ImmersiveMode sample
This lesson describes how to hide the status bar on different versions of Android. Hiding the status bar (and optionally, the navigation bar) lets the content use more of the display space, thereby providing a more immersive user experience.
Figure 1 shows an app with a visible status bar:
Figure 1. Visible status bar.
Figure 2 shows an app with a hidden status bar. Note that the action bar is hidden too. You should never show the action bar without the status bar.
Figure 2. Hidden status bar.
You can hide the status bar on Android 4.0 (API level 14) and lower by setting {@link android.view.WindowManager} flags. You can do this programmatically or by setting an activity theme in your app's manifest file. Setting an activity theme in your app's manifest file is the preferred approach if the status bar should always remain hidden in your app (though strictly speaking, you could programmatically override the theme if you wanted to). For example:
<application
...
android:theme="@android:style/Theme.Holo.NoActionBar.Fullscreen" >
...
</application>
The advantages of using an activity theme are as follows:
Alternatively, you can programmatically set {@link android.view.WindowManager} flags. This approach makes it easier to hide and show the status bar as the user interacts with your app:
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// If the Android version is lower than Jellybean, use this call to hide
// the status bar.
if (Build.VERSION.SDK_INT < 16) {
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
}
setContentView(R.layout.activity_main);
}
...
}
When you set {@link android.view.WindowManager} flags (whether through an activity theme or programmatically), the flags remain in effect unless your app clears them.
You can use {@link android.view.WindowManager.LayoutParams#FLAG_LAYOUT_IN_SCREEN} to set your activity layout to use the same screen area that's available when you've enabled {@link android.view.WindowManager.LayoutParams#FLAG_FULLSCREEN}. This prevents your content from resizing when the status bar hides and shows.
You can hide the status bar on Android 4.1 (API level 16) and higher by using {@link android.view.View#setSystemUiVisibility setSystemUiVisibility()}. {@link android.view.View#setSystemUiVisibility setSystemUiVisibility()} sets UI flags at the individual view level; these settings are aggregated to the window level. Using {@link android.view.View#setSystemUiVisibility setSystemUiVisibility()} to set UI flags gives you more granular control over the system bars than using {@link android.view.WindowManager} flags. This snippet hides the status bar:
View decorView = getWindow().getDecorView(); // Hide the status bar. int uiOptions = View.SYSTEM_UI_FLAG_FULLSCREEN; decorView.setSystemUiVisibility(uiOptions); // Remember that you should never show the action bar if the // status bar is hidden, so hide that too if necessary. ActionBar actionBar = getActionBar(); actionBar.hide();
Note the following:
On Android 4.1 and higher, you can set your application's content to appear behind the status bar, so that the content doesn't resize as the status bar hides and shows. To do this, use {@link android.view.View#SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN}. You may also need to use {@link android.view.View#SYSTEM_UI_FLAG_LAYOUT_STABLE} to help your app maintain a stable layout.
When you use this approach, it becomes your responsibility to ensure that critical parts of your app's UI (for example, the built-in controls in a Maps application) don't end up getting covered by system bars. This could make your app unusable. In most cases you can handle this by adding the {@code android:fitsSystemWindows} attribute to your XML layout file, set to {@code true}. This adjusts the padding of the parent {@link android.view.ViewGroup} to leave space for the system windows. This is sufficient for most applications.
In some cases, however, you may need to modify the default padding to get the desired layout for your app. To directly manipulate how your content lays out relative to the system bars (which occupy a space known as the window's "content insets"), override {@link android.view.View#fitSystemWindows fitSystemWindows(Rect insets)}. The {@link android.view.View#fitSystemWindows fitSystemWindows()} method is called by the view hierarchy when the content insets for a window have changed, to allow the window to adjust its content accordingly. By overriding this method you can handle the insets (and hence your app's layout) however you want.
On Android 4.1 and higher, to avoid resizing your layout when the action bar hides and shows, you can enable overlay mode for the action bar. When in overlay mode, your activity layout uses all the space available as if the action bar is not there and the system draws the action bar in front of your layout. This obscures some of the layout at the top, but now when the action bar hides or appears, the system does not need to resize your layout and the transition is seamless.
To enable overlay mode for the action bar, you need to create a custom theme that extends an existing theme with an action bar and set the {@code android:windowActionBarOverlay} attribute to {@code true}. For more discussion of this topic, see Overlaying the Action Bar in the Adding the Action Bar class.
Then use {@link android.view.View#SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN}, as described above, to set your activity layout to use the same screen area that's available when you've enabled {@link android.view.View#SYSTEM_UI_FLAG_FULLSCREEN}. When you want to hide the system UI, use {@link android.view.View#SYSTEM_UI_FLAG_FULLSCREEN}. This also hides the action bar (because {@code windowActionBarOverlay=”true”)} and does so with a coordinated animation when both hiding and showing the two.