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AppBar.kt
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/*
* Copyright 2021 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
*
* http://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.
*/
package androidx.compose.material3
import androidx.compose.animation.animateColorAsState
import androidx.compose.animation.core.AnimationState
import androidx.compose.animation.core.DecayAnimationSpec
import androidx.compose.animation.core.FastOutLinearInEasing
import androidx.compose.animation.core.LinearOutSlowInEasing
import androidx.compose.animation.core.animateDecay
import androidx.compose.animation.core.animateTo
import androidx.compose.animation.core.tween
import androidx.compose.foundation.interaction.Interaction
import androidx.compose.foundation.interaction.InteractionSource
import androidx.compose.foundation.interaction.MutableInteractionSource
import androidx.compose.foundation.layout.Arrangement
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.PaddingValues
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.layout.RowScope
import androidx.compose.foundation.layout.Spacer
import androidx.compose.foundation.layout.fillMaxHeight
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.height
import androidx.compose.foundation.layout.padding
import androidx.compose.material3.BottomAppBarDefaults.FloatingActionButton
import androidx.compose.material3.tokens.BottomAppBarTokens
import androidx.compose.material3.tokens.FabSecondaryTokens
import androidx.compose.material3.tokens.TopAppBarLargeTokens
import androidx.compose.material3.tokens.TopAppBarMediumTokens
import androidx.compose.material3.tokens.TopAppBarSmallCenteredTokens
import androidx.compose.material3.tokens.TopAppBarSmallTokens
import androidx.compose.runtime.Composable
import androidx.compose.runtime.CompositionLocalProvider
import androidx.compose.runtime.SideEffect
import androidx.compose.runtime.Stable
import androidx.compose.runtime.State
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.rememberUpdatedState
import androidx.compose.runtime.saveable.Saver
import androidx.compose.runtime.saveable.listSaver
import androidx.compose.runtime.saveable.rememberSaveable
import androidx.compose.runtime.setValue
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.draw.clipToBounds
import androidx.compose.ui.geometry.Offset
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.graphics.Shape
import androidx.compose.ui.graphics.lerp
import androidx.compose.ui.input.nestedscroll.NestedScrollConnection
import androidx.compose.ui.input.nestedscroll.NestedScrollSource
import androidx.compose.ui.layout.AlignmentLine
import androidx.compose.ui.layout.LastBaseline
import androidx.compose.ui.layout.Layout
import androidx.compose.ui.layout.layoutId
import androidx.compose.ui.platform.LocalDensity
import androidx.compose.ui.semantics.clearAndSetSemantics
import androidx.compose.ui.text.TextStyle
import androidx.compose.ui.unit.Constraints
import androidx.compose.ui.unit.Dp
import androidx.compose.ui.unit.Velocity
import androidx.compose.ui.unit.dp
import kotlin.math.abs
import kotlin.math.max
import kotlin.math.roundToInt
/**
* <a href="https://m3.material.io/components/top-app-bar/overview" class="external" target="_blank">Material Design small top app bar</a>.
*
* Top app bars display information and actions at the top of a screen.
*
* This SmallTopAppBar has slots for a title, navigation icon, and actions.
*
* 
*
* A simple top app bar looks like:
* @sample androidx.compose.material3.samples.SimpleSmallTopAppBar
* A top app bar that uses a [scrollBehavior] to customize its nested scrolling behavior when
* working in conjunction with a scrolling content looks like:
* @sample androidx.compose.material3.samples.PinnedSmallTopAppBar
* @sample androidx.compose.material3.samples.EnterAlwaysSmallTopAppBar
*
* @param title the title to be displayed in the top app bar
* @param modifier the [Modifier] to be applied to this top app bar
* @param navigationIcon the navigation icon displayed at the start of the top app bar. This should
* typically be an [IconButton] or [IconToggleButton].
* @param actions the actions displayed at the end of the top app bar. This should typically be
* [IconButton]s. The default layout here is a [Row], so icons inside will be placed horizontally.
* @param colors [TopAppBarColors] that will be used to resolve the colors used for this top app
* bar in different states. See [TopAppBarDefaults.smallTopAppBarColors].
* @param scrollBehavior a [TopAppBarScrollBehavior] which holds various offset values that will be
* applied by this top app bar to set up its height and colors. A scroll behavior is designed to
* work in conjunction with a scrolled content to change the top app bar appearance as the content
* scrolls. See [TopAppBarScrollBehavior.nestedScrollConnection].
*/
@Composable
fun SmallTopAppBar(
title: @Composable () -> Unit,
modifier: Modifier = Modifier,
navigationIcon: @Composable () -> Unit = {},
actions: @Composable RowScope.() -> Unit = {},
colors: TopAppBarColors = TopAppBarDefaults.smallTopAppBarColors(),
scrollBehavior: TopAppBarScrollBehavior? = null
) {
SingleRowTopAppBar(
modifier = modifier,
title = title,
titleTextStyle = MaterialTheme.typography.fromToken(TopAppBarSmallTokens.HeadlineFont),
centeredTitle = false,
navigationIcon = navigationIcon,
actions = actions,
colors = colors,
scrollBehavior = scrollBehavior
)
}
/**
* <a href="https://m3.material.io/components/top-app-bar/overview" class="external" target="_blank">Material Design center-aligned small top app bar</a>.
*
* Top app bars display information and actions at the top of a screen.
*
* This small top app bar has a header title that is horizontally aligned to the center.
*
* 
*
* This CenterAlignedTopAppBar has slots for a title, navigation icon, and actions.
*
* A center aligned top app bar that uses a [scrollBehavior] to customize its nested scrolling
* behavior when working in conjunction with a scrolling content looks like:
* @sample androidx.compose.material3.samples.SimpleCenterAlignedTopAppBar
*
* @param title the title to be displayed in the top app bar
* @param modifier the [Modifier] to be applied to this top app bar
* @param navigationIcon the navigation icon displayed at the start of the top app bar. This should
* typically be an [IconButton] or [IconToggleButton].
* @param actions the actions displayed at the end of the top app bar. This should typically be
* [IconButton]s. The default layout here is a [Row], so icons inside will be placed horizontally.
* @param colors [TopAppBarColors] that will be used to resolve the colors used for this top app
* bar in different states. See [TopAppBarDefaults.centerAlignedTopAppBarColors].
* @param scrollBehavior a [TopAppBarScrollBehavior] which holds various offset values that will be
* applied by this top app bar to set up its height and colors. A scroll behavior is designed to
* work in conjunction with a scrolled content to change the top app bar appearance as the content
* scrolls. See [TopAppBarScrollBehavior.nestedScrollConnection].
*/
@Composable
fun CenterAlignedTopAppBar(
title: @Composable () -> Unit,
modifier: Modifier = Modifier,
navigationIcon: @Composable () -> Unit = {},
actions: @Composable RowScope.() -> Unit = {},
colors: TopAppBarColors = TopAppBarDefaults.centerAlignedTopAppBarColors(),
scrollBehavior: TopAppBarScrollBehavior? = null
) {
SingleRowTopAppBar(
modifier = modifier,
title = title,
titleTextStyle =
MaterialTheme.typography.fromToken(TopAppBarSmallTokens.HeadlineFont),
centeredTitle = true,
navigationIcon = navigationIcon,
actions = actions,
colors = colors,
scrollBehavior = scrollBehavior
)
}
/**
* <a href="https://m3.material.io/components/top-app-bar/overview" class="external" target="_blank">Material Design medium top app bar</a>.
*
* Top app bars display information and actions at the top of a screen.
*
* 
*
* This MediumTopAppBar has slots for a title, navigation icon, and actions. In its default expanded
* state, the title is displayed in a second row under the navigation and actions.
*
* A medium top app bar that uses a [scrollBehavior] to customize its nested scrolling behavior when
* working in conjunction with scrolling content looks like:
* @sample androidx.compose.material3.samples.ExitUntilCollapsedMediumTopAppBar
*
* @param title the title to be displayed in the top app bar. This title will be used in the app
* bar's expanded and collapsed states, although in its collapsed state it will be composed with a
* smaller sized [TextStyle]
* @param modifier the [Modifier] to be applied to this top app bar
* @param navigationIcon the navigation icon displayed at the start of the top app bar. This should
* typically be an [IconButton] or [IconToggleButton].
* @param actions the actions displayed at the end of the top app bar. This should typically be
* [IconButton]s. The default layout here is a [Row], so icons inside will be placed horizontally.
* @param colors [TopAppBarColors] that will be used to resolve the colors used for this top app
* bar in different states. See [TopAppBarDefaults.mediumTopAppBarColors].
* @param scrollBehavior a [TopAppBarScrollBehavior] which holds various offset values that will be
* applied by this top app bar to set up its height and colors. A scroll behavior is designed to
* work in conjunction with a scrolled content to change the top app bar appearance as the content
* scrolls. See [TopAppBarScrollBehavior.nestedScrollConnection].
*/
@Composable
fun MediumTopAppBar(
title: @Composable () -> Unit,
modifier: Modifier = Modifier,
navigationIcon: @Composable () -> Unit = {},
actions: @Composable RowScope.() -> Unit = {},
colors: TopAppBarColors = TopAppBarDefaults.mediumTopAppBarColors(),
scrollBehavior: TopAppBarScrollBehavior? = null
) {
TwoRowsTopAppBar(
modifier = modifier,
title = title,
titleTextStyle = MaterialTheme.typography.fromToken(TopAppBarMediumTokens.HeadlineFont),
smallTitleTextStyle = MaterialTheme.typography.fromToken(TopAppBarSmallTokens.HeadlineFont),
titleBottomPadding = MediumTitleBottomPadding,
smallTitle = title,
navigationIcon = navigationIcon,
actions = actions,
colors = colors,
maxHeight = TopAppBarMediumTokens.ContainerHeight,
pinnedHeight = TopAppBarSmallTokens.ContainerHeight,
scrollBehavior = scrollBehavior
)
}
/**
* <a href="https://m3.material.io/components/top-app-bar/overview" class="external" target="_blank">Material Design large top app bar</a>.
*
* Top app bars display information and actions at the top of a screen.
*
* 
*
* This LargeTopAppBar has slots for a title, navigation icon, and actions. In its default expanded
* state, the title is displayed in a second row under the navigation and actions.
*
* A large top app bar that uses a [scrollBehavior] to customize its nested scrolling behavior when
* working in conjunction with scrolling content looks like:
* @sample androidx.compose.material3.samples.ExitUntilCollapsedLargeTopAppBar
*
* @param title the title to be displayed in the top app bar. This title will be used in the app
* bar's expanded and collapsed states, although in its collapsed state it will be composed with a
* smaller sized [TextStyle]
* @param modifier the [Modifier] to be applied to this top app bar
* @param navigationIcon the navigation icon displayed at the start of the top app bar. This should
* typically be an [IconButton] or [IconToggleButton].
* @param actions the actions displayed at the end of the top app bar. This should typically be
* [IconButton]s. The default layout here is a [Row], so icons inside will be placed horizontally.
* @param colors [TopAppBarColors] that will be used to resolve the colors used for this top app
* bar in different states. See [TopAppBarDefaults.largeTopAppBarColors].
* @param scrollBehavior a [TopAppBarScrollBehavior] which holds various offset values that will be
* applied by this top app bar to set up its height and colors. A scroll behavior is designed to
* work in conjunction with a scrolled content to change the top app bar appearance as the content
* scrolls. See [TopAppBarScrollBehavior.nestedScrollConnection].
*/
@Composable
fun LargeTopAppBar(
title: @Composable () -> Unit,
modifier: Modifier = Modifier,
navigationIcon: @Composable () -> Unit = {},
actions: @Composable RowScope.() -> Unit = {},
colors: TopAppBarColors = TopAppBarDefaults.largeTopAppBarColors(),
scrollBehavior: TopAppBarScrollBehavior? = null
) {
TwoRowsTopAppBar(
title = title,
titleTextStyle = MaterialTheme.typography.fromToken(TopAppBarLargeTokens.HeadlineFont),
smallTitleTextStyle = MaterialTheme.typography.fromToken(TopAppBarSmallTokens.HeadlineFont),
titleBottomPadding = LargeTitleBottomPadding,
smallTitle = title,
modifier = modifier,
navigationIcon = navigationIcon,
actions = actions,
colors = colors,
maxHeight = TopAppBarLargeTokens.ContainerHeight,
pinnedHeight = TopAppBarSmallTokens.ContainerHeight,
scrollBehavior = scrollBehavior
)
}
/**
* <a href="https://m3.material.io/components/bottom-app-bar/overview" class="external" target="_blank">Material Design bottom app bar</a>.
*
* A bottom app bar displays navigation and key actions at the bottom of mobile screens.
*
* 
*
* @sample androidx.compose.material3.samples.SimpleBottomAppBar
*
* It can optionally display a [FloatingActionButton] embedded at the end of the BottomAppBar.
*
* @sample androidx.compose.material3.samples.BottomAppBarWithFAB
*
* Also see [NavigationBar].
*
* @param icons the icon content of this BottomAppBar. The default layout here is a [Row],
* so content inside will be placed horizontally.
* @param modifier the [Modifier] to be applied to this BottomAppBar
* @param floatingActionButton optional floating action button at the end of this BottomAppBar
* @param containerColor the color used for the background of this BottomAppBar. Use
* [Color.Transparent] to have no color.
* @param contentColor the preferred color for content inside this BottomAppBar. Defaults to either
* the matching content color for [containerColor], or to the current [LocalContentColor] if
* [containerColor] is not a color from the theme.
* @param tonalElevation when [containerColor] is [ColorScheme.surface], a translucent primary color
* overlay is applied on top of the container. A higher tonal elevation value will result in a
* darker color in light theme and lighter color in dark theme. See also: [Surface].
* @param contentPadding the padding applied to the content of this BottomAppBar
*/
@Composable
fun BottomAppBar(
icons: @Composable RowScope.() -> Unit,
modifier: Modifier = Modifier,
floatingActionButton: @Composable (() -> Unit)? = null,
containerColor: Color = BottomAppBarDefaults.ContainerColor,
contentColor: Color = contentColorFor(containerColor),
tonalElevation: Dp = BottomAppBarDefaults.ContainerElevation,
contentPadding: PaddingValues = BottomAppBarDefaults.ContentPadding,
) = BottomAppBar(
modifier = modifier,
containerColor = containerColor,
contentColor = contentColor,
tonalElevation = tonalElevation,
contentPadding = contentPadding
) {
icons()
if (floatingActionButton != null) {
Spacer(Modifier.weight(1f, true))
Box(
Modifier
.fillMaxHeight()
.padding(
top = FABVerticalPadding,
end = FABHorizontalPadding
),
contentAlignment = Alignment.TopStart
) {
floatingActionButton()
}
}
}
/**
* <a href="https://m3.material.io/components/bottom-app-bar/overview" class="external" target="_blank">Material Design bottom app bar</a>.
*
* A bottom app bar displays navigation and key actions at the bottom of mobile screens.
*
* 
*
* If you are interested in displaying a [FloatingActionButton], consider using another overload.
*
* Also see [NavigationBar].
*
* @param modifier the [Modifier] to be applied to this BottomAppBar
* @param containerColor the color used for the background of this BottomAppBar. Use
* [Color.Transparent] to have no color.
* @param contentColor the preferred color for content inside this BottomAppBar. Defaults to either
* the matching content color for [containerColor], or to the current [LocalContentColor] if
* [containerColor] is not a color from the theme.
* @param tonalElevation when [containerColor] is [ColorScheme.surface], a translucent primary color
* overlay is applied on top of the container. A higher tonal elevation value will result in a
* darker color in light theme and lighter color in dark theme. See also: [Surface].
* @param contentPadding the padding applied to the content of this BottomAppBar
* @param content the content of this BottomAppBar. The default layout here is a [Row],
* so content inside will be placed horizontally.
*/
@Composable
fun BottomAppBar(
modifier: Modifier = Modifier,
containerColor: Color = BottomAppBarDefaults.ContainerColor,
contentColor: Color = contentColorFor(containerColor),
tonalElevation: Dp = BottomAppBarDefaults.ContainerElevation,
contentPadding: PaddingValues = BottomAppBarDefaults.ContentPadding,
content: @Composable RowScope.() -> Unit
) {
Surface(
color = containerColor,
contentColor = contentColor,
tonalElevation = tonalElevation,
// TODO(b/209583788): Consider adding a shape parameter if updated design guidance allows
shape = BottomAppBarTokens.ContainerShape.toShape(),
modifier = modifier
) {
Row(
Modifier
.fillMaxWidth()
.height(BottomAppBarTokens.ContainerHeight)
.padding(contentPadding),
horizontalArrangement = Arrangement.Start,
verticalAlignment = Alignment.CenterVertically,
content = content
)
}
}
/**
* A TopAppBarScrollBehavior defines how an app bar should behave when the content under it is
* scrolled.
*
* @see [TopAppBarDefaults.pinnedScrollBehavior]
* @see [TopAppBarDefaults.enterAlwaysScrollBehavior]
* @see [TopAppBarDefaults.exitUntilCollapsedScrollBehavior]
*/
@Stable
interface TopAppBarScrollBehavior {
/**
* A [TopAppBarScrollState] that is attached to this behavior and is read and updated when
* scrolling happens.
*/
val state: TopAppBarScrollState
/**
* A [NestedScrollConnection] that should be attached to a [Modifier.nestedScroll] in order to
* keep track of the scroll events.
*/
val nestedScrollConnection: NestedScrollConnection
/**
* Returns the top app bar's current scroll fraction.
*
* A scrollFraction is a value between `0.0` to `1.0` that provides a percentage of the app
* bar scroll position when the content is scrolled. `0.0` represents an expanded app bar,
* while `1.0` represents a collapsed one (e.g. the app bar is scrolled to its target offset).
* Note that this value will be updated on scroll even if the [TopAppBarScrollState.offset] is
* pinned to a specific value (see [TopAppBarDefaults.pinnedScrollBehavior]). In this case a
* value of 1.0 represents that the scroll value has exceeded the height of the pinned app bar,
* as if the app bar was collapsing.
*/
val scrollFraction: Float
}
/**
* Represents the colors used by a top app bar in different states.
*
* Each app bar has their own default implementation available in [TopAppBarDefaults], such as
* [TopAppBarDefaults.smallTopAppBarColors] for [SmallTopAppBar].
*/
@Stable
interface TopAppBarColors {
/**
* Represents the container color used for the top app bar, depending on whether the app bar is
* scrolled, and the percentage of its area that is scrolled.
*
* @param scrollFraction the scroll percentage of the top app bar (0.0 when the app bar is
* considered expanded to 1.0 when the app bar is scrolled to its target offset)
*/
@Composable
fun containerColor(scrollFraction: Float): State<Color>
/**
* Represents the content color used for the top app bar's navigation icon depending on whether
* the app bar is scrolled, and the percentage of its area that is scrolled.
*
* @param scrollFraction the scroll percentage of the top app bar (0.0 when the app bar is
* considered expanded to 1.0 when the app bar is scrolled to its target offset)
*/
@Composable
fun navigationIconContentColor(scrollFraction: Float): State<Color>
/**
* Represents the content color used for the top app bar's title depending on whether the app
* bar is scrolled, and the percentage of its area that is scrolled.
*
* @param scrollFraction the scroll percentage of the top app bar (0.0 when the app bar is
* considered expanded to 1.0 when the app bar is scrolled to its target offset)
*/
@Composable
fun titleContentColor(scrollFraction: Float): State<Color>
/**
* Represents the content color used for the top app bar's action icons depending on whether the
* app bar is scrolled, and the percentage of its area that is scrolled.
*
* @param scrollFraction the scroll percentage of the top app bar (0.0 when the app bar is
* considered expanded to 1.0 when the app bar is scrolled to its target offset)
*/
@Composable
fun actionIconContentColor(scrollFraction: Float): State<Color>
}
/** Contains default values used for the top app bar implementations. */
object TopAppBarDefaults {
/**
* Creates a [TopAppBarColors] for small top app bars. The default implementation animates
* between the provided colors according to the Material Design specification.
*
* @param containerColor the container color
* @param scrolledContainerColor the container color when content is scrolled behind it
* @param navigationIconContentColor the content color used for the navigation icon
* @param titleContentColor the content color used for the title
* @param actionIconContentColor the content color used for actions
* @return the resulting [TopAppBarColors] used for the top app bar
*/
@Composable
fun smallTopAppBarColors(
containerColor: Color = TopAppBarSmallTokens.ContainerColor.toColor(),
scrolledContainerColor: Color = MaterialTheme.colorScheme.applyTonalElevation(
backgroundColor = containerColor,
elevation = TopAppBarSmallTokens.OnScrollContainerElevation
),
navigationIconContentColor: Color = TopAppBarSmallTokens.LeadingIconColor.toColor(),
titleContentColor: Color = TopAppBarSmallTokens.HeadlineColor.toColor(),
actionIconContentColor: Color = TopAppBarSmallTokens.TrailingIconColor.toColor(),
): TopAppBarColors {
return remember(
containerColor,
scrolledContainerColor,
navigationIconContentColor,
titleContentColor,
actionIconContentColor
) {
AnimatingTopAppBarColors(
containerColor,
scrolledContainerColor,
navigationIconContentColor,
titleContentColor,
actionIconContentColor
)
}
}
/**
* Creates a [TopAppBarColors] for center aligned top app bars. The default implementation
* animates between the provided colors according to the Material Design specification.
*
* @param containerColor the container color
* @param scrolledContainerColor the container color when content is scrolled behind it
* @param navigationIconContentColor the content color used for the navigation icon
* @param titleContentColor the content color used for the title
* @param actionIconContentColor the content color used for actions
* @return the resulting [TopAppBarColors] used for the top app bar
*/
@Composable
fun centerAlignedTopAppBarColors(
containerColor: Color = TopAppBarSmallCenteredTokens.ContainerColor.toColor(),
scrolledContainerColor: Color = MaterialTheme.colorScheme.applyTonalElevation(
backgroundColor = containerColor,
elevation = TopAppBarSmallTokens.OnScrollContainerElevation
),
navigationIconContentColor: Color = TopAppBarSmallCenteredTokens.LeadingIconColor.toColor(),
titleContentColor: Color = TopAppBarSmallCenteredTokens.HeadlineColor.toColor(),
actionIconContentColor: Color = TopAppBarSmallCenteredTokens.TrailingIconColor.toColor(),
): TopAppBarColors {
return remember(
containerColor,
scrolledContainerColor,
navigationIconContentColor,
titleContentColor,
actionIconContentColor
) {
AnimatingTopAppBarColors(
containerColor,
scrolledContainerColor,
navigationIconContentColor,
titleContentColor,
actionIconContentColor
)
}
}
/**
* Creates a [TopAppBarColors] for medium top app bars. The default implementation interpolates
* between the provided colors as the top app bar scrolls according to the Material Design
* specification.
*
* @param containerColor the container color
* @param scrolledContainerColor the container color when content is scrolled behind it
* @param navigationIconContentColor the content color used for the navigation icon
* @param titleContentColor the content color used for the title
* @param actionIconContentColor the content color used for actions
* @return the resulting [TopAppBarColors] used for the top app bar
*/
@Composable
fun mediumTopAppBarColors(
containerColor: Color = TopAppBarMediumTokens.ContainerColor.toColor(),
scrolledContainerColor: Color = MaterialTheme.colorScheme.applyTonalElevation(
backgroundColor = containerColor,
elevation = TopAppBarSmallTokens.OnScrollContainerElevation
),
navigationIconContentColor: Color = TopAppBarMediumTokens.LeadingIconColor.toColor(),
titleContentColor: Color = TopAppBarMediumTokens.HeadlineColor.toColor(),
actionIconContentColor: Color = TopAppBarMediumTokens.TrailingIconColor.toColor(),
): TopAppBarColors {
return remember(
containerColor,
scrolledContainerColor,
navigationIconContentColor,
titleContentColor,
actionIconContentColor
) {
InterpolatingTopAppBarColors(
containerColor,
scrolledContainerColor,
navigationIconContentColor,
titleContentColor,
actionIconContentColor
)
}
}
/**
* Creates a [TopAppBarColors] for large top app bars. The default implementation interpolates
* between the provided colors as the top app bar scrolls according to the Material Design
* specification.
*
* @param containerColor the container color
* @param scrolledContainerColor the container color when content is scrolled behind it
* @param navigationIconContentColor the content color used for the navigation icon
* @param titleContentColor the content color used for the title
* @param actionIconContentColor the content color used for actions
* @return the resulting [TopAppBarColors] used for the top app bar
*/
@Composable
fun largeTopAppBarColors(
containerColor: Color = TopAppBarLargeTokens.ContainerColor.toColor(),
scrolledContainerColor: Color = MaterialTheme.colorScheme.applyTonalElevation(
backgroundColor = containerColor,
elevation = TopAppBarSmallTokens.OnScrollContainerElevation
),
navigationIconContentColor: Color = TopAppBarLargeTokens.LeadingIconColor.toColor(),
titleContentColor: Color = TopAppBarLargeTokens.HeadlineColor.toColor(),
actionIconContentColor: Color = TopAppBarLargeTokens.TrailingIconColor.toColor(),
): TopAppBarColors {
return remember(
containerColor,
scrolledContainerColor,
navigationIconContentColor,
titleContentColor,
actionIconContentColor
) {
InterpolatingTopAppBarColors(
containerColor,
scrolledContainerColor,
navigationIconContentColor,
titleContentColor,
actionIconContentColor
)
}
}
/**
* Returns a pinned [TopAppBarScrollBehavior] that tracks nested-scroll callbacks and
* updates its [TopAppBarScrollState.contentOffset] accordingly.
*
* @param state the state object to be used to control or observe the top app bar's scroll
* state. See also [rememberTopAppBarScrollState] to create a state that is remembered across
* compositions.
* @param canScroll a callback used to determine whether scroll events are to be handled by this
* pinned [TopAppBarScrollBehavior]
*/
@ExperimentalMaterial3Api
fun pinnedScrollBehavior(
state: TopAppBarScrollState,
canScroll: () -> Boolean = { true }
): TopAppBarScrollBehavior = PinnedScrollBehavior(state, canScroll)
/**
* Returns a [TopAppBarScrollBehavior]. A top app bar that is set up with this
* [TopAppBarScrollBehavior] will immediately collapse when the content is pulled up, and will
* immediately appear when the content is pulled down.
*
* @param state the state object to be used to control or observe the top app bar's scroll
* state. See also [rememberTopAppBarScrollState] to create a state that is remembered across
* compositions.
* @param canScroll a callback used to determine whether scroll events are to be
* handled by this [EnterAlwaysScrollBehavior]
*/
@ExperimentalMaterial3Api
fun enterAlwaysScrollBehavior(
state: TopAppBarScrollState,
canScroll: () -> Boolean = { true }
): TopAppBarScrollBehavior = EnterAlwaysScrollBehavior(state, canScroll)
/**
* Returns a [TopAppBarScrollBehavior] that adjusts its properties to affect the colors and
* height of the top app bar.
*
* A top app bar that is set up with this [TopAppBarScrollBehavior] will immediately collapse
* when the nested content is pulled up, and will expand back the collapsed area when the
* content is pulled all the way down.
*
* @param decayAnimationSpec a [DecayAnimationSpec] that will be used by the top app bar motion
* when the user flings the content. Preferably, this should match the animation spec used by
* the scrollable content. See also [androidx.compose.animation.rememberSplineBasedDecay] for a
* default [DecayAnimationSpec] that can be used with this behavior.
* @param state the state object to be used to control or observe the top app bar's scroll
* state. See also [rememberTopAppBarScrollState] to create a state that is remembered across
* compositions.
* @param canScroll a callback used to determine whether scroll events are to be
* handled by this [ExitUntilCollapsedScrollBehavior]
*/
@ExperimentalMaterial3Api
fun exitUntilCollapsedScrollBehavior(
decayAnimationSpec: DecayAnimationSpec<Float>,
state: TopAppBarScrollState,
canScroll: () -> Boolean = { true }
): TopAppBarScrollBehavior =
ExitUntilCollapsedScrollBehavior(
state,
decayAnimationSpec,
canScroll
)
}
/**
* Creates a [TopAppBarScrollState] that is remembered across compositions.
*
* Changes to the provided initial values will **not** result in the state being recreated or
* changed in any way if it has already been created.
*
* @param initialOffsetLimit the initial value for [TopAppBarScrollState.offsetLimit], which
* represents the offset that a top app bar is allowed to scroll when the scrollable content is
* scrolled
* @param initialOffset the initial value for [TopAppBarScrollState.offset]. The initial offset
* should be between zero and [initialOffsetLimit].
* @param initialContentOffset the initial value for [TopAppBarScrollState.contentOffset]
*/
@Composable
fun rememberTopAppBarScrollState(
initialOffsetLimit: Float = -Float.MAX_VALUE,
initialOffset: Float = 0f,
initialContentOffset: Float = 0f
): TopAppBarScrollState {
return rememberSaveable(saver = TopAppBarScrollState.Saver) {
TopAppBarScrollState(
initialOffsetLimit,
initialOffset,
initialContentOffset
)
}
}
/**
* A state object that can be hoisted to control and observe the top app bar scroll state. The state
* is read and updated by a [TopAppBarScrollBehavior] implementation.
*
* In most cases, this will be created via [rememberTopAppBarScrollState].
*
* @param offsetLimit the initial value for [TopAppBarScrollState.offsetLimit]
* @param offset the initial value for [TopAppBarScrollState.offset]
* @param contentOffset the initial value for [TopAppBarScrollState.contentOffset]
*/
@Stable
class TopAppBarScrollState(offsetLimit: Float, offset: Float, contentOffset: Float) {
/**
* The top app bar's offset limit in pixels, which represents the offset that a top app bar is
* allowed to scroll when the scrollable content is scrolled.
*
* This limit is represented by a negative [Float], and used to coerce the [offset] value when
* the content is scrolled.
*/
var offsetLimit by mutableStateOf(offsetLimit)
/**
* The top app bar's current offset in pixels.
*
* The offset is usually between zero and the [offsetLimit].
*/
var offset by mutableStateOf(offset)
/**
* The current content offset that is updated when the nested scroll connection consumes scroll
* events.
*
* A common behavior implementation would update this value to be the sum of all
* [NestedScrollConnection.onPostScroll] `consumed.y` values.
*/
var contentOffset by mutableStateOf(contentOffset)
companion object {
/**
* The default [Saver] implementation for [TopAppBarScrollState].
*/
val Saver: Saver<TopAppBarScrollState, *> = listSaver(
save = { listOf(it.offsetLimit, it.offset, it.contentOffset) },
restore = {
TopAppBarScrollState(
offsetLimit = it[0],
offset = it[1],
contentOffset = it[2]
)
}
)
}
}
/** Contains default values used for the bottom app bar implementations. */
object BottomAppBarDefaults {
/** Default color used for [BottomAppBar] container **/
val ContainerColor: Color @Composable get() = BottomAppBarTokens.ContainerColor.toColor()
/** Default elevation used for [BottomAppBar] **/
val ContainerElevation: Dp = BottomAppBarTokens.ContainerElevation
/**
* Default padding used for [BottomAppBar] when content are default size (24dp) icons in
* [IconButton] that meet the minimum touch target (48.dp).
*/
val ContentPadding = PaddingValues(
start = BottomAppBarHorizontalPadding,
top = BottomAppBarVerticalPadding,
end = BottomAppBarHorizontalPadding
)
// Bottom App Bar FAB Defaults
/**
* Creates a [FloatingActionButtonElevation] that represents the default elevation of a
* [FloatingActionButton] used for [BottomAppBar] in different states.
*/
object FloatingActionButtonElevation :
androidx.compose.material3.FloatingActionButtonElevation {
val elevation = mutableStateOf(0.dp)
@Composable
override fun shadowElevation(interactionSource: InteractionSource) = elevation
@Composable
override fun tonalElevation(interactionSource: InteractionSource) = elevation
}
/** The color of a [BottomAppBar]'s [FloatingActionButton] */
val FloatingActionButtonContainerColor: Color @Composable get() =
FabSecondaryTokens.ContainerColor.toColor()
/** The shape of a [BottomAppBar]'s [FloatingActionButton] */
val FloatingActionButtonShape: Shape @Composable get() =
FabSecondaryTokens.ContainerShape.toShape()
/**
* The default [FloatingActionButton] for [BottomAppBar]
*
* A [BottomAppBar]'s FAB follows a secondary color style, as well as an elevation of zero.
*
* @sample androidx.compose.material3.samples.BottomAppBarWithFAB
*
* @param onClick callback invoked when this FAB is clicked
* @param modifier [Modifier] to be applied to this FAB.
* @param interactionSource the [MutableInteractionSource] representing the stream of
* [Interaction]s for this FAB. You can create and pass in your own `remember`ed instance to
* observe [Interaction]s and customize the appearance / behavior of this FAB in different
* states.
* @param shape defines the shape of this FAB's container and shadow (when using [elevation])
* @param containerColor the color used for the background of this FAB. Use [Color.Transparent]
* to have no color.
* @param contentColor the preferred color for content inside this FAB. Defaults to either the
* matching content color for [containerColor], or to the current [LocalContentColor] if
* [containerColor] is not a color from the theme.
* @param elevation [FloatingActionButtonElevation] used to resolve the elevation for this FAB
* in different states. This controls the size of the shadow below the FAB. Additionally, when
* the container color is [ColorScheme.surface], this controls the amount of primary color
* applied as an overlay. See also: [Surface].
* @param content the content of this FAB - this is typically an [Icon].
*/
@Composable
fun FloatingActionButton(
onClick: () -> Unit,
modifier: Modifier = Modifier,
interactionSource: MutableInteractionSource = remember { MutableInteractionSource() },
shape: Shape = FloatingActionButtonShape,
containerColor: Color = FloatingActionButtonContainerColor,
contentColor: Color = contentColorFor(containerColor),
elevation: androidx.compose.material3.FloatingActionButtonElevation =
FloatingActionButtonElevation,
content: @Composable () -> Unit,
) = androidx.compose.material3.FloatingActionButton(
onClick = onClick,
modifier = modifier,
interactionSource = interactionSource,
shape = shape,
containerColor = containerColor,
contentColor = contentColor,
elevation = elevation,
content = content
)
}
// Padding minus IconButton's min touch target expansion
private val BottomAppBarHorizontalPadding = 16.dp - 12.dp
// Padding minus IconButton's min touch target expansion
private val BottomAppBarVerticalPadding = 16.dp - 12.dp
// Padding minus content padding
private val FABHorizontalPadding = 16.dp - BottomAppBarHorizontalPadding
private val FABVerticalPadding = 12.dp - BottomAppBarVerticalPadding
/**
* A single-row top app bar that is designed to be called by the small and center aligned top app
* bar composables.
*
* This SingleRowTopAppBar has slots for a title, navigation icon, and actions. When the
* [centeredTitle] flag is true, the title will be horizontally aligned to the center of the top app
* bar width.
*/
@Composable
private fun SingleRowTopAppBar(
modifier: Modifier = Modifier,
title: @Composable () -> Unit,
titleTextStyle: TextStyle,
centeredTitle: Boolean,
navigationIcon: @Composable () -> Unit,
actions: @Composable RowScope.() -> Unit,
colors: TopAppBarColors,
scrollBehavior: TopAppBarScrollBehavior?
) {
// TODO(b/182393826): Check if there is a better place to set the offsetLimit.
// Set a scroll offset limit to hide the entire app bar area when scrolling.
val offsetLimit = with(LocalDensity.current) { -TopAppBarSmallTokens.ContainerHeight.toPx() }
SideEffect {
if (scrollBehavior?.state?.offsetLimit != offsetLimit) {
scrollBehavior?.state?.offsetLimit = offsetLimit
}
}
// Obtain the container color from the TopAppBarColors.
// This may potentially animate or interpolate a transition between the container-color and the
// container's scrolled-color according to the app bar's scroll state.
val scrollFraction = scrollBehavior?.scrollFraction ?: 0f
val appBarContainerColor by colors.containerColor(scrollFraction)
// Wrap the given actions in a Row.
val actionsRow = @Composable {
Row(
horizontalArrangement = Arrangement.End,
verticalAlignment = Alignment.CenterVertically,
content = actions
)
}
// Compose a Surface with a TopAppBarLayout content. The surface's background color will be
// animated as specified above, and the height of the app bar will be determined by the current
// scroll-state offset.
Surface(modifier = modifier, color = appBarContainerColor) {
val height = LocalDensity.current.run {
TopAppBarSmallTokens.ContainerHeight.toPx() + (scrollBehavior?.state?.offset ?: 0f)
}
TopAppBarLayout(
modifier = Modifier,
heightPx = height,
navigationIconContentColor = colors.navigationIconContentColor(scrollFraction).value,
titleContentColor = colors.titleContentColor(scrollFraction).value,
actionIconContentColor = colors.actionIconContentColor(scrollFraction).value,
title = title,
titleTextStyle = titleTextStyle,
titleAlpha = 1f,
titleVerticalArrangement = Arrangement.Center,
titleHorizontalArrangement =
if (centeredTitle) Arrangement.Center else Arrangement.Start,
titleBottomPadding = 0,
hideTitleSemantics = false,
navigationIcon = navigationIcon,
actions = actionsRow,
)
}
}
/**
* A two-rows top app bar that is designed to be called by the Large and Medium top app bar
* composables.
*
* @throws [IllegalArgumentException] if the given [maxHeight] is equal or smaller than the
* [pinnedHeight]
*/
@Composable
private fun TwoRowsTopAppBar(
modifier: Modifier = Modifier,
title: @Composable () -> Unit,
titleTextStyle: TextStyle,
titleBottomPadding: Dp,
smallTitle: @Composable () -> Unit,
smallTitleTextStyle: TextStyle,
navigationIcon: @Composable () -> Unit,
actions: @Composable RowScope.() -> Unit,
colors: TopAppBarColors,
maxHeight: Dp,
pinnedHeight: Dp,
scrollBehavior: TopAppBarScrollBehavior?
) {
if (maxHeight <= pinnedHeight) {
throw IllegalArgumentException(
"A TwoRowsTopAppBar max height should be greater than its pinned height"
)
}
val pinnedHeightPx: Float
val maxHeightPx: Float
val titleBottomPaddingPx: Int