android image blur

blur.kt

import android.content.Context
import android.graphics.Bitmap
import android.os.Build
import android.renderscript.Allocation
import android.renderscript.Element
import android.renderscript.RenderScript
import android.renderscript.ScriptIntrinsicBlur

fun blur(context: Context, sourceBitmap: Bitmap, radius: Float): Bitmap {

    if (Build.VERSION.SDK_INT > Build.VERSION_CODES.JELLY_BEAN) {
        val bitmap = sourceBitmap.copy(sourceBitmap.config, true)
        val rs = RenderScript.create(context)
        val input = Allocation.createFromBitmap(rs, sourceBitmap,
                Allocation.MipmapControl.MIPMAP_NONE, Allocation.USAGE_SCRIPT)
        val output = Allocation.createTyped(rs, input.type)

        ScriptIntrinsicBlur.create(rs, Element.U8_4(rs)).run {
            setRadius(radius)   // 0.0f - 25.0f
            setInput(input)
            forEach(output)
            output.copyTo(bitmap)
        }
        return bitmap
    }

    return sourceBitmap
}