Menu.kt

/*
 * Copyright 2020 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.animation.core.LinearOutSlowInEasing
import androidx.compose.animation.core.MutableTransitionState
import androidx.compose.animation.core.animateFloat
import androidx.compose.animation.core.tween
import androidx.compose.animation.core.updateTransition
import androidx.compose.foundation.interaction.MutableInteractionSource
import androidx.compose.foundation.clickable
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.ColumnScope
import androidx.compose.foundation.layout.IntrinsicSize
import androidx.compose.foundation.layout.PaddingValues
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.layout.RowScope
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.sizeIn
import androidx.compose.foundation.layout.width
import androidx.compose.foundation.rememberScrollState
import androidx.compose.foundation.verticalScroll
import androidx.compose.material.ripple.rememberRipple
import androidx.compose.runtime.Composable
import androidx.compose.runtime.CompositionLocalProvider
import androidx.compose.runtime.Immutable
import androidx.compose.runtime.getValue
import androidx.compose.runtime.MutableState
import androidx.compose.runtime.remember
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.TransformOrigin
import androidx.compose.ui.graphics.graphicsLayer
import androidx.compose.ui.unit.Density
import androidx.compose.ui.unit.DpOffset
import androidx.compose.ui.unit.IntOffset
import androidx.compose.ui.unit.IntRect
import androidx.compose.ui.unit.IntSize
import androidx.compose.ui.unit.LayoutDirection
import androidx.compose.ui.unit.dp
import androidx.compose.ui.window.PopupPositionProvider
import kotlin.math.max
import kotlin.math.min

@Suppress("ModifierParameter")
@Composable
internal fun DropdownMenuContent(
    expandedStates: MutableTransitionState<Boolean>,
    transformOriginState: MutableState<TransformOrigin>,
    modifier: Modifier = Modifier,
    content: @Composable ColumnScope.() -> Unit
) {
    // Menu open/close animation.
    val transition = updateTransition(expandedStates, "DropDownMenu")

    val scale by transition.animateFloat(
        transitionSpec = {
            if (false isTransitioningTo true) {
                // Dismissed to expanded
                tween(
                    durationMillis = InTransitionDuration,
                    easing = LinearOutSlowInEasing
                )
            } else {
                // Expanded to dismissed.
                tween(
                    durationMillis = 1,
                    delayMillis = OutTransitionDuration - 1
                )
            }
        }
    ) {
        if (it) {
            // Menu is expanded.
            1f
        } else {
            // Menu is dismissed.
            0.8f
        }
    }

    val alpha by transition.animateFloat(
        transitionSpec = {
            if (false isTransitioningTo true) {
                // Dismissed to expanded
                tween(durationMillis = 30)
            } else {
                // Expanded to dismissed.
                tween(durationMillis = OutTransitionDuration)
            }
        }
    ) {
        if (it) {
            // Menu is expanded.
            1f
        } else {
            // Menu is dismissed.
            0f
        }
    }
    Card(
        modifier = Modifier.graphicsLayer {
            scaleX = scale
            scaleY = scale
            this.alpha = alpha
            transformOrigin = transformOriginState.value
        },
        elevation = MenuElevation
    ) {
        Column(
            modifier = modifier
                .padding(vertical = DropdownMenuVerticalPadding)
                .width(IntrinsicSize.Max)
                .verticalScroll(rememberScrollState()),
            content = content
        )
    }
}

@Composable
internal fun DropdownMenuItemContent(
    onClick: () -> Unit,
    modifier: Modifier = Modifier,
    enabled: Boolean = true,
    contentPadding: PaddingValues = MenuDefaults.DropdownMenuItemContentPadding,
    interactionSource: MutableInteractionSource = remember { MutableInteractionSource() },
    content: @Composable RowScope.() -> Unit
) {
    // TODO(popam, b/156911853): investigate replacing this Row with ListItem
    Row(
        modifier = modifier
            .clickable(
                enabled = enabled,
                onClick = onClick,
                interactionSource = interactionSource,
                indication = rememberRipple(true)
            )
            .fillMaxWidth()
            // Preferred min and max width used during the intrinsic measurement.
            .sizeIn(
                minWidth = DropdownMenuItemDefaultMinWidth,
                maxWidth = DropdownMenuItemDefaultMaxWidth,
                minHeight = DropdownMenuItemDefaultMinHeight
            )
            .padding(contentPadding),
        verticalAlignment = Alignment.CenterVertically
    ) {
        val typography = MaterialTheme.typography
        ProvideTextStyle(typography.subtitle1) {
            val contentAlpha = if (enabled) ContentAlpha.high else ContentAlpha.disabled
            CompositionLocalProvider(LocalContentAlpha provides contentAlpha) {
                content()
            }
        }
    }
}

/**
 * Contains default values used for [DropdownMenuItem].
 */
object MenuDefaults {
    /**
     * Default padding used for [DropdownMenuItem].
     */
    val DropdownMenuItemContentPadding = PaddingValues(
        horizontal = DropdownMenuItemHorizontalPadding,
        vertical = 0.dp
    )
}

// Size defaults.
private val MenuElevation = 8.dp
private val MenuVerticalMargin = 32.dp
private val DropdownMenuItemHorizontalPadding = 16.dp
internal val DropdownMenuVerticalPadding = 8.dp
private val DropdownMenuItemDefaultMinWidth = 112.dp
private val DropdownMenuItemDefaultMaxWidth = 280.dp
private val DropdownMenuItemDefaultMinHeight = 48.dp

// Menu open/close animation.
internal const val InTransitionDuration = 120
internal const val OutTransitionDuration = 75

internal fun calculateTransformOrigin(
    parentBounds: IntRect,
    menuBounds: IntRect
): TransformOrigin {
    val pivotX = when {
        menuBounds.left >= parentBounds.right -> 0f
        menuBounds.right <= parentBounds.left -> 1f
        menuBounds.width == 0 -> 0f
        else -> {
            val intersectionCenter =
                (
                    max(parentBounds.left, menuBounds.left) +
                        min(parentBounds.right, menuBounds.right)
                    ) / 2
            (intersectionCenter - menuBounds.left).toFloat() / menuBounds.width
        }
    }
    val pivotY = when {
        menuBounds.top >= parentBounds.bottom -> 0f
        menuBounds.bottom <= parentBounds.top -> 1f
        menuBounds.height == 0 -> 0f
        else -> {
            val intersectionCenter =
                (
                    max(parentBounds.top, menuBounds.top) +
                        min(parentBounds.bottom, menuBounds.bottom)
                    ) / 2
            (intersectionCenter - menuBounds.top).toFloat() / menuBounds.height
        }
    }
    return TransformOrigin(pivotX, pivotY)
}

// Menu positioning.

/**
 * Calculates the position of a Material [DropdownMenu].
 */
// TODO(popam): Investigate if this can/should consider the app window size rather than screen size
@Immutable
internal data class DropdownMenuPositionProvider(
    val contentOffset: DpOffset,
    val density: Density,
    val onPositionCalculated: (IntRect, IntRect) -> Unit = { _, _ -> }
) : PopupPositionProvider {
    override fun calculatePosition(
        anchorBounds: IntRect,
        windowSize: IntSize,
        layoutDirection: LayoutDirection,
        popupContentSize: IntSize
    ): IntOffset {
        // The min margin above and below the menu, relative to the screen.
        val verticalMargin = with(density) { MenuVerticalMargin.roundToPx() }
        // The content offset specified using the dropdown offset parameter.
        val contentOffsetX = with(density) { contentOffset.x.roundToPx() }
        val contentOffsetY = with(density) { contentOffset.y.roundToPx() }

        // Compute horizontal position.
        val toRight = anchorBounds.left + contentOffsetX
        val toLeft = anchorBounds.right - contentOffsetX - popupContentSize.width
        val toDisplayRight = windowSize.width - popupContentSize.width
        val toDisplayLeft = 0
        val x = if (layoutDirection == LayoutDirection.Ltr) {
            sequenceOf(toRight, toLeft, toDisplayRight)
        } else {
            sequenceOf(toLeft, toRight, toDisplayLeft)
        }.firstOrNull {
            it >= 0 && it + popupContentSize.width <= windowSize.width
        } ?: toLeft

        // Compute vertical position.
        val toBottom = maxOf(anchorBounds.bottom + contentOffsetY, verticalMargin)
        val toTop = anchorBounds.top - contentOffsetY - popupContentSize.height
        val toCenter = anchorBounds.top - popupContentSize.height / 2
        val toDisplayBottom = windowSize.height - popupContentSize.height - verticalMargin
        val y = sequenceOf(toBottom, toTop, toCenter, toDisplayBottom).firstOrNull {
            it >= verticalMargin &&
                it + popupContentSize.height <= windowSize.height - verticalMargin
        } ?: toTop

        onPositionCalculated(
            anchorBounds,
            IntRect(x, y, x + popupContentSize.width, y + popupContentSize.height)
        )
        return IntOffset(x, y)
    }
}