Custom Vertical Padding for Dropdown Menu

Currently the default vertical padding for a dropdown menu is 8dp and it is not possible to override such padding (I dug into the source code).

Is there a way to override the default padding, as I have tried using Modifier.padding(vertical = <custom padding>) and it doesn’t work (probably the subsequent calls to the same method in the library overrode that)?

[mahozad]

I think https://github.com/JetBrains/compose-jb/issues/1878 is related.

[nguoitriki1]

Remove all padding content dropdown. U need coppy all to new file and call “DropdownMenuNoPaddingVeitical” inside compose

import androidx.compose.animation.core.*
import androidx.compose.foundation.layout.*
import androidx.compose.foundation.rememberScrollState
import androidx.compose.foundation.verticalScroll
import androidx.compose.material.*
import androidx.compose.runtime.*
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.TransformOrigin
import androidx.compose.ui.graphics.graphicsLayer
import androidx.compose.ui.platform.LocalDensity
import androidx.compose.ui.unit.*
import androidx.compose.ui.window.Popup
import androidx.compose.ui.window.PopupPositionProvider
import androidx.compose.ui.window.PopupProperties

// Menu open/close animation.
const val InTransitionDuration = 120
const val OutTransitionDuration = 75
private val MenuElevation = 8.dp

@Composable
fun DropdownMenuNoPaddingVeitical(
    expanded: Boolean,
    onDismissRequest: () -> Unit,
    modifier: Modifier = Modifier,
    offset: DpOffset = DpOffset(0.dp, 0.dp),
    properties: PopupProperties = PopupProperties(focusable = true),
    content: @Composable ColumnScope.() -> Unit
) {
    val expandedStates = remember { MutableTransitionState(false) }
    expandedStates.targetState = expanded

    if (expandedStates.currentState || expandedStates.targetState) {
        val transformOriginState = remember { mutableStateOf(TransformOrigin.Center) }
        val density = LocalDensity.current
        val popupPositionProvider = DropdownMenuPositionProvider(
            offset,
            density
        ) { parentBounds, menuBounds ->
            transformOriginState.value = calculateTransformOrigin(parentBounds, menuBounds)
        }

        Popup(
            onDismissRequest = onDismissRequest,
            popupPositionProvider = popupPositionProvider,
            properties = properties
        ) {
            DropdownMenuContent(
                expandedStates = expandedStates,
                transformOriginState = transformOriginState,
                modifier = modifier,
                content = content
            )
        }
    }
}

@Composable
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
                )
            }
        }, label = ""
    ) {
        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)
            }
        }, label = ""
    ) {
        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
                .width(IntrinsicSize.Max)
                .verticalScroll(rememberScrollState()),
            content = content
        )
    }
}


private val MenuVerticalMargin = 48.dp

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,
                // If the anchor gets outside of the window on the left, we want to position
                // toDisplayLeft for proximity to the anchor. Otherwise, toDisplayRight.
                if (anchorBounds.left >= 0) toDisplayRight else toDisplayLeft
            )
        } else {
            sequenceOf(
                toLeft,
                toRight,
                // If the anchor gets outside of the window on the right, we want to position
                // toDisplayRight for proximity to the anchor. Otherwise, toDisplayLeft.
                if (anchorBounds.right <= windowSize.width) toDisplayLeft else toDisplayRight
            )
        }.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)
    }
}

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 =
                (
                        kotlin.math.max(parentBounds.left, menuBounds.left) +
                                kotlin.math.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 =
                (
                        kotlin.math.max(parentBounds.top, menuBounds.top) +
                                kotlin.math.min(parentBounds.bottom, menuBounds.bottom)
                        ) / 2
            (intersectionCenter - menuBounds.top).toFloat() / menuBounds.height
        }
    }
    return TransformOrigin(pivotX, pivotY)
}