canvas-animation-api.kt

const val G = -9.8f

// we are sending one item to the producerChannel at a time

val xVelocity = Random.nextInt(-50, 50)
val yVelocity = 100 // Random.nextInt(0, 200)
return ItemStateBuilder(
    composeCanvasDrawItem = getTextCanvasObject("\uD83D\uDD25"),
    initialX = width / 2,
    initialY = (height - 500f),
)
    .animateX {
        object : Animation<Float, AnimationVector1D> {
            override val durationNanos: Long
                get() = Long.MAX_VALUE
            override val isInfinite: Boolean
                get() = true
            override val targetValue: Float
                get() = 0f
            override val typeConverter: TwoWayConverter<Float, AnimationVector1D>
                get() = Float.VectorConverter
            override fun getValueFromNanos(playTimeNanos: Long): Float {
                return initialX + (xVelocity * playTimeNanos / 100_000_000).toFloat()
            }
            override fun getVelocityVectorFromNanos(playTimeNanos: Long): AnimationVector1D {
                return Float.VectorConverter.convertToVector(targetValue)
            }
        }
    }
    .animateY {
        object : Animation<Float, AnimationVector1D> {
            override val durationNanos: Long
                get() = Long.MAX_VALUE
            override val isInfinite: Boolean
                get() = true
            override val targetValue: Float
                get() = 0f
            override val typeConverter: TwoWayConverter<Float, AnimationVector1D>
                get() = Float.VectorConverter
            override fun getValueFromNanos(playTimeNanos: Long): Float {
                val time = playTimeNanos / 100_000_000f
                return initialY - ((yVelocity * time) + (0.5 * G * (time * time))).toFloat()
            }
            override fun getVelocityVectorFromNanos(playTimeNanos: Long): AnimationVector1D {
                return Float.VectorConverter.convertToVector(targetValue)
            }
        }
    }
    .terminalCondition { _, interpolatedY, _, _, _, _, _ ->
        interpolatedY > height
    }
    .build()