Has anyone experienced a `java.lang.NullPointerExc...

# compose

[Jeisson Sáchica]

Has anyone experienced a java.lang.NullPointerException: null cannot be cast to non-null type androidx.compose.ui.graphics.AndroidPathEffect when using a androidx.compose.ui.graphics.PathEffect on a ContentDrawScope.drawCircle ?

[Jeisson Sáchica]

I have defined the following component:

val pathEffectIntervalsDp: Array<Dp> = arrayOf(6.dp, 3.dp)
val strokeWidthDp = 1.dp

@Suppress("UNUSED_VARIABLE")
@Composable
fun DashedCircle(
    strokeColor: Color,
    modifier: Modifier = Modifier,
) {
    val pathEffectIntervals: FloatArray = pathEffectIntervalsDp.map {
        with (AmbientDensity.current) { it.toPx() }
    }.toFloatArray()
    val strokeWidth = with (AmbientDensity.current) { strokeWidthDp.toPx() }
    Box(modifier.drawWithCache {
        val pathEffect: PathEffect = PathEffect.dashPathEffect(pathEffectIntervals, 1f)
        val start = Offset(size.width / 2, size.height / 2)
        val end = Offset(size.width, size.height / 2)

        onDrawWithContent {
            drawCircle(
                strokeColor,
                style = Stroke(
                    width = strokeWidth,
//                    pathEffect = pathEffect
                )
            )
            drawLine(
                color = strokeColor,
                start = start,
                end = end
            )
        }
    })
}

[Jeisson Sáchica]

Which correctly renders this:

[Jeisson Sáchica]

But If I uncomment the pathEffect line of the drawCircle, The error occurs on the preview and when running it. Strangely, if I remove the drawLine and only leave the drawCircle, it outputs correctly this:

[Jeisson Sáchica]

I think this problem started happening in alpha09 when the Stroke stopped taking an android.graphics.PathEffect as DashPathEffect(pathEffectIntervals, 1f) to now take an a`ndroidx.compose.ui.graphics.PathEffect` as PathEffect.dashPathEffect(pathEffectIntervals, 1f)

[Nader Jawad]

Thanks for raising this issue. I just root caused and pushed up a fix. DrawScope internally manages a Paint object and there is an issue where if the PathEffect parameter is non-null in one call then null in a subsequent draw call you run into null pointer exceptions as you have noted.

For this specific example as a workaround you could try re-arranging the drawing order to draw the line first then the circle. Otherwise you can use the drawIntoCanvas API to manually draw into the canvas directly.

[Jeisson Sáchica]

Amazing! Thank you, I will try that in the meantime 💯

[Jeisson Sáchica]

Also if anyone might need it, here is the issue: https://issuetracker.google.com/issues/179062252