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Making LavaBeats shader time relative to the STARTED lifecycle state #434

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Making LavaBeats shader time relative to the STARTED lifecycle state #434

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27 changes: 16 additions & 11 deletions ...face/haptics/src/main/java/com/example/platform/ui/haptics/lavabeats/LavaBeatsGraphics.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -27,12 +27,16 @@ import androidx.compose.runtime.Composable
import androidx.compose.runtime.LaunchedEffect
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableFloatStateOf
import androidx.compose.runtime.mutableLongStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.setValue
import androidx.compose.ui.Modifier
import androidx.compose.ui.draw.drawWithCache
import androidx.compose.ui.graphics.ShaderBrush
import androidx.compose.ui.platform.LocalDensity
import androidx.lifecycle.Lifecycle
import androidx.lifecycle.compose.LocalLifecycleOwner
import androidx.lifecycle.repeatOnLifecycle

@Composable
fun LavaBeatsGraphics(
Expand All @@ -47,21 +51,22 @@ fun LavaBeatsGraphics(
val density = LocalDensity.current
val width = with(density) { constraints.maxWidth.toPx() }
val height = with(density) { constraints.maxHeight.toPx() }
var firstTime by remember { mutableFloatStateOf(-1f) }
var startTimeMillis by remember { mutableLongStateOf(-1L) }
var time by remember { mutableFloatStateOf(0f) }

val lifecycleOwner = LocalLifecycleOwner.current
val isInDarkMode = isSystemInDarkTheme()
val surfaceColor = MaterialTheme.colorScheme.background

LaunchedEffect(Unit) {
// Use withInfiniteAnimationFrameMillis to update the time uniform per frame.
// This is a more efficient approach than passing a new shader instance
// or re-creating the RenderEffect on every frame.
while (true) {
withInfiniteAnimationFrameMillis { frameTime ->
if (firstTime == -1f) {
firstTime = frameTime / 1000f
} else {
time = frameTime / 1000f - firstTime
LaunchedEffect(lifecycleOwner) {
lifecycleOwner.lifecycle.repeatOnLifecycle(Lifecycle.State.STARTED) {

@yrezgui yrezgui Sep 10, 2026

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Why not using RESUMED state instead?

@JuanSMartinez JuanSMartinez Sep 10, 2026 •
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I tried this at first, but because RESUME occurs later, this resulted in a visible pause between the UI rendering and the animation actually starting. It is mostly a visual preference, as the most important part is to let the time reset once the user leaves the app. If RESUME gives us more performance benefits I could do that

startTimeMillis = -1L
while (true) {
withInfiniteAnimationFrameMillis { frameTime ->
if (startTimeMillis == -1L) {
startTimeMillis = frameTime
}
time = (frameTime - startTimeMillis) / 1000f
}
}
}
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