How to convert a color resource to a Color object in Jetpack Compose?-CodePudding

I have a Text and I want to draw a circle that should have a color that exists inside my resource file.

Text(
    modifier = Modifier.align(Alignment.TopEnd).drawBehind {
        drawCircle(
            color = colorResource(R.color.primary),
            radius = 96.00f
        )
    },
    text = "X"
)

But I get:

@Composable invocations can only happen from the context of a @Composable function

If I use color = Color.Red, it works fine. So I don't want to use any of those colors, I want to use mine. So I thought to make a conversion, but I cannot find any solution. How can I convert that?

CodePudding user response：

You need to call Composable functions from a scope that has @Composable annotation.

Box() {
  val color = colorResource(R.color.black)
  Text(
      modifier = Modifier.align(Alignment.TopEnd).drawBehind {
          drawCircle(
              color = color,
              radius = 96.00f
          )
      },
      text = "X"
  )
}

colorResource is a @Composable function

@Composable
@ReadOnlyComposable
fun colorResource(@ColorRes id: Int): Color {
    val context = LocalContext.current
    return if (Build.VERSION.SDK_INT >= 23) {
        ColorResourceHelper.getColor(context, id)
    } else {
        @Suppress("DEPRECATION")
        Color(context.resources.getColor(id))
    }
}

but lambda of Modifier.drawBehind isn't

fun Modifier.drawBehind(
    onDraw: DrawScope.() -> Unit
) = this.then(
    DrawBackgroundModifier(
        onDraw = onDraw,
        inspectorInfo = debugInspectorInfo {
            name = "drawBehind"
            properties["onDraw"] = onDraw
        }
    )
)

You can check this answer for difference between function, lambdas or params with @Composable annotation or the ones without