scanner
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agra
243
android/src/main/kotlin/io/swipelab/ux/ScannerPlugin.kt
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243
android/src/main/kotlin/io/swipelab/ux/ScannerPlugin.kt
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package io.swipelab.ux
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import android.Manifest
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import android.app.Activity
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import android.content.Context
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import android.content.pm.PackageManager
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import android.os.Handler
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import android.os.Looper
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import android.view.View
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import androidx.camera.core.CameraSelector
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import androidx.camera.core.ImageAnalysis
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import androidx.camera.core.ImageProxy
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import androidx.camera.core.Preview
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import androidx.camera.lifecycle.ProcessCameraProvider
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import androidx.camera.view.PreviewView
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import androidx.core.app.ActivityCompat
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import androidx.core.content.ContextCompat
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import androidx.lifecycle.LifecycleOwner
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import com.google.zxing.BarcodeFormat
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import com.google.zxing.BinaryBitmap
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import com.google.zxing.DecodeHintType
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import com.google.zxing.MultiFormatReader
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import com.google.zxing.PlanarYUVLuminanceSource
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import com.google.zxing.common.HybridBinarizer
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import io.flutter.embedding.engine.plugins.FlutterPlugin
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import io.flutter.embedding.engine.plugins.activity.ActivityPluginBinding
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import io.flutter.plugin.common.EventChannel
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import io.flutter.plugin.common.MethodCall
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import io.flutter.plugin.common.MethodChannel
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import io.flutter.plugin.common.StandardMessageCodec
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import io.flutter.plugin.platform.PlatformView
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import io.flutter.plugin.platform.PlatformViewFactory
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import java.util.concurrent.Executors
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class ScannerPlugin :
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NativePlugin,
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MethodChannel.MethodCallHandler {
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companion object {
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// Single shared event sink — the app only ever shows one scanner
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// at a time (settings → scan), so collapsing to one channel keeps
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// the platform-view factory free of per-view registrar wiring.
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@JvmStatic
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@Volatile
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var eventSink: EventChannel.EventSink? = null
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private val mainHandler = Handler(Looper.getMainLooper())
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/// EventChannel methods are @UiThread; the analyzer runs on a
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/// background pool. Bounce through the main looper.
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@JvmStatic
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fun emit(code: String) {
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mainHandler.post { eventSink?.success(code) }
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}
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private const val PERMISSION_REQUEST_CODE = 0xC1A0
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}
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private var methodChannel: MethodChannel? = null
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private var eventChannel: EventChannel? = null
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private var lifecycleOwner: LifecycleOwner? = null
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private var activity: Activity? = null
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private var activityBinding: ActivityPluginBinding? = null
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private var pendingPermissionResult: MethodChannel.Result? = null
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override fun onAttachedToEngine(binding: FlutterPlugin.FlutterPluginBinding) {
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val ec = EventChannel(binding.binaryMessenger, "ux/scanner/events")
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ec.setStreamHandler(object : EventChannel.StreamHandler {
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override fun onListen(arguments: Any?, events: EventChannel.EventSink?) {
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eventSink = events
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}
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override fun onCancel(arguments: Any?) {
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eventSink = null
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}
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})
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eventChannel = ec
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val mc = MethodChannel(binding.binaryMessenger, "ux/scanner")
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mc.setMethodCallHandler(this)
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methodChannel = mc
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binding.platformViewRegistry.registerViewFactory(
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"ux/scanner",
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ScannerViewFactory { lifecycleOwner },
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)
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}
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override fun onDetachedFromEngine(binding: FlutterPlugin.FlutterPluginBinding) {
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eventChannel?.setStreamHandler(null)
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eventChannel = null
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eventSink = null
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methodChannel?.setMethodCallHandler(null)
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methodChannel = null
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}
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override fun onAttachedToActivity(binding: ActivityPluginBinding) {
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// The host app's MainActivity is a `FlutterActivity`, which extends
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// `LifecycleOwner` indirectly via `androidx.activity.ComponentActivity`.
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lifecycleOwner = binding.activity as? LifecycleOwner
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activity = binding.activity
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activityBinding = binding
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binding.addRequestPermissionsResultListener { code, _, results ->
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if (code != PERMISSION_REQUEST_CODE) return@addRequestPermissionsResultListener false
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val granted = results.isNotEmpty() &&
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results[0] == PackageManager.PERMISSION_GRANTED
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pendingPermissionResult?.success(granted)
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pendingPermissionResult = null
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true
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}
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}
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override fun onDetachedFromActivity() {
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lifecycleOwner = null
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activity = null
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activityBinding = null
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// If the activity tears down with a request still in flight, settle
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// it cleanly rather than leaking the Result.
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pendingPermissionResult?.success(false)
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pendingPermissionResult = null
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}
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override fun onMethodCall(call: MethodCall, result: MethodChannel.Result) {
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when (call.method) {
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"requestPermission" -> handleRequestPermission(result)
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else -> result.notImplemented()
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}
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}
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private fun handleRequestPermission(result: MethodChannel.Result) {
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val act = activity
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?: return result.error("no_activity", "plugin not attached to an activity", null)
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val granted = ContextCompat.checkSelfPermission(
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act, Manifest.permission.CAMERA,
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) == PackageManager.PERMISSION_GRANTED
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if (granted) return result.success(true)
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if (pendingPermissionResult != null) {
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return result.error("in_progress", "another permission request is in flight", null)
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}
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pendingPermissionResult = result
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ActivityCompat.requestPermissions(
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act,
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arrayOf(Manifest.permission.CAMERA),
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PERMISSION_REQUEST_CODE,
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)
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}
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}
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private class ScannerViewFactory(
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private val lifecycleOwnerProvider: () -> LifecycleOwner?,
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) : PlatformViewFactory(StandardMessageCodec.INSTANCE) {
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override fun create(context: Context, viewId: Int, args: Any?): PlatformView {
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return ScannerPlatformView(context, lifecycleOwnerProvider())
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}
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}
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private class ScannerPlatformView(
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context: Context,
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private val lifecycleOwner: LifecycleOwner?,
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) : PlatformView {
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// COMPATIBLE forces a TextureView under the hood; SurfaceView (the
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// PERFORMANCE default) is its own window and won't composite under
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// Flutter overlays in hybrid composition.
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private val previewView = PreviewView(context).apply {
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implementationMode = PreviewView.ImplementationMode.COMPATIBLE
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}
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private val analysisExecutor = Executors.newSingleThreadExecutor()
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private val reader: MultiFormatReader = MultiFormatReader().apply {
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setHints(
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mapOf(
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DecodeHintType.POSSIBLE_FORMATS to listOf(BarcodeFormat.QR_CODE),
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),
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)
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}
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init {
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if (lifecycleOwner != null) bindCamera(context, lifecycleOwner)
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}
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private fun bindCamera(context: Context, lifecycleOwner: LifecycleOwner) {
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val cameraProviderFuture = ProcessCameraProvider.getInstance(context)
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cameraProviderFuture.addListener({
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val cameraProvider = cameraProviderFuture.get()
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val preview = Preview.Builder().build().also {
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it.setSurfaceProvider(previewView.surfaceProvider)
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}
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val analysis = ImageAnalysis.Builder()
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.setBackpressureStrategy(ImageAnalysis.STRATEGY_KEEP_ONLY_LATEST)
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.build()
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.also { it.setAnalyzer(analysisExecutor, ::analyze) }
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try {
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cameraProvider.unbindAll()
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cameraProvider.bindToLifecycle(
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lifecycleOwner,
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CameraSelector.DEFAULT_BACK_CAMERA,
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preview,
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analysis,
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)
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} catch (_: Throwable) {
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// Permission denied / camera unavailable — preview stays
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// black. Caller surfaces a fallback (e.g. paste-hex).
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}
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}, androidx.core.content.ContextCompat.getMainExecutor(context))
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}
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private fun analyze(image: ImageProxy) {
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try {
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val plane = image.planes.firstOrNull() ?: return
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val buffer = plane.buffer
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val bytes = ByteArray(buffer.remaining()).also { buffer.get(it) }
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val source = PlanarYUVLuminanceSource(
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bytes,
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plane.rowStride,
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image.height,
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0, 0,
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image.width, image.height,
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false,
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)
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val bitmap = BinaryBitmap(HybridBinarizer(source))
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val result = try {
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reader.decode(bitmap)
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} catch (_: Throwable) {
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null
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} finally {
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reader.reset()
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}
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val text = result?.text
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if (!text.isNullOrEmpty()) {
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ScannerPlugin.emit(text)
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}
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} finally {
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image.close()
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}
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}
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override fun getView(): View = previewView
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override fun dispose() {
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analysisExecutor.shutdown()
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}
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}
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@@ -9,6 +9,7 @@ class UxPlugin : FlutterPlugin, ActivityAware {
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KeyboardPlugin(),
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SensorPlugin(),
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FilePlugin(),
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ScannerPlugin(),
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)
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override fun onAttachedToEngine(binding: FlutterPlugin.FlutterPluginBinding) =
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