docs/html/design/patterns/buttons.jd

page.title=Buttons
page.tags="buttons"
@jd:body

<p>
  Some content is best experienced full screen, like videos, games, image
  galleries, books, and slides in a presentation. You can engage users more
  deeply with content in full screen by minimizing visual distraction from app
  controls and protecting users from escaping the app accidentally.
</p>

<div style="margin:auto;padding:auto;text-align:center;">
    <img src="{@docRoot}design/media/fullscreen_landing.png" style="margin:1em auto 2em auto;">
</div>
<p>
  In version 4.4, Android offers two approaches for making your app go full
  screen: Lean Back and Immersive. In both approaches, all persistent system
  bars are hidden. The difference between them is how the user brings the bars
  back into view.
</p>

<div class="layout-content-row">
  <div class="layout-content-col span-6">
    <h4>Lean Back</h4>
    <p>Touch the screen anywhere to bring back system bars. </p>
    <img src="{@docRoot}design/media/fullscreen_leanback.png" style="width:311px;">
  </div>
  <div class="layout-content-col span-6">
    <h4>Immersive</h4>
    <p>Swipe from the any edge of the screen with a hidden bar to bring back system bars. </p>
    <img src="{@docRoot}design/media/fullscreen_immersive_swipe_bottom.png" style="width:160px;float:right">
    <img src="{@docRoot}design/media/fullscreen_immersive_swipe_top.png" style="width:160px">
  </div>
</div>

<h2 id="leanback">
  Lean Back
</h2>

<p>
  The Lean Back approach is for full-screen experiences in which users won't be
  interacting heavily with the screen while consuming content, like while
  watching a video.
</p>

<p>
  In this type of experience, users are leaning back and watching the screen.
  Then, when they need to bring back the bars, they simply touch anywhere. This
  gesture is easy and intuitive.
</p>

    <img src="{@docRoot}design/media/fullscreen_leanback.png" style="width:311px;">

<h2 id="immersive">
  Immersive
</h2>

<p>
  The Immersive approach is mainly intended for apps in which the user will be
  heavily interacting with the full screen as part of the primary experience.
  Examples are games, viewing images in a gallery, or reading paginated
  content, like a book or slides in a presentation.
</p>

<p>
  In this type of experience, when users need to bring back the system bars,
  they swipe from any edge where a system bar is hidden. By requiring this more
  deliberate gesture, the user's deep engagement with your app won't be
  interrupted by accidental touches and swipes.
</p>

<div class="layout-content-row">
  <div class="layout-content-col span-6">
    <img src="{@docRoot}design/media/fullscreen_immersive_swipe_bottom.png" style="width:160px;float:right">
    <img src="{@docRoot}design/media/fullscreen_immersive_swipe_top.png" style="width:160px">
  </div>
</div>

<p>
  The user learns about the gesture to bring back the system bars through a
  message that appears the first time the app goes full screen.
</p>

<p>
  If your app has its own controls that aren't needed when a user is immersed
  in content, make them disappear and reappear in sync with the system bars.
  This rule also applies to any app-specific gestures you might have for hiding
  and showing app controls. For example, if touching anywhere on the screen
  toggles the appearance of an action bar or a palette, then it must also
  toggle the appearance of system bars.
</p>

<p>
  You might be tempted to use this approach just to maximize screen real
  estate. But be mindful of how often users jump in and out of apps to check
  notifications, do impromptu searches, and more. This approach will cause
  users to lose easy access to system navigation, so a little extra space
  should not be the only benefit they're getting in return.
</p>

<h2 id="variation_using_edges">
  Variation: Swiping from edges with bars also affects the app
</h2>

<p>
  In the Immersive approach, any time a user swipes from an edge with a system
  bar, the Android framework takes care of revealing the system bars. Your app
  won't even be aware that this gesture occurred.
</p>

<p>
  But in some apps, the user might occasionally need to swipe from the edge as
  <strong>part of the primary app experience</strong>. Examples are games and
  drawing applications.
</p>

<p>
  For apps with this requirement, you can use a variation on the Immersive
  approach: when a user swipes from an edge with a system bar, system bars are
  shown and the gesture is passed to the app so the app can respond to the
  gesture.
</p>

<p>
  For example, in a drawing app that uses this approach, if a user wants to
  draw a line that begins at the very edge of the screen, swiping from the edge
  would reveal the system bars and also start drawing a line that begins at the
  very edge.
</p>

<p>
  In this approach, to minimize disruption while a user is deeply engaged in
  the app, the system bars are 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.
</p>

<h2 id="lightsout">What About Lights Out Mode?</h2>

<p>
  Before Android 4.4, the design guideline was to use Lights Out mode, a mode
  in which the Action Bar and Status Bar fades away and becomes unavailable
  after a few seconds of inactivity. The Navigation Bar is still available and
  responds to touches but appears dimmed.
</p>

<p>
  Replace previous implementations of Lights Out mode with the Lean Back or
  Immersive approaches. Continue to use Lights Out mode for implementations of
  your app targeted for earlier releases.
</p>