Hi, quick question. I have a `LinearProgressIndicator` below an app bar. Can I hide the progress ind...

# compose

[Julius Marozas]

Hi, quick question. I have a LinearProgressIndicator below an app bar. Can I hide the progress indicator without affecting the content below it? I am looking for something like View.INVISIBLE (and not View.GONE).

[Alejandro Rios]

maybe put it inside a Box and hide the Box?

[Zach Klippenstein (he/him) [MOD]]

You could also just apply Modifier.opacity(0f) to your indicator.

[Julius Marozas]

Thanks for the quick replies! I was able to do this both ways:
with `Box`:

Box(modifier = Modifier.height(ProgressIndicatorConstants.DefaultStrokeWidth)) {
    if (showProgress)
        LinearProgressIndicator(modifier = Modifier.fillMaxWidth()
}

with `opacity`:

LinearProgressIndicator(modifier = Modifier.fillMaxWidth().drawOpacity(if (showProgress) 1f else 0f))

The opacity approach is a little bit simpler. But I think something like View.INVISIBLE would also be useful.

[Zach Klippenstein (he/him) [MOD]]

Could be as simple as fun Modifier.visible(visible: Boolean) = drawOpacity(if (visible) 1f else 0f), although there’s probably also some semantics/input considerations that it should take into account (e.g. disabling input, marking as hidden for accessibility, etc).

[Zach Klippenstein (he/him) [MOD]]

Progress indicators don’t handle input events so for your case that part doesn’t matter.

[Timo Drick]

Here is a simple Visibility modifier implementation:

enum class Visibility {
    VISIBLE, INVISIBLE, GONE
}

@Composable
fun Modifier.visibility(visibility: Visibility) = this + object : LayoutModifier {
    override fun MeasureScope.measure(
        measurable: Measurable,
        constraints: Constraints,
        layoutDirection: LayoutDirection
    ): MeasureScope.MeasureResult = if (visibility == Visibility.GONE) {
        layout(0, 0) {
            // Empty placement block
        }
    } else {
        val placeable = measurable.measure(constraints)
        layout(placeable.width, placeable.height) {
            if (visibility == Visibility.VISIBLE) {
                placeable.place(0, 0)
            }
        }
    }
}

[Zach Klippenstein (he/him) [MOD]]

What’s that constraints.offset() call for in the else block?

[Timo Drick]

upps i think this was just a test. It should not do anything

[Timo Drick]

Just remove this line

[Zach Klippenstein (he/him) [MOD]]

Nice!