我正在为我的自定义相机应用程序使用 camera2 api，我能够成功拍摄照片并保存它。现在，当尝试在没有用户干预的情况下拍摄多张图像时，预览会中断或暂停片刻。我该如何解决这个问题？所以基本上拍照应该在后台进行，而不会阻碍预览。下面是我的代码
import android.annotation.SuppressLint;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.pm.PackageManager;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.ImageFormat;
import android.graphics.Matrix;
import android.graphics.Point;
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.CameraMetadata;
import android.hardware.camera2.CaptureRequest;
import android.hardware.camera2.TotalCaptureResult;
import android.hardware.camera2.params.StreamConfigurationMap;
import android.media.Image;
import android.media.ImageReader;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Environment;
import android.os.Handler;
import android.os.HandlerThread;
import android.support.annotation.NonNull;
import android.support.media.ExifInterface;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.util.Log;
import android.util.Size;
import android.util.SparseIntArray;
import android.view.Surface;
import android.view.TextureView;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.Toast;
import com.google.android.gms.tasks.OnFailureListener;
import com.google.android.gms.tasks.OnSuccessListener;
import org.json.JSONArray;
import org.json.JSONException;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Timer;
import java.util.TimerTask;
import java.util.concurrent.TimeUnit;
public class Activity extends AppCompatActivity {
private TextureView textureView;
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 String cameraId;
protected CameraDevice cameraDevice;
protected CameraCaptureSession cameraCaptureSessions;
protected CaptureRequest.Builder captureRequestBuilder;
private Size imageDimension;
private static final int REQUEST_CAMERA_PERMISSION = 200;
private Handler mBackgroundHandler;
private HandlerThread mBackgroundThread;
Size largest;
public static Response response1;
float Sx, Sy, Ix, Iy;
public float[] pixelArrayy;
Bitmap rotatedBitmap;
public static String ovalPixelsJsonArrayString1;
Bitmap croppedBitmap;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_gesture1_cam_camera2);
//Get startTime for Gesture1Cam
start = System.currentTimeMillis();
//Log.e("shashankStart", String.valueOf(start));
dialog = new ProgressDialog(Gesture1CamCamera2Activity.this);
//Get screen pixels
DisplayMetrics metrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(metrics);
Sx = metrics.widthPixels;
Sy = metrics.heightPixels;
// Log.e("Sx and Sy", Sx + ", " + Sy);
textureView = findViewById(R.id.texture_gesture1Cam2);
assert textureView != null;
textureView.setSurfaceTextureListener(textureListener);
takePictureButton = findViewById(R.id.btn_takepicture_gesture1Cam2);
assert takePictureButton != null;
new Timer().schedule(new TimerTask() {
@Override
public void run() {
takePicture();
// this code will be executed after 2 seconds
}
}, 1000);
}
TextureView.SurfaceTextureListener textureListener = new
TextureView.SurfaceTextureListener() {
@Override
public void onSurfaceTextureAvailable(SurfaceTexture surface, int width, int height) {
//open your camera here
openCamera();
}
@Override
public void onSurfaceTextureSizeChanged(SurfaceTexture surface, int
width, int height) {
// Transform you image captured size according to the surface width and height
}
@Override
public boolean onSurfaceTextureDestroyed(SurfaceTexture surface) {
return false;
}
@Override
public void onSurfaceTextureUpdated(SurfaceTexture surface) {
}
};
private final CameraDevice.StateCallback stateCallback = new
CameraDevice.StateCallback() {
@Override
public void onOpened(CameraDevice camera) {
//This is called when the camera is open
// Log.e(TAG, "onOpened");
cameraDevice = camera;
createCameraPreview();
}
@Override
public void onDisconnected(CameraDevice camera) {
cameraDevice.close();
}
@Override
public void onError(CameraDevice camera, int error) {
cameraDevice.close();
cameraDevice = null;
}
};
protected void startBackgroundThread() {
mBackgroundThread = new HandlerThread("Camera Background");
mBackgroundThread.start();
mBackgroundHandler = new Handler(mBackgroundThread.getLooper());
}
protected void stopBackgroundThread() {
mBackgroundThread.quitSafely();
try {
mBackgroundThread.join();
mBackgroundThread = null;
mBackgroundHandler = null;
} catch (InterruptedException e) {
e.printStackTrace();
}
}
protected void takePicture() {
if (null == cameraDevice) {
// Log.e(TAG, "cameraDevice is null");
return;
}
try {
ImageReader reader = ImageReader.newInstance(largest.getWidth(), largest.getHeight(), ImageFormat.JPEG, 2);
List<Surface> outputSurfaces = new ArrayList<Surface>(2);
outputSurfaces.add(reader.getSurface());
outputSurfaces.add(new Surface(textureView.getSurfaceTexture()));
final CaptureRequest.Builder captureBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
captureBuilder.addTarget(reader.getSurface());
captureBuilder.set(CaptureRequest.CONTROL_MODE, CameraMetadata.CONTROL_MODE_AUTO);
// Orientation
int rotation = getWindowManager().getDefaultDisplay().getRotation();
captureBuilder.set(CaptureRequest.JPEG_ORIENTATION, ORIENTATIONS.get(rotation));
final File file = getOutputMediaFile();
ImageReader.OnImageAvailableListener readerListener = new ImageReader.OnImageAvailableListener() {
@Override
public void onImageAvailable(ImageReader reader) {
Image image = null;
try {
image = reader.acquireLatestImage();
ByteBuffer buffer = image.getPlanes()[0].getBuffer();
byte[] bytes = new byte[buffer.capacity()];
buffer.get(bytes);
save(bytes);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
} finally {
if (image != null) {
image.close();
}
}
}
private void save(byte[] bytes) throws IOException, JSONException {
Bitmap bitmap = BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
//Get orientation
InputStream io = new ByteArrayInputStream(bytes);
ExifInterface exif = null;
try {
exif = new ExifInterface(io);
} catch (IOException e) {
e.printStackTrace();
}
int orientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION,
ExifInterface.ORIENTATION_UNDEFINED);
// Log.e("orientation", String.valueOf(orientation));
//Get rotated bitmap
bitmap = rotateBitmap(bitmap, orientation);
//
Ix = bitmap.getWidth();
Iy = bitmap.getHeight();
try {
FileOutputStream out = new FileOutputStream(file);
bitmap.compress(Bitmap.CompressFormat.JPEG, 90, out);
out.flush();
out.close();
// Log.e("Image1", "Saved");
imageSavedTime = System.currentTimeMillis();
imageSaveTime = String.valueOf(imageSavedTime - takePic);
Log.e("shashank_SaveImageTime", imageSaveTime);
takePicture();
} catch (Exception e) {
e.printStackTrace();
}
}
};
reader.setOnImageAvailableListener(readerListener, mBackgroundHandler);
final CameraCaptureSession.CaptureCallback captureListener = new CameraCaptureSession.CaptureCallback() {
@Override
public void onCaptureCompleted(CameraCaptureSession session, CaptureRequest request, TotalCaptureResult result) {
super.onCaptureCompleted(session, request, result);
// Toast.makeText(Gesture1CamCamera2Activity.this, "Saved:" + file, Toast.LENGTH_SHORT).show();
createCameraPreview();
}
};
cameraDevice.createCaptureSession(outputSurfaces, new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(CameraCaptureSession session) {
try {
session.capture(captureBuilder.build(), captureListener, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
@Override
public void onConfigureFailed(CameraCaptureSession session) {
}
}, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
protected void createCameraPreview() {
try {
DisplayMetrics metrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(metrics);
int rotatedPreviewWidth = textureView.getWidth();
int rotatedPreviewHeight = textureView.getHeight();
int maxPreviewWidth = metrics.widthPixels;
int maxPreviewHeight = metrics.heightPixels;
CameraManager manager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
CameraCharacteristics characteristics = manager.getCameraCharacteristics(cameraDevice.getId());
StreamConfigurationMap map = characteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
largest = Collections.max(Arrays.asList(map.getOutputSizes(ImageFormat.JPEG)), new CompareSizesByArea());
imageDimension = Utils.chooseOptimalSize(map.getOutputSizes(SurfaceTexture.class),
rotatedPreviewWidth, rotatedPreviewHeight, maxPreviewWidth,
maxPreviewHeight, largest);
SurfaceTexture texture = textureView.getSurfaceTexture();
assert texture != null;
texture.setDefaultBufferSize(imageDimension.getWidth(), imageDimension.getHeight());
Surface surface = new Surface(texture);
captureRequestBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
captureRequestBuilder.addTarget(surface);
cameraDevice.createCaptureSession(Arrays.asList(surface), new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(@NonNull CameraCaptureSession cameraCaptureSession) {
//The camera is already closed
if (null == cameraDevice) {
return;
}
// When the session is ready, we start displaying the preview.
cameraCaptureSessions = cameraCaptureSession;
updatePreview();
}
@Override
public void onConfigureFailed(@NonNull CameraCaptureSession cameraCaptureSession) {
Toast.makeText(Gesture1CamCamera2Activity.this, "Configuration change", Toast.LENGTH_SHORT).show();
}
}, null);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
private void openCamera() {
CameraManager manager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
// Log.e(TAG, "is camera open");
try {
cameraId = "1";
CameraCharacteristics characteristics = manager.getCameraCharacteristics(cameraId);
StreamConfigurationMap map = characteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
assert map != null;
imageDimension = map.getOutputSizes(SurfaceTexture.class)[0];
// Add permission for camera and let user grant the permission
if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, android.Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(Gesture1CamCamera2Activity.this, new String[]{android.Manifest.permission.CAMERA, android.Manifest.permission.WRITE_EXTERNAL_STORAGE}, REQUEST_CAMERA_PERMISSION);
return;
}
manager.openCamera(cameraId, stateCallback, null);
} catch (CameraAccessException e) {
e.printStackTrace();
}
// Log.e(TAG, "openCamera X");
}
protected void updatePreview() {
if (null == cameraDevice) {
// Log.e(TAG, "updatePreview error, return");
}
captureRequestBuilder.set(CaptureRequest.CONTROL_MODE, CameraMetadata.CONTROL_MODE_AUTO);
try {
cameraCaptureSessions.setRepeatingRequest(captureRequestBuilder.build(), null, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
if (requestCode == REQUEST_CAMERA_PERMISSION) {
if (grantResults[0] == PackageManager.PERMISSION_DENIED) {
// close the app
Toast.makeText(Gesture1CamCamera2Activity.this, "Sorry!!!, you can't use this app without granting permission", Toast.LENGTH_LONG).show();
finish();
}
}
}
@SuppressLint("LongLogTag")
@Override
protected void onResume() {
super.onResume();
//Log.e(TAG, "onResume");
startBackgroundThread();
if (textureView.isAvailable()) {
openCamera();
} else {
textureView.setSurfaceTextureListener(textureListener);
}
}
@Override
protected void onPause() {
// Log.e(TAG, "onPause");
//closeCamera();
stopBackgroundThread();
super.onPause();
}
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 File getOutputMediaFile() {
final String TAG = "CameraPreview";
File mediaStorageDir =
new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), "GesturesAppGes1");
// Create the storage directory if it does not exist
if (!mediaStorageDir.exists()) {
if (!mediaStorageDir.mkdirs()) {
// Log.d(TAG, "failed to create directory");
return null;
}
}
SharedPreferences prefs = getSharedPreferences("shanksPrefs", MODE_PRIVATE);
File file = new File(mediaStorageDir.getPath() + File.separator + username + "_deltaTime1_" + deltaTime1 + "_deltaTime2_" + deltaTime2 + ".jpg");
path1 = file.getPath();
return file;
}
@Override
public void onBackPressed() {
}
}
您正在设置一个最大 JPEG 缓冲区仅为 2 张图像的图像阅读器：
ImageReader.newInstance(largest.getWidth(), largest.getHeight(), ImageFormat.JPEG, 2);
如果收到的 Image 对象没有及时关闭，则 onImageAvailable 回调将停止，直到这些对象关闭，当 onImageAvailable 的缓冲区中没有更多可用图像时，预览将冻结。
为了解决这个问题，在 ImageReader.newInstance(( 中将 maxImages 增加到更多。请注意，如果输入较大的数字并且Image对象未及时关闭，则可能会耗尽内存。
除了 maxImages 缓冲区之外，其他可能影响性能的因素是，您正在 onImageAvailable 回调中为每个 JPEG 创建一个字节缓冲区。更好的方法是将 Image 对象传递给单独的保存后台线程。但是，此路径需要更多的工作，因为您需要执行一些额外的步骤来确保 Image 对象在保存之前不会释放，如果相机设备关闭，可能会发生这种情况。有关此方法，请参阅 Camera2Raw 示例。