In my app I have a top level Theme wrapper functio...

# compose

[zt]

In my app I have a top level Theme wrapper function that just sets up the material 3 theme. It takes in a color for a custom dynamic theme and the variant (light/dark). For the longest time I couldn't figure out why everything was constantly recomposing. I just figured out the issue was with the color parameter
So I changed from
fun Theme(color: Color, theme: Theme, useDynamicTheme: Boolean, content: @Composable () -> Unit)
to
fun Theme(color: ColorProducer, theme: Theme, useDynamicTheme: Boolean, content: @Composable () -> Unit)
What I don't get is why ColorProducer lambda fixes it. Color is immutable, so it shouldn't trigger recomposition, right? Is there something else I'm not understanding?

[Stylianos Gakis]

It shouldn't trigger recomposition unless it actually did change. Then it should. You say it happens when the color changes, no?

[zt]

Yes, anytime the color changed it triggered, even if the color isnt being used when the dynamic theme is disabled. Heres the full function

@Composable
fun Theme(color: ColorProducer, theme: Theme, useDynamicTheme: Boolean, content: @Composable () -> Unit) {
    if (useDynamicTheme) {
        DynamicMaterialTheme(
            seedColor = color(),
            useDarkTheme = theme == Theme.DARK || theme == Theme.SYSTEM && isSystemInDarkTheme(),
            style = PaletteStyle.Fidelity,
            content = content
        )
    } else {
        MaterialTheme(
            colorScheme = if (theme == Theme.DARK || theme == Theme.SYSTEM && isSystemInDarkTheme()) {
                darkColorScheme()
            } else {
                lightColorScheme()
            }
        ) {
            content()
        }
    }
}

[Stylianos Gakis]

Yeah that still makes sense. In the case of ColorProducer the ColorProducer itself does not change, so there is no reason for this composable to recompose. In the case of color, the color itself changes, so this composable needs to recompose to make sure that it does not show any stale data.
I would assume that if you changed it to

fun Theme(getColor: () -> Color, theme: Theme, useDynamicTheme: Boolean, content: @Composable () -> Unit) {

it would also manage to not recompose, since it'd be the same lambda across compositions and nobody would be asking for the color from inside of it