| /* |
| * 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.ui.material |
| |
| import androidx.compose.Composable |
| import androidx.ui.core.Alignment |
| import androidx.ui.core.AlignmentLine |
| import androidx.ui.core.Layout |
| import androidx.ui.core.Modifier |
| import androidx.ui.core.id |
| import androidx.ui.core.layoutId |
| import androidx.compose.foundation.Box |
| import androidx.compose.foundation.ProvideTextStyle |
| import androidx.ui.graphics.Color |
| import androidx.ui.graphics.Shape |
| import androidx.ui.graphics.compositeOver |
| import androidx.compose.foundation.layout.Column |
| import androidx.compose.foundation.layout.fillMaxWidth |
| import androidx.compose.foundation.layout.padding |
| import androidx.compose.foundation.layout.relativePaddingFrom |
| import androidx.ui.text.FirstBaseline |
| import androidx.ui.text.LastBaseline |
| import androidx.ui.unit.Dp |
| import androidx.ui.unit.dp |
| import kotlin.math.max |
| |
| /** |
| * Snackbars provide brief messages about app processes at the bottom of the screen. |
| * |
| * Snackbars inform users of a process that an app has performed or will perform. They appear |
| * temporarily, towards the bottom of the screen. They shouldn’t interrupt the user experience, |
| * and they don’t require user input to disappear. |
| * |
| * A Snackbar can contain a single action. Because they disappear automatically, the action |
| * shouldn't be "Dismiss" or "Cancel". |
| * |
| * @sample androidx.ui.material.samples.SimpleSnackbar |
| * |
| * @param text text component to show information about a process that an app has performed or |
| * will perform |
| * @param action action / button component to add as an action to the snackbar. Consider using |
| * [snackbarPrimaryColorFor] as the color for the action, if you do not have a predefined color |
| * you wish to use instead. |
| * @param modifier modifiers for the the Snackbar layout |
| * @param actionOnNewLine whether or not action should be put on the separate line. Recommended |
| * for action with long action text |
| * @param shape Defines the Snackbar's shape as well as its shadow |
| * @param elevation The z-coordinate at which to place the SnackBar. This controls the size |
| * of the shadow below the SnackBar |
| */ |
| @Composable |
| fun Snackbar( |
| text: @Composable () -> Unit, |
| action: @Composable (() -> Unit)? = null, |
| modifier: Modifier = Modifier, |
| actionOnNewLine: Boolean = false, |
| shape: Shape = MaterialTheme.shapes.small, |
| elevation: Dp = 6.dp |
| ) { |
| val colors = MaterialTheme.colors |
| // Snackbar has a background color of onSurface with an alpha applied blended on top of surface |
| val snackbarOverlayColor = colors.onSurface.copy(alpha = SnackbarOverlayAlpha) |
| val snackbarColor = snackbarOverlayColor.compositeOver(colors.surface) |
| Surface( |
| modifier = modifier, |
| shape = shape, |
| elevation = elevation, |
| color = snackbarColor, |
| contentColor = colors.surface |
| ) { |
| ProvideEmphasis(EmphasisAmbient.current.high) { |
| val textStyle = MaterialTheme.typography.body2 |
| ProvideTextStyle(value = textStyle) { |
| when { |
| action == null -> TextOnlySnackbar(text) |
| actionOnNewLine -> NewLineButtonSnackbar(text, action) |
| else -> OneRowSnackbar(text, action) |
| } |
| } |
| } |
| } |
| } |
| |
| @Composable |
| private fun TextOnlySnackbar(text: @Composable () -> Unit) { |
| Layout( |
| text, |
| modifier = Modifier.padding( |
| start = HorizontalSpacing, |
| end = HorizontalSpacing, |
| top = SnackbarVerticalPadding, |
| bottom = SnackbarVerticalPadding |
| ) |
| ) { measurables, constraints -> |
| require(measurables.size == 1) { |
| "text for Snackbar expected to have exactly only one child" |
| } |
| val textPlaceable = measurables.first().measure(constraints) |
| val firstBaseline = textPlaceable[FirstBaseline] |
| val lastBaseline = textPlaceable[LastBaseline] |
| require(firstBaseline != AlignmentLine.Unspecified) { "No baselines for text" } |
| require(lastBaseline != AlignmentLine.Unspecified) { "No baselines for text" } |
| |
| val minHeight = |
| if (firstBaseline == lastBaseline) { |
| SnackbarMinHeightOneLine |
| } else { |
| SnackbarMinHeightTwoLines |
| } |
| val containerHeight = max(minHeight.toIntPx(), textPlaceable.height) |
| layout(constraints.maxWidth, containerHeight) { |
| val textPlaceY = (containerHeight - textPlaceable.height) / 2 |
| textPlaceable.place(0, textPlaceY) |
| } |
| } |
| } |
| |
| @Composable |
| private fun NewLineButtonSnackbar( |
| text: @Composable () -> Unit, |
| action: @Composable () -> Unit |
| ) { |
| Column( |
| modifier = Modifier.fillMaxWidth() |
| .padding( |
| start = HorizontalSpacing, |
| end = HorizontalSpacingButtonSide, |
| bottom = SeparateButtonExtraY |
| ) |
| ) { |
| Box( |
| Modifier |
| .relativePaddingFrom(LastBaseline, after = LongButtonVerticalOffset) |
| .relativePaddingFrom(FirstBaseline, before = HeightToFirstLine) |
| .padding(end = HorizontalSpacingButtonSide), |
| children = text |
| ) |
| Box(Modifier.gravity(Alignment.End), children = action) |
| } |
| } |
| |
| @Composable |
| private fun OneRowSnackbar( |
| text: @Composable () -> Unit, |
| action: @Composable () -> Unit |
| ) { |
| val textTag = "text" |
| val actionTag = "action" |
| Layout( |
| { |
| Box(Modifier.layoutId(textTag), children = text) |
| Box(Modifier.layoutId(actionTag), children = action) |
| }, |
| modifier = Modifier.padding( |
| start = HorizontalSpacing, |
| end = HorizontalSpacingButtonSide, |
| top = SnackbarVerticalPadding, |
| bottom = SnackbarVerticalPadding |
| ) |
| ) { measurables, constraints -> |
| val buttonPlaceable = measurables.first { it.id == actionTag }.measure(constraints) |
| val textMaxWidth = |
| (constraints.maxWidth - buttonPlaceable.width - TextEndExtraSpacing.toIntPx()) |
| .coerceAtLeast(constraints.minWidth) |
| val textPlaceable = measurables.first { it.id == textTag }.measure( |
| constraints.copy(minHeight = 0, maxWidth = textMaxWidth) |
| ) |
| |
| val firstTextBaseline = textPlaceable[FirstBaseline] |
| require(firstTextBaseline != AlignmentLine.Unspecified) { "No baselines for text" } |
| val lastTextBaseline = textPlaceable[LastBaseline] |
| require(lastTextBaseline != AlignmentLine.Unspecified) { "No baselines for text" } |
| val isOneLine = firstTextBaseline == lastTextBaseline |
| val buttonPlaceX = constraints.maxWidth - buttonPlaceable.width |
| |
| val textPlaceY: Int |
| val containerHeight: Int |
| val buttonPlaceY: Int |
| if (isOneLine) { |
| val minContainerHeight = SnackbarMinHeightOneLine.toIntPx() |
| val contentHeight = buttonPlaceable.height |
| containerHeight = max(minContainerHeight, contentHeight) |
| textPlaceY = (containerHeight - textPlaceable.height) / 2 |
| val buttonBaseline = buttonPlaceable[FirstBaseline] |
| buttonPlaceY = buttonBaseline.let { |
| if (it != AlignmentLine.Unspecified) { |
| textPlaceY + firstTextBaseline - it |
| } else { |
| 0 |
| } |
| } |
| } else { |
| val baselineOffset = HeightToFirstLine.toIntPx() |
| textPlaceY = baselineOffset - firstTextBaseline - SnackbarVerticalPadding.toIntPx() |
| val minContainerHeight = SnackbarMinHeightTwoLines.toIntPx() |
| val contentHeight = textPlaceY + textPlaceable.height |
| containerHeight = max(minContainerHeight, contentHeight) |
| buttonPlaceY = (containerHeight - buttonPlaceable.height) / 2 |
| } |
| |
| layout(constraints.maxWidth, containerHeight) { |
| textPlaceable.place(0, textPlaceY) |
| buttonPlaceable.place(buttonPlaceX, buttonPlaceY) |
| } |
| } |
| } |
| |
| /** |
| * Provides a best-effort 'primary' color to be used as the primary color inside a [Snackbar]. |
| * Given that [Snackbar]s have an 'inverted' theme, i.e in a light theme they appear dark, and |
| * in a dark theme they appear light, just using [ColorPalette.primary] will not work, and has |
| * incorrect contrast. |
| * |
| * If your light theme has a corresponding dark theme, you should instead directly use |
| * [ColorPalette.primary] from the dark theme when in a light theme, and use |
| * [ColorPalette.primaryVariant] from the dark theme when in a dark theme. |
| * |
| * When in a light theme, this function applies a color overlay to [ColorPalette.primary] from |
| * [colors] to attempt to reduce the contrast, and when in a dark theme this function uses |
| * [ColorPalette.primaryVariant]. |
| * |
| * @param colors the [ColorPalette] to calculate the Snackbar primary color for |
| */ |
| fun snackbarPrimaryColorFor(colors: ColorPalette): Color { |
| return if (colors.isLight) { |
| val primary = colors.primary |
| val overlayColor = colors.surface.copy(alpha = 0.6f) |
| |
| overlayColor.compositeOver(primary) |
| } else { |
| colors.primaryVariant |
| } |
| } |
| |
| private const val SnackbarOverlayAlpha = 0.8f |
| |
| private val HeightToFirstLine = 30.dp |
| private val HorizontalSpacing = 16.dp |
| private val HorizontalSpacingButtonSide = 8.dp |
| private val SeparateButtonExtraY = 8.dp |
| private val SnackbarVerticalPadding = 6.dp |
| private val TextEndExtraSpacing = 8.dp |
| private val LongButtonVerticalOffset = 18.dp |
| private val SnackbarMinHeightOneLine = 48.dp - SnackbarVerticalPadding * 2 |
| private val SnackbarMinHeightTwoLines = 68.dp - SnackbarVerticalPadding * 2 |