AlertDialog.kt

/*
 * 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.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.padding
import androidx.compose.foundation.layout.sizeIn
import androidx.compose.material3.tokens.DialogTokens
import androidx.compose.runtime.Composable
import androidx.compose.runtime.CompositionLocalProvider
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.graphics.Shape
import androidx.compose.ui.layout.Layout
import androidx.compose.ui.layout.Placeable
import androidx.compose.ui.unit.Dp
import androidx.compose.ui.unit.dp
import kotlin.math.max

@Composable
internal fun AlertDialogContent(
    buttons: @Composable () -> Unit,
    modifier: Modifier = Modifier,
    icon: (@Composable () -> Unit)?,
    title: (@Composable () -> Unit)?,
    text: @Composable (() -> Unit)?,
    shape: Shape,
    containerColor: Color,
    tonalElevation: Dp,
    buttonContentColor: Color,
    iconContentColor: Color,
    titleContentColor: Color,
    textContentColor: Color,
) {
    Surface(
        modifier = modifier,
        shape = shape,
        color = containerColor,
        tonalElevation = tonalElevation,
    ) {
        Column(
            modifier = Modifier
                .sizeIn(minWidth = MinWidth, maxWidth = MaxWidth)
                .padding(DialogPadding)
        ) {
            icon?.let {
                CompositionLocalProvider(LocalContentColor provides iconContentColor) {
                    Box(
                        Modifier
                            .padding(IconPadding)
                            .align(Alignment.CenterHorizontally)
                    ) {
                        icon()
                    }
                }
            }
            title?.let {
                CompositionLocalProvider(LocalContentColor provides titleContentColor) {
                    val textStyle = MaterialTheme.typography.fromToken(DialogTokens.SubheadFont)
                    ProvideTextStyle(textStyle) {
                        Box(
                            // Align the title to the center when an icon is present.
                            Modifier
                                .padding(TitlePadding)
                                .align(
                                    if (icon == null) {
                                        Alignment.Start
                                    } else {
                                        Alignment.CenterHorizontally
                                    }
                                )
                        ) {
                            title()
                        }
                    }
                }
            }
            text?.let {
                CompositionLocalProvider(LocalContentColor provides textContentColor) {
                    val textStyle =
                        MaterialTheme.typography.fromToken(DialogTokens.SupportingTextFont)
                    ProvideTextStyle(textStyle) {
                        Box(
                            Modifier
                                .weight(weight = 1f, fill = false)
                                .padding(TextPadding)
                                .align(Alignment.Start)
                        ) {
                            text()
                        }
                    }
                }
            }
            Box(modifier = Modifier.align(Alignment.End)) {
                CompositionLocalProvider(LocalContentColor provides buttonContentColor) {
                    val textStyle =
                        MaterialTheme.typography.fromToken(DialogTokens.ActionLabelTextFont)
                    ProvideTextStyle(value = textStyle, content = buttons)
                }
            }
        }
    }
}

/**
 * Simple clone of FlowRow that arranges its children in a horizontal flow with limited
 * customization.
 */
@Composable
internal fun AlertDialogFlowRow(
    mainAxisSpacing: Dp,
    crossAxisSpacing: Dp,
    content: @Composable () -> Unit
) {
    Layout(content) { measurables, constraints ->
        val sequences = mutableListOf<List<Placeable>>()
        val crossAxisSizes = mutableListOf<Int>()
        val crossAxisPositions = mutableListOf<Int>()

        var mainAxisSpace = 0
        var crossAxisSpace = 0

        val currentSequence = mutableListOf<Placeable>()
        var currentMainAxisSize = 0
        var currentCrossAxisSize = 0

        // Return whether the placeable can be added to the current sequence.
        fun canAddToCurrentSequence(placeable: Placeable) =
            currentSequence.isEmpty() || currentMainAxisSize + mainAxisSpacing.roundToPx() +
                placeable.width <= constraints.maxWidth

        // Store current sequence information and start a new sequence.
        fun startNewSequence() {
            if (sequences.isNotEmpty()) {
                crossAxisSpace += crossAxisSpacing.roundToPx()
            }
            sequences += currentSequence.toList()
            crossAxisSizes += currentCrossAxisSize
            crossAxisPositions += crossAxisSpace

            crossAxisSpace += currentCrossAxisSize
            mainAxisSpace = max(mainAxisSpace, currentMainAxisSize)

            currentSequence.clear()
            currentMainAxisSize = 0
            currentCrossAxisSize = 0
        }

        for (measurable in measurables) {
            // Ask the child for its preferred size.
            val placeable = measurable.measure(constraints)

            // Start a new sequence if there is not enough space.
            if (!canAddToCurrentSequence(placeable)) startNewSequence()

            // Add the child to the current sequence.
            if (currentSequence.isNotEmpty()) {
                currentMainAxisSize += mainAxisSpacing.roundToPx()
            }
            currentSequence.add(placeable)
            currentMainAxisSize += placeable.width
            currentCrossAxisSize = max(currentCrossAxisSize, placeable.height)
        }

        if (currentSequence.isNotEmpty()) startNewSequence()

        val mainAxisLayoutSize = max(mainAxisSpace, constraints.minWidth)

        val crossAxisLayoutSize = max(crossAxisSpace, constraints.minHeight)

        val layoutWidth = mainAxisLayoutSize

        val layoutHeight = crossAxisLayoutSize

        layout(layoutWidth, layoutHeight) {
            sequences.forEachIndexed { i, placeables ->
                val childrenMainAxisSizes = IntArray(placeables.size) { j ->
                    placeables[j].width +
                        if (j < placeables.lastIndex) mainAxisSpacing.roundToPx() else 0
                }
                val arrangement = Arrangement.Bottom
                // TODO(soboleva): rtl support
                // Handle vertical direction
                val mainAxisPositions = IntArray(childrenMainAxisSizes.size) { 0 }
                with(arrangement) {
                    arrange(mainAxisLayoutSize, childrenMainAxisSizes, mainAxisPositions)
                }
                placeables.forEachIndexed { j, placeable ->
                    placeable.place(
                        x = mainAxisPositions[j],
                        y = crossAxisPositions[i]
                    )
                }
            }
        }
    }
}

// Paddings for each of the dialog's parts.
private val DialogPadding = PaddingValues(all = 24.dp)
private val IconPadding = PaddingValues(bottom = 16.dp)
private val TitlePadding = PaddingValues(bottom = 16.dp)
private val TextPadding = PaddingValues(bottom = 24.dp)

private val MinWidth = 280.dp
private val MaxWidth = 560.dp