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Refresh live compose scan by observing RecomposerInfo instead of only the top-most recompose scope. #135

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Refresh live compose scan by observing RecomposerInfo instead of only the top-most recompose scope. #135

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76 changes: 67 additions & 9 deletions sample-compose/src/main/java/com/squareup/radiography/sample/compose/ComposeSampleApp.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,6 @@ import android.util.Log
import android.widget.LinearLayout
import android.widget.TextView
import androidx.appcompat.app.AlertDialog.Builder
import androidx.compose.animation.ExperimentalAnimationApi
import androidx.compose.foundation.horizontalScroll
import androidx.compose.foundation.layout.Arrangement
import androidx.compose.foundation.layout.Column
Expand All @@ -25,7 +24,9 @@ import androidx.compose.material.TextButton
import androidx.compose.material.TextField
import androidx.compose.material.TextFieldDefaults
import androidx.compose.runtime.Composable
import androidx.compose.runtime.SideEffect
import androidx.compose.runtime.LaunchedEffect
import androidx.compose.runtime.Recomposer
import androidx.compose.runtime.Recomposer.State.Idle
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
Expand All @@ -40,6 +41,20 @@ import androidx.compose.ui.tooling.preview.Preview
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.sp
import androidx.compose.ui.viewinterop.AndroidView
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.ExperimentalCoroutinesApi
import kotlinx.coroutines.FlowPreview
import kotlinx.coroutines.channels.BufferOverflow.DROP_OLDEST
import kotlinx.coroutines.delay
import kotlinx.coroutines.flow.Flow
import kotlinx.coroutines.flow.buffer
import kotlinx.coroutines.flow.collect
import kotlinx.coroutines.flow.combine
import kotlinx.coroutines.flow.distinctUntilChanged
import kotlinx.coroutines.flow.flatMapLatest
import kotlinx.coroutines.flow.flow
import kotlinx.coroutines.flow.flowOf
import kotlinx.coroutines.withContext
import radiography.ExperimentalRadiographyComposeApi
import radiography.Radiography
import radiography.ScanScopes.FocusedWindowScope
Expand All @@ -59,7 +74,6 @@ internal const val LIVE_HIERARCHY_TEST_TAG = "live-hierarchy"
ComposeSampleApp()
}

@OptIn(ExperimentalRadiographyComposeApi::class, ExperimentalAnimationApi::class)
@Composable fun ComposeSampleApp() {
val context = LocalContext.current
val liveHierarchy = remember { mutableStateOf<String?>(null) }
Expand Down Expand Up @@ -131,12 +145,8 @@ internal const val LIVE_HIERARCHY_TEST_TAG = "live-hierarchy"
Text("SHOW STRING RENDERING DIALOG")
}

SideEffect {
liveHierarchy.value = Radiography.scan(
viewStateRenderers = DefaultsIncludingPii,
// Don't trigger infinite recursion.
viewFilter = skipComposeTestTagsFilter(LIVE_HIERARCHY_TEST_TAG)
)
LaunchedEffect(Unit) {
runLiveScanning { liveHierarchy.value = it }
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cool so this effectively says "rescan every time we've recomposed". btw does that not retrigger a composition / any risk of infinite loop?

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@zach-klippenstein zach-klippenstein Mar 2, 2021 •
edited
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Correct. It does not trigger infinite composition loop, although I'm not super clear on why not. I can look into it and document, because it does seem like that should happen.

  • Figure out why no infinite loop

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@zach-klippenstein zach-klippenstein Mar 3, 2021 •
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Ok I get why there's no infinite loop now. Because we exclude the scan result composable from the scan, a scan in which only the scan output changes will result in the scan string being set to the same value, which won't invalidate any recompose scopes.

I'll add a comment about this and punch up the docs on the Recomposers stuff.

}
}
}
Expand Down Expand Up @@ -210,3 +220,51 @@ private fun showResult(
messageView.textSize = 9f
messageView.typeface = Typeface.MONOSPACE
}

@OptIn(
ExperimentalCoroutinesApi::class,
FlowPreview::class,
ExperimentalRadiographyComposeApi::class
)
private suspend fun runLiveScanning(onScanResult: (String) -> Unit) {
// A Flow that emits false when all Recomposers are idle, and true when at least one Recomposer
// is non-idle.
val isComposing: Flow<Boolean> = Recomposer.runningRecomposers
.flatMapLatest { recomposers ->
combine(recomposers.map { it.state }) { states ->
states.any { it != Idle }
}
}
.distinctUntilChanged()

fun emitEvery(periodMs: Long): Flow<Unit> = flow {
while (true) {
emit(Unit)
delay(periodMs)
}
}

@Suppress("NAME_SHADOWING")
val scanTrigger = isComposing.flatMapLatest { isComposing ->
if (isComposing) {
// While any Recomposer's state is not idle, do a scan every 500 millis. This effectively
// throttles scans during continuously-recomposing periods like animations.
emitEvery(500)
} else {
// Emit once to scan the now-settled composition, then stop.
flowOf(Unit)
}
}

// If a scan takes too long and other scan requests were fired in the meantime, coalesce them.
scanTrigger.buffer(1, DROP_OLDEST)
.collect {
withContext(Dispatchers.Default) {
Radiography.scan(
viewStateRenderers = DefaultsIncludingPii,
// Don't trigger infinite recursion.
viewFilter = skipComposeTestTagsFilter(LIVE_HIERARCHY_TEST_TAG)
).let(onScanResult)
}
}
}