Show latest possible result point in camera view

app/src/main/kotlin/de/markusfisch/android/binaryeye/activity/CameraActivity.kt

@@ -17,6 +17,7 @@ import android.widget.SeekBar
 import android.widget.Toast
 import com.google.zxing.Result
 import com.google.zxing.ResultMetadataType
+import com.google.zxing.ResultPointCallback
 import de.markusfisch.android.binaryeye.R
 import de.markusfisch.android.binaryeye.app.db
 import de.markusfisch.android.binaryeye.app.hasCameraPermission
@@ -33,7 +34,11 @@ import kotlinx.coroutines.GlobalScope
 import kotlinx.coroutines.launch
 
 class CameraActivity : AppCompatActivity() {
-	private val zxing = Zxing()
+	private val zxing = Zxing(ResultPointCallback { point ->
+		detectorView.post {
+			mapping?.map(point)?.let { detectorView.mark(listOf(it)) }
+		}
+	})
 
 	private lateinit var vibrator: Vibrator
 	private lateinit var cameraView: CameraView
@@ -42,6 +47,7 @@ class CameraActivity : AppCompatActivity() {
 	private lateinit var flashFab: View
 
 	private var preprocessor: Preprocessor? = null
+	private var mapping: Mapping? = null
 	private var invert = false
 	private var flash = false
 	private var returnResult = false
@@ -278,7 +284,6 @@ class CameraActivity : AppCompatActivity() {
 				val frameWidth = cameraView.frameWidth
 				val frameHeight = cameraView.frameHeight
 				val frameOrientation = cameraView.frameOrientation
-				var mapping: Mapping? = null
 				var decoding = true
 				camera.setPreviewCallback { frameData, _ ->
 					if (decoding) {
@@ -289,13 +294,6 @@ class CameraActivity : AppCompatActivity() {
 							frameOrientation
 						)
 						result?.let {
-							preprocessor?.let {
-								mapping = mapping ?: frameToView(
-									it.outWidth,
-									it.outHeight,
-									cameraView.previewRect
-								)
-							}
 							cameraView.post {
 								val rp = result.resultPoints
 								val m = mapping
@@ -403,8 +401,7 @@ class CameraActivity : AppCompatActivity() {
 	): Result? {
 		frameData ?: return null
 		invert = invert xor true
-		val pp = preprocessor ?: Preprocessor(
-			this,
+		val pp = preprocessor ?: createPreprocessorAndMapping(
 			frameWidth,
 			frameHeight,
 			frameOrientation
@@ -419,6 +416,25 @@ class CameraActivity : AppCompatActivity() {
 		)
 	}
 
+	private fun createPreprocessorAndMapping(
+		frameWidth: Int,
+		frameHeight: Int,
+		frameOrientation: Int
+	): Preprocessor {
+		val pp = Preprocessor(
+			this,
+			frameWidth,
+			frameHeight,
+			frameOrientation
+		)
+		mapping = frameToView(
+			pp.outWidth,
+			pp.outHeight,
+			cameraView.previewRect
+		)
+		return pp
+	}
+
 	companion object {
 		private const val REQUEST_CAMERA = 1
 		private const val PICK_FILE_RESULT_CODE = 1

app/src/main/kotlin/de/markusfisch/android/binaryeye/graphics/Candidates.kt

@@ -55,12 +55,10 @@ data class Mapping(
 	val offsetX: Int,
 	val offsetY: Int
 ) {
-	fun map(points: Array<ResultPoint>): List<Point> {
-		return points.map {
-			Point(
-				(it.x * ratioX).roundToInt() + offsetX,
-				(it.y * ratioY).roundToInt() + offsetY
-			)
-		}
-	}
+	fun map(point: ResultPoint) = Point(
+		(point.x * ratioX).roundToInt() + offsetX,
+		(point.y * ratioY).roundToInt() + offsetY
+	)
+
+	fun map(points: Array<ResultPoint>): List<Point> = points.map { map(it) }
 }

app/src/main/kotlin/de/markusfisch/android/binaryeye/widget/DetectorView.kt

@@ -10,6 +10,10 @@ import de.markusfisch.android.binaryeye.graphics.Candidates
 
 class DetectorView : View {
 	private val candidates = Candidates(context)
+	private val invalidateRunnable: Runnable = Runnable {
+		marks = null
+		invalidate()
+	}
 	private var marks: List<Point>? = null
 
 	constructor(context: Context, attrs: AttributeSet) :
@@ -21,10 +25,8 @@ class DetectorView : View {
 	fun mark(points: List<Point>) {
 		marks = points
 		invalidate()
-		postDelayed({
-			marks = null
-			invalidate()
-		}, 500)
+		removeCallbacks(invalidateRunnable)
+		postDelayed(invalidateRunnable, 500)
 	}
 
 	override fun onDraw(canvas: Canvas) {

app/src/main/kotlin/de/markusfisch/android/binaryeye/zxing/Zxing.kt

@@ -5,7 +5,7 @@ import com.google.zxing.*
 import com.google.zxing.common.HybridBinarizer
 import java.util.*
 
-class Zxing {
+class Zxing(possibleResultPoint: ResultPointCallback? = null) {
 	private val multiFormatReader = MultiFormatReader()
 
 	init {
@@ -38,6 +38,9 @@ class Zxing {
 
 		val hints = EnumMap<DecodeHintType, Any>(DecodeHintType::class.java)
 		hints[DecodeHintType.POSSIBLE_FORMATS] = decodeFormats
+		possibleResultPoint?.let {
+			hints[DecodeHintType.NEED_RESULT_POINT_CALLBACK] = it
+		}
 
 		multiFormatReader.setHints(hints)
 	}