docs/html/wear/preview/behavior-changes.jd

page.title=Behavior Changes
meta.keywords="preview", "wear"
page.tags="preview", "developer preview"

@jd:body

<p>
  Along with new features, Android Wear 2.0 includes a variety of behavior
  changes. This document highlights some of the key changes to
  account for in your apps.
</p>

<p>
  If you have previously published an app for Android Wear, be aware that
  your app might be affected by these changes in the platform.
</p>

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

<h2>In this document</h2>

<ul>
  <li><a href="#activity-dismissal">Activity Dismissal</a></li>
  <li><a href="#invalid-fields">Invalid Fields for a Complication Type</a></li>
  <li><a href="#empty">Complication Types for Empty Data</a></li>
</ul>

</div>
</div>

<h2 id="activity-dismissal">Activity Dismissal</h2>

<p>
  Starting in <a href="{@docRoot}wear/preview/index.html">Android Wear 2.0</a>,
  users dismiss apps and activities by using
  the power (stem) button on the watch.
  Long-pressing to dismiss an app is no longer suggested.
  Additionally, developers should not implement the
  long-press for dismissing
  <a href="{@docRoot}training/wearables/ui/exit.html">full screen</a>
  activities (panning or immersive activities such as Google Maps).
</p>

<p>
  In Android Wear 2.0, the power button of the watch is used
  to navigate back in the
  <a href="{@docRoot}guide/components/tasks-and-back-stack.html">back stack</a>,
  including for full-screen panning activities.
  Before Android Wear 2.0, the <code>DismissOverlayView</code> class was
  used to implement the long-press for a user to dismiss an app.
  (The <code>DismissOverlayView</code> class was added to a layout
  for full-screen drawing and to draw over the other views.)
  Developers should test the power button for going back
  between an app's activities and for exiting an app.
</p>

<p>
  Additionally, swipe for exiting an app or activity is not available.
  Developers can consider how their user interfaces
  can be enhanced with swipe-left and swipe-right,
  in a way similar to the functionality described for
  <a href="{@docRoot}wear/preview/features/ui-nav-actions.html">navigation
  drawers</a>.
</p>

<h2 id="invalid-fields">Invalid Fields for a Complication Type</h2>

<p>
  When a watch face uses the <a href="{@docRoot}wear/preview/features/complications.html">
  Complications API</a>, the watch face requests data from a chosen provider.
  A <code>ComplicationData</code> object, which contains
  complication types, is returned.
</p>

<p>
  A complication type determines the
  kinds of data that a watch face can render. This section describes
  a behavior change related to the <code>ComplicationData</code> object.
</p>

<p>
  Starting with
  <a href="https://developer.android.com/wear/preview/support.html#dp3">
  Developer Preview 3</a>, when a watch face requests a field that is invalid
  for a complication type, a default value for the field is returned.
  For example, if a watch face tries to access a <code>Long text</code>
  field in a <code>SHORT_TEXT</code> type, the default value for the
  <code>Long text</code> field is returned.
  In previous releases, such a request for an invalid field
  (for a type) resulted in an exception.
</p>

<h2 id="empty">Complication Types for Empty Data</h2>

<p>
  Starting with
  <a href="https://developer.android.com/wear/preview/support.html#dp3">
  Developer Preview 3</a>, the complication types used for "empty" data are
  changed. Apps that use the Complications API
  may need to be updated to use
  <code>TYPE_NO_DATA</code>. See the information
  about <code>TYPE_NO_DATA</code> in the
  <a href="{@docRoot}wear/preview/features/complications.html#types_and_fields">
  Types and fields</a> section.
</p>