Example of border modifier for Jetpack Compose

BorderModifier.kt

import androidx.compose.runtime.Stable
import androidx.compose.ui.Modifier
import androidx.compose.ui.drawBehind
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.graphics.Path
import androidx.compose.ui.graphics.drawscope.DrawScope
import androidx.compose.ui.unit.Dp

/**
 * Border definition can be extended to provide border style or [androidx.compose.ui.graphics.Brush]
 * One more way is make it sealed class and provide different implementations:
 * SolidBorder, DashedBorder etc
 */
data class Border(val strokeWidth: Dp, val color: Color)

@Stable
fun Modifier.border(
    start: Border? = null,
    top: Border? = null,
    end: Border? = null,
    bottom: Border? = null,
) =
    drawBehind {
        start?.let {
            drawStartBorder(it, shareTop = top != null, shareBottom = bottom != null)
        }
        top?.let {
            drawTopBorder(it, shareStart = start != null, shareEnd = end != null)
        }
        end?.let {
            drawEndBorder(it, shareTop = top != null, shareBottom = bottom != null)
        }
        bottom?.let {
            drawBottomBorder(border = it, shareStart = start != null, shareEnd = end != null)
        }
    }

private fun DrawScope.drawTopBorder(
    border: Border,
    shareStart: Boolean = true,
    shareEnd: Boolean = true
) {
    val strokeWidthPx = border.strokeWidth.toPx()
    if (strokeWidthPx == 0f) return
    drawPath(
        Path().apply {
            moveTo(0f, 0f)
            lineTo(if (shareStart) strokeWidthPx else 0f, strokeWidthPx)
            val width = size.width
            lineTo(if (shareEnd) width - strokeWidthPx else width, strokeWidthPx)
            lineTo(width, 0f)
            close()
        },
        color = border.color
    )
}

private fun DrawScope.drawBottomBorder(
    border: Border,
    shareStart: Boolean,
    shareEnd: Boolean
) {
    val strokeWidthPx = border.strokeWidth.toPx()
    if (strokeWidthPx == 0f) return
    drawPath(
        Path().apply {
            val width = size.width
            val height = size.height
            moveTo(0f, height)
            lineTo(if (shareStart) strokeWidthPx else 0f, height - strokeWidthPx)
            lineTo(if (shareEnd) width - strokeWidthPx else width, height - strokeWidthPx)
            lineTo(width, height)
            close()
        },
        color = border.color
    )
}

private fun DrawScope.drawStartBorder(
    border: Border,
    shareTop: Boolean = true,
    shareBottom: Boolean = true
) {
    val strokeWidthPx = border.strokeWidth.toPx()
    if (strokeWidthPx == 0f) return
    drawPath(
        Path().apply {
            moveTo(0f, 0f)
            lineTo(strokeWidthPx, if (shareTop) strokeWidthPx else 0f)
            val height = size.height
            lineTo(strokeWidthPx, if (shareBottom) height - strokeWidthPx else height)
            lineTo(0f, height)
            close()
        },
        color = border.color
    )
}

private fun DrawScope.drawEndBorder(
    border: Border,
    shareTop: Boolean = true,
    shareBottom: Boolean = true
) {
    val strokeWidthPx = border.strokeWidth.toPx()
    if (strokeWidthPx == 0f) return
    drawPath(
        Path().apply {
            val width = size.width
            val height = size.height
            moveTo(width, 0f)
            lineTo(width - strokeWidthPx, if (shareTop) strokeWidthPx else 0f)
            lineTo(width - strokeWidthPx, if (shareBottom) height - strokeWidthPx else height)
            lineTo(width, height)
            close()
        },
        color = border.color
    )
}

MainActivity.kt

import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import androidx.compose.foundation.Text
import androidx.compose.foundation.layout.*
import androidx.compose.runtime.Composable
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.platform.setContent
import androidx.compose.ui.unit.dp
import androidx.ui.tooling.preview.Preview

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            BordersDemo()
        }
    }
}

data class Borders(
    val start: Border? = null,
    val end: Border? = null,
    val top: Border? = null,
    val bottom: Border? = null
)

@Preview(showBackground = true)
@Composable
fun BordersDemo() {
    Column(
        horizontalGravity = Alignment.CenterHorizontally,
        verticalArrangement = Arrangement.Center,
        modifier = Modifier.fillMaxSize()
    ) {
        val strokeWidth = 8.dp
        val start = Border(strokeWidth, Color.Cyan)
        val end = Border(strokeWidth, Color.Green)
        val bottom = Border(strokeWidth, Color.Blue)
        val top = Border(strokeWidth, Color.Red)
        val samples = listOf(
            Borders(bottom = bottom, end = end),
            Borders(bottom = bottom, top = top),
            Borders(start = start, end = end),
            Borders(top = top, start = start, end = end),
            Borders(bottom = bottom, top = top, start = start, end = end),
        )
        samples.forEach { borders ->
            Text(
                text = "Hello Android!",
                modifier = Modifier
                    .border(
                        bottom = borders.bottom,
                        end = borders.end,
                        start = borders.start,
                        top = borders.top
                    )
                    .padding(strokeWidth + 8.dp)
            )
            Spacer(modifier = Modifier.height(24.dp))
        }
    }
}

Thank you!