Barcode Detector for Mobile Vision API (Add support for inverted color)Benchmark on Pixel 2: Invert color (8ms) + Decode (15ms)

BarcodeAdvancedDetector.kt

package com.satispay.customer.profile.visionapi

import android.graphics.ImageFormat
import android.util.SparseArray
import com.google.android.gms.vision.Detector
import com.google.android.gms.vision.Frame
import com.google.android.gms.vision.barcode.Barcode
import java.nio.ByteBuffer


/**
 * Created by omarmiatello on 14/02/18.
 */
class BarcodeAdvancedDetector(private val delegate: Detector<Barcode>) : Detector<Barcode>() {
    override fun isOperational() = delegate.isOperational
    override fun setFocus(id: Int) = delegate.setFocus(id)

    var lastFound = 0

    override fun detect(originalFrame: Frame): SparseArray<Barcode> {

        // Benchmark on Pixel 2 XL

        val frames = listOf({
            originalFrame
        }, {
            // [Benchmark] frame with inverted colors: 8 ms
            Frame.Builder()
                .setImageData(
                    ByteBuffer.wrap(originalFrame.grayscaleImageData.array().let { b ->
                        ByteArray(b.size) { (0xFFFFFFFF - b[it].toInt()).toByte() }
                    }),
                    originalFrame.metadata.width,
                    originalFrame.metadata.height,
                    ImageFormat.NV21
                )
                .setRotation(originalFrame.metadata.rotation)
                .build()
        })

        // Try first `lastFound` frame
        val order = (lastFound..lastFound) + ((0 until frames.size) - lastFound)

        order.forEach {
            val frame = frames[it]()
            val detections = delegate.detect(frame)  // [Benchmark] each loop, detect: 12-18 ms
            if (detections.size() != 0) {
                lastFound = it
                return detections
            }
        }
        return SparseArray()
    }
}