CameraX是构建的,analyze()方法被调用并传入一张图片,然后使用close()方法关闭(删除)该图片。从这张图片创建FirebaseVisionImage并传递进行处理(文本识别)。代码示例和代码实验室存在差异,并且不实现与CameraX或使用旧API版本的TextRecognition。
override fun analyze(imageProxy: ImageProxy) {
if (isValidText) {
imageProxy.close()
return
}
val mediaImage = imageProxy.image // requires annotation
val degrees = imageProxy.imageInfo.rotationDegrees
val rotation = rotationDegreesToFirebaseRotation(degrees)
if (mediaImage != null) {
runTextRecognition(mediaImage, rotation) // line 44
}
imageProxy.close()
}
private fun runTextRecognition(mediaImage: Image, rotation: Int) {
// Create FirebaseVisionImage from frame
val visionImage = FirebaseVisionImage.fromMediaImage(mediaImage, rotation) // line 64
val recognizer = FirebaseVision.getInstance()
.onDeviceTextRecognizer
recognizer.processImage(visionImage)
.addOnSuccessListener { texts ->
processTextRecognitionResult(texts!!, recognizer)
if (isValidText) {
recognizer.close()
return@addOnSuccessListener
}
}
.addOnFailureListener { e -> // Task failed with an exception
e.printStackTrace()
}
}
在我的项目中,我正在使用这些依赖项。
def firebase_version = '24.0.2'
def camerax_version = '1.0.0-beta02'
implementation "com.google.firebase:firebase-ml-vision:$firebase_version"
implementation "androidx.camera:camera-camera2:$camerax_version"
implementation "androidx.camera:camera-view:1.0.0-alpha09"
implementation "androidx.camera:camera-lifecycle:${camerax_version}"
这就是我构建CameraX的方式。
private fun bindPreview(cameraProvider: ProcessCameraProvider) {
// Get screen metrics used to setup camera for full screen resolution
val metrics = DisplayMetrics().also { viewFinder?.display?.getRealMetrics(it) }
val screenAspectRatio = aspectRatio(metrics.widthPixels, metrics.heightPixels)
val rotation = viewFinder?.display?.rotation
// Set up the preview use case to display camera preview
val preview = Preview.Builder()// Request aspect ratio but no resolution
.setTargetAspectRatio(screenAspectRatio)
// Set initial target rotation
.setTargetRotation(rotation!!)
.build()
// Choose the camera by requiring a lens facing
val cameraSelector = CameraSelector.Builder()
.requireLensFacing(CameraSelector.LENS_FACING_BACK)
.build()
val executor = Executors.newSingleThreadExecutor()
// Must unbind the use-cases before rebinding them
cameraProvider.unbindAll()
val imageAnalyzer = ImageAnalysis.Builder()
// Request aspect ratio but no resolution
.setTargetAspectRatio(screenAspectRatio)
// Set initial target rotation, have to call this again if rotation changes
// during the lifecycle of this use case
.setTargetRotation(rotation)
.setBackpressureStrategy(ImageAnalysis.STRATEGY_KEEP_ONLY_LATEST)
.build()
imageAnalyzer.setAnalyzer(executor, analyzer)
var camera = cameraProvider.bindToLifecycle(viewFinder?.context as LifecycleOwner, cameraSelector, preview, imageAnalyzer)
// Attach the viewfinder's surface provider to preview use case
preview.setSurfaceProvider(viewFinder?.createSurfaceProvider(camera.cameraInfo))
}