是否可以使用 Google Play Vision 从一个 CameraSource 运行两个检测器

Question

I have an app, on Android only and using Xamarin that I want to do text recognition (OCR) and barcode scanning at approximately the same time. I am using Google Play Services Vision for this.

I have created the TextRecognizer instance like this:

var textRecognizer = new TextRecognizer.Builder(ApplicationContext).Build();

And, after creating this instance, you can now instantiate the CameraSource like this:

cameraSource = new CameraSource.Builder(ApplicationContext, textRecognizer)
     .SetFacing(CameraFacing.Back)
     .SetRequestedPreviewSize(1280, 1024)
     .SetRequestedFps(2.0f)
     .SetAutoFocusEnabled(true)
     .Build();

As you can see, I had to pass the TextRecognizer instance into the CameraSource builder. However, I also want to have a BarcodeDetector like this:

barcodeDetector = new BarcodeDetector.Builder(this)
   .SetBarcodeFormats(BarcodeFormat.Code128)
   .SetBarcodeFormats(BarcodeFormat.Code39)
   .SetBarcodeFormats(BarcodeFormat.Pdf417)
   .Build();

The camera source does not allow me to pass in both the text recognizer and the barcode detector. How can I achieve this?

Thanks!

Mike

Answer 1

Works OK for me to create a new CameraSource every time u switch between the detectors:

private void AssignAndStartCameraSource(Detector detector)
        {
            if (!detector.IsOperational)
            {
                // Note: The first time that an app using barcode API is installed on a device, GMS will
                // download a native library to the device in order to do detection.  Usually this
                // completes before the app is run for the first time.  But if that download has not yet
                // completed, then the above call will not detect any barcodes.
                //
                // IsOperational can be used to check if the required native library is currently
                // available.  The detector will automatically become operational once the library
                // download completes on device.
                Android.Util.Log.Warn(TAG, "Barcode detector dependencies are not yet available.");
            }

            cameraSource = new CameraSource.Builder(Application.Context, detector)
                .SetRequestedPreviewSize(_requestedPreviewHeight, _requestedPreviewWidth)
                .SetFacing(CameraFacing.Back)
                .SetRequestedFps(20.0f)
                .SetAutoFocusEnabled(true)
                .Build();

            startCameraSource();

            AppLoger.TrackEvent("End RunBarcodeScanner");
        }