JetpackCompose-DropShadow

DropShadow.kt

@Stable
fun Modifier.dropShadow(
  borderRadius: Dp,
  spreadRadius: Dp = 3.dp,
  blurRadius: Dp = spreadRadius,
  color: Color = Color.DarkGray.copy(alpha = 0.1f),
  offsetX: Dp = 0.dp,
  offsetY: Dp = 0.dp,
) =
  drawBehind {
    drawIntoCanvas { canvas ->
      val paint = Paint().also { paint ->
        paint.asFrameworkPaint().apply {
          this.color = color.toArgb()

          if (blurRadius != 0.dp) {
            maskFilter = BlurMaskFilter(blurRadius.toPx(), BlurMaskFilter.Blur.NORMAL)
          }
        }
      }

      val spreadPixel = spreadRadius.toPx()
      val leftPixel = (0f - spreadPixel) + offsetX.toPx()
      val topPixel = (0f - spreadPixel) + offsetY.toPx()
      val rightPixel = size.width + spreadPixel
      val bottomPixel = size.height + spreadPixel

      canvas.drawRoundRect(
        left = leftPixel,
        top = topPixel,
        right = rightPixel,
        bottom = bottomPixel,
        radiusX = borderRadius.toPx(),
        radiusY = borderRadius.toPx(),
        paint = paint,
      )
    }
  }