training/system-ui/immersive.jd

page.title=Using Immersive Full-Screen Mode

trainingnavtop=true

@jd:body

<div id="tb-wrapper">
<div id="tb">

<!-- table of contents -->
<h2>This lesson teaches you to</h2>
<ol>
  <li><a href="#compare">Choose an Approach</a></li>
  <li><a href="#nonsticky">Use Non-Sticky Immersion</a></li>
  <li><a href="#sticky">Use Sticky Immersion</a></li>
</ol>


<!-- other docs (NOT javadocs) -->
<h2>You should also read</h2>

<ul>
    <li>
        <a href="{@docRoot}training/appbar/index.html">Adding the App Bar</a>
    </li>
    <li>
        <a href="{@docRoot}design/patterns/fullscreen.html">
        Android Design Guide
        </a>
    </li>
</ul>


<h2>Try it out</h2>

<div class="download-box">
  <a href="{@docRoot}samples/ImmersiveMode/index.html"
class="button">Get the sample</a>
 <p class="filename">ImmersiveMode sample</p>
</div>

</div>
</div>

<a class="notice-developers-video wide" href="http://www.youtube.com/watch?v=cBi8fjv90E4">
<div>
    <h3>Video</h3>
    <p>DevBytes: Android 4.4 Immersive Mode</p>
</div>
</a>

<p>Android 4.4 (API Level 19) introduces a new
{@link android.view.View#SYSTEM_UI_FLAG_IMMERSIVE} flag for
{@link android.view.View#setSystemUiVisibility setSystemUiVisibility()} that lets your app
go truly "full screen." This flag, when combined with the
{@link android.view.View#SYSTEM_UI_FLAG_HIDE_NAVIGATION} and
{@link android.view.View#SYSTEM_UI_FLAG_FULLSCREEN} flags, hides the navigation and status
bars and lets your app capture all touch events on the screen.</p>

<p>When immersive full-screen mode is
enabled, your activity continues to receive all touch events. The user can reveal the
system bars with an inward swipe along the region where the system bars normally appear.
This clears the {@link android.view.View#SYSTEM_UI_FLAG_HIDE_NAVIGATION} flag
(and the {@link android.view.View#SYSTEM_UI_FLAG_FULLSCREEN} flag, if applied) so the
system bars become visible. This also triggers your
{@link android.view.View.OnSystemUiVisibilityChangeListener},
if set. However, if you'd like the system bars to automatically hide
again after a few moments, you can instead use the
{@link android.view.View#SYSTEM_UI_FLAG_IMMERSIVE_STICKY} flag. Note that the
"sticky" version of the flag doesn't trigger any listeners, as system bars temporarily
shown in this mode are in a transient state.
</p>

<p>Figure 1 illustrates the different "immersive mode" states:</p>

 <img src="{@docRoot}images/training/imm-states.png"
  alt="system bars">
<p class="img-caption"><strong>Figure 1.</strong> Immersive mode states.</p>

<p>In figure 1:</p>
<ol>
<li><strong>Non-immersive mode</strong>&mdash;This is how the app
appears before it enters immersive mode. It is also how the app appears if you use the
{@link android.view.View#SYSTEM_UI_FLAG_IMMERSIVE IMMERSIVE} flag, and the user swipes to
display the system bars, thereby clearing the {@link android.view.View#SYSTEM_UI_FLAG_HIDE_NAVIGATION} and
{@link android.view.View#SYSTEM_UI_FLAG_FULLSCREEN} flags. Once these flags are cleared, the system
bars reappear and remain visible.</li>

<p>Note that it's best practice to
 keep all UI controls in sync with the system bars, to minimize the
 number of states your screen can be in. This provides a more seamless user experience. So
 here all UI controls are displayed along with the status bars. Once the app enters
 immersive mode, the UI controls are hidden along with the system bars.
 To ensure that your UI visibility stays in sync with system bar visibility, make sure to
 provide an appropriate {@link android.view.View.OnSystemUiVisibilityChangeListener}
 to watch for changes, as described in
 <a href="visibility.html">Responding to UI Visibility Changes</a>.</p></li>

<li><strong>Reminder bubble</strong>&mdash;The system displays a reminder bubble
the first time users enter
immersive mode in your app. The reminder bubble reminds users how to display
the system bars.
<p class="note"><strong>Note:</strong> If you want to force the reminder bubble to appear
for testing purposes, you can do so by putting the app in immersive mode, turning off the
screen with the power button, and then turning the screen back on again within 5 seconds.
</p></li>

<li><strong>Immersive mode</strong>&mdash;This is the app in immersive mode, with the
system bars and other UI controls hidden. You can achieve this state with either
{@link android.view.View#SYSTEM_UI_FLAG_IMMERSIVE IMMERSIVE} or
 {@link android.view.View#SYSTEM_UI_FLAG_IMMERSIVE_STICKY IMMERSIVE_STICKY}. </li>

<li><strong>Sticky flag</strong>&mdash;This is the UI you see if you use the
{@link android.view.View#SYSTEM_UI_FLAG_IMMERSIVE_STICKY IMMERSIVE_STICKY} flag,
and the user swipes to display the system bars. Semi-transparent bars temporarily appear and then
hide again. The act of swiping doesn't clear any flags, nor does it trigger your
system UI visibility change listeners, because the transient appearance of the system bars isn't
considered a UI visibility change.</li>
</ol>

<p class="note"><strong>Note:</strong> Remember that the "immersive" flags only take effect
if you use them in conjunction with {@link android.view.View#SYSTEM_UI_FLAG_HIDE_NAVIGATION},
{@link android.view.View#SYSTEM_UI_FLAG_FULLSCREEN}, or
 both. You can just use one or the other, but it's common to hide both the status and the
 navigation bar when you're implementing "full immersion" mode.</p>

 <h2 id="compare">Choose an Approach</h2>

 <p>The flags  {@link android.view.View#SYSTEM_UI_FLAG_IMMERSIVE} and
 {@link android.view.View#SYSTEM_UI_FLAG_IMMERSIVE_STICKY} both provide an immersive
 experience, but with the differences in behavior described above. Here are
 examples of when you would use one flag vs. the other:</p>

<ul>
<li>If you're building a book reader, news reader, or a magazine, use
the {@link android.view.View#SYSTEM_UI_FLAG_IMMERSIVE IMMERSIVE} flag in conjunction
with {@link android.view.View#SYSTEM_UI_FLAG_FULLSCREEN} and
{@link android.view.View#SYSTEM_UI_FLAG_HIDE_NAVIGATION}. Because users may want to access
the action bar and other UI controls somewhat frequently, but not be bothered with any UI
elements while flipping through content,
{@link android.view.View#SYSTEM_UI_FLAG_IMMERSIVE IMMERSIVE} is a good option for this
use case.</li>

<li>If you're building a truly immersive app, where you expect users to interact near
the edges of the screen and you don't expect them to need frequent access to the system
UI, use the
{@link android.view.View#SYSTEM_UI_FLAG_IMMERSIVE_STICKY IMMERSIVE_STICKY} flag
in conjunction with {@link android.view.View#SYSTEM_UI_FLAG_FULLSCREEN} and
{@link android.view.View#SYSTEM_UI_FLAG_HIDE_NAVIGATION}. For example, this approach
might be suitable for a game or a drawing app.</li>

<li>If you're building a video player or some other app that requires minimal user
interaction, you can probably get by with the <a href="{@docRoot}design/patterns/fullscreen.html">
lean back</a> approach, available since
Android 4.0 (API Level 14). For this type of app, simply using
{@link android.view.View#SYSTEM_UI_FLAG_FULLSCREEN}
 and {@link android.view.View#SYSTEM_UI_FLAG_HIDE_NAVIGATION} should be
sufficient. Don't use the "immersive" flags in this case.</li>
</ul>

<h2 id="nonsticky">Use Non-Sticky Immersion</h2>

 <p>When you use the {@link android.view.View#SYSTEM_UI_FLAG_IMMERSIVE} flag, it hides
 the system bars based on what other UI flags you have set
 ({@link android.view.View#SYSTEM_UI_FLAG_HIDE_NAVIGATION},
 {@link android.view.View#SYSTEM_UI_FLAG_FULLSCREEN}, or
 both). When the user swipes inward in a system bars region, the
system bars reappear and remain visible.</p>

<p>It's good practice to include other system UI flags (such as
{@link android.view.View#SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION} and
{@link android.view.View#SYSTEM_UI_FLAG_LAYOUT_STABLE}) to keep the content from resizing
when the system bars hide and show. You should also make sure that the action bar and other
UI controls are hidden at the same time. This snippet demonstrates how to hide and show the
status and navigation bars, without resizing the content:</p>

<pre>
// This snippet hides the system bars.
private void hideSystemUI() {
    // Set the IMMERSIVE flag.
    // Set the content to appear under the system bars so that the content
    // doesn't resize when the system bars hide and show.
    mDecorView.setSystemUiVisibility(
            View.SYSTEM_UI_FLAG_LAYOUT_STABLE
            | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
            | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
            | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION // hide nav bar
            | View.SYSTEM_UI_FLAG_FULLSCREEN // hide status bar
            | View.SYSTEM_UI_FLAG_IMMERSIVE);
}

// This snippet shows the system bars. It does this by removing all the flags
// except for the ones that make the content appear under the system bars.
private void showSystemUI() {
    mDecorView.setSystemUiVisibility(
            View.SYSTEM_UI_FLAG_LAYOUT_STABLE
            | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
            | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN);
}
</pre>


<p>You may also want to implement the following in conjunction with the
{@link android.view.View#SYSTEM_UI_FLAG_IMMERSIVE IMMERSIVE} flag to provide a better user
experience:</p>

<ul>
<li>Register a listener so that your app can get notified of system UI visibility changes,
as described in <a href="visibility.html">Responding to UI Visibility Changes</a>.</li>

<li>Implement {@link android.app.Activity#onWindowFocusChanged onWindowFocusChanged()}.
If you gain window focus, you may want to re-hide the system bars.
If you lose window focus, for example due to a dialog or pop up menu showing above your app,
you'll probably want to cancel any pending "hide" operations you previously scheduled
with {@link android.os.Handler#postDelayed Handler.postDelayed()} or something similar.</li>

<li>Implement a {@link android.view.GestureDetector} that detects
{@link android.view.GestureDetector.OnGestureListener#onSingleTapUp}, to allow users to
manually toggle the visibility of the system bars by touching your content.
Simple click listeners aren't the best solution for this because they get triggered even
if the user drags a finger across the screen (assuming the click target takes up the whole
screen).
</li>

</ul>

<p>
For more discussion of these topics, watch the video
<a class ="external-link" href="http://www.youtube.com/embed/cBi8fjv90E4">DevBytes:
 Android 4.4 Immersive Mode</a>.</p>

<h2 id="sticky">Use Sticky Immersion</h2>

<p>When you use the {@link android.view.View#SYSTEM_UI_FLAG_IMMERSIVE_STICKY} flag,
an inward swipe in the system bars areas causes the bars to temporarily appear in a
semi-transparent state, but no flags are cleared, and your
system UI visibility change listeners are not triggered. The bars
automatically hide again after a short delay, or if the user interacts with the middle of the
screen.</p>

<p>Figure 2 shows the semi-transparent system bars that briefly appear and then hide again
when you use the {@link android.view.View#SYSTEM_UI_FLAG_IMMERSIVE_STICKY IMMERSIVE_STICKY} flag.</p>

 <img src="{@docRoot}images/training/imm-sticky.png"
  alt="system bars">
<p class="img-caption"><strong>Figure 2.</strong> Auto-hiding system bars.</p>

<p>Below is a simple approach to using this flag. Any time the window receives focus, simply
set the {@link android.view.View#SYSTEM_UI_FLAG_IMMERSIVE_STICKY IMMERSIVE_STICKY} flag, along
with the other flags discussed in <a href="#nonsticky">Use IMMERSIVE</a>. For example:</p>

<pre>
&#64;Override
public void onWindowFocusChanged(boolean hasFocus) {
        super.onWindowFocusChanged(hasFocus);
    if (hasFocus) {
        decorView.setSystemUiVisibility(
                View.SYSTEM_UI_FLAG_LAYOUT_STABLE
                | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
                | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
                | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
                | View.SYSTEM_UI_FLAG_FULLSCREEN
                | View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY);}
}
</pre>

<p class="note"><strong>Note:</strong> If you like the auto-hiding behavior of
{@link android.view.View#SYSTEM_UI_FLAG_IMMERSIVE_STICKY IMMERSIVE_STICKY}
but need to show your own UI controls as well, just use
{@link android.view.View#SYSTEM_UI_FLAG_IMMERSIVE IMMERSIVE} combined with
{@link android.os.Handler#postDelayed Handler.postDelayed()} or something similar to
re-enter immersive mode after a few seconds.</p>