Question

I’m looking into creating a widget that supports animation, ideally via the android.view.animation framework, otherwise by setting properties on the remote views in code triggered from a background service.

Does anyone have any experience with either of these approaches, and is what I’m trying doable, or am I heading up a blind alley?

Answer 1

It’s actually possible to animate RemoteView widgets. The problem is it is super restrictive which is by design because of the security implications of running custom code in a system process.

What I mean by this is that Android will only work with animations that are expressed in res/anim xml files that are tied to layouts via xml. Some RemoteView widgets support this

An example of this is the News and Weather app widget that comes on a stock android system. What it is doing is using a ViewFlipper to cycle through each news story every 10 seconds or so.

    <ViewFlipper android:layout_width="match_parent" android:layout_height="wrap_content" android:measureAllChildren="true" android:flipInterval="10000" android:autoStart="true"
android:inAnimation="@android:anim/fade_in" android:outAnimation="@android:anim/fade_out" android:animateFirstView="true">
      <TextView android:id="@+id/Description1TextView" style="@style/AWCText.Centered" android:layout_width="match_parent" android:layout_height="wrap_content"/>
      <TextView android:id="@+id/Description2TextView" style="@style/AWCText.Centered" android:layout_width="match_parent" android:layout_height="wrap_content"/>
      <TextView android:id="@+id/Description3TextView" style="@style/AWCText.Centered" android:layout_width="match_parent" android:layout_height="wrap_content"/>
      <TextView android:id="@+id/Description4TextView" style="@style/AWCText.Centered" android:layout_width="match_parent" android:layout_height="wrap_content"/>
    </ViewFlipper>

In this example you can tie pending intents to each TextView. So when a user clicks on any one a different action can occur.

Lastly, Android has been slowly adding support for animated views in each version. For example TransitionDrawables (cross fading selector drawable) don’t cross-fade until Android 3.0.