有没有人使用Camera2 API的经验？我想在没有用户交互（按钮点击）和使用后台服务的情况下捕获图像。我使用过Google的Camera2 API示例项目。请帮我。现在，我只能使用Activity和按钮点击来捕获图像。 以下是我的代码：
public class Camera2BasicFragment extends Fragment
implements View.OnClickListener, FragmentCompat.OnRequestPermissionsResultCallback {
private static final SparseIntArray ORIENTATIONS = new SparseIntArray();
private static final int REQUEST_CAMERA_PERMISSION = 1;
private static final String FRAGMENT_DIALOG = "dialog";
int mPictureCounter = 0;
static {
ORIENTATIONS.append(Surface.ROTATION_0, 90);
ORIENTATIONS.append(Surface.ROTATION_90, 0);
ORIENTATIONS.append(Surface.ROTATION_180, 270);
ORIENTATIONS.append(Surface.ROTATION_270, 180);
}
private static final String TAG = "Camera2BasicFragment";
private static final int STATE_PREVIEW = 0, STATE_WAITING_LOCK = 1, STATE_WAITING_PRECAPTURE = 2, STATE_WAITING_NON_PRECAPTURE = 3, STATE_PICTURE_TAKEN = 4, MAX_PREVIEW_WIDTH = 1920, MAX_PREVIEW_HEIGHT = 1080;
private final TextureView.SurfaceTextureListener mSurfaceTextureListener
= new TextureView.SurfaceTextureListener() {
@Override
public void onSurfaceTextureAvailable(SurfaceTexture texture, int width, int height) {
openCamera(width, height);
}
@Override
public void onSurfaceTextureSizeChanged(SurfaceTexture texture, int width, int height) {
configureTransform(width, height);
}
@Override
public boolean onSurfaceTextureDestroyed(SurfaceTexture texture) {
return true;
}
@Override
public void onSurfaceTextureUpdated(SurfaceTexture texture) {
}
};
private String mCameraId;
private AutoFitTextureView mTextureView;
private CameraCaptureSession mCaptureSession;
private CameraDevice mCameraDevice;
private Size mPreviewSize;
private final CameraDevice.StateCallback mStateCallback = new CameraDevice.StateCallback() {
@Override
public void onOpened(@NonNull CameraDevice cameraDevice) {
mCameraOpenCloseLock.release();
mCameraDevice = cameraDevice;
createCameraPreviewSession();
}
@Override
public void onDisconnected(@NonNull CameraDevice cameraDevice) {
mCameraOpenCloseLock.release();
cameraDevice.close();
mCameraDevice = null;
}
@Override
public void onError(@NonNull CameraDevice cameraDevice, int error) {
mCameraOpenCloseLock.release();
cameraDevice.close();
mCameraDevice = null;
Activity activity = getActivity();
if (null != activity) {
activity.finish();
}
}
};
private HandlerThread mBackgroundThread;
private Handler mBackgroundHandler;
private ImageReader mImageReader;
private File mFile;
private final ImageReader.OnImageAvailableListener mOnImageAvailableListener
= new ImageReader.OnImageAvailableListener() {
@Override
public void onImageAvailable(ImageReader reader) {
Calendar c = Calendar.getInstance();
mFile = new File(getActivity().getExternalFilesDir(null), "pic" + c.get(Calendar.MILLISECOND) + "" + c.get(Calendar.SECOND) + "" + c.get(Calendar.MINUTE) + "" + c.get(Calendar.HOUR_OF_DAY) + "" + c.get(Calendar.DAY_OF_MONTH) + "" + c.get(Calendar.MONTH) + "" + c.get(Calendar.YEAR) + ".jpg");
Log.e("TestingProject", "\n\n\n--------------------------------**********************************\n" +
"Files Absolute Path : " + mFile.getAbsolutePath()
+ "\n**********************************--------------------------------\n\n\n");
mBackgroundHandler.post(new ImageSaver(reader.acquireNextImage(), mFile));
}
};
private CaptureRequest.Builder mPreviewRequestBuilder;
private CaptureRequest mPreviewRequest;
private int mState = STATE_PREVIEW;
private Semaphore mCameraOpenCloseLock = new Semaphore(1);
private boolean mFlashSupported;
private int mSensorOrientation;
private CameraCaptureSession.CaptureCallback mCaptureCallback
= new CameraCaptureSession.CaptureCallback() {
private void process(CaptureResult result) {
switch (mState) {
case STATE_PREVIEW: {
break;
}
case STATE_WAITING_LOCK: {
Integer afState = result.get(CaptureResult.CONTROL_AF_STATE);
if (afState == null) {
captureStillPicture();
} else if (CaptureResult.CONTROL_AF_STATE_FOCUSED_LOCKED == afState ||
CaptureResult.CONTROL_AF_STATE_NOT_FOCUSED_LOCKED == afState) {
Integer aeState = result.get(CaptureResult.CONTROL_AE_STATE);
if (aeState == null ||
aeState == CaptureResult.CONTROL_AE_STATE_CONVERGED) {
mState = STATE_PICTURE_TAKEN;
captureStillPicture();
} else {runPrecaptureSequence();}}
break;
}
case STATE_WAITING_PRECAPTURE: {
Integer aeState = result.get(CaptureResult.CONTROL_AE_STATE);
if (aeState == null ||
aeState == CaptureResult.CONTROL_AE_STATE_PRECAPTURE ||
aeState == CaptureRequest.CONTROL_AE_STATE_FLASH_REQUIRED) {
mState = STATE_WAITING_NON_PRECAPTURE;
}
break;
}
case STATE_WAITING_NON_PRECAPTURE: {
Integer aeState = result.get(CaptureResult.CONTROL_AE_STATE);
if (aeState == null || aeState != CaptureResult.CONTROL_AE_STATE_PRECAPTURE) {
mState = STATE_PICTURE_TAKEN;
captureStillPicture();}
break;}}}
@Override
public void onCaptureProgressed(@NonNull CameraCaptureSession session,
@NonNull CaptureRequest request,
@NonNull CaptureResult partialResult) {process(partialResult);}
@Override
public void onCaptureCompleted(@NonNull CameraCaptureSession session,
@NonNull CaptureRequest request,
@NonNull TotalCaptureResult result) {process(result);}
};
private void showToast(final String text) {
final Activity activity = getActivity();
if (activity != null) {
activity.runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(activity, text, Toast.LENGTH_SHORT).show();
}
});}}
private static Size chooseOptimalSize(Size[] choices, int textureViewWidth,
int textureViewHeight, int maxWidth, int maxHeight, Size aspectRatio) {
List<Size> bigEnough = new ArrayList<>();
List<Size> notBigEnough = new ArrayList<>();
int w = aspectRatio.getWidth();
int h = aspectRatio.getHeight();
for (Size option : choices) {
if (option.getWidth() <= maxWidth && option.getHeight() <= maxHeight &&
option.getHeight() == option.getWidth() * h / w) {
if (option.getWidth() >= textureViewWidth &&
option.getHeight() >= textureViewHeight) {
bigEnough.add(option);
} else {notBigEnough.add(option);}}
}
if (bigEnough.size() > 0) {return Collections.min(bigEnough, new CompareSizesByArea());} else if (notBigEnough.size() > 0) {
return Collections.max(notBigEnough, new CompareSizesByArea());
} else {
Log.e(TAG, "Couldn't find any suitable preview size");
return choices[0];}
}
public static Camera2BasicFragment newInstance() {return new Camera2BasicFragment();}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_camera2_basic, container, false);
}
@Override
public void onViewCreated(final View view, Bundle savedInstanceState) {
view.findViewById(R.id.picture).setOnClickListener(this);
view.findViewById(R.id.info).setOnClickListener(this);
mTextureView = (AutoFitTextureView) view.findViewById(R.id.texture);
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
Calendar c = Calendar.getInstance();
mFile = new File(getActivity().getExternalFilesDir(null), "proof_" + c.get(Calendar.MILLISECOND) + c.get(Calendar.SECOND) + c.get(Calendar.MINUTE) + c.get(Calendar.HOUR_OF_DAY) + c.get(Calendar.DAY_OF_MONTH) + c.get(Calendar.MONTH) + c.get(Calendar.YEAR) + ".jpg");
Log.e("TestingProject", "\n\n\n--------------------------------**********************************\n" +
"File Path : " + mFile.getAbsolutePath()
+ "\n**********************************--------------------------------\n\n\n");
}
@Override
public void onResume() {
super.onResume();
startBackgroundThread();
if (mTextureView.isAvailable()) {openCamera(mTextureView.getWidth(), mTextureView.getHeight());} else {
mTextureView.setSurfaceTextureListener(mSurfaceTextureListener);}
}
@Override
public void onPause() {
closeCamera();
stopBackgroundThread();
super.onPause();
}
private void requestCameraPermission() {
if (FragmentCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.CAMERA)) {
new ConfirmationDialog().show(getChildFragmentManager(), FRAGMENT_DIALOG);
} else {
FragmentCompat.requestPermissions(this, new String[]{Manifest.permission.CAMERA},
REQUEST_CAMERA_PERMISSION);
}}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions,
@NonNull int[] grantResults) {
if (requestCode == REQUEST_CAMERA_PERMISSION) {
if (grantResults.length != 1 || grantResults[0] != PackageManager.PERMISSION_GRANTED) {
ErrorDialog.newInstance(getString(R.string.request_permission))
.show(getChildFragmentManager(), FRAGMENT_DIALOG);
}
} else {super.onRequestPermissionsResult(requestCode, permissions, grantResults);}}
private void setUpCameraOutputs(int width, int height) {
Activity activity = getActivity();
CameraManager manager = (CameraManager) activity.getSystemService(Context.CAMERA_SERVICE);
try {
for (String cameraId : manager.getCameraIdList()) {
CameraCharacteristics characteristics
= manager.getCameraCharacteristics(cameraId);
Integer facing = characteristics.get(CameraCharacteristics.LENS_FACING);
if (facing != null && facing == CameraCharacteristics.LENS_FACING_FRONT) {continue;}
StreamConfigurationMap map = characteristics.get(
CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
if (map == null) {
continue;
}
Size largest = Collections.max(
Arrays.asList(map.getOutputSizes(ImageFormat.JPEG)),
new CompareSizesByArea());
mImageReader = ImageReader.newInstance(largest.getWidth(), largest.getHeight(),
ImageFormat.JPEG, /*maxImages*/2);
mImageReader.setOnImageAvailableListener(
mOnImageAvailableListener, mBackgroundHandler);
int displayRotation = activity.getWindowManager().getDefaultDisplay().getRotation();
mSensorOrientation = characteristics.get(CameraCharacteristics.SENSOR_ORIENTATION);
boolean swappedDimensions = false;
switch (displayRotation) {
case Surface.ROTATION_0:
case Surface.ROTATION_180:
if (mSensorOrientation == 90 || mSensorOrientation == 270) {
swappedDimensions = true;
}
break;
case Surface.ROTATION_90:
case Surface.ROTATION_270:
if (mSensorOrientation == 0 || mSensorOrientation == 180) {
swappedDimensions = true;
}
break;
default:
Log.e(TAG, "Display rotation is invalid: " + displayRotation);
}
Point displaySize = new Point();
activity.getWindowManager().getDefaultDisplay().getSize(displaySize);
int rotatedPreviewWidth = width;
int rotatedPreviewHeight = height;
int maxPreviewWidth = displaySize.x;
int maxPreviewHeight = displaySize.y;
if (swappedDimensions) {
rotatedPreviewWidth = height;
rotatedPreviewHeight = width;
maxPreviewWidth = displaySize.y;
maxPreviewHeight = displaySize.x;
}
if (maxPreviewWidth > MAX_PREVIEW_WIDTH) {
maxPreviewWidth = MAX_PREVIEW_WIDTH;
}
if (maxPreviewHeight > MAX_PREVIEW_HEIGHT) {
maxPreviewHeight = MAX_PREVIEW_HEIGHT;
}
mPreviewSize = chooseOptimalSize(map.getOutputSizes(SurfaceTexture.class),
rotatedPreviewWidth, rotatedPreviewHeight, maxPreviewWidth,
maxPreviewHeight, largest);
int orientation = getResources().getConfiguration().orientation;
if (orientation == Configuration.ORIENTATION_LANDSCAPE) {
mTextureView.setAspectRatio(
mPreviewSize.getWidth(), mPreviewSize.getHeight());
} else {
mTextureView.setAspectRatio(
mPreviewSize.getHeight(), mPreviewSize.getWidth());
}
Boolean available = characteristics.get(CameraCharacteristics.FLASH_INFO_AVAILABLE);
mFlashSupported = available == null ? false : available;
mCameraId = cameraId;
return;
}
} catch (CameraAccessException e) {
e.printStackTrace();
} catch (NullPointerException e) {
ErrorDialog.newInstance(getString(R.string.camera_error))
.show(getChildFragmentManager(), FRAGMENT_DIALOG);
}
}
private void openCamera(int width, int height) {
if (ContextCompat.checkSelfPermission(getActivity(), Manifest.permission.CAMERA)
!= PackageManager.PERMISSION_GRANTED) {
requestCameraPermission();
return;
}
setUpCameraOutputs(width, height);
configureTransform(width, height);
Activity activity = getActivity();
CameraManager manager = (CameraManager) activity.getSystemService(Context.CAMERA_SERVICE);
try {
if (!mCameraOpenCloseLock.tryAcquire(2500, TimeUnit.MILLISECONDS)) {
throw new RuntimeException("Time out waiting to lock camera opening.");
}
manager.openCamera(mCameraId, mStateCallback, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
} catch (InterruptedException e) {
throw new RuntimeException("Interrupted while trying to lock camera opening.", e);
}
}
private void closeCamera() {
try {
mCameraOpenCloseLock.acquire();
if (null != mCaptureSession) {
mCaptureSession.close();
mCaptureSession = null;
}
if (null != mCameraDevice) {
mCameraDevice.close();
mCameraDevice = null;
}
if (null != mImageReader) {
mImageReader.close();
mImageReader = null;
}
} catch (InterruptedException e) {
throw new RuntimeException("Interrupted while trying to lock camera closing.", e);
} finally {
mCameraOpenCloseLock.release();
}
}
private void startBackgroundThread() {
mBackgroundThread = new HandlerThread("CameraBackground");
mBackgroundThread.start();
mBackgroundHandler = new Handler(mBackgroundThread.getLooper());
}
private void stopBackgroundThread() {
mBackgroundThread.quitSafely();
try {
mBackgroundThread.join();
mBackgroundThread = null;
mBackgroundHandler = null;
} catch (InterruptedException e) {
e.printStackTrace();
}
}
private void createCameraPreviewSession() {
try {
SurfaceTexture texture = mTextureView.getSurfaceTexture();
assert texture != null;
texture.setDefaultBufferSize(mPreviewSize.getWidth(), mPreviewSize.getHeight());
Surface surface = new Surface(texture); mPreviewRequestBuilder=mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
mPreviewRequestBuilder.addTarget(surface);
mCameraDevice.createCaptureSession(Arrays.asList(surface, mImageReader.getSurface()),
new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(@NonNull CameraCaptureSession cameraCaptureSession) {
if (null == mCameraDevice){return;}
mCaptureSession = cameraCaptureSession;
try { mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE,CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
setAutoFlash(mPreviewRequestBuilder);
mPreviewRequest = mPreviewRequestBuilder.build(); mCaptureSession.setRepeatingRequest(mPreviewRequest,
mCaptureCallback, mBackgroundHandler);} catch (CameraAccessException e) {e.printStackTrace();}}
@Override
public void onConfigureFailed(
@NonNull CameraCaptureSession cameraCaptureSession) {showToast("Failed");}
}, null
);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
private void configureTransform(int viewWidth, int viewHeight) {
Activity activity = getActivity();
if (null == mTextureView || null == mPreviewSize || null == activity) {
return;
}
int rotation = activity.getWindowManager().getDefaultDisplay().getRotation();
Matrix matrix = new Matrix();
RectF viewRect = new RectF(0, 0, viewWidth, viewHeight);
RectF bufferRect = new RectF(0, 0, mPreviewSize.getHeight(), mPreviewSize.getWidth());
float centerX = viewRect.centerX();
float centerY = viewRect.centerY();
if (Surface.ROTATION_90 == rotation || Surface.ROTATION_270 == rotation) {
bufferRect.offset(centerX - bufferRect.centerX(), centerY - bufferRect.centerY());
matrix.setRectToRect(viewRect, bufferRect, Matrix.ScaleToFit.FILL);
float scale = Math.max(
(float) viewHeight / mPreviewSize.getHeight(),
(float) viewWidth / mPreviewSize.getWidth());
matrix.postScale(scale, scale, centerX, centerY);
matrix.postRotate(90 * (rotation - 2), centerX, centerY);
} else if (Surface.ROTATION_180 == rotation) {
matrix.postRotate(180, centerX, centerY);
}
mTextureView.setTransform(matrix);
}
private void takePicture() {
lockFocus();
}
private void lockFocus() {
try {
List<CaptureRequest> captureList = new ArrayList<CaptureRequest>();
mPreviewRequestBuilder.addTarget(mImageReader.getSurface());
for (int i = 0; i < 10; i++) {
captureList.add(mPreviewRequestBuilder.build());
}
mCaptureSession.stopRepeating();
mCaptureSession.captureBurst(captureList, cameraCaptureCallback, null);
mPreviewRequestBuilder.removeTarget(mImageReader.getSurface());
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
CameraCaptureSession.CaptureCallback cameraCaptureCallback = new CameraCaptureSession.CaptureCallback() {
@Override
public void onCaptureCompleted(CameraCaptureSession session, CaptureRequest request,TotalCaptureResult result) {
Log.e("TestingProject", "pic # " + (mPictureCounter + 1));
mPictureCounter++;
if (mPictureCounter >= 10)
unlockFocus();
}
};
private void runPrecaptureSequence() {
try { mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AE_PRECAPTURE_TRIGGER,
CaptureRequest.CONTROL_AE_PRECAPTURE_TRIGGER_START);
mState = STATE_WAITING_PRECAPTURE;
mCaptureSession.capture(mPreviewRequestBuilder.build(), mCaptureCallback,
mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
private void captureStillPicture() {
try {
final Activity activity = getActivity();
if (null == activity || null == mCameraDevice) {return;}
final CaptureRequest.Builder captureBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
captureBuilder.addTarget(mImageReader.getSurface());
captureBuilder.set(CaptureRequest.CONTROL_AF_MODE,
CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
setAutoFlash(captureBuilder);
int rotation = activity.getWindowManager().getDefaultDisplay().getRotation();
captureBuilder.set(CaptureRequest.JPEG_ORIENTATION, getOrientation(rotation));
CameraCaptureSession.CaptureCallback CaptureCallback
= new CameraCaptureSession.CaptureCallback() {
@Override
public void onCaptureCompleted(@NonNull CameraCaptureSession session,
@NonNull CaptureRequest request,
@NonNull TotalCaptureResult result) {
showToast("Saved: " + mFile);
Log.d(TAG, mFile.toString());
unlockFocus();
}
};
mCaptureSession.stopRepeating();
mCaptureSession.capture(captureBuilder.build(), CaptureCallback, null);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
private int getOrientation(int rotation) {
return (ORIENTATIONS.get(rotation) + mSensorOrientation + 270) % 360;
}
private void unlockFocus() {
try {
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER,
CameraMetadata.CONTROL_AF_TRIGGER_CANCEL);
setAutoFlash(mPreviewRequestBuilder);
mCaptureSession.capture(mPreviewRequestBuilder.build(), mCaptureCallback,
mBackgroundHandler);
mState = STATE_PREVIEW;
mCaptureSession.setRepeatingRequest(mPreviewRequest, mCaptureCallback,
mBackgroundHandler);
} catch (CameraAccessException e) {
Log.e("TestingProject", "BHAND... "+e.getMessage());
}
}
@Override
public void onClick(View view) {
switch (view.getId()) {
case R.id.picture: {
takePicture();
break;
}
case R.id.info: {
Activity activity = getActivity();
if (null != activity) {
new AlertDialog.Builder(activity)
.setMessage(R.string.intro_message)
.setPositiveButton(android.R.string.ok, null)
.show();
}
break;
}
}
}
private void setAutoFlash(CaptureRequest.Builder requestBuilder) {
if (mFlashSupported) {
requestBuilder.set(CaptureRequest.CONTROL_AE_MODE,
CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH);
}
}
private static class ImageSaver implements Runnable {
private final Image mImage;
private final File mFile;
public ImageSaver(Image image, File file) {
mImage = image;
mFile = file;
}
@Override
public void run() {
ByteBuffer buffer = mImage.getPlanes()[0].getBuffer();
byte[] bytes = new byte[buffer.remaining()];
buffer.get(bytes);
FileOutputStream output = null;
try {
output = new FileOutputStream(mFile);
output.write(bytes);
} catch (IOException e) {
e.printStackTrace();
} finally {
mImage.close();
if (null != output) {
try {
output.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
static class CompareSizesByArea implements Comparator<Size> {
@Override
public int compare(Size lhs, Size rhs) {
return Long.signum((long) lhs.getWidth() * lhs.getHeight() -
(long) rhs.getWidth() * rhs.getHeight());
}
}
public static class ErrorDialog extends DialogFragment {
private static final String ARG_MESSAGE = "message";
public static ErrorDialog newInstance(String message) {
ErrorDialog dialog = new ErrorDialog();
Bundle args = new Bundle();
args.putString(ARG_MESSAGE, message);
dialog.setArguments(args);
return dialog;
}
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
final Activity activity = getActivity();
return new AlertDialog.Builder(activity)
.setMessage(getArguments().getString(ARG_MESSAGE))
.setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
activity.finish();
}
})
.create();
}
}
public static class ConfirmationDialog extends DialogFragment {
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
final Fragment parent = getParentFragment();
return new AlertDialog.Builder(getActivity())
.setMessage(R.string.request_permission)
.setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
FragmentCompat.requestPermissions(parent,
new String[]{Manifest.permission.CAMERA},
REQUEST_CAMERA_PERMISSION);
}
})
.setNegativeButton(android.R.string.cancel,
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
Activity activity = parent.getActivity();
if (activity != null) {
activity.finish();
}
}
})
.create();
}
}}