Get One Sides Shadow In View

ViewDrawableUtils.kt

/**
* Get Shadow Drawable with most elevation on provided shadowGravity Attribute
*/
fun getBoxShadowBackground(
    view: View,
    @ColorRes backgroundColor: Int = android.R.color.white,
    radiusInDP: Float = view.convertDpTpPx(5F),
    @ColorRes shadowColor: Int = android.R.color.black,
    elevation: Int = 0,
    shadowGravity: Int = Gravity.BOTTOM
): Drawable? {
    val shadowColorValue = ContextCompat.getColor(view.context, shadowColor)
    val backgroundColorValue = ContextCompat.getColor(view.context, backgroundColor)
    val outerRadius = floatArrayOf(
        radiusInDP, // top-left
        radiusInDP, // top-left
        radiusInDP, // top-right
        radiusInDP, // top-right
        radiusInDP, // bottom-right
        radiusInDP, // bottom-right
        radiusInDP, // bottom-left
        radiusInDP  // bottom-left
    )
    val backgroundPaint = Paint()
    backgroundPaint.style = Paint.Style.FILL
    backgroundPaint.setShadowLayer(radiusInDP, 0f, 0f, 0)
    val shapeDrawablePadding = Rect()
    shapeDrawablePadding.left = elevation
    shapeDrawablePadding.right = elevation

    val DY: Int
    when (shadowGravity) {
        Gravity.CENTER -> {
            shapeDrawablePadding.top = elevation
            shapeDrawablePadding.bottom = elevation
            DY = 0
        }
        Gravity.TOP -> {
            shapeDrawablePadding.top = elevation * 2
            shapeDrawablePadding.bottom = elevation
            DY = -1 * elevation / 3
        }
        Gravity.BOTTOM -> {
            shapeDrawablePadding.top = elevation
            shapeDrawablePadding.bottom = elevation * 2
            DY = elevation / 3
        }
        else -> {
            shapeDrawablePadding.top = elevation
            shapeDrawablePadding.bottom = elevation * 2
            DY = elevation / 3
        }
    }

    val shapeDrawable = ShapeDrawable()
    shapeDrawable.setPadding(shapeDrawablePadding)
    shapeDrawable.paint.color = backgroundColorValue
    shapeDrawable.paint.setShadowLayer(radiusInDP / 3, 0f, DY.toFloat(), shadowColorValue)
    view.setLayerType(View.LAYER_TYPE_SOFTWARE, shapeDrawable.paint)
    shapeDrawable.shape = RoundRectShape(outerRadius, null, null)

    val drawable = LayerDrawable(arrayOf<Drawable>(shapeDrawable))
    drawable.setLayerInset(
        0,
        elevation,
        elevation * 2,
        elevation,
        elevation * 2
    )

    return drawable
}