CameraActivity with Google ML KIT for decoding QR codes

client/android/src/org/amnezia/vpn/qt/CameraActivity.kt

@@ -0,0 +1,150 @@
+package org.amnezia.vpn.qt
+
+import android.Manifest
+import android.annotation.SuppressLint
+import android.app.Activity
+import android.content.Intent
+import android.content.pm.PackageManager
+import android.os.Bundle
+import android.util.Log
+import android.widget.Toast
+import androidx.appcompat.app.AppCompatActivity
+import androidx.camera.core.*
+import androidx.camera.lifecycle.ProcessCameraProvider
+import androidx.camera.view.PreviewView
+import androidx.core.content.ContextCompat
+import com.google.mlkit.vision.barcode.BarcodeScannerOptions
+import com.google.mlkit.vision.barcode.BarcodeScanning
+import com.google.mlkit.vision.barcode.common.Barcode
+import com.google.mlkit.vision.common.InputImage
+import java.util.concurrent.ExecutorService
+import java.util.concurrent.Executors
+import org.amnezia.vpn.R
+
+
+class CameraActivity : AppCompatActivity() {
+
+    private val CAMERA_REQUEST = 100
+
+    private lateinit var cameraExecutor: ExecutorService
+    private lateinit var analyzerExecutor: ExecutorService
+
+    private lateinit var viewFinder: PreviewView
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_camera)
+
+        viewFinder = findViewById(R.id.viewFinder)
+
+        cameraExecutor = Executors.newSingleThreadExecutor()
+        analyzerExecutor = Executors.newSingleThreadExecutor()
+
+        checkPermissions()
+
+        configureVideoPreview()
+    }
+
+    private fun checkPermissions() {
+        if (checkSelfPermission(Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
+            requestPermissions(arrayOf(Manifest.permission.CAMERA), CAMERA_REQUEST)
+        }
+    }
+
+    override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<out String>, grantResults: IntArray) {
+        super.onRequestPermissionsResult(requestCode, permissions, grantResults)
+        if (requestCode == CAMERA_REQUEST) {
+            if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
+                Toast.makeText(this, "CameraX permission granted", Toast.LENGTH_SHORT).show();
+            } else {
+                Toast.makeText(this, "CameraX permission denied", Toast.LENGTH_SHORT).show();
+            }
+        }
+    }
+
+    @SuppressLint("UnsafeOptInUsageError")
+    private fun configureVideoPreview() {
+        val cameraProviderFuture = ProcessCameraProvider.getInstance(this)
+        val imageCapture = ImageCapture.Builder().build()
+
+        cameraProviderFuture.addListener({
+            val cameraProvider: ProcessCameraProvider = cameraProviderFuture.get()
+
+            val preview = Preview.Builder().build()
+
+            val cameraSelector = CameraSelector.DEFAULT_BACK_CAMERA
+
+            val listener = object : OnBarcodeActivityResult {
+                override fun onSuccess(result: String) {
+                    val resultIntent = Intent()
+                    resultIntent.putExtra("result", result)
+                    setResult(Activity.RESULT_OK, resultIntent)
+                    finish()
+                }
+
+                override fun onFailure(result: Exception) {
+                    Log.d("WUTT", "exception: $result")
+                }
+            }
+
+            val imageAnalyzer = BarCodeAnalyzer(listener)
+
+            val analysisUseCase = ImageAnalysis.Builder()
+                .setBackpressureStrategy(ImageAnalysis.STRATEGY_KEEP_ONLY_LATEST)
+                .build()
+
+            analysisUseCase.setAnalyzer(analyzerExecutor, imageAnalyzer)
+
+            try {
+                preview.setSurfaceProvider(viewFinder.surfaceProvider)
+                cameraProvider.unbindAll()
+                cameraProvider.bindToLifecycle(this, cameraSelector, preview, imageCapture, analysisUseCase)
+            } catch(exc: Exception) {
+                Log.e("WUTT", "Use case binding failed", exc)
+            }
+        }, ContextCompat.getMainExecutor(this))
+    }
+
+    override fun onDestroy() {
+        cameraExecutor.shutdown()
+        analyzerExecutor.shutdown()
+
+        super.onDestroy()
+    }
+
+    private class BarCodeAnalyzer(val callback: OnBarcodeActivityResult): ImageAnalysis.Analyzer {
+
+        private val options = BarcodeScannerOptions.Builder()
+            .setBarcodeFormats(Barcode.FORMAT_QR_CODE)
+            .build()
+
+        private val scanner = BarcodeScanning.getClient(options)
+
+        @SuppressLint("UnsafeOptInUsageError")
+        override fun analyze(imageProxy: ImageProxy) {
+            val mediaImage = imageProxy.image
+
+            if (mediaImage != null) {
+                val image = InputImage.fromMediaImage(mediaImage, imageProxy.imageInfo.rotationDegrees)
+
+                scanner.process(image)
+                    .addOnSuccessListener { barcodes ->
+                        if (barcodes.isNotEmpty()) {
+                            callback.onSuccess(barcodes[0]?.displayValue ?: "empty?")
+                        }
+
+                        imageProxy.close()
+                    }
+                    .addOnFailureListener {
+                        callback.onFailure(it)
+                        imageProxy.close()
+                    }
+            }
+        }
+    }
+
+    interface OnBarcodeActivityResult {
+        fun onSuccess(result: String)
+        fun onFailure(result: Exception)
+    }
+}