I’m trying to draw a circle when the user tap on the screen. I have a `var inputPosition: Offset? by...

# compose

[Luca Nicoletti]

I’m trying to draw a circle when the user tap on the screen.
I have a var inputPosition: Offset? by +state { null as Offset? }
I updated it inside the PressGestureDetector observer with: inputPosition = Offset(position.x.value, position.y.value)
then I have a @Composable function that accept an Offset? as input and Draw { canvas, _ -> canvas.drawCircle(pos, size.value, paint = paint) } with that position.

I’m getting the following error as soon as the user tap somewhere:

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[Yann Badoual]

Did you try with hardcoded position and/or paint to see which one is causing the issue?

[Yann Badoual]

I tested the following, it works fine:

Container(width = 50.dp, height = 50.dp) {
    Draw { canvas, _ ->
        canvas.drawCircle(
            center = Offset(75f, 75f),
            radius = 75f,
            paint = Paint().apply {
                color = Color.Blue
            }
        )
    }
}

[Leland Richardson [G]]

if you ever get this exception, it’s an indication of a bug in our runtime/compiler, not yours. In particular, this is often seen today because effects don’t fully work as advertised… they are meant to be “positional”, but right now they are unsafe to use inside of conditional logic (though this is strictly a bug)

[Leland Richardson [G]]

if you send snippets of code that happen above this, i might be able to spot the issue. But i’m guessing that somewhere you’re using a conditional that compose is handling incorrectly

[Leland Richardson [G]]

this is one of the things that will be fixed when we get rid of the +

[Luca Nicoletti]

Sure, will send the code over

[Luca Nicoletti]

Thanks

[Luca Nicoletti]

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