I think Crossfade should not clip graphicsLayer. W...

# compose

[Konyaco]

I think Crossfade should not clip graphicsLayer.
When crossfade is animating, it uses:

keys.mapTo(items) { key ->
    CrossfadeAnimationItem(key) {
        val alpha by transition.animateFloat(
            transitionSpec = { animationSpec }
        ) { if (it == key) 1f else 0f }
        // NOTICE
        Box(Modifier.alpha(alpha = alpha)) {
            content(key)
        }
    }
}

And if it is not animating, it uses:

Box(modifier) {
    items.fastForEach {
        key(it.key) {
            it.content()
        }
    }
}

The problem is, Modifier.alpha()  is an alias of graphicsLayer(alpha = alpha, clip = true) ,
If you are holding a Button, Card or anything with shadow, Crossfade will clip the shadow when animation starts, and resume when animation finishes, that will be very unnatural.
And I wonder the reason that Modifier.alpha() sets clip property to true, is that really necessary?

[Doris Liu]

You are right, it's not a desirable behavior to clip in Crossfade. Could you file a bug on that?

@Nader Jawad on the question regarding Modifier.alpha clipping by default.

[Konyaco]

Done. https://issuetracker.google.com/issues/182551484

[Nader Jawad]

Whenever a layer has alpha applied to it, an offscreen buffer is created and the composable is drawn into that layer before the alpha is applied and drawn to the display

[Nader Jawad]

When this happens we size the layer to the bounds of the composable, however whenever content extends beyond the bounds of the layer it gets ommitted from this layer showing the "clipping" behavior you are seeing

[Nader Jawad]

It is a known issue and the layer sizing should take into account the extended bounds of the shadow itself.

[Nader Jawad]

I believe if the alpha and shadow are applied on the same layer it would work