当前使用Nexus 5设备进行测试。
捕获包含UPC-A条形码的图像后，将调用FirebaseVisionBarcodeDetector的onSuccess方法。但是，列表为空。不知道什么会导致此问题。
CameraManager camera_manager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
try{
CameraCharacteristics camera_characteristics = camera_manager.getCameraCharacteristics(camera_device.getId());
Size [] yuvSizes = null;
if (camera_characteristics != null) {
yuvSizes = camera_characteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP).getOutputSizes(ImageFormat.YUV_420_888);
}
int width = 640;
int height = 480;
if (yuvSizes != null && 0 < yuvSizes.length) {
width = yuvSizes[0].getWidth();
height = yuvSizes[0].getHeight();
}
image_reader = ImageReader.newInstance(width, height, ImageFormat.YUV_420_888, 1);
List<Surface> output_surface = new ArrayList<Surface>(2);
output_surface.add(image_reader.getSurface());
output_surface.add(new Surface(texture_view.getSurfaceTexture()));
final CaptureRequest.Builder capture_builder = camera_device.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
capture_builder.addTarget(image_reader.getSurface());
capture_builder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
capture_builder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON);
ImageReader.OnImageAvailableListener reader_listener = new ImageReader.OnImageAvailableListener() {
@Override
public void onImageAvailable(ImageReader reader) {
Image image = reader.acquireLatestImage();
upc_image = image;
if(image != null){
upc_image = image;
Scan scan = new Scan(Camera.this, Camera.this, upc_image);
scan.scanning();
}
}
};
image_reader.setOnImageAvailableListener(reader_listener, background_handler);
final CameraCaptureSession.CaptureCallback capture_callback = new CameraCaptureSession.CaptureCallback() {
@Override
public void onCaptureCompleted(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull TotalCaptureResult result) {
super.onCaptureCompleted(session, request, result);
create_camera_preview();
}
};
camera_device.createCaptureSession(output_surface, new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(@NonNull CameraCaptureSession session) {
try{
session.capture(capture_builder.build(), capture_callback, background_handler);
}catch (CameraAccessException camera_access_error){
camera_access_error.printStackTrace();
}
}
@Override
public void onConfigureFailed(@NonNull CameraCaptureSession session) {
}
}, background_handler);
}catch(CameraAccessException camera_access_error){
camera_access_error.printStackTrace();
}
camera_open_close_lock.release();
}
当捕获图像并调用onImageAvailable时，宽度和高度分别为3264和2448像素。
image_reader = ImageReader.newInstance(width, height, ImageFormat.YUV_420_888, 1);
执行条形码检测的地方
public void scanning(){
FirebaseVisionImage image = null;
try {
image = FirebaseVisionImage.fromMediaImage(upc_image, Rotation_Compenstation());
}catch(CameraAccessException camera_access_error){
camera_access_error.printStackTrace();
}
try {
Task<List<FirebaseVisionBarcode>> result = firebase_barcode_detector.detectInImage(image)
.addOnSuccessListener(new OnSuccessListener<List<FirebaseVisionBarcode>>() {
@Override
public void onSuccess(List<FirebaseVisionBarcode> firebase_vision_barcodes) {
// Task was successful
for (FirebaseVisionBarcode firebase_vision_barcode : firebase_vision_barcodes) {
}
}
}).addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception error) {
// Task was a failure
error.printStackTrace();
}
}).addOnCanceledListener(new OnCanceledListener() {
@Override
public void onCanceled() {
}
}).addOnCompleteListener(new OnCompleteListener<List<FirebaseVisionBarcode>>() {
@Override
public void onComplete(@NonNull Task<List<FirebaseVisionBarcode>> task) {
Log.d(TAG, "Result: " + task.getResult().toString());
}
});
}catch (Exception error){
error.printStackTrace();
Log.d(TAG, "Error, read fail");
}
}
创建FirebaseVisionImage对象时，必须计算旋转补偿。
public int Rotation_Compenstation(){
int current_device_rotation = activity.getWindowManager().getDefaultDisplay().getRotation();
// current_device_rotation is 0
int rotation_compensation = ORIENTATION.get(current_device_rotation);
// rotation_compensation is 90
CameraManager camera_manager = (CameraManager) context.getSystemService(Context.CAMERA_SERVICE);
String cameraId = camera_manager.getCameraIdList()[0];
int device_sensor_orientation = camera_manager.getCameraCharacteristics(cameraId).get(CameraCharacteristics.SENSOR_ORIENTATION);
// device_sensor_oreintation is 90
rotation_compensation = (rotation_compensation + device_sensor_orientation + 270) % 360;
// rotation_compensation here is 90
int result_rotation;
switch(rotation_compensation){
case 0:
result_rotation = FirebaseVisionImageMetadata.ROTATION_0;
break;
case 90:
result_rotation = FirebaseVisionImageMetadata.ROTATION_90;
break;
case 180:
result_rotation = FirebaseVisionImageMetadata.ROTATION_180;
break;
case 270:
result_rotation = FirebaseVisionImageMetadata.ROTATION_270;
break;
default:
result_rotation = FirebaseVisionImageMetadata.ROTATION_0;
Log.d(TAG, "Bad Rotation Value: " + result_rotation);
break;
}
return result_rotation;
// result_rotation is 1
}
运行时的旋转补偿信息
current_device_rotation: 0
device_sensor_orientation: 90
rotation_compensation: 90
result_rotation: 1
电话设备始终保持竖立状态（人像）。条形码是竖直的（能够从左到右读取）。不知道可能是什么问题。最初我以为图片就像我打电话
一样大upc_image.getWidth() and upc_image.getHeight()
该值分别是3264和2448像素。我试图将upc与电话设备分开，但这也没有产生影响。列表仍然为空。
有人知道什么可能导致此问题。