Let's practice how to control the System UI by referring to the Android documentation

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Download PPT : https://github.com/ggujangi/ggu.system.ui/files/4094927/System.UI.Visibility.ppt.pptx

• Dimming the System Bars
• Hiding the Status Bar
• Hiding the Navigation Bar
• Using Immersive Full-Screen Mode

• Available in Android 4.0 (API level 14) and higher
• You can dim the status and notification bars using the SYSTEM_UI_FLAG_LOW_PROFILE flag
• As soon as the user touches the status or navigation bar, the flag is cleared

• Calling setSystemUiVisibility() with SYSTEM_UI_FLAG_VISIBLE flag clears all flags
• As soon as the user touches the status or navigation bar, the flag is cleared

View mDecorView = getActivity().getWindow().getDecorView();
int mOption = View.SYSTEM_UI_FLAG_LOW_PROFILE;
mDecorView.setSystemUiVisibility(mOption);
// clear all flags
mDecorView.setSystemUiVisibility(SYSTEM_UI_FLAG_VISIBLE);

• Setting an activity theme

  <application
    ...
    android:theme="@android:style/Theme.Holo.NoActionBar.Fullscreen">
    ...
  </application>

• Setting WindowManager flags

  • When you set WindowManager flags, the flags remain in effect unless your app clears them
  • You can use FLAG_LAYOUT_IN_SCREEN to set your activity layout to use the same screen area that's available when you've enabled FLAG_FULL_SCREEN

  getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);

• Setting UI Flags

  • Calling setSystemUiVisibility() with SYSTEM_UI_FLAG_FULLSCREEN flag hides the status bar

  View mDecorView = getActivity().getWindow().getDecorView();
  int mOption = View.SYSTEM_UI_FLAG_FULLSCREEN;
  mDecorView.setSystemUiVisibility(mOption);

• Responding to UI Visibility Changes

  • When the user reopens the activity, onCreate() won't get called, so if you want system UI changes to persist, set UI flags in onResume() of onWindowFocusChanged()

• Available in Android 4.1 (API level 16) and higher
• If you use SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION, the content will not be resized when the navigation bar is hidden and visible.
• SYSTEM_UI_FLAG_LAYOUT_STABLE helps your app maintain a stable layout.
• android:fitsSystemWindows adjusts the padding of the parent ViewGroup and if set to true the app's UI will not be covered by the system bar

• Calling setSystemUiVisibility() with SYSTEM_UI_FLAG_HIDE_NAVIGATION flag hides the navigation bar
• You can also hide the status bar by using the SYSTEM_UI_FLAG_FULLSCREEN flag together. This works the same as Lean back in Full screen Options

View mDecorView = getActivity().getWindow().getDecorView();
int mOption = View.SYSTEM_UI_FLAG_HIDE_NAVIGATION;
// Hide both the navigation bar and the status bar
int bothOption = View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
              | View.SYSTEM_UI_FLAG_FULLSCREEN;
mDecorView.setSystemUiVisibility(mOption);

• Available in Android 4.1 (API level 16) and higher
• If you use SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION, the content will not be resized when the navigation bar is hidden and visible
• SYSTEM_UI_FLAG_LAYOUT_STABLE helps your app maintain a stable layout

• The lean back mode is for fullscreen experiences in which users won't be interacting heavily with the screen
• For example, watching a video.
• When the user taps anywhere on the screen, the system bar appears
• Calling setSystemUiVisibility() with SYSTEM_UI_FLAG_FULLSCREEN and SYSTEM_UI_FLAG_HIDE_NAVIGATION
• When the system bars re-appear, you can receive a callback to make other appropriate updates to your UI

View mDecorView = getActivity().getWindow().getDecorView();
int mOption = View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
          | View.SYSTEM_UI_FLAG_FULLSCREEN;
mDecorView.setSystemUiVisibility(mOption);

• The immersive mode is intended for apps in which user will be heavily interacting with the screen
• For example, games, viewing images in a gallery, or reading paginated content
• When user swipe from any edge where a system bar is hidden, the system bars appear
• Calling setSystemUiVisibility() with SYSTEM_UI_FLAG_IMMERSIVE and SYSTEM_UI_FLAG_FULLSCREEN, SYSTEM_UI_FLAG_HIDE_NAVIGATION
• When the system bars re-appear, you can receive a callback to make other appropriate updates to your UI

View mDecorView = getActivity().getWindow().getDecorView();
int mOption = View.SYSTEM_UI_FLAG_IMMERSIVE
          | View.SYSTEM_UI_FLAG_FULLSCREEN
          | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION;
mDecorView.setSystemUiVisibility(mOption);

• For example, drawing app, playing a game that requires lots of swiping
• When user swipe from any edge where a system bar is hidden, the system bars appear but they're semi-transparent
• The bars automatically disappear after a few seconds of no interaction or as soon as the user touches or gestures anywhere outside the system bars
• Calling setSystemUiVisibility() with SYSTEM_UI_FLAG_IMMERSIVE_STICKY and SYSTEM_UI_FLAG_FULLSCREEN, SYSTEM_UI_FLAG_HIDE_NAVIGATION
• With sticky immersive, You cannot receive a callback when the system UI visibility changes

View mDecorView = getActivity().getWindow().getDecorView();
int mOption =  View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY
          | View.SYSTEM_UI_FLAG_FULLSCREEN
          | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION;
mDecorView.setSystemUiVisibility(mOption);