Try and make iOS fling more 'native'

At the moment Compose MP using the same spline decay animation that Android uses, which isn't great. This PR changes this by using our own fling behavior throughout the app. This allows us to tweak the decay animation to better match iOS. It isn't perfect, but it's a lot better than default.
chrisbanes · Jul 8, 2023 · a14ff28 · a14ff28
1 parent 7408224
commit a14ff28
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diff --git a/common/ui/compose/src/androidMain/kotlin/app/tivi/common/compose/FlingBehavior.android.kt b/common/ui/compose/src/androidMain/kotlin/app/tivi/common/compose/FlingBehavior.android.kt
@@ -0,0 +1,11 @@
+// Copyright 2023, Christopher Banes and the Tivi project contributors
+// SPDX-License-Identifier: Apache-2.0
+
+package app.tivi.common.compose
+
+import androidx.compose.animation.core.DecayAnimationSpec
+import androidx.compose.animation.rememberSplineBasedDecay
+import androidx.compose.runtime.Composable
+
+@Composable
+actual fun decayAnimationSpec(): DecayAnimationSpec<Float> = rememberSplineBasedDecay()
diff --git a/common/ui/compose/src/commonMain/kotlin/app/tivi/common/compose/EntryGrid.kt b/common/ui/compose/src/commonMain/kotlin/app/tivi/common/compose/EntryGrid.kt
@@ -133,6 +133,7 @@ fun <E : Entry> EntryGrid(
                     PaddingValues(horizontal = bodyMargin, vertical = gutter),
                 horizontalArrangement = Arrangement.spacedBy(gutter),
                 verticalArrangement = Arrangement.spacedBy(gutter),
+                flingBehavior = rememberTiviFlingBehavior(),
                 modifier = Modifier
                     .nestedScroll(scrollBehavior.nestedScrollConnection)
                     .bodyWidth()

diff --git a/common/ui/compose/src/commonMain/kotlin/app/tivi/common/compose/FlingBehavior.kt b/common/ui/compose/src/commonMain/kotlin/app/tivi/common/compose/FlingBehavior.kt
@@ -0,0 +1,91 @@
+// Copyright 2021, Google LLC, Christopher Banes and the Tivi project contributors
+// SPDX-License-Identifier: Apache-2.0
+
+package app.tivi.common.compose
+
+import androidx.compose.animation.core.AnimationState
+import androidx.compose.animation.core.DecayAnimationSpec
+import androidx.compose.animation.core.LinearEasing
+import androidx.compose.animation.core.Spring
+import androidx.compose.animation.core.animateDecay
+import androidx.compose.animation.core.spring
+import androidx.compose.animation.core.tween
+import androidx.compose.foundation.ExperimentalFoundationApi
+import androidx.compose.foundation.gestures.FlingBehavior
+import androidx.compose.foundation.gestures.ScrollScope
+import androidx.compose.foundation.gestures.snapping.SnapFlingBehavior
+import androidx.compose.foundation.gestures.snapping.SnapLayoutInfoProvider
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.remember
+import androidx.compose.ui.MotionDurationScale
+import androidx.compose.ui.platform.LocalDensity
+import kotlin.math.abs
+import kotlinx.coroutines.withContext
+
+@Composable
+fun rememberTiviFlingBehavior(): FlingBehavior {
+    val decayAnimationSpec = decayAnimationSpec()
+    return remember(decayAnimationSpec) {
+        DefaultFlingBehavior(decayAnimationSpec)
+    }
+}
+
+@ExperimentalFoundationApi
+@Composable
+fun rememberTiviSnapFlingBehavior(
+    snapLayoutInfoProvider: SnapLayoutInfoProvider,
+): SnapFlingBehavior {
+    val density = LocalDensity.current
+    val highVelocityApproachSpec: DecayAnimationSpec<Float> = rememberTiviDecayAnimationSpec()
+    return remember(snapLayoutInfoProvider, highVelocityApproachSpec, density) {
+        SnapFlingBehavior(
+            snapLayoutInfoProvider = snapLayoutInfoProvider,
+            lowVelocityAnimationSpec = tween(easing = LinearEasing),
+            highVelocityAnimationSpec = highVelocityApproachSpec,
+            snapAnimationSpec = spring(stiffness = Spring.StiffnessMediumLow),
+            density = density,
+        )
+    }
+}
+
+@Composable
+fun rememberTiviDecayAnimationSpec(): DecayAnimationSpec<Float> {
+    val spec = decayAnimationSpec()
+    return remember { spec }
+}
+
+@Composable
+internal expect fun decayAnimationSpec(): DecayAnimationSpec<Float>
+
+internal val DefaultScrollMotionDurationScale = object : MotionDurationScale {
+    override val scaleFactor: Float get() = 1f
+}
+
+internal class DefaultFlingBehavior(
+    private val flingDecay: DecayAnimationSpec<Float>,
+    private val motionDurationScale: MotionDurationScale = DefaultScrollMotionDurationScale,
+) : FlingBehavior {
+    override suspend fun ScrollScope.performFling(initialVelocity: Float): Float {
+        // come up with the better threshold, but we need it since spline curve gives us NaNs
+        return withContext(motionDurationScale) {
+            if (abs(initialVelocity) > 1f) {
+                var velocityLeft = initialVelocity
+                var lastValue = 0f
+                AnimationState(
+                    initialValue = 0f,
+                    initialVelocity = initialVelocity,
+                ).animateDecay(flingDecay) {
+                    val delta = value - lastValue
+                    val consumed = scrollBy(delta)
+                    lastValue = value
+                    velocityLeft = this.velocity
+                    // avoid rounding errors and stop if anything is unconsumed
+                    if (abs(delta - consumed) > 0.5f) cancelAnimation()
+                }
+                velocityLeft
+            } else {
+                initialVelocity
+            }
+        }
+    }
+}
diff --git a/common/ui/compose/src/iosMain/kotlin/app/tivi/common/compose/FlingBehavior.ios.kt b/common/ui/compose/src/iosMain/kotlin/app/tivi/common/compose/FlingBehavior.ios.kt
@@ -0,0 +1,14 @@
+// Copyright 2023, Christopher Banes and the Tivi project contributors
+// SPDX-License-Identifier: Apache-2.0
+
+package app.tivi.common.compose
+
+import androidx.compose.animation.core.DecayAnimationSpec
+import androidx.compose.animation.core.exponentialDecay
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.remember
+
+@Composable
+actual fun decayAnimationSpec(): DecayAnimationSpec<Float> {
+    return remember { exponentialDecay(frictionMultiplier = 0.85f) }
+}
diff --git a/common/ui/compose/src/jvmMain/kotlin/app/tivi/common/compose/FlingBehavior.desktop.kt b/common/ui/compose/src/jvmMain/kotlin/app/tivi/common/compose/FlingBehavior.desktop.kt
@@ -0,0 +1,11 @@
+// Copyright 2023, Christopher Banes and the Tivi project contributors
+// SPDX-License-Identifier: Apache-2.0
+
+package app.tivi.common.compose
+
+import androidx.compose.animation.core.DecayAnimationSpec
+import androidx.compose.animation.rememberSplineBasedDecay
+import androidx.compose.runtime.Composable
+
+@Composable
+actual fun decayAnimationSpec(): DecayAnimationSpec<Float> = rememberSplineBasedDecay()
diff --git a/ui/discover/src/commonMain/kotlin/app/tivi/home/discover/Discover.kt b/ui/discover/src/commonMain/kotlin/app/tivi/home/discover/Discover.kt
@@ -8,7 +8,6 @@ package app.tivi.home.discover
 import androidx.compose.animation.AnimatedVisibility
 import androidx.compose.foundation.ExperimentalFoundationApi
 import androidx.compose.foundation.gestures.snapping.SnapLayoutInfoProvider
-import androidx.compose.foundation.gestures.snapping.rememberSnapFlingBehavior
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
@@ -57,6 +56,8 @@ import app.tivi.common.compose.LocalTiviTextCreator
 import app.tivi.common.compose.ReportDrawnWhen
 import app.tivi.common.compose.bodyWidth
 import app.tivi.common.compose.rememberCoroutineScope
+import app.tivi.common.compose.rememberTiviFlingBehavior
+import app.tivi.common.compose.rememberTiviSnapFlingBehavior
 import app.tivi.common.compose.ui.AutoSizedCircularProgressIndicator
 import app.tivi.common.compose.ui.PosterCard
 import app.tivi.common.compose.ui.TiviStandardAppBar
@@ -191,6 +192,7 @@ internal fun Discover(
         Box(modifier = Modifier.pullRefresh(state = refreshState)) {
             LazyColumn(
                 contentPadding = paddingValues,
+                flingBehavior = rememberTiviFlingBehavior(),
                 modifier = Modifier.bodyWidth(),
             ) {
                 item {
@@ -380,7 +382,7 @@ private fun <T : EntryWithShow<*>> EntryShowCarousel(
     LazyRow(
         state = lazyListState,
         modifier = modifier,
-        flingBehavior = rememberSnapFlingBehavior(
+        flingBehavior = rememberTiviSnapFlingBehavior(
             snapLayoutInfoProvider = remember(lazyListState) {
                 SnapLayoutInfoProvider(
                     lazyListState = lazyListState,

diff --git a/ui/library/src/commonMain/kotlin/app/tivi/home/library/Library.kt b/ui/library/src/commonMain/kotlin/app/tivi/home/library/Library.kt
@@ -69,6 +69,7 @@ import app.tivi.common.compose.fullSpanItem
 import app.tivi.common.compose.items
 import app.tivi.common.compose.rememberCoroutineScope
 import app.tivi.common.compose.rememberLazyGridState
+import app.tivi.common.compose.rememberTiviFlingBehavior
 import app.tivi.common.compose.ui.EmptyContent
 import app.tivi.common.compose.ui.PosterCard
 import app.tivi.common.compose.ui.SearchTextField
@@ -253,6 +254,7 @@ private fun LibraryGrid(
     LazyVerticalGrid(
         state = rememberLazyGridState(lazyPagingItems.itemCount == 0),
         columns = GridCells.Fixed(columns / 4),
+        flingBehavior = rememberTiviFlingBehavior(),
         contentPadding = paddingValues + PaddingValues(
             horizontal = (bodyMargin - 8.dp).coerceAtLeast(0.dp),
             vertical = (gutter - 8.dp).coerceAtLeast(0.dp),

diff --git a/ui/search/src/commonMain/kotlin/app/tivi/home/search/Search.kt b/ui/search/src/commonMain/kotlin/app/tivi/home/search/Search.kt
@@ -44,6 +44,7 @@ import androidx.compose.ui.text.style.TextOverflow
 import androidx.compose.ui.unit.dp
 import app.tivi.common.compose.Layout
 import app.tivi.common.compose.bodyWidth
+import app.tivi.common.compose.rememberTiviFlingBehavior
 import app.tivi.common.compose.ui.EmptyContent
 import app.tivi.common.compose.ui.PosterCard
 import app.tivi.common.compose.ui.SearchTextField
@@ -200,6 +201,7 @@ private fun SearchList(
         contentPadding = contentPadding,
         verticalArrangement = arrangement,
         horizontalArrangement = arrangement,
+        flingBehavior = rememberTiviFlingBehavior(),
         modifier = modifier,
     ) {
         items(

diff --git a/ui/show/details/src/commonMain/kotlin/app/tivi/showdetails/details/ShowDetails.kt b/ui/show/details/src/commonMain/kotlin/app/tivi/showdetails/details/ShowDetails.kt
@@ -10,7 +10,6 @@ import androidx.compose.foundation.Image
 import androidx.compose.foundation.border
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.gestures.snapping.SnapLayoutInfoProvider
-import androidx.compose.foundation.gestures.snapping.rememberSnapFlingBehavior
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
@@ -88,6 +87,8 @@ import app.tivi.common.compose.LocalTiviTextCreator
 import app.tivi.common.compose.bodyWidth
 import app.tivi.common.compose.gutterSpacer
 import app.tivi.common.compose.itemSpacer
+import app.tivi.common.compose.rememberTiviFlingBehavior
+import app.tivi.common.compose.rememberTiviSnapFlingBehavior
 import app.tivi.common.compose.ui.AsyncImage
 import app.tivi.common.compose.ui.Backdrop
 import app.tivi.common.compose.ui.ExpandingText
@@ -287,6 +288,7 @@ private fun ShowDetailsScrollingContent(
         state = listState,
         contentPadding = contentPadding,
         modifier = modifier,
+        flingBehavior = rememberTiviFlingBehavior(),
     ) {
         item {
             Backdrop(
@@ -635,7 +637,7 @@ private fun RelatedShows(
     LazyRow(
         state = lazyListState,
         modifier = modifier,
-        flingBehavior = rememberSnapFlingBehavior(
+        flingBehavior = rememberTiviSnapFlingBehavior(
             snapLayoutInfoProvider = remember(lazyListState) {
                 SnapLayoutInfoProvider(
                     lazyListState = lazyListState,

diff --git a/ui/show/seasons/src/commonMain/kotlin/app/tivi/showdetails/seasons/ShowSeasons.kt b/ui/show/seasons/src/commonMain/kotlin/app/tivi/showdetails/seasons/ShowSeasons.kt
@@ -20,6 +20,7 @@ import androidx.compose.foundation.layout.wrapContentHeight
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.items
 import androidx.compose.foundation.pager.HorizontalPager
+import androidx.compose.foundation.pager.PagerDefaults
 import androidx.compose.foundation.pager.PagerState
 import androidx.compose.foundation.pager.rememberPagerState
 import androidx.compose.material.DismissValue
@@ -65,6 +66,8 @@ import app.tivi.common.compose.Layout
 import app.tivi.common.compose.LocalTiviTextCreator
 import app.tivi.common.compose.bodyWidth
 import app.tivi.common.compose.rememberCoroutineScope
+import app.tivi.common.compose.rememberTiviDecayAnimationSpec
+import app.tivi.common.compose.rememberTiviFlingBehavior
 import app.tivi.common.compose.ui.RefreshButton
 import app.tivi.common.compose.ui.TopAppBarWithBottomContent
 import app.tivi.common.ui.resources.MR
@@ -270,6 +273,10 @@ private fun SeasonsPager(
     HorizontalPager(
         pageCount = seasons.size,
         state = pagerState,
+        flingBehavior = PagerDefaults.flingBehavior(
+            state = pagerState,
+            highVelocityAnimationSpec = rememberTiviDecayAnimationSpec(),
+        ),
         modifier = modifier,
     ) { page ->
         EpisodesList(
@@ -286,7 +293,10 @@ private fun EpisodesList(
     onEpisodeClick: (episodeId: Long) -> Unit,
     modifier: Modifier = Modifier,
 ) {
-    LazyColumn(modifier = modifier) {
+    LazyColumn(
+        modifier = modifier,
+        flingBehavior = rememberTiviFlingBehavior(),
+    ) {
         items(episodes, key = { it.episode.id }) { item ->
             EpisodeWithWatchesRow(
                 episode = item.episode,

diff --git a/ui/upnext/src/commonMain/kotlin/app/tivi/home/upnext/UpNext.kt b/ui/upnext/src/commonMain/kotlin/app/tivi/home/upnext/UpNext.kt
@@ -64,6 +64,7 @@ import app.tivi.common.compose.fullSpanItem
 import app.tivi.common.compose.items
 import app.tivi.common.compose.rememberCoroutineScope
 import app.tivi.common.compose.rememberLazyGridState
+import app.tivi.common.compose.rememberTiviFlingBehavior
 import app.tivi.common.compose.ui.AsyncImage
 import app.tivi.common.compose.ui.EmptyContent
 import app.tivi.common.compose.ui.SortChip
@@ -223,6 +224,7 @@ internal fun UpNext(
                 // We minus 8.dp off the grid padding, as we use content padding on the items below
                 horizontalArrangement = Arrangement.spacedBy((gutter - 8.dp).coerceAtLeast(0.dp)),
                 verticalArrangement = Arrangement.spacedBy((gutter - 8.dp).coerceAtLeast(0.dp)),
+                flingBehavior = rememberTiviFlingBehavior(),
                 modifier = Modifier
                     .nestedScroll(scrollBehavior.nestedScrollConnection)
                     .bodyWidth()