s",
  765.                         getResourceName(getCurrentView().getId()),
  766.                         getCurrentView().getWidth(), getCurrentView().getHeight(),
  767.                         visibilityToString(getCurrentView().getVisibility())));
  768.  
  769.         pw.println(String.format("      disabled=0x%08x vertical=%s menu=%s",
  770.                         mDisabledFlags,
  771.                         mVertical ? "true" : "false",
  772.                         mShowMenu ? "true" : "false"));
  773.  
  774.         dumpButton(pw, "back", getBackButton());
  775.         dumpButton(pw, "home", getHomeButton());
  776.         dumpButton(pw, "rcnt", getRecentsButton());
  777.         dumpButton(pw, "menu", getMenuButton());
  778.  
  779.         pw.println("    }");
  780.     }
  781.  
  782.     private static void dumpButton(PrintWriter pw, String caption, ButtonDispatcher button) {
  783.         pw.print("      " + caption + ": ");
  784.         if (button == null) {
  785.             pw.print("null");
  786.         } else {
  787.             pw.print(visibilityToString(button.getVisibility())
  788.                     + " alpha=" + button.getAlpha()
  789.                     );
  790.         }
  791.         pw.println();
  792.     }
  793.  
  794.     public interface OnVerticalChangedListener {
  795.         void onVerticalChanged(boolean isVertical);
  796.     }
  797.  
  798. }

    分析：

              1.在这里面我们可以控制不同方向的导航栏布局

             2  导航栏的图片的显示。

            

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