性能不佳的 ML Kit 条码扫描

Posted 2023-03-16

【中文标题】性能不佳的 ML Kit 条码扫描

【英文标题】：Bad performance ML Kit barcode scanning

【发布时间】：2021-12-31 23:31:56

【问题描述】：

我正在使用 Google 的 ML Kit 进行条形码扫描，并从 Google 提供的示例和教程中收集了以下代码。然而，表演是戏剧性的。识别条码需要几秒钟，可以是 10、15 秒。有什么办法可以改善吗？

另外，这如何与倒置条形码一起使用？我发现我需要反转图像，但是，如果在分析器中我尝试获取 image.bitmapInternal 或 image.byteBuffer，它总是为空。

构建.gradle

 implementation 'com.google.mlkit:barcode-scanning:17.0.0'
 // CameraX core library using camera2 implementation
implementation "androidx.camera:camera-camera2:1.0.2"
// CameraX Lifecycle Library
implementation "androidx.camera:camera-lifecycle:1.0.2"
// CameraX View class
implementation "androidx.camera:camera-view:1.0.0-alpha31"

然后，在一个片段中：

typealias BarCodeListener = (barCode: String) -> Unit
const val TAG = "ConnectorScanner"
[...]

override fun onResume() 
    super.onResume()
    cameraExecutor = Executors.newSingleThreadExecutor()
    startCamera()


private fun startCamera() 
    val cameraProviderFuture = ProcessCameraProvider.getInstance(requireContext())
    val resolution = Size(720, 1280)
    cameraProviderFuture.addListener(
        // Used to bind the lifecycle of cameras to the lifecycle owner
        val cameraProvider: ProcessCameraProvider = cameraProviderFuture.get()

        // Preview
        val preview = Preview.Builder()
            .setTargetResolution(resolution)
            .build()
            .also 
                it.setSurfaceProvider(binding.viewFinder.surfaceProvider)
            

        imageCapture = ImageCapture.Builder()
            .setTargetResolution(resolution)
            .setCaptureMode(ImageCapture.CAPTURE_MODE_MAXIMIZE_QUALITY)
            .build()

        val imageAnalyzer = ImageAnalysis.Builder()
            .setBackpressureStrategy(ImageAnalysis.STRATEGY_KEEP_ONLY_LATEST)
            .build()
            .also 
                it.setAnalyzer(cameraExecutor, BarCodeAnalyzer  barCode ->
                    if (BuildConfig.DEBUG) 
                        Toast.makeText(context, "Code: $barCode", Toast.LENGTH_LONG).show()
                    
                    viewModel.onConnectorCodeScanned(barCode)
                    cameraProvider.unbindAll()
                )
            

        // Select back camera as a default
        val cameraSelector = CameraSelector.DEFAULT_BACK_CAMERA

        try 
            // Unbind use cases before rebinding
            cameraProvider.unbindAll()

            // Bind use cases to camera
            cameraProvider.bindToLifecycle(
                this, cameraSelector, preview, imageCapture, imageAnalyzer
            )

         catch (exc: Exception) 
            Log.e(TAG, "Use case binding failed", exc)
            showErrorDialog()
        

    , ContextCompat.getMainExecutor(requireContext()))

图像分析器

private class BarCodeAnalyzer(private val listener: BarCodeListener) : ImageAnalysis.Analyzer 
    val options = BarcodeScannerOptions.Builder()
        .setBarcodeFormats(
            Barcode.FORMAT_DATA_MATRIX
        )
        .build()

    @SuppressLint("UnsafeOptInUsageError")
    override fun analyze(imageProxy: ImageProxy) 
        val mediaImage = imageProxy.image
        mediaImage?.let 
            val image =
                InputImage.fromMediaImage(it, imageProxy.imageInfo.rotationDegrees)
                val scanner = BarcodeScanning.getClient(options)

            scanner.process(image)
                .addOnSuccessListener  barcodes ->
                    if (barcodes.isNotEmpty()) 
                        barcodes.firstOrNull()?.rawValue?.let  barcode ->
                            Log.d(TAG, barcode)
                            listener(barcode)
                        
                        imageProxy.close()
                    
                
        
        imageProxy.close()
    

【问题讨论】：

你可以在这里查看我的二维码示例 - ***.com/a/64504871/3437352。条形码也会非常相似。

【参考方案1】：

幸运的是，我找到了性能问题的解决方案，它添加了一个 OnCompleteListener 并在那里关闭图像。所以分析器将是

scanner.process(image)
                .addOnSuccessListener  barcodes ->
                    if (barcodes.isNotEmpty()) 
                        barcodes.firstOrNull()?.rawValue?.let  barcode ->
                            Log.d(TAG, barcode)
                                listener(barcode)
                        
                    
                
                .addOnCompleteListener 
                    imageProxy.close()
                
        

现在条码的扫描速度快如闪电！