【发布时间】：2020-04-01 23:20:12
【问题描述】：
[已解决]
在搜索了答案后，我没有找到在图片模式下打开闪光灯的解决方案。
应用程序在后台打开相机，并连续处理图片并检测物体，但手机位于没有光线的容器中，因此我需要确保闪光灯始终打开。
我还可以考虑其他方法，但我不确定如何使这些方法也起作用：
切换到视频模式。 （因为无论如何我都在处理相机预览的图片，而在视频模式下，闪光灯模式可以在不录制视频的情况下工作）。
将相机默认应用设置为支持在屏幕上点击时使用闪光灯进行图像预览的其他应用（我需要弄清楚如何切换到不同的应用以及如何模拟点击，甚至可能使用另一台设备已通过蓝牙连接到应用并发送点击）。
覆盖相机的 API 并确保 Flash 可以打开，或者只是禁用并让其他应用打开闪光灯。
这似乎不起作用：（在最后一个代码块中）
Camera.Parameters parameters = camera.getParameters();
parameters.setFlashMode(Camera.Parameters.FLASH_MODE_ON);
解决方案 1 或 3 应该是理想的，任何想法如何使它工作？这是我正在使用的代码：
import android.annotation.SuppressLint;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.app.DialogFragment;
import android.app.Fragment;
import android.content.Context;
import android.content.DialogInterface;
import android.content.res.Configuration;
import android.graphics.ImageFormat;
import android.graphics.Matrix;
import android.graphics.RectF;
import android.graphics.SurfaceTexture;
import android.hardware.camera2.CameraAccessException;
import android.hardware.camera2.CameraCaptureSession;
import android.hardware.camera2.CameraCharacteristics;
import android.hardware.camera2.CameraDevice;
import android.hardware.camera2.CameraManager;
import android.hardware.camera2.CaptureRequest;
import android.hardware.camera2.CaptureResult;
import android.hardware.camera2.TotalCaptureResult;
import android.hardware.camera2.params.StreamConfigurationMap;
import android.media.ImageReader;
import android.media.ImageReader.OnImageAvailableListener;
import android.os.Bundle;
import android.os.Handler;
import android.os.HandlerThread;
import android.text.TextUtils;
import android.util.Size;
import android.util.SparseIntArray;
import android.view.LayoutInflater;
import android.view.Surface;
import android.view.TextureView;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;
import org.tensorflow.lite.examples.classification.customview.AutoFitTextureView;
import org.tensorflow.lite.examples.classification.env.Logger;
public class CameraConnectionFragment extends Fragment {
private static final Logger LOGGER = new Logger();
/**
* The camera preview size will be chosen to be the smallest frame by pixel size capable of
* containing a DESIRED_SIZE x DESIRED_SIZE square.
*/
private static final int MINIMUM_PREVIEW_SIZE = 320;
/** Conversion from screen rotation to JPEG orientation. */
private static final SparseIntArray ORIENTATIONS = new SparseIntArray();
private static final String FRAGMENT_DIALOG = "dialog";
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);
}
/** A {@link Semaphore} to prevent the app from exiting before closing the camera. */
private final Semaphore cameraOpenCloseLock = new Semaphore(1);
/** A {@link OnImageAvailableListener} to receive frames as they are available. */
private final OnImageAvailableListener imageListener;
/** The input size in pixels desired by TensorFlow (width and height of a square bitmap). */
private final Size inputSize;
/** The layout identifier to inflate for this Fragment. */
private final int layout;
private final ConnectionCallback cameraConnectionCallback;
private final CameraCaptureSession.CaptureCallback captureCallback =
new CameraCaptureSession.CaptureCallback() {
@Override
public void onCaptureProgressed(
final CameraCaptureSession session,
final CaptureRequest request,
final CaptureResult partialResult) {}
@Override
public void onCaptureCompleted(
final CameraCaptureSession session,
final CaptureRequest request,
final TotalCaptureResult result) {}
};
/** ID of the current {@link CameraDevice}. */
private String cameraId;
/** An {@link AutoFitTextureView} for camera preview. */
private AutoFitTextureView textureView;
/** A {@link CameraCaptureSession } for camera preview. */
private CameraCaptureSession captureSession;
/** A reference to the opened {@link CameraDevice}. */
private CameraDevice cameraDevice;
/** The rotation in degrees of the camera sensor from the display. */
private Integer sensorOrientation;
/** The {@link Size} of camera preview. */
private Size previewSize;
/** An additional thread for running tasks that shouldn't block the UI. */
private HandlerThread backgroundThread;
/** A {@link Handler} for running tasks in the background. */
private Handler backgroundHandler;
/**
* {@link TextureView.SurfaceTextureListener} handles several lifecycle events on a {@link
* TextureView}.
*/
private final TextureView.SurfaceTextureListener surfaceTextureListener =
new TextureView.SurfaceTextureListener() {
@Override
public void onSurfaceTextureAvailable(
final SurfaceTexture texture, final int width, final int height) {
openCamera(width, height);
}
@Override
public void onSurfaceTextureSizeChanged(
final SurfaceTexture texture, final int width, final int height) {
configureTransform(width, height);
}
@Override
public boolean onSurfaceTextureDestroyed(final SurfaceTexture texture) {
return true;
}
@Override
public void onSurfaceTextureUpdated(final SurfaceTexture texture) {}
};
/** An {@link ImageReader} that handles preview frame capture. */
private ImageReader previewReader;
/** {@link CaptureRequest.Builder} for the camera preview */
private CaptureRequest.Builder previewRequestBuilder;
/** {@link CaptureRequest} generated by {@link #previewRequestBuilder} */
private CaptureRequest previewRequest;
/** {@link CameraDevice.StateCallback} is called when {@link CameraDevice} changes its state. */
private final CameraDevice.StateCallback stateCallback =
new CameraDevice.StateCallback() {
@Override
public void onOpened(final CameraDevice cd) {
// This method is called when the camera is opened. We start camera preview here.
cameraOpenCloseLock.release();
cameraDevice = cd;
createCameraPreviewSession();
}
@Override
public void onDisconnected(final CameraDevice cd) {
cameraOpenCloseLock.release();
cd.close();
cameraDevice = null;
}
@Override
public void onError(final CameraDevice cd, final int error) {
cameraOpenCloseLock.release();
cd.close();
cameraDevice = null;
final Activity activity = getActivity();
if (null != activity) {
activity.finish();
}
}
};
@SuppressLint("ValidFragment")
private CameraConnectionFragment(
final ConnectionCallback connectionCallback,
final OnImageAvailableListener imageListener,
final int layout,
final Size inputSize) {
this.cameraConnectionCallback = connectionCallback;
this.imageListener = imageListener;
this.layout = layout;
this.inputSize = inputSize;
}
/**
* Given {@code choices} of {@code Size}s supported by a camera, chooses the smallest one whose
* width and height are at least as large as the minimum of both, or an exact match if possible.
*
* @param choices The list of sizes that the camera supports for the intended output class
* @param width The minimum desired width
* @param height The minimum desired height
* @return The optimal {@code Size}, or an arbitrary one if none were big enough
*/
protected static Size chooseOptimalSize(final Size[] choices, final int width, final int height) {
final int minSize = Math.max(Math.min(width, height), MINIMUM_PREVIEW_SIZE);
final Size desiredSize = new Size(width, height);
// Collect the supported resolutions that are at least as big as the preview Surface
boolean exactSizeFound = false;
final List<Size> bigEnough = new ArrayList<Size>();
final List<Size> tooSmall = new ArrayList<Size>();
for (final Size option : choices) {
if (option.equals(desiredSize)) {
// Set the size but don't return yet so that remaining sizes will still be logged.
exactSizeFound = true;
}
if (option.getHeight() >= minSize && option.getWidth() >= minSize) {
bigEnough.add(option);
} else {
tooSmall.add(option);
}
}
LOGGER.i("Desired size: " + desiredSize + ", min size: " + minSize + "x" + minSize);
LOGGER.i("Valid preview sizes: [" + TextUtils.join(", ", bigEnough) + "]");
LOGGER.i("Rejected preview sizes: [" + TextUtils.join(", ", tooSmall) + "]");
if (exactSizeFound) {
LOGGER.i("Exact size match found.");
return desiredSize;
}
// Pick the smallest of those, assuming we found any
if (bigEnough.size() > 0) {
final Size chosenSize = Collections.min(bigEnough, new CompareSizesByArea());
LOGGER.i("Chosen size: " + chosenSize.getWidth() + "x" + chosenSize.getHeight());
return chosenSize;
} else {
LOGGER.e("Couldn't find any suitable preview size");
return choices[0];
}
}
public static CameraConnectionFragment newInstance(
final ConnectionCallback callback,
final OnImageAvailableListener imageListener,
final int layout,
final Size inputSize) {
return new CameraConnectionFragment(callback, imageListener, layout, inputSize);
}
/**
* Shows a {@link Toast} on the UI thread.
*
* @param text The message to show
*/
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();
}
});
}
}
@Override
public View onCreateView(
final LayoutInflater inflater, final ViewGroup container, final Bundle savedInstanceState) {
return inflater.inflate(layout, container, false);
}
@Override
public void onViewCreated(final View view, final Bundle savedInstanceState) {
textureView = (AutoFitTextureView) view.findViewById(R.id.texture);
}
@Override
public void onActivityCreated(final Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
}
@Override
public void onResume() {
super.onResume();
startBackgroundThread();
// When the screen is turned off and turned back on, the SurfaceTexture is already
// available, and "onSurfaceTextureAvailable" will not be called. In that case, we can open
// a camera and start preview from here (otherwise, we wait until the surface is ready in
// the SurfaceTextureListener).
if (textureView.isAvailable()) {
openCamera(textureView.getWidth(), textureView.getHeight());
} else {
textureView.setSurfaceTextureListener(surfaceTextureListener);
}
}
@Override
public void onPause() {
closeCamera();
stopBackgroundThread();
super.onPause();
}
public void setCamera(String cameraId) {
this.cameraId = cameraId;
}
/** Sets up member variables related to camera. */
private void setUpCameraOutputs() {
final Activity activity = getActivity();
final CameraManager manager = (CameraManager) activity.getSystemService(Context.CAMERA_SERVICE);
try {
final CameraCharacteristics characteristics = manager.getCameraCharacteristics(cameraId);
final StreamConfigurationMap map =
characteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
sensorOrientation = characteristics.get(CameraCharacteristics.SENSOR_ORIENTATION);
// Danger, W.R.! Attempting to use too large a preview size could exceed the camera
// bus' bandwidth limitation, resulting in gorgeous previews but the storage of
// garbage capture data.
previewSize =
chooseOptimalSize(
map.getOutputSizes(SurfaceTexture.class),
inputSize.getWidth(),
inputSize.getHeight());
// We fit the aspect ratio of TextureView to the size of preview we picked.
final int orientation = getResources().getConfiguration().orientation;
if (orientation == Configuration.ORIENTATION_LANDSCAPE) {
textureView.setAspectRatio(previewSize.getWidth(), previewSize.getHeight());
textureView.setVisibility(View.GONE);
} else {
textureView.setAspectRatio(previewSize.getHeight(), previewSize.getWidth());
textureView.setVisibility(View.GONE);
}
} catch (final CameraAccessException e) {
LOGGER.e(e, "Exception!");
} catch (final NullPointerException e) {
// Currently an NPE is thrown when the Camera2API is used but not supported on the
// device this code runs.
// TODO(andrewharp): abstract ErrorDialog/RuntimeException handling out into new method and
// reuse throughout app.
ErrorDialog.newInstance(getString(R.string.camera_error))
.show(getChildFragmentManager(), FRAGMENT_DIALOG);
throw new RuntimeException(getString(R.string.camera_error));
}
cameraConnectionCallback.onPreviewSizeChosen(previewSize, sensorOrientation);
}
/** Opens the camera specified by {@link CameraConnectionFragment#cameraId}. */
private void openCamera(final int width, final int height) {
setUpCameraOutputs();
configureTransform(width, height);
final Activity activity = getActivity();
final CameraManager manager = (CameraManager) activity.getSystemService(Context.CAMERA_SERVICE);
try {
if (!cameraOpenCloseLock.tryAcquire(2500, TimeUnit.MILLISECONDS)) {
throw new RuntimeException("Time out waiting to lock camera opening.");
}
manager.openCamera(cameraId, stateCallback, backgroundHandler);
} catch (final CameraAccessException e) {
LOGGER.e(e, "Exception!");
} catch (final InterruptedException e) {
throw new RuntimeException("Interrupted while trying to lock camera opening.", e);
}
}
/** Closes the current {@link CameraDevice}. */
private void closeCamera() {
try {
cameraOpenCloseLock.acquire();
if (null != captureSession) {
captureSession.close();
captureSession = null;
}
if (null != cameraDevice) {
cameraDevice.close();
cameraDevice = null;
}
if (null != previewReader) {
previewReader.close();
previewReader = null;
}
} catch (final InterruptedException e) {
throw new RuntimeException("Interrupted while trying to lock camera closing.", e);
} finally {
cameraOpenCloseLock.release();
}
}
/** Starts a background thread and its {@link Handler}. */
private void startBackgroundThread() {
backgroundThread = new HandlerThread("ImageListener");
backgroundThread.start();
backgroundHandler = new Handler(backgroundThread.getLooper());
}
/** Stops the background thread and its {@link Handler}. */
private void stopBackgroundThread() {
backgroundThread.quitSafely();
try {
backgroundThread.join();
backgroundThread = null;
backgroundHandler = null;
} catch (final InterruptedException e) {
LOGGER.e(e, "Exception!");
}
}
/** Creates a new {@link CameraCaptureSession} for camera preview. */
private void createCameraPreviewSession() {
try {
final SurfaceTexture texture = textureView.getSurfaceTexture();
assert texture != null;
// We configure the size of default buffer to be the size of camera preview we want.
texture.setDefaultBufferSize(previewSize.getWidth(), previewSize.getHeight());
// This is the output Surface we need to start preview.
final Surface surface = new Surface(texture);
// We set up a CaptureRequest.Builder with the output Surface.
previewRequestBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
previewRequestBuilder.addTarget(surface);
LOGGER.i("Opening camera preview: " + previewSize.getWidth() + "x" + previewSize.getHeight());
// Create the reader for the preview frames.
previewReader =
ImageReader.newInstance(
previewSize.getWidth(), previewSize.getHeight(), ImageFormat.YUV_420_888, 2);
previewReader.setOnImageAvailableListener(imageListener, backgroundHandler);
previewRequestBuilder.addTarget(previewReader.getSurface());
// Here, we create a CameraCaptureSession for camera preview.
cameraDevice.createCaptureSession(
Arrays.asList(surface, previewReader.getSurface()),
new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(final CameraCaptureSession cameraCaptureSession) {
// The camera is already closed
if (null == cameraDevice) {
return;
}
// When the session is ready, we start displaying the preview.
captureSession = cameraCaptureSession;
try {
// Auto focus should be continuous for camera preview.
previewRequestBuilder.set(
CaptureRequest.CONTROL_AF_MODE,
CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
// Flash is automatically enabled when necessary.
// previewRequestBuilder.set(
// CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH);
previewRequestBuilder.set(
CaptureRequest.FLASH_MODE, CaptureRequest.CONTROL_AE_MODE_ON_ALWAYS_FLASH);
// Finally, we start displaying the camera preview.
previewRequest = previewRequestBuilder.build();
captureSession.setRepeatingRequest(
previewRequest, captureCallback, backgroundHandler);
} catch (final CameraAccessException e) {
LOGGER.e(e, "Exception!");
}
}
@Override
public void onConfigureFailed(final CameraCaptureSession cameraCaptureSession) {
showToast("Failed");
}
},
null);
} catch (final CameraAccessException e) {
LOGGER.e(e, "Exception!");
}
}
}
}
第二个：
public class LegacyCameraConnectionFragment extends Fragment {
private static final Logger LOGGER = new Logger();
/** Conversion from screen rotation to JPEG orientation. */
private static final SparseIntArray ORIENTATIONS = new SparseIntArray();
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 Camera camera;
private Camera.PreviewCallback imageListener;
private Size desiredSize;
/** The layout identifier to inflate for this Fragment. */
private int layout;
/** An {@link AutoFitTextureView} for camera preview. */
private AutoFitTextureView textureView;
/**
* {@link TextureView.SurfaceTextureListener} handles several lifecycle events on a {@link
* TextureView}.
*/
private final TextureView.SurfaceTextureListener surfaceTextureListener =
new TextureView.SurfaceTextureListener() {
@Override
public void onSurfaceTextureAvailable(
final SurfaceTexture texture, final int width, final int height) {
int index = getCameraId();
camera = Camera.open(index);
try {
Camera.Parameters parameters = camera.getParameters();
List<String> focusModes = parameters.getSupportedFocusModes();
if (focusModes != null
&& focusModes.contains(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE)) {
parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);
}
List<Camera.Size> cameraSizes = parameters.getSupportedPreviewSizes();
Size[] sizes = new Size[cameraSizes.size()];
int i = 0;
for (Camera.Size size : cameraSizes) {
sizes[i++] = new Size(size.width, size.height);
}
Size previewSize =
CameraConnectionFragment.chooseOptimalSize(
sizes, desiredSize.getWidth(), desiredSize.getHeight());
parameters.setPreviewSize(previewSize.getWidth(), previewSize.getHeight());
camera.setDisplayOrientation(90);
camera.setParameters(parameters);
camera.setPreviewTexture(texture);
} catch (IOException exception) {
camera.release();
}
camera.setPreviewCallbackWithBuffer(imageListener);
Camera.Size s = camera.getParameters().getPreviewSize();
camera.addCallbackBuffer(new byte[ImageUtils.getYUVByteSize(s.height, s.width)]);
textureView.setAspectRatio(s.height, s.width);
camera.startPreview();
}
@Override
public void onSurfaceTextureSizeChanged(
final SurfaceTexture texture, final int width, final int height) {}
@Override
public boolean onSurfaceTextureDestroyed(final SurfaceTexture texture) {
return true;
}
@Override
public void onSurfaceTextureUpdated(final SurfaceTexture texture) {}
};
/** An additional thread for running tasks that shouldn't block the UI. */
private HandlerThread backgroundThread;
@SuppressLint("ValidFragment")
public LegacyCameraConnectionFragment(
final Camera.PreviewCallback imageListener, final int layout, final Size desiredSize) {
this.imageListener = imageListener;
this.layout = layout;
this.desiredSize = desiredSize;
}
@Override
public View onCreateView(
final LayoutInflater inflater, final ViewGroup container, final Bundle savedInstanceState) {
return inflater.inflate(layout, container, false);
}
@Override
public void onViewCreated(final View view, final Bundle savedInstanceState) {
textureView = (AutoFitTextureView) view.findViewById(R.id.texture);
}
@Override
public void onActivityCreated(final Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
}
@Override
public void onResume() {
super.onResume();
startBackgroundThread();
// When the screen is turned off and turned back on, the SurfaceTexture is already
// available, and "onSurfaceTextureAvailable" will not be called. In that case, we can open
// a camera and start preview from here (otherwise, we wait until the surface is ready in
// the SurfaceTextureListener).
if (textureView.isAvailable()) {
camera.startPreview();
} else {
textureView.setSurfaceTextureListener(surfaceTextureListener);
}
}
@Override
public void onPause() {
stopCamera();
stopBackgroundThread();
super.onPause();
}
/** Starts a background thread and its {@link Handler}. */
private void startBackgroundThread() {
backgroundThread = new HandlerThread("CameraBackground");
backgroundThread.start();
}
/** Stops the background thread and its {@link Handler}. */
private void stopBackgroundThread() {
backgroundThread.quitSafely();
try {
backgroundThread.join();
backgroundThread = null;
} catch (final InterruptedException e) {
LOGGER.e(e, "Exception!");
}
}
protected void stopCamera() {
if (camera != null) {
camera.stopPreview();
camera.setPreviewCallback(null);
camera.release();
camera = null;
}
}
private int getCameraId() {
CameraInfo ci = new CameraInfo();
for (int i = 0; i < Camera.getNumberOfCameras(); i++) {
Camera.getCameraInfo(i, ci);
if (ci.facing == CameraInfo.CAMERA_FACING_BACK) return i;
}
return -1; // No camera found
}
}
解决方案：在第二块代码中：
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE,
CaptureRequest.CONTROL_AE_MODE_ON);
mPreviewRequestBuilder.set(CaptureRequest.FLASH_MODE,
CaptureRequest.FLASH_MODE_TORCH);
在第一个代码块中：
//Check Whether device supports AutoFlash, If you YES then set AutoFlash
List<String> flashModes = parameters.getSupportedFlashModes();
if (flashModes.contains(android.hardware.Camera.Parameters.FLASH_MODE_AUTO))
{
parameters.setFlashMode(parameters.FLASH_MODE_AUTO);
}
【问题讨论】：
标签： camera