Declarative & implicit animations Library for Xamarin Forms.

Xamarin Forms provides a common animation API, especially powerful with its async/await structure and extensibility. For many apps, it may be all that is necessary. However, it operates by setting up its own timing and modifying native view propertiies as it goes. This means the platform's hardware acceleration around animations can't be leveraged. Our experience was a sluggish feel that didn't "pop" the way a native app would.

To automatically animate the opacity of an element, simply add the transition to its attached property. Any property changes will then be animated according to the declaration.

xmlns:trans="clr-namespace:OliveTree.Transitions;assembly=OliveTree.Transitions"

<Grid x:Name="StatusIndicator">
  <trans:Interaction.Transitions>
    <trans:TransitionCollection>
      <trans:OpacityTransition />
    </trans:TransitionCollection>
  </trans:Interaction.Transitions>

  <Grid.Triggers>
    <DataTrigger Binding="{Binding IsProcessing}" Value="False" TargetType="Grid" >
      <Setter Property="Opacity" Value="0" />
    </DataTrigger>
  </Grid.Triggers>
</Grid>

Or triggered in code-behind:

StatusIndicator.Opacity = 0;

For the common implementation to resolve platform animations, it must be given an ITransitionProvider. Each platform has one built in, but you are welcome to override it should needs arise. Generally, you will initialize it with:

Forms.Init();
TransitionsLibrary.Register<Provider>();