| /* |
| * Copyright 2019 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.material |
| |
| import androidx.compose.Composable |
| import androidx.compose.Providers |
| import androidx.compose.Stable |
| import androidx.compose.getValue |
| import androidx.compose.mutableStateOf |
| import androidx.compose.onDispose |
| import androidx.compose.remember |
| import androidx.compose.setValue |
| import androidx.compose.staticAmbientOf |
| import androidx.compose.structuralEqualityPolicy |
| import androidx.ui.core.Alignment |
| import androidx.ui.core.DensityAmbient |
| import androidx.ui.core.Layout |
| import androidx.ui.core.Modifier |
| import androidx.ui.core.boundsInParent |
| import androidx.ui.core.onPositioned |
| import androidx.ui.core.zIndex |
| import androidx.compose.ui.graphics.Color |
| import androidx.compose.ui.graphics.Shape |
| import androidx.compose.foundation.layout.Column |
| import androidx.compose.foundation.layout.InnerPadding |
| import androidx.compose.foundation.layout.Stack |
| import androidx.compose.foundation.layout.fillMaxSize |
| import androidx.compose.foundation.layout.fillMaxWidth |
| import androidx.compose.foundation.layout.padding |
| import androidx.compose.material.Scaffold.FabPosition |
| import androidx.compose.ui.unit.Dp |
| import androidx.compose.ui.unit.PxBounds |
| import androidx.compose.ui.geometry.Size |
| import androidx.compose.ui.unit.dp |
| import androidx.compose.ui.unit.height |
| import androidx.compose.ui.unit.toSize |
| |
| /** |
| * State for [Scaffold] composable component. |
| * |
| * Contains basic screen state, e.g. Drawer configuration, as well as sizes of components after |
| * layout has happened |
| * |
| * @param drawerState initial state of the Drawer in [Scaffold]. |
| * @param isDrawerGesturesEnabled whether or not drawer can be interacted with via gestures |
| */ |
| @Stable |
| class ScaffoldState( |
| drawerState: DrawerState = DrawerState.Closed, |
| isDrawerGesturesEnabled: Boolean = true |
| ) { |
| |
| /** |
| * drawer state position. Change this value to programmatically open or close drawer sheet |
| * in Scaffold (if set). |
| */ |
| var drawerState by mutableStateOf(drawerState) |
| |
| /** |
| * Whether or not drawer sheet in scaffold (if set) can be interacted by gestures. |
| */ |
| var isDrawerGesturesEnabled by mutableStateOf(isDrawerGesturesEnabled) |
| // TODO: add showSnackbar() method here |
| |
| /** |
| * Get current size of the topBar in [Scaffold], if known. `null` if this unknown or topBar |
| * parameter in scaffold is not set |
| */ |
| val topBarSize: Size? |
| get() = scaffoldGeometry.topBarBounds?.toSize() |
| |
| /** |
| * Get current size of the bottomBar in [Scaffold], if known. `null` if this unknown or |
| * bottomBar parameter in scaffold is not set |
| */ |
| val bottomBarSize: Size? |
| get() = scaffoldGeometry.bottomBarBounds?.toSize() |
| |
| /** |
| * Get current size of the floatingActionButton in [Scaffold], if known. `null` if this unknown |
| * or floatingActionButton parameter in scaffold is not set |
| */ |
| val floatingActionButtonSize: Size? |
| get() = scaffoldGeometry.fabBounds?.toSize() |
| |
| internal val scaffoldGeometry = ScaffoldGeometry() |
| } |
| |
| @Stable |
| internal class ScaffoldGeometry { |
| var topBarBounds by mutableStateOf<PxBounds?>(null, structuralEqualityPolicy()) |
| var bottomBarBounds by mutableStateOf<PxBounds?>(null, structuralEqualityPolicy()) |
| var fabBounds by mutableStateOf<PxBounds?>(null, structuralEqualityPolicy()) |
| |
| var isFabDocked by mutableStateOf(false) |
| } |
| |
| internal val ScaffoldGeometryAmbient = staticAmbientOf { ScaffoldGeometry() } |
| |
| object Scaffold { |
| /** |
| * The possible positions for a [FloatingActionButton] attached to a [Scaffold]. |
| */ |
| enum class FabPosition { |
| /** |
| * Position FAB at the bottom of the screen in the center, above the [BottomAppBar] (if it |
| * exists) |
| */ |
| Center, |
| /** |
| * Position FAB at the bottom of the screen at the end, above the [BottomAppBar] (if it |
| * exists) |
| */ |
| End |
| } |
| } |
| |
| /** |
| * Scaffold implements the basic material design visual layout structure. |
| * |
| * This component provides API to put together several material components to construct your |
| * screen, by ensuring proper layout strategy for them and collecting necessary data so these |
| * components will work together correctly. |
| * |
| * Simple example of a Scaffold with [TopAppBar], [FloatingActionButton] and drawer: |
| * |
| * @sample androidx.compose.material.samples.SimpleScaffoldWithTopBar |
| * |
| * More fancy usage with [BottomAppBar] with cutout and docked [FloatingActionButton], which |
| * animates it's shape when clicked: |
| * |
| * @sample androidx.compose.material.samples.ScaffoldWithBottomBarAndCutout |
| * |
| * @param scaffoldState state of this scaffold widget. It contains the state of the screen, e.g. |
| * variables to provide manual control over the drawer behavior, sizes of components, etc |
| * @param topBar top app bar of the screen. Consider using [TopAppBar]. |
| * @param bottomBar bottom bar of the screen. Consider using [BottomAppBar]. |
| * @param floatingActionButton Main action button of your screen. Consider using |
| * [FloatingActionButton] for this slot. |
| * @param floatingActionButtonPosition position of the FAB on the screen. See [FabPosition] for |
| * possible options available. |
| * @param isFloatingActionButtonDocked whether [floatingActionButton] should overlap with |
| * [bottomBar] for half a height, if [bottomBar] exists. Ignored if there's no [bottomBar] or no |
| * [floatingActionButton]. |
| * @param drawerContent content of the Drawer sheet that can be pulled from the left side (right |
| * for RTL). |
| * @param drawerShape shape of the drawer sheet (if set) |
| * @param drawerElevation drawer sheet elevation. This controls the size of the shadow |
| * below the drawer sheet (if set) |
| * @param bodyContent content of your screen. The lambda receives an [InnerPadding] that should be |
| * applied to the content root via [Modifier.padding] to properly offset top and bottom bars. If |
| * you're using VerticalScroller, apply this modifier to the child of the scroller, and not on |
| * the scroller itself. |
| */ |
| @Composable |
| fun Scaffold( |
| scaffoldState: ScaffoldState = remember { ScaffoldState() }, |
| topBar: @Composable (() -> Unit)? = null, |
| bottomBar: @Composable (() -> Unit)? = null, |
| floatingActionButton: @Composable (() -> Unit)? = null, |
| floatingActionButtonPosition: FabPosition = FabPosition.End, |
| isFloatingActionButtonDocked: Boolean = false, |
| drawerContent: @Composable (() -> Unit)? = null, |
| drawerShape: Shape = MaterialTheme.shapes.large, |
| drawerElevation: Dp = DrawerConstants.DefaultElevation, |
| backgroundColor: Color = MaterialTheme.colors.background, |
| bodyContent: @Composable (InnerPadding) -> Unit |
| ) { |
| scaffoldState.scaffoldGeometry.isFabDocked = isFloatingActionButtonDocked |
| val child = @Composable { |
| Surface(color = backgroundColor) { |
| Column(Modifier.fillMaxSize()) { |
| if (topBar != null) { |
| TopBarContainer(Modifier.zIndex(TopAppBarZIndex), scaffoldState, topBar) |
| } |
| Stack(Modifier.weight(1f, fill = true)) { |
| ScaffoldContent(Modifier.fillMaxSize(), scaffoldState, bodyContent) |
| ScaffoldBottom( |
| Modifier.gravity(Alignment.BottomCenter), |
| scaffoldState = scaffoldState, |
| fabPos = floatingActionButtonPosition, |
| isFabDocked = isFloatingActionButtonDocked, |
| fab = floatingActionButton, |
| bottomBar = bottomBar |
| ) |
| } |
| } |
| } |
| } |
| |
| if (drawerContent != null) { |
| ModalDrawerLayout( |
| drawerState = scaffoldState.drawerState, |
| onStateChange = { scaffoldState.drawerState = it }, |
| gesturesEnabled = scaffoldState.isDrawerGesturesEnabled, |
| drawerContent = { ScaffoldSlot(content = drawerContent) }, |
| drawerShape = drawerShape, |
| drawerElevation = drawerElevation, |
| bodyContent = child |
| ) |
| } else { |
| child() |
| } |
| } |
| |
| private fun FabPosition.toColumnAlign() = |
| if (this == FabPosition.End) Alignment.End else Alignment.CenterHorizontally |
| |
| /** |
| * Scaffold part that is on the bottom. Includes FAB and BottomBar |
| */ |
| @Composable |
| private fun ScaffoldBottom( |
| modifier: Modifier, |
| scaffoldState: ScaffoldState, |
| fabPos: FabPosition, |
| isFabDocked: Boolean, |
| fab: @Composable (() -> Unit)? = null, |
| bottomBar: @Composable (() -> Unit)? = null |
| ) { |
| if (isFabDocked && bottomBar != null && fab != null) { |
| DockedBottomBar( |
| modifier = modifier, |
| fabPosition = fabPos, |
| fab = { FabContainer(Modifier, scaffoldState, fab) }, |
| bottomBar = { BottomBarContainer(scaffoldState, bottomBar) } |
| ) |
| } else { |
| Column(modifier.fillMaxWidth()) { |
| if (fab != null) { |
| FabContainer( |
| Modifier.gravity(fabPos.toColumnAlign()) |
| .padding(start = FabSpacing, end = FabSpacing, bottom = FabSpacing), |
| scaffoldState, |
| fab |
| ) |
| } |
| if (bottomBar != null) { |
| BottomBarContainer(scaffoldState, bottomBar) |
| } |
| } |
| } |
| } |
| |
| /** |
| * Simple `Stack` implementation that places [fab] on top (z-axis) of [bottomBar], with the midpoint |
| * of the [fab] aligned to the top edge of the [bottomBar]. |
| * |
| * This is needed as we want the total height of the BottomAppBar to be equal to the height of |
| * [bottomBar] + half the height of [fab], which is only possible with a custom layout. |
| */ |
| @Composable |
| private fun DockedBottomBar( |
| modifier: Modifier, |
| fabPosition: FabPosition, |
| fab: @Composable () -> Unit, |
| bottomBar: @Composable () -> Unit |
| ) { |
| Layout( |
| modifier = modifier, |
| children = { |
| bottomBar() |
| fab() |
| }) { measurables, constraints -> |
| val (appBarPlaceable, fabPlaceable) = measurables.map { it.measure(constraints) } |
| |
| val layoutWidth = appBarPlaceable.width |
| // Total height is the app bar height + half the fab height |
| val layoutHeight = appBarPlaceable.height + (fabPlaceable.height / 2) |
| |
| val appBarVerticalOffset = layoutHeight - appBarPlaceable.height |
| val fabPosX = if (fabPosition == FabPosition.End) { |
| layoutWidth - fabPlaceable.width - DockedFabEndSpacing.toIntPx() |
| } else { |
| (layoutWidth - fabPlaceable.width) / 2 |
| } |
| |
| layout(layoutWidth, layoutHeight) { |
| appBarPlaceable.place(0, appBarVerticalOffset) |
| fabPlaceable.place(fabPosX, 0) |
| } |
| } |
| } |
| |
| @Composable |
| private fun ScaffoldContent( |
| modifier: Modifier, |
| scaffoldState: ScaffoldState, |
| content: @Composable (InnerPadding) -> Unit |
| ) { |
| ScaffoldSlot(modifier) { |
| val innerPadding = with(DensityAmbient.current) { |
| val bottom = scaffoldState.scaffoldGeometry.bottomBarBounds?.height?.toDp() ?: 0.dp |
| InnerPadding(bottom = bottom) |
| } |
| content(innerPadding) |
| } |
| } |
| |
| @Composable |
| private fun BottomBarContainer( |
| scaffoldState: ScaffoldState, |
| bottomBar: @Composable () -> Unit |
| ) { |
| BoundsAwareScaffoldSlot( |
| Modifier, |
| { scaffoldState.scaffoldGeometry.bottomBarBounds = it }, |
| slotContent = { |
| Providers(ScaffoldGeometryAmbient provides scaffoldState.scaffoldGeometry) { |
| bottomBar() |
| } |
| } |
| ) |
| } |
| |
| @Composable |
| private fun FabContainer( |
| modifier: Modifier, |
| scaffoldState: ScaffoldState, |
| fab: @Composable () -> Unit |
| ) { |
| BoundsAwareScaffoldSlot(modifier, { scaffoldState.scaffoldGeometry.fabBounds = it }, fab) |
| } |
| |
| @Composable |
| private fun TopBarContainer( |
| modifier: Modifier, |
| scaffoldState: ScaffoldState, |
| topBar: @Composable () -> Unit |
| ) { |
| BoundsAwareScaffoldSlot(modifier, { scaffoldState.scaffoldGeometry.topBarBounds = it }, topBar) |
| } |
| |
| @Composable |
| private fun BoundsAwareScaffoldSlot( |
| modifier: Modifier, |
| onBoundsKnown: (PxBounds?) -> Unit, |
| slotContent: @Composable () -> Unit |
| ) { |
| onDispose { |
| onBoundsKnown(null) |
| } |
| ScaffoldSlot( |
| modifier = modifier.onPositioned { coords -> onBoundsKnown(coords.boundsInParent) }, |
| content = slotContent |
| ) |
| } |
| |
| /** |
| * Default slot implementation for Scaffold slots content |
| */ |
| @Composable |
| private fun ScaffoldSlot(modifier: Modifier = Modifier, content: @Composable () -> Unit) { |
| Stack(modifier) { content() } |
| } |
| |
| private val FabSpacing = 16.dp |
| private val DockedFabEndSpacing = 16.dp |
| private const val TopAppBarZIndex = 1f |