Android导航栏功能项的显示与屏蔽介绍

 Android 的导航栏有诸多功能,例入 截屏，音量加，音量减，最近任务，菜单．返回，主页面，输入法开关．．．．．．

代码源路径：frameworks\base\packages\SystemUI\src\com\android\systemui\statusbar\phone\NavigationBarView.java

   public ButtonDispatcher getScreenshotButton() {
       return mButtonDispatchers.get(R.id.screenshot);
   }

public ButtonDispatcher getVolumeAddButton() {
       return mButtonDispatchers.get(R.id.volume_add);
   }

public ButtonDispatcher getVolumeSubButton() {
       return mButtonDispatchers.get(R.id.volume_sub);
   }

public ButtonDispatcher getRecentsButton() {
       return mButtonDispatchers.get(R.id.recent_apps);
   }

public ButtonDispatcher getMenuButton() {
       return mButtonDispatchers.get(R.id.menu);
   }

public ButtonDispatcher getBackButton() {
       return mButtonDispatchers.get(R.id.back);
   }

public ButtonDispatcher getHomeButton() {
       return mButtonDispatchers.get(R.id.home);
   }

public ButtonDispatcher getImeSwitchButton() {
       return mButtonDispatchers.get(R.id.ime_switcher);
   }

public ButtonDispatcher getAccessibilityButton() {
       return mButtonDispatchers.get(R.id.accessibility_button);
   }

Android 即在此类中完成对 Button图标 的选择 . 

若需要展示/隐藏对应的 功能选项时，需要在此处修改：

private void prepareNavigationBarView() {
       mNavigationBarView.reorient();

ButtonDispatcher recentsButton = mNavigationBarView.getRecentsButton();
       recentsButton.setOnClickListener(this::onRecentsClick);
       recentsButton.setOnTouchListener(this::onRecentsTouch);
       recentsButton.setLongClickable(true);
       recentsButton.setOnLongClickListener(this::onLongPressBackRecents);

ButtonDispatcher backButton = mNavigationBarView.getBackButton();
       backButton.setLongClickable(true);
       backButton.setOnLongClickListener(this::onLongPressBackRecents);

ButtonDispatcher homeButton = mNavigationBarView.getHomeButton();
       homeButton.setOnTouchListener(this::onHomeTouch);
       homeButton.setOnLongClickListener(this::onHomeLongClick);

ButtonDispatcher accessibilityButton =         mNavigationBarView.getAccessibilityButton();
       accessibilityButton.setOnClickListener(this::onAccessibilityClick);
       accessibilityButton.setOnLongClickListener(this::onAccessibilityLongClick);
       updateAccessibilityServicesState(mAccessibilityManager);

ButtonDispatcher screenshotButton = mNavigationBarView.getScreenshotButton();
       screenshotButton.setOnClickListener(this:: screenshotClick);
       screenshotButton.setOnTouchListener(this:: screenshotTouch);
       boolean isShow=Settings.System.getInt(getContext().getContentResolver(), Settings.System.SCREENSHOT_BUTTON_SHOW, 1) == 1;
       if(isShow){
           screenshotButton.setVisibility(View.VISIBLE);
       }else{
           screenshotButton.setVisibility(View.GONE);
       }

ButtonDispatcher volumeAddButton=mNavigationBarView.getVolumeAddButton();
       ButtonDispatcher volumeSubButton=mNavigationBarView.getVolumeSubButton();
       boolean isShowVolumeButton="true".equals(SystemProperties.get("ro.rk.systembar.voiceicon","true"));
       if(isShowVolumeButton){
           volumeAddButton.setVisibility(View.VISIBLE);
           volumeSubButton.setVisibility(View.VISIBLE);
       }else{
           volumeAddButton.setVisibility(View.GONE);
           volumeSubButton.setVisibility(View.GONE);
       }
       if (getContext().getResources().getConfiguration().smallestScreenWidthDp < 400) {
           volumeAddButton.setVisibility(View.GONE);
           volumeSubButton.setVisibility(View.GONE);
       }
   }

可以将对应的Button 设置 setVisibility(View.GONE / View.INVISIBLE / View.VISIBLE); 

 当加上setVisibility时,UI界面还没显示时,需要注意config.xml中是否有写进去需要的Button . 

frameworks\base\packages\SystemUI\res\values\config.xml

<string name="config_navBarLayout" translatable="false">left;volume_sub,back,home,recent,volume_add;right</string>

需要注意的是,config中配置的顺序 即为 UI的显示顺序 .

提一嘴，如果需要用到屏蔽状态栏以及任务栏，可以将如下status_bar_height的高度设为０.

 frameworks\base\core\res\res\values\dimens.xml

   <!-- Height of the status bar -->
   <dimen name="status_bar_height">0dp</dimen>

来源：https://blog.csdn.net/qq_44844314/article/details/122059496