我正在为我的自定义相机应用程序使用 camera2 api，我能够成功拍照并保存。现在，当尝试在没有用户干预的情况下拍摄多张图像时，预览会被击中或暂停片刻。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妨碍预览。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() {
}
}
最佳答案
您设置的 ImageReader 的最大 JPEG 缓冲区仅为 2 张图像:
ImageReader.newInstance(largest.getWidth(), largest.getHeight(), ImageFormat.JPEG, 2);
如果收到Image对象没有及时关闭，那么 onImageAvailable回调将停止，直到它们关闭，当 onImageAvailable 的缓冲区中没有更多免费图像时，预览将卡住。
要解决这个问题，请在 ImageReader.newInstance() 中将 maxImages 增加几个.请注意，如果您输入的数字很大并且 Image 对象没有及时关闭，您可能会耗尽内存。
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，这条路径需要做更多的工作，因为您需要执行一些额外的步骤以确保图像对象在保存之前不会被释放，这可能在相机设备关闭时发生。查看Camera2Raw这种方法的示例。
关于android - 使用 camera2api 捕获多张图像使预览在拍照时暂停片刻，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/51932112/