Skip to content

[JetSnack] Move scroll state reads into layout phase via lambdas #778

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
bentrengrove merged 1 commit into from
Apr 13, 2022
Merged

[JetSnack] Move scroll state reads into layout phase via lambdas #778

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
29 changes: 19 additions & 10 deletions Jetsnack/app/src/main/java/com/example/jetsnack/ui/snackdetail/SnackDetail.kt
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,7 @@ import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.height
import androidx.compose.foundation.layout.heightIn
import androidx.compose.foundation.layout.navigationBarsPadding
import androidx.compose.foundation.layout.offset
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.size
import androidx.compose.foundation.layout.statusBarsPadding
Expand All @@ -50,14 +51,14 @@ import androidx.compose.runtime.setValue
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Brush
import androidx.compose.ui.graphics.graphicsLayer
import androidx.compose.ui.layout.Layout
import androidx.compose.ui.platform.LocalDensity
import androidx.compose.ui.res.stringResource
import androidx.compose.ui.text.style.TextAlign
import androidx.compose.ui.text.style.TextOverflow
import androidx.compose.ui.tooling.preview.Preview
import androidx.compose.ui.unit.Constraints
import androidx.compose.ui.unit.IntOffset
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.lerp
import androidx.compose.ui.unit.sp
Expand Down Expand Up @@ -102,8 +103,8 @@ fun SnackDetail(
val scroll = rememberScrollState(0)
Header()
Body(related, scroll)
Title(snack, scroll.value)
Image(snack.imageUrl, scroll.value)
Title(snack) { scroll.value }
Image(snack.imageUrl) { scroll.value }
Up(upPress)
CartBottomBar(modifier = Modifier.align(Alignment.BottomCenter))
}
Expand Down Expand Up @@ -237,16 +238,20 @@ private fun Body(
}

@Composable
private fun Title(snack: Snack, scroll: Int) {
private fun Title(snack: Snack, scrollProvider: () -> Int) {
val maxOffset = with(LocalDensity.current) { MaxTitleOffset.toPx() }
val minOffset = with(LocalDensity.current) { MinTitleOffset.toPx() }
val offset = (maxOffset - scroll).coerceAtLeast(minOffset)

Column(
verticalArrangement = Arrangement.Bottom,
modifier = Modifier
.heightIn(min = TitleHeight)
.statusBarsPadding()
.graphicsLayer { translationY = offset }
.offset {
val scroll = scrollProvider()
val offset = (maxOffset - scroll).coerceAtLeast(minOffset)
IntOffset(x = 0, y = offset.toInt())
}
.background(color = JetsnackTheme.colors.uiBackground)
) {
Spacer(Modifier.height(16.dp))
Expand Down Expand Up @@ -279,13 +284,15 @@ private fun Title(snack: Snack, scroll: Int) {
@Composable
private fun Image(
imageUrl: String,
scroll: Int
scrollProvider: () -> Int
) {
val collapseRange = with(LocalDensity.current) { (MaxTitleOffset - MinTitleOffset).toPx() }
val collapseFraction = (scroll / collapseRange).coerceIn(0f, 1f)
val collapseFractionProvider = {
(scrollProvider() / collapseRange).coerceIn(0f, 1f)
}

CollapsingImageLayout(
collapseFraction = collapseFraction,
collapseFractionProvider = collapseFractionProvider,
modifier = HzPadding.then(Modifier.statusBarsPadding())
) {
SnackImage(
Expand All @@ -298,7 +305,7 @@ private fun Image(

@Composable
private fun CollapsingImageLayout(
collapseFraction: Float,
collapseFractionProvider: () -> Float,
modifier: Modifier = Modifier,
content: @Composable () -> Unit
) {
Expand All @@ -308,6 +315,8 @@ private fun CollapsingImageLayout(
) { measurables, constraints ->
check(measurables.size == 1)

val collapseFraction = collapseFractionProvider()

val imageMaxSize = min(ExpandedImageSize.roundToPx(), constraints.maxWidth)
val imageMinSize = max(CollapsedImageSize.roundToPx(), constraints.minWidth)
val imageWidth = lerp(imageMaxSize, imageMinSize, collapseFraction)
Expand Down