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Support fling for nested scroll on TimetableGrid. #1273

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merged 4 commits into from
Oct 4, 2023
+58 −21
Merged

Support fling for nested scroll on TimetableGrid. #1273

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30580bb
Create NestedScrollDispatcher object in TimeTableGrid.
usuiat Sep 20, 2023
b786a70
Implement fling for nested scroll of TimetableGrid.
usuiat Sep 23, 2023
98e0c88
Format codes.
usuiat Sep 23, 2023
3f69c52
Fix unexpected fling behaviors.
usuiat Sep 26, 2023
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50 changes: 37 additions & 13 deletions ...ssions/src/main/java/io/github/droidkaigi/confsched2023/sessions/section/TimetableGrid.kt
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,6 +1,8 @@
package io.github.droidkaigi.confsched2023.sessions.section

import androidx.compose.animation.core.Animatable
import androidx.compose.animation.core.AnimationState
import androidx.compose.animation.core.animateDecay
import androidx.compose.animation.core.exponentialDecay
import androidx.compose.foundation.ExperimentalFoundationApi
import androidx.compose.foundation.focusGroup
Expand Down Expand Up @@ -35,8 +37,10 @@ import androidx.compose.ui.Modifier
import androidx.compose.ui.draw.clipToBounds
import androidx.compose.ui.draw.drawBehind
import androidx.compose.ui.geometry.Offset
import androidx.compose.ui.input.nestedscroll.NestedScrollConnection
import androidx.compose.ui.input.nestedscroll.NestedScrollDispatcher
import androidx.compose.ui.input.nestedscroll.NestedScrollSource
import androidx.compose.ui.input.nestedscroll.nestedScroll
import androidx.compose.ui.input.pointer.PointerInputChange
import androidx.compose.ui.input.pointer.PointerInputScope
import androidx.compose.ui.input.pointer.pointerInput
Expand Down Expand Up @@ -84,14 +88,12 @@ data class TimetableGridUiState(val timetable: Timetable)
@Composable
fun TimetableGrid(
uiState: TimetableGridUiState,
nestedScrollDispatcher: NestedScrollDispatcher,
onTimetableItemClick: (TimetableItem) -> Unit,
modifier: Modifier = Modifier,
contentPadding: PaddingValues = PaddingValues(),
) {
TimetableGrid(
timetable = uiState.timetable,
nestedScrollDispatcher = nestedScrollDispatcher,
onTimetableItemClick = onTimetableItemClick,
modifier = modifier,
contentPadding = contentPadding,
Expand All @@ -101,7 +103,6 @@ fun TimetableGrid(
@Composable
fun TimetableGrid(
timetable: Timetable,
nestedScrollDispatcher: NestedScrollDispatcher,
onTimetableItemClick: (TimetableItem) -> Unit,
modifier: Modifier = Modifier,
contentPadding: PaddingValues = PaddingValues(),
Expand Down Expand Up @@ -133,7 +134,6 @@ fun TimetableGrid(
TimetableGrid(
timetable = timetable,
timetableState = timetableGridState,
nestedScrollDispatcher = nestedScrollDispatcher,
modifier = modifier,
contentPadding = PaddingValues(
top = 16.dp + contentPadding.calculateTopPadding(),
Expand All @@ -157,7 +157,6 @@ fun TimetableGrid(
fun TimetableGrid(
timetable: Timetable,
timetableState: TimetableState,
nestedScrollDispatcher: NestedScrollDispatcher,
modifier: Modifier = Modifier,
contentPadding: PaddingValues = PaddingValues(),
content: @Composable (TimetableItem, Int) -> Unit,
Expand Down Expand Up @@ -186,10 +185,14 @@ fun TimetableGrid(
content(timetableItemWithFavorite.timetableItem, itemHeightPx)
}

val nestedScrollConnection = remember { object : NestedScrollConnection {} }
val nestedScrollDispatcher = remember { NestedScrollDispatcher() }

LazyLayout(
modifier = modifier
.focusGroup()
.clipToBounds()
.nestedScroll(nestedScrollConnection, nestedScrollDispatcher)
.drawBehind {
timetableScreen.timeHorizontalLines.value.forEach {
drawLine(
Expand Down Expand Up @@ -245,7 +248,7 @@ fun TimetableGrid(
},
onDragEnd = {
coroutineScope.launch {
scrollState.flingIfPossible()
scrollState.flingIfPossible(nestedScrollDispatcher)
}
},
)
Expand Down Expand Up @@ -322,7 +325,6 @@ fun TimetableGrid(
fun TimetablePreview() {
TimetableGrid(
timetable = Timetable.fake(),
nestedScrollDispatcher = remember { NestedScrollDispatcher() },
onTimetableItemClick = {},
modifier = Modifier.fillMaxSize(),
)
Expand Down Expand Up @@ -510,19 +512,41 @@ class ScreenScrollState(
}
}

suspend fun flingIfPossible() = coroutineScope {
suspend fun flingIfPossible(nestedScrollDispatcher: NestedScrollDispatcher) = coroutineScope {
val velocity = velocityTracker.calculateVelocity()
launch {
_scrollX.animateDecay(
velocity.x / 2f,
exponentialDecay(),
)
}
launch {
_scrollY.animateDecay(
velocity.y / 2f,
exponentialDecay(),
)

var lastValue = 0f
AnimationState(
initialValue = 0f,
initialVelocity = velocity.y,
).animateDecay(
exponentialDecay(),
) {
launch {
val delta = Offset(0f, value - lastValue)
lastValue = value
val preConsumed = nestedScrollDispatcher.dispatchPreScroll(
available = delta,
source = NestedScrollSource.Fling,
)

val weAvailable = delta - preConsumed
val previousY = _scrollY.value
_scrollY.snapTo(_scrollY.value + weAvailable.y)
val weConsumed = Offset(0f, _scrollY.value - previousY)

nestedScrollDispatcher.dispatchPostScroll(
consumed = preConsumed + weConsumed,
available = weAvailable - weConsumed,
source = NestedScrollSource.Fling,
)
}
}
}

Expand Down
7 changes: 0 additions & 7 deletions ...sions/src/main/java/io/github/droidkaigi/confsched2023/sessions/section/TimetableSheet.kt
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,6 @@ import androidx.compose.runtime.setValue
import androidx.compose.ui.Modifier
import androidx.compose.ui.geometry.Offset
import androidx.compose.ui.input.nestedscroll.NestedScrollConnection
import androidx.compose.ui.input.nestedscroll.NestedScrollDispatcher
import androidx.compose.ui.input.nestedscroll.NestedScrollSource
import androidx.compose.ui.input.nestedscroll.nestedScroll
import androidx.compose.ui.platform.LocalLayoutDirection
Expand Down Expand Up @@ -128,17 +127,11 @@ fun TimetableSheet(
}

is GridTimetable -> {
val nestedScrollDispatcher = remember { NestedScrollDispatcher() }
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@swimmy-reo swimmy-reo Sep 25, 2023 •
edited
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Thanks for the great PR!
I would like to comment on a point of concern.
Is there any reason why you originally defined the NestedScrollDispatcher and applied Modifier nestedScroll here?

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At first I was misunderstanding that I needed to pass a nestedScrollDispatcher and a timetableSheetContentScrollState.nestedScrollConnection to one Modifier.nestedScroll() argument.
But in this case, the TimetableGrid's nestedScrollDispatcher is independent of the TimetableSheet. Therefore I moved the dispatcher into TimetableGrid class.

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@swimmy-reo swimmy-reo Sep 25, 2023 •
edited
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Thank you very much. I am convinced.

TimetableGrid(
uiState = requireNotNull(uiState.timetableGridUiState[selectedDay]),
nestedScrollDispatcher = nestedScrollDispatcher,
onTimetableItemClick = onTimetableItemClick,
modifier = Modifier
.fillMaxSize()
.nestedScroll(
timetableSheetContentScrollState.nestedScrollConnection,
nestedScrollDispatcher,
)
.weight(1f),
contentPadding = PaddingValues(
bottom = contentPadding.calculateBottomPadding(),
Expand Down
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