Hi! I'm having some difficulties to understand how...

# compose

[Miguel Coleto]

Hi! I'm having some difficulties to understand how my components are being recomposed.

I'm making a simple dice roller app and I want to animate every dice every time I produce a new roll.
The thing is that if a dice gets the same result as the previous roll it won't animate again. This is working as expected I suppose. But there are sometimes when a new result won't animate the dice again and this I don't understand.

I'd like to fix that and force the animation even if the result is the same

[Miguel Coleto]

ComposeDice

[Miguel Coleto]

There's a video of the described issue

[Miguel Coleto]

@Composable
fun Dice(
    number: DiceNumber,
    isEnabled: Boolean = true,
    modifier: Modifier = Modifier
) {
    val diceNumberDrawable = when (number) {
        DiceNumber.One -> R.drawable.dice_one
        DiceNumber.Two -> R.drawable.dice_two
        DiceNumber.Three -> R.drawable.dice_three
        DiceNumber.Four -> R.drawable.dice_four
        DiceNumber.Five -> R.drawable.dice_five
        DiceNumber.Six -> R.drawable.dice_six
    }.run { vectorResource(id = this) }

    val rotation = animatedFloat(0f)
    val randomSpins = remember(number.value) { Random.nextInt(2, 4) }
    val randomDuration = remember(number.value) { Random.nextInt(600, 1200) }
    rotation.animateTo(
        targetValue = 360f * randomSpins,
        anim = tween(
            durationMillis = randomDuration,
            easing = CubicBezierEasing(0.3f, 0.9f, 1f, 1f)
        )
    )

    Image(
        asset = diceNumberDrawable,
        alpha = if (isEnabled) 1f else 0.4f,
        modifier = modifier
            .size(80.dp)
            .drawLayer(rotationZ = rotation.value)
    )
}

[Yann Badoual]

You could use an Int that you increment each time you press the roll button. And use this int as a key to the remember calls instead of number.value . This way each roll will reset the value remembered and should re-trigger the animateTo call

[Miguel Coleto]

Makes sense, I'll try 👌

[Miguel Coleto]

I've tried to pass the seed I use for generating a Random object for remembering it but the behavior is still the same :/

[Miguel Coleto]

https://github.com/Cotel/ComposeDice/tree/master/app/src/main/java/com/cotel/composedice/diceroller

[Timo Drick]

I do not really understand your DiceNumber system. But my guess is that this DiceNumber class confuses compose and compose is not able to associate the different composables each time you do a new roll.
You could add in DiceDrawer.kt:31

chunk.forEach { number ->
    key(number) {
        Dice(
            number = number,
            isEnabled = number.value >= minimumResult,
            modifier = Modifier.weight(1f)
        )
    }
}

But in theory this should not be necessary.

[Miguel Coleto]

The dice number class is an attempt to strongly type the restriction of dice results. I'll try to simplify and see what happens

[Timo Drick]

When you add this key(number) all dices will roll every time

[Miguel Coleto]

Should this be done for every list, even if they are not for dices like this one? React forces you to use unique keys in lists

[Timo Drick]

No also i found out that when you use this key the savedinstanceState thing is not working as expected. So better to not use this.