如何使用firebase ML Kit识别条形码？

Question

我想在我的应用程序中，当相机打开时，识别qr码，然后根据qr码的文字转移到相应的活动中。然后根据qr码文本转移到相应的活动。

我在google文档的帮助下，用firebase ML kit和CameraX库来做，但是我在ImageAnalyzer的analyze方法上出现了错误。

ImageAnalyzer提供给我实现analyze方法，尽管它已经实现了。但它有两个参数。(imageProxy: ImageProxy?, degrees: Int)，并说它没有覆盖任何东西。如果我删除第二个参数(degree: Int)，它就会识别，但 "degree "不被识别。

我试着按照一些教程去做，但他们使用了很多第三方库。我想使用 cameraX 和 ML Kit。

我如何解决这个问题？

这是我的代码。

package ge.softservice.nfcwithactivties

import android.Manifest
import android.annotation.SuppressLint
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.core.app.ActivityCompat
import androidx.core.content.ContextCompat
import com.google.firebase.ml.vision.FirebaseVision
import com.google.firebase.ml.vision.barcode.FirebaseVisionBarcode
import com.google.firebase.ml.vision.barcode.FirebaseVisionBarcodeDetectorOptions
import com.google.firebase.ml.vision.common.FirebaseVisionImage
import com.google.firebase.ml.vision.common.FirebaseVisionImageMetadata
import kotlinx.android.synthetic.main.activity_qr.*
import java.io.File
import java.util.concurrent.ExecutorService
import java.util.concurrent.Executors


class QrActivity : AppCompatActivity() {
    private var preview: Preview? = null
    private var imageAnalyzer: ImageAnalysis? = null
    private var camera: Camera? = null

    internal var isDetected = false

    private lateinit var outputDirectory: File
    private lateinit var cameraExecutor: ExecutorService
    override fun onRequestPermissionsResult(
        requestCode: Int, permissions: Array<String>, grantResults:
        IntArray
    ) {
        if (requestCode == REQUEST_CODE_PERMISSIONS) {
            if (allPermissionsGranted()) {
                startCamera()
            } else {
                Toast.makeText(
                    this,
                    "Permissions not granted by the user.",
                    Toast.LENGTH_SHORT
                ).show()
                finish()
            }
        }
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_qr)

        // Request camera permissions
        if (allPermissionsGranted()) {
            startCamera()
        } else {
            ActivityCompat.requestPermissions(
                this, REQUIRED_PERMISSIONS, REQUEST_CODE_PERMISSIONS
            )
        }

        //      outputDirectory = getOutputDirectory()

        cameraExecutor = Executors.newSingleThreadExecutor()
    }

    private fun startCamera() {

        val options = FirebaseVisionBarcodeDetectorOptions.Builder()
            .setBarcodeFormats(
                FirebaseVisionBarcode.FORMAT_QR_CODE,
                FirebaseVisionBarcode.FORMAT_AZTEC
            )
            .build()
        val detector = FirebaseVision.getInstance().getVisionBarcodeDetector(options)
        val result = detector.detectInImage(image)
            .addOnSuccessListener { barcodes ->
                // Task completed successfully
                // ...
            }
            .addOnFailureListener {
                // Task failed with an exception
                // ...
            }
        val cameraProviderFuture = ProcessCameraProvider.getInstance(this)
        cameraProviderFuture.addListener(Runnable {
            // Used to bind the lifecycle of cameras to the lifecycle owner
            val cameraProvider: ProcessCameraProvider = cameraProviderFuture.get()

            // Preview
            preview = Preview.Builder()
                .build()

            // Select back camera
            val cameraSelector =
                CameraSelector.Builder().requireLensFacing(CameraSelector.LENS_FACING_BACK).build()

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

                // Bind use cases to camera
                camera = cameraProvider.bindToLifecycle(
                    this, cameraSelector, preview
                )
                preview?.setSurfaceProvider(viewFinder.createSurfaceProvider(/*camera?.cameraInfo*/))
            } catch (exc: Exception) {
                Log.e(TAG, "Use case binding failed", exc)
            }

        }, ContextCompat.getMainExecutor(this))
    }

    private fun takePhoto() {
        // TODO
    }

    private fun allPermissionsGranted() = REQUIRED_PERMISSIONS.all {
        ContextCompat.checkSelfPermission(
            baseContext, it
        ) == PackageManager.PERMISSION_GRANTED
    }

/*    fun getOutputDirectory(): File {
        val mediaDir = externalMediaDirs.firstOrNull()?.let {
            File(it, resources.getString(R.string.app_name)).apply { mkdirs() } }
        return if (mediaDir != null && mediaDir.exists())
            mediaDir else filesDir
    }*/

    companion object {
        private const val TAG = "CameraXBasic"
        private const val FILENAME_FORMAT = "yyyy-MM-dd-HH-mm-ss-SSS"
        private const val REQUEST_CODE_PERMISSIONS = 10
        private val REQUIRED_PERMISSIONS = arrayOf(Manifest.permission.CAMERA)
    }
}

private class MyImageAnalyzer : ImageAnalysis.Analyzer {
    private fun degreesToFirebaseRotation(degrees: Int): Int = when(degrees) {
        0 -> FirebaseVisionImageMetadata.ROTATION_0
        90 -> FirebaseVisionImageMetadata.ROTATION_90
        180 -> FirebaseVisionImageMetadata.ROTATION_180
        270 -> FirebaseVisionImageMetadata.ROTATION_270
        else -> throw Exception("Rotation must be 0, 90, 180, or 270.")
    }

    @SuppressLint("UnsafeExperimentalUsageError")
    override fun analyze(imageProxy: ImageProxy?, degrees: Int) {
        val mediaImage = imageProxy?.image
        val imageRotation = degreesToFirebaseRotation(degrees)
        if (mediaImage != null) {
            val image = FirebaseVisionImage.fromMediaImage(mediaImage, imageRotation)
            // Pass image to an ML Kit Vision API
            // ...
        }
    }
}

Answer 1

从你的代码片段来看，你使用的是Camera-camera2 beta04版本和camerax-view alpha11版本。

文件可能已经过期了，你的 Analyzer 现在只收到 ImageProxy 其内 analyze 回调。之前传入的学位信息现在可以通过 ImageProxy.getImageInfo().getRotationDegrees().

所以你的分析器应该是这样的

private class MyImageAnalyzer : ImageAnalysis.Analyzer {

    private fun degreesToFirebaseRotation(degrees: Int): Int {
        // ...
    }

    override fun analyze(imageProxy: ImageProxy) {
        val mediaImage = imageProxy.image
        val imageRotation = degreesToFirebaseRotation(imageProxy.imageInfo.rotationDegrees)
        val image = FirebaseVisionImage.fromMediaImage(mediaImage, imageRotation)
        // ...
    }
}