Annoying `AdditiveAnimator` constructor with Kotlin about android_additive_animations HOT 7 CLOSED

Found another really annoying side-effect of the generic types on AdditiveAnimator in Kotlin. It makes extension functions difficult as well:

  fun <T : AdditiveAnimator<T>> AdditiveAnimator<T>.visibleAlpha(isVisible: Boolean): AdditiveAnimator<T> {
    val endAlpha = if (isVisible) 1f else 0f
    return alpha(endAlpha)
  }

Kotlin errors out when you try to use this function, taking issue with the recursive types.

I've had to work around it by using:

  fun <T : AdditiveAnimator<*>> AdditiveAnimator<T>.visibleAlpha(isVisible: Boolean): AdditiveAnimator<T> {
    val endAlpha = if (isVisible) 1f else 0f
    @Suppress("UNCHECKED_CAST")
    return alpha(endAlpha) as AdditiveAnimator<T>
  }

from android_additive_animations.

Hi,

I will add the static creation methods you suggested, but I'm having no problem using the AdditiveAnimator.animate() methods in Kotlin.

I don't really know Kotlin very well (I only just installed AS 3.0 after I read your comment), but I came up with a few solutions to the function extension problem:

First, you can provide a subclass which instantiates the generic type.
Second, you can simply omit the generic specification and use AdditiveAnimator<*>.

Let me know if these approaches seem usable to you:

// subclass specifies generic type
class AdditiveAnimatorSubclass : AdditiveAnimator<AdditiveAnimatorSubclass> {
    constructor(view: View) : super(view)

    // can simply return subclass
    fun visibleAlpha(visible: Boolean) : AdditiveAnimatorSubclass {
        return alpha(if(visible) 1f else 0f)
    }
}

// generic extension function
fun AdditiveAnimator<*>.visibleAlpha(isVisible: Boolean): AdditiveAnimator<*> {
    val endAlpha = if (isVisible) 1f else 0f
    return alpha(endAlpha)
}

// subclass extension function doesn't require generics
fun AdditiveAnimatorSubclass.xy(x: Float, y: Float): AdditiveAnimatorSubclass {
    return x(x).y(y)
}

class KotlinTestFragment : Fragment() {
    override fun onCreateView(inflater: LayoutInflater?, container: ViewGroup?, savedInstanceState: Bundle?): View? {
        val root = inflater?.inflate(R.layout.fragment_tap_to_move_demo, container, false)!!
        val animatedView = root.findViewById(R.id.animated_view)!!
        root.setOnTouchListener({ _, motionEvent ->
            AdditiveAnimatorSubclass(animatedView).xy(motionEvent.x, motionEvent.y).visibleAlpha(true).start()
            // this works fine as well:
//            AdditiveAnimator.animate(animatedView).x(motionEvent.x).y(motionEvent.y).visibleAlpha(true).start()
            true
        })
        return root
    }
}

I also pushed these changes to the /wirecube/android_additive_animations/tree/kotlin branch, if you'd like to try it out yourself.

from android_additive_animations.

@ScottPierce did you have a chance to try out the code sample?

from android_additive_animations.

from android_additive_animations.

Extending the base animation seems to be working well enough for the time being. Did you want me to keep this open to track the creation of the above mentioned static methods, or should this just be closed?

from android_additive_animations.

I wanted to wait until I merged the animate_objects branch, which has the improved construction methods, but got sidetracked working on performance improvements.
I'll finally merge this on the weekend, and close this issue once I do.

Thanks for reminding me!

from android_additive_animations.

Hi, I just merged the animate_objects branch which removes the generics from AdditiveAnimator. This should remove the need for subclassing and make working with Kotlin easier!

from android_additive_animations.