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ScalingLazyColumnState.kt
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ScalingLazyColumnState.kt
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/*
* Copyright 2022 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
@file:Suppress("ObjectLiteralToLambda")
@file:OptIn(ExperimentalWearFoundationApi::class)
package com.google.android.horologist.compose.layout
import androidx.compose.foundation.MutatePriority
import androidx.compose.foundation.gestures.FlingBehavior
import androidx.compose.foundation.gestures.ScrollScope
import androidx.compose.foundation.gestures.ScrollableDefaults
import androidx.compose.foundation.gestures.ScrollableState
import androidx.compose.foundation.layout.Arrangement
import androidx.compose.foundation.layout.PaddingValues
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.runtime.Composable
import androidx.compose.runtime.saveable.rememberSaveable
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.platform.LocalConfiguration
import androidx.compose.ui.platform.LocalDensity
import androidx.compose.ui.unit.dp
import androidx.wear.compose.foundation.ExperimentalWearFoundationApi
import androidx.wear.compose.foundation.lazy.AutoCenteringParams
import androidx.wear.compose.foundation.lazy.ScalingLazyColumn
import androidx.wear.compose.foundation.lazy.ScalingLazyListAnchorType
import androidx.wear.compose.foundation.lazy.ScalingLazyListScope
import androidx.wear.compose.foundation.lazy.ScalingLazyListState
import androidx.wear.compose.foundation.lazy.ScalingParams
import androidx.wear.compose.foundation.rememberActiveFocusRequester
import com.google.android.horologist.annotations.ExperimentalHorologistApi
import com.google.android.horologist.compose.layout.ScalingLazyColumnDefaults.responsiveScalingParams
import com.google.android.horologist.compose.layout.ScalingLazyColumnState.RotaryMode
import com.google.android.horologist.compose.rotaryinput.rememberDisabledHaptic
import com.google.android.horologist.compose.rotaryinput.rememberRotaryHapticHandler
import com.google.android.horologist.compose.rotaryinput.rotaryWithScroll
import com.google.android.horologist.compose.rotaryinput.rotaryWithSnap
import com.google.android.horologist.compose.rotaryinput.toRotaryScrollAdapter
import androidx.wear.compose.foundation.lazy.ScalingLazyColumnDefaults as WearScalingLazyColumnDefaults
/**
* A Config and State object wrapping up all configuration for a [ScalingLazyColumn].
* This allows defaults such as [ScalingLazyColumnDefaults.responsive].
*/
@ExperimentalHorologistApi
public class ScalingLazyColumnState(
public val initialScrollPosition: ScrollPosition = ScrollPosition(1, 0),
public val autoCentering: AutoCenteringParams? = AutoCenteringParams(
initialScrollPosition.index,
initialScrollPosition.offsetPx,
),
public val anchorType: ScalingLazyListAnchorType = ScalingLazyListAnchorType.ItemCenter,
public val contentPadding: PaddingValues = PaddingValues(horizontal = 10.dp),
public val rotaryMode: RotaryMode? = RotaryMode.Scroll,
public val reverseLayout: Boolean = false,
public val verticalArrangement: Arrangement.Vertical =
Arrangement.spacedBy(
space = 4.dp,
alignment = if (!reverseLayout) Alignment.Top else Alignment.Bottom,
),
public val horizontalAlignment: Alignment.Horizontal = Alignment.CenterHorizontally,
public val flingBehavior: FlingBehavior? = null,
public val userScrollEnabled: Boolean = true,
public val scalingParams: ScalingParams = WearScalingLazyColumnDefaults.scalingParams(),
public val hapticsEnabled: Boolean = true,
) : ScrollableState {
private var _state: ScalingLazyListState? = null
public var state: ScalingLazyListState
get() {
if (_state == null) {
_state = ScalingLazyListState(
initialScrollPosition.index,
initialScrollPosition.offsetPx,
)
}
return _state!!
}
set(value) {
_state = value
}
override val canScrollBackward: Boolean
get() = state.canScrollBackward
override val canScrollForward: Boolean
get() = state.canScrollForward
override val isScrollInProgress: Boolean
get() = state.isScrollInProgress
override fun dispatchRawDelta(delta: Float): Float = state.dispatchRawDelta(delta)
override suspend fun scroll(
scrollPriority: MutatePriority,
block: suspend ScrollScope.() -> Unit,
) {
state.scroll(scrollPriority, block)
}
public sealed interface RotaryMode {
public object Snap : RotaryMode
public object Scroll : RotaryMode
@Deprecated(
"Use RotaryMode.Scroll instead",
replaceWith = ReplaceWith("RotaryMode.Scroll"),
)
public object Fling : RotaryMode
}
public data class ScrollPosition(
val index: Int,
val offsetPx: Int,
)
public fun interface Factory {
@Composable
public fun create(): ScalingLazyColumnState
}
}
@Composable
public fun rememberColumnState(
factory: ScalingLazyColumnState.Factory = ScalingLazyColumnDefaults.responsive(),
): ScalingLazyColumnState {
val columnState = factory.create()
columnState.state = rememberSaveable(saver = ScalingLazyListState.Saver) {
columnState.state
}
return columnState
}
@Composable
public fun rememberResponsiveColumnState(
contentPadding: @Composable () -> PaddingValues = ScalingLazyColumnDefaults.padding(
first = ScalingLazyColumnDefaults.ItemType.Unspecified,
last = ScalingLazyColumnDefaults.ItemType.Unspecified,
),
verticalArrangement: Arrangement.Vertical =
Arrangement.spacedBy(
space = 4.dp,
alignment = Alignment.Top,
),
rotaryMode: RotaryMode? = RotaryMode.Scroll,
hapticsEnabled: Boolean = true,
reverseLayout: Boolean = false,
userScrollEnabled: Boolean = true,
): ScalingLazyColumnState {
val density = LocalDensity.current
val configuration = LocalConfiguration.current
val screenWidthDp = configuration.screenWidthDp.toFloat()
val screenHeightDp = configuration.screenHeightDp.toFloat()
val scalingParams = responsiveScalingParams(screenWidthDp)
val contentPaddingCalculated = contentPadding()
val screenHeightPx =
with(density) { screenHeightDp.dp.roundToPx() }
val topPaddingPx = with(density) { contentPaddingCalculated.calculateTopPadding().roundToPx() }
val topScreenOffsetPx = screenHeightPx / 2 - topPaddingPx
val initialScrollPosition = ScalingLazyColumnState.ScrollPosition(
index = 0,
offsetPx = topScreenOffsetPx,
)
val columnState = ScalingLazyColumnState(
initialScrollPosition = initialScrollPosition,
autoCentering = null,
anchorType = ScalingLazyListAnchorType.ItemStart,
rotaryMode = rotaryMode,
verticalArrangement = verticalArrangement,
horizontalAlignment = Alignment.CenterHorizontally,
contentPadding = contentPaddingCalculated,
scalingParams = scalingParams,
hapticsEnabled = hapticsEnabled,
reverseLayout = reverseLayout,
userScrollEnabled = userScrollEnabled,
)
columnState.state = rememberSaveable(saver = ScalingLazyListState.Saver) {
columnState.state
}
return columnState
}
@ExperimentalHorologistApi
@Composable
public fun ScalingLazyColumn(
columnState: ScalingLazyColumnState,
modifier: Modifier = Modifier,
content: ScalingLazyListScope.() -> Unit,
) {
val focusRequester = rememberActiveFocusRequester()
val rotaryHaptics = if (columnState.hapticsEnabled) {
rememberRotaryHapticHandler(columnState.state)
} else {
rememberDisabledHaptic()
}
@Suppress("DEPRECATION")
val modifierWithRotary = when (columnState.rotaryMode) {
RotaryMode.Snap -> modifier.rotaryWithSnap(
focusRequester = focusRequester,
rotaryScrollAdapter = columnState.state.toRotaryScrollAdapter(),
reverseDirection = columnState.reverseLayout,
rotaryHaptics = rotaryHaptics,
)
RotaryMode.Scroll, RotaryMode.Fling -> modifier.rotaryWithScroll(
focusRequester = focusRequester,
scrollableState = columnState.state,
reverseDirection = columnState.reverseLayout,
rotaryHaptics = rotaryHaptics,
)
else -> modifier
}
ScalingLazyColumn(
modifier = modifierWithRotary.fillMaxSize(),
state = columnState.state,
contentPadding = columnState.contentPadding,
reverseLayout = columnState.reverseLayout,
verticalArrangement = columnState.verticalArrangement,
horizontalAlignment = columnState.horizontalAlignment,
flingBehavior = columnState.flingBehavior ?: ScrollableDefaults.flingBehavior(),
userScrollEnabled = columnState.userScrollEnabled,
scalingParams = columnState.scalingParams,
anchorType = columnState.anchorType,
autoCentering = columnState.autoCentering,
content = content,
)
}