ScannerActivity.kt

package io.scanbot.example

import android.os.Bundle
import android.widget.Button
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity

import io.scanbot.example.common.applyEdgeToEdge
import io.scanbot.sdk.ScanbotSDK
import io.scanbot.sdk.camera.CameraPreviewMode
import io.scanbot.sdk.geometry.AspectRatio
import io.scanbot.sdk.textpattern.ContentValidationCallback
import io.scanbot.sdk.textpattern.CustomContentValidator
import io.scanbot.sdk.textpattern.TextPatternScanner
import io.scanbot.sdk.textpattern.TextPatternScannerFrameHandler
import io.scanbot.sdk.ui.camera.IScanbotCameraView
import io.scanbot.sdk.ui.camera.ScanbotCameraXView
import io.scanbot.sdk.ui.camera.ZoomFinderOverlayView

class ScannerActivity : AppCompatActivity() {
    // @Tag("Text Pattern Custom UI")
    private lateinit var cameraView: IScanbotCameraView
    private lateinit var resultTextView: TextView
    
    private var useFlash = false

    private lateinit var patternScanner: TextPatternScanner
    private lateinit var patternScannerFrameHandler: TextPatternScannerFrameHandler

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_scanner)
        supportActionBar!!.hide()
        applyEdgeToEdge(findViewById(R.id.root_view))

        cameraView = findViewById<ScanbotCameraXView>(R.id.cameraView)
        resultTextView = findViewById(R.id.resultTextView)

        val zoomFinderOverlay = findViewById<ZoomFinderOverlayView>(R.id.finder_overlay)
        // The smaller finder view brings better performance and allows user to scan text more precise
        zoomFinderOverlay.setRequiredAspectRatios(listOf(AspectRatio(4.0, 1.0)))
        zoomFinderOverlay.zoomLevel = 1.8f

        cameraView.setPreviewMode(CameraPreviewMode.FIT_IN)
        patternScanner = ScanbotSDK(this).createTextPatternScanner().getOrThrow()

        // TODO: set validation string and validation callback which matches the need of the task
        // For the pattern: # - digits, ? - for any character. Other characters represent themselves
        // In this example we are waiting for a string which starts with 1 or 2, and then 5 more digits
        patternScanner.setConfiguration( patternScanner.copyCurrentConfiguration().copy(
            // validator = PresetContentValidator(preset = ValidatorPreset.VEHICLE_IDENTIFICATION_NUMBER),
            // validator = PatternContentValidator(pattern = "######"),
            validator = CustomContentValidator(callback =  object : ContentValidationCallback {
                override fun clean(rawText: String): String {
                    return rawText.replace(" ", "_")
                }

                override fun validate(text: String): Boolean {
                    return text.firstOrNull() in listOf('1', '2') // TODO: add additional validation for the recognized text
                }
            })
        ))

        patternScannerFrameHandler = TextPatternScannerFrameHandler.attach(cameraView, patternScanner)
        patternScannerFrameHandler.addResultHandler { result, frame ->
            val resultText: String = result.getOrNull()?.rawText ?:   result.errorOrNull()?.localizedMessage ?: "No result"
            runOnUiThread { resultTextView.text = resultText }

            false
        }

        cameraView.setCameraOpenCallback {
            cameraView.useFlash(useFlash)
            cameraView.continuousFocus()
        }
        findViewById<Button>(R.id.flashButton).setOnClickListener { toggleFlash() }
    }

    private fun toggleFlash() {
        useFlash = !useFlash
        cameraView.useFlash(useFlash)
    }
    // @EndTag("Text Pattern Custom UI")
}