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X and Y offset, blur, opacity and colour of shadow in Jetpack Compose?

Since Jetpack Compose has this limitation I'm looking for workaround solution for this problem?

Maybe Canvas could do the trick? I really appreciate if someone can provide code snippets of how to render shadow in Jetpack Compose for Card, Box, Column, Row etc utilising additional parameters like X and Y offset, blur and opacity with custom implementation (Canvas or something else)?

Answer*

kotlin mutiplatform can use as this.
```

import androidx.compose.runtime.Stable
import androidx.compose.ui.Modifier
import androidx.compose.ui.draw.clip
import androidx.compose.ui.draw.drawWithCache
import androidx.compose.ui.geometry.Size
import androidx.compose.ui.graphics.Canvas
import androidx.compose.ui.graphics.ClipOp
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.graphics.ColorMatrix
import androidx.compose.ui.graphics.ColorMatrixColorFilter
import androidx.compose.ui.graphics.NativePaint
import androidx.compose.ui.graphics.Outline
import androidx.compose.ui.graphics.Paint
import androidx.compose.ui.graphics.Path
import androidx.compose.ui.graphics.RectangleShape
import androidx.compose.ui.graphics.Shape
import androidx.compose.ui.graphics.asSkiaColorFilter
import androidx.compose.ui.graphics.drawOutline
import androidx.compose.ui.graphics.drawscope.drawIntoCanvas
import androidx.compose.ui.graphics.isSpecified
import androidx.compose.ui.graphics.nativeCanvas
import androidx.compose.ui.graphics.toArgb
import androidx.compose.ui.unit.Density
import androidx.compose.ui.unit.Dp
import androidx.compose.ui.unit.DpOffset
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.isSpecified
import org.jetbrains.skia.FilterBlurMode
import org.jetbrains.skia.MaskFilter


@Stable
fun Modifier.boxShadow(
    color: Color,
    blurRadius: Dp,
    spreadRadius: Dp = 0.dp,
    offset: DpOffset = DpOffset.Zero,
    shape: Shape = RectangleShape,
    clip: Boolean = true,
    inset: Boolean = false
): Modifier {

    require(color.isSpecified) { "color must be specified." }
    require(blurRadius.isSpecified) { "blurRadius must be specified." }
    require(spreadRadius.isSpecified) { "spreadRadius must be specified." }
    require(blurRadius.value >= 0f) { "blurRadius can't be negative." }
    require(offset.isSpecified) { "offset must be specified." }

    return drawWithCache {
        onDrawWithContent {

            if (inset) drawContent()

            drawIntoCanvas { canvas ->

                val colorArgb = color.toArgb()
                val hasBlurRadius = blurRadius.value.let { it.isFinite() && it != 0f }
                val paint = Paint()

                paint.asFrameworkPaint().let { frameworkPaint ->
                    if (hasBlurRadius) {
                        frameworkPaint.maskFilter =
                            MaskFilter.makeBlur(FilterBlurMode.NORMAL, blurRadius.toPx())
                    }
                    frameworkPaint.color = colorArgb
                }

                val spreadRadiusPx = spreadRadius.toPx().let { spreadRadiusPx ->
                    when {
                        inset -> -spreadRadiusPx
                        else -> spreadRadiusPx
                    }
                }

                val hasSpreadRadius = spreadRadiusPx != 0f
                val size = size
                val layoutDirection = layoutDirection

                val density = Density(
                    density = density,
                    fontScale = fontScale
                )

                val shadowOutline = shape.createOutline(
                    size = when {
                        hasSpreadRadius -> size.let { (width, height) ->
                            (2 * spreadRadiusPx).let { outset ->
                                Size(
                                    width = width + outset,
                                    height = height + outset
                                )
                            }
                        }

                        else -> size
                    },
                    layoutDirection = layoutDirection,
                    density = density
                )

                val nativeCanvas = canvas.nativeCanvas
                val count = nativeCanvas.save()

                if (inset) {

                    val boxOutline = when {
                        hasSpreadRadius -> shape.createOutline(
                            size = size,
                            layoutDirection = layoutDirection,
                            density = density
                        )

                        else -> shadowOutline
                    }

                    canvas.clipToOutline(boxOutline)

                    val bounds = boxOutline.bounds

                    val colorMatrix = ColorMatrix(
                        floatArrayOf(
                            1f, 0f, 0f, 0f, 0f,
                            0f, 1f, 0f, 0f, 0f,
                            0f, 0f, 1f, 0f, 0f,
                            0f, 0f, 0f, -1f, 255f * color.alpha
                        )
                    )


                    val nativePaint = NativePaint()
                    nativePaint.colorFilter = ColorMatrixColorFilter(colorMatrix = colorMatrix).asSkiaColorFilter();
                    nativeCanvas.saveLayer(
                        bounds.left,
                        bounds.top,
                        bounds.right,
                        bounds.bottom,
                        nativePaint
                    )
                }

                canvas.translate(
                    dx = offset.x.toPx() - spreadRadiusPx,
                    dy = offset.y.toPx() - spreadRadiusPx
                )

                canvas.drawOutline(
                    outline = shadowOutline,
                    paint = paint
                )

                nativeCanvas.restoreToCount(count)
            }

            if (!inset) drawContent()
        }
    }.run {
        when {
            clip -> clip(shape)
            else -> this
        }
    }
}

fun Canvas.clipToOutline(
    outline: Outline,
    clipOp: ClipOp = ClipOp.Intersect
) {
    when (outline) {
        is Outline.Generic ->
            clipPath(path = outline.path, clipOp = clipOp)

        is Outline.Rectangle ->
            clipRect(rect = outline.rect, clipOp = clipOp)

        is Outline.Rounded ->
            clipPath(
                path = Path().apply { addRoundRect(outline.roundRect) },
                clipOp = clipOp
            )
    }
}
```

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Community
– Community Bot

2024-05-28 18:36:24 +00:00
Commented May 28, 2024 at 18:36

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X and Y offset, blur, opacity and colour of shadow in Jetpack Compose?

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