AI 150538: add note that appwidget updates will wake the device and suggest an alarm
BUG=1962600
Automated import of CL 150538
diff --git a/docs/html/guide/topics/appwidgets/index.jd b/docs/html/guide/topics/appwidgets/index.jd
index 01a9648..fc0061d 100644
--- a/docs/html/guide/topics/appwidgets/index.jd
+++ b/docs/html/guide/topics/appwidgets/index.jd
@@ -150,14 +150,26 @@
<code>(number of cells * 74) - 2</code><br/>
Following this formula, you should use 72 dp for a height of one cell, 294 dp and for a width of four cells.</p>
</li>
- <li>The <code>updatePerdiodMillis</code> attribute defines how often the App Widget framework should
+ <li>The <code>updatePeriodMillis</code> attribute defines how often the App Widget framework should
request an update from the {@link android.appwidget.AppWidgetProvider} by calling the
{@link android.appwidget.AppWidgetProvider#onUpdate(Context,AppWidgetManager,int[])
onUpdate()} method. The actual update is not guaranteed to occur exactly on time with this value
and we suggest updating as infrequently as possible—perhaps no more than once an hour to
conserve the battery. You might also allow the user to adjust the frequency in a
configuration—some people might want a stock ticker to update every 15 minutes, or maybe
- only four times a day.</li>
+ only four times a day.
+ <p class="note"><strong>Note:</strong> If the device is asleep when it is time for an update
+ (as defined by <code>updatePeriodMillis</code>), then the device will wake up in order
+ to perform the update. If you don't update more than once per hour, this probably won't
+ cause significant problems for the battery life. If, however, you need to update more
+ frequently and/or you do not need to update while the device is asleep, then you can instead
+ perform updates based on an alarm that will not wake the device. To do so, set an alarm with
+ an Intent that your AppWidgetProvider receives, using the {@link android.app.AlarmManager}.
+ Set the alarm type to either {@link android.app.AlarmManager#ELAPSED_REALTIME} or
+ {@link android.app.AlarmManager#RTC}, which will only
+ deliver the alarm when the device is awake. Then set <code>updatePeriodMillis</code> to
+ zero (<code>"0"</code>).</p>
+ </li>
<li>The <code>initialLayout</code> attribute points to the layout resource that defines the
App Widget layout.</li>
<li>The <code>configure</code> attribute defines the {@link android.app.Activity} to launch when
