90 per cent of the stack overflow responses on

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

refer to

onClick()

, instead i get this error every time i try to extract some long code from a composable function for instance a

Canvas

I cannot find IN GENERAL what this error means and so I am not able to solve my case

you can't call composable functions from inside Canvas onDraw either

In general, you can't call any composable functions from callbacks

is the error not clear?

mmh can i paste some code?

You can press CTRL Q on the opening bracket of any lambda to print its signature, if it doesn't say @Composable, then you can't call composable functions

version 2(gives

@Composable invocations

error):

Canvas(modifier = modifier) {
        val spacePerHour = (size.width - spacing) / infos.size
        (0 until infos.size - 1 step 2).forEach { i ->
            val info = infos[i]
            val hour = info.date.hour
            drawContext.canvas.nativeCanvas.apply {
                BuildXAxis(this, hour, spacing, i, spacePerHour, this, textPaint)
            }
        }
    }


@Composable
private fun BuildXAxis(
    canvas: NativeCanvas,
    hour: Int,
    spacing: Float,
    i: Int,
    spacePerHour: Float,
    drawScope: DrawScope,
    textPaint: Paint
) {
    canvas.drawText(
        hour.toString(),
        spacing + i * spacePerHour,
        drawScope.size.height - 5,
        textPaint
    )
}

remove

@Composable

from the function if you want to use it in that position

@ephemient it works, thanks, now i understand where the error is! @CLOVIS thank you for your tip of using ctrl+Q and also @vide for the simple english explanation about callbacks!