我有一个由按钮组成的Android应用程序
当您单击按钮时，应从相机捕获图像而不打开相机应用程序（图像应在后台拍摄）。
如何实现这个功能？
任何建议都会有很大的帮助
非常感谢。
答案 0 :(得分：17)
这是我的整个工作项目如何在没有SurfaceView的背景下捕获图像。
//您可以启动您的服务，以便在活动中随时随地捕获图像。
Intent front_translucent = new Intent(getApplication()
.getApplicationContext(), CameraService.class);
front_translucent.putExtra("Front_Request", true);
front_translucent.putExtra("Quality_Mode",
camCapture.getQuality());
getApplication().getApplicationContext().startService(
front_translucent);
public class CamerService extends Service implements
SurfaceHolder.Callback {
// Camera variables
// a surface holder
// a variable to control the camera
private Camera mCamera;
// the camera parameters
private Parameters parameters;
private Bitmap bmp;
FileOutputStream fo;
private String FLASH_MODE;
private int QUALITY_MODE = 0;
private boolean isFrontCamRequest = false;
private Camera.Size pictureSize;
SurfaceView sv;
private SurfaceHolder sHolder;
private WindowManager windowManager;
WindowManager.LayoutParams params;
public Intent cameraIntent;
SharedPreferences pref;
Editor editor;
int width = 0, height = 0;
/** Called when the activity is first created. */
@Override
public void onCreate() {
super.onCreate();
}
private Camera openFrontFacingCameraGingerbread() {
if (mCamera != null) {
mCamera.stopPreview();
mCamera.release();
}
int cameraCount = 0;
Camera cam = null;
Camera.CameraInfo cameraInfo = new Camera.CameraInfo();
cameraCount = Camera.getNumberOfCameras();
for (int camIdx = 0; camIdx < cameraCount; camIdx++) {
Camera.getCameraInfo(camIdx, cameraInfo);
if (cameraInfo.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {
try {
cam = Camera.open(camIdx);
} catch (RuntimeException e) {
Log.e("Camera",
"Camera failed to open: " + e.getLocalizedMessage());
/*
* Toast.makeText(getApplicationContext(),
* "Front Camera failed to open", Toast.LENGTH_LONG)
* .show();
*/
}
}
}
return cam;
}
private void setBesttPictureResolution() {
// get biggest picture size
width = pref.getInt("Picture_Width", 0);
height = pref.getInt("Picture_height", 0);
if (width == 0 | height == 0) {
pictureSize = getBiggesttPictureSize(parameters);
if (pictureSize != null)
parameters
.setPictureSize(pictureSize.width, pictureSize.height);
// save width and height in sharedprefrences
width = pictureSize.width;
height = pictureSize.height;
editor.putInt("Picture_Width", width);
editor.putInt("Picture_height", height);
editor.commit();
} else {
// if (pictureSize != null)
parameters.setPictureSize(width, height);
}
}
private Camera.Size getBiggesttPictureSize(Camera.Parameters parameters) {
Camera.Size result = null;
for (Camera.Size size : parameters.getSupportedPictureSizes()) {
if (result == null) {
result = size;
} else {
int resultArea = result.width * result.height;
int newArea = size.width * size.height;
if (newArea > resultArea) {
result = size;
}
}
}
return (result);
}
/** Check if this device has a camera */
private boolean checkCameraHardware(Context context) {
if (context.getPackageManager().hasSystemFeature(
PackageManager.FEATURE_CAMERA)) {
// this device has a camera
return true;
} else {
// no camera on this device
return false;
}
}
/** Check if this device has front camera */
private boolean checkFrontCamera(Context context) {
if (context.getPackageManager().hasSystemFeature(
PackageManager.FEATURE_CAMERA_FRONT)) {
// this device has front camera
return true;
} else {
// no front camera on this device
return false;
}
}
Handler handler = new Handler();
private class TakeImage extends AsyncTask<Intent, Void, Void> {
@Override
protected Void doInBackground(Intent... params) {
takeImage(params[0]);
return null;
}
@Override
protected void onPostExecute(Void result) {
}
}
private synchronized void takeImage(Intent intent) {
if (checkCameraHardware(getApplicationContext())) {
Bundle extras = intent.getExtras();
if (extras != null) {
String flash_mode = extras.getString("FLASH");
FLASH_MODE = flash_mode;
boolean front_cam_req = extras.getBoolean("Front_Request");
isFrontCamRequest = front_cam_req;
int quality_mode = extras.getInt("Quality_Mode");
QUALITY_MODE = quality_mode;
}
if (isFrontCamRequest) {
// set flash 0ff
FLASH_MODE = "off";
// only for gingerbread and newer versions
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.GINGERBREAD) {
mCamera = openFrontFacingCameraGingerbread();
if (mCamera != null) {
try {
mCamera.setPreviewDisplay(sv.getHolder());
} catch (IOException e) {
handler.post(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),
"API dosen't support front camera",
Toast.LENGTH_LONG).show();
}
});
stopSelf();
}
Camera.Parameters parameters = mCamera.getParameters();
pictureSize = getBiggesttPictureSize(parameters);
if (pictureSize != null)
parameters
.setPictureSize(pictureSize.width, pictureSize.height);
// set camera parameters
mCamera.setParameters(parameters);
mCamera.startPreview();
mCamera.takePicture(null, null, mCall);
// return 4;
} else {
mCamera = null;
handler.post(new Runnable() {
@Override
public void run() {
Toast.makeText(
getApplicationContext(),
"Your Device dosen't have Front Camera !",
Toast.LENGTH_LONG).show();
}
});
stopSelf();
}
/*
* sHolder = sv.getHolder(); // tells Android that this
* surface will have its data // constantly // replaced if
* (Build.VERSION.SDK_INT < 11)
*
* sHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS)
*/
} else {
if (checkFrontCamera(getApplicationContext())) {
mCamera = openFrontFacingCameraGingerbread();
if (mCamera != null) {
try {
mCamera.setPreviewDisplay(sv.getHolder());
} catch (IOException e) {
handler.post(new Runnable() {
@Override
public void run() {
Toast.makeText(
getApplicationContext(),
"API dosen't support front camera",
Toast.LENGTH_LONG).show();
}
});
stopSelf();
}
Camera.Parameters parameters = mCamera.getParameters();
pictureSize = getBiggesttPictureSize(parameters);
if (pictureSize != null)
parameters
.setPictureSize(pictureSize.width, pictureSize.height);
// set camera parameters
mCamera.setParameters(parameters);
mCamera.startPreview();
mCamera.takePicture(null, null, mCall);
// return 4;
} else {
mCamera = null;
/*
* Toast.makeText(getApplicationContext(),
* "API dosen't support front camera",
* Toast.LENGTH_LONG).show();
*/
handler.post(new Runnable() {
@Override
public void run() {
Toast.makeText(
getApplicationContext(),
"Your Device dosen't have Front Camera !",
Toast.LENGTH_LONG).show();
}
});
stopSelf();
}
// Get a surface
/*
* sHolder = sv.getHolder(); // tells Android that this
* surface will have its data // constantly // replaced
* if (Build.VERSION.SDK_INT < 11)
*
* sHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS
* );
*/
}
}
} else {
if (mCamera != null) {
mCamera.stopPreview();
mCamera.release();
mCamera = Camera.open();
} else
mCamera = getCameraInstance();
try {
if (mCamera != null) {
mCamera.setPreviewDisplay(sv.getHolder());
parameters = mCamera.getParameters();
if (FLASH_MODE == null || FLASH_MODE.isEmpty()) {
FLASH_MODE = "auto";
}
parameters.setFlashMode(FLASH_MODE);
// set biggest picture
setBesttPictureResolution();
// log quality and image format
Log.d("Qaulity", parameters.getJpegQuality() + "");
Log.d("Format", parameters.getPictureFormat() + "");
// set camera parameters
mCamera.setParameters(parameters);
mCamera.startPreview();
Log.d("ImageTakin", "OnTake()");
mCamera.takePicture(null, null, mCall);
} else {
handler.post(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),
"Camera is unavailable !",
Toast.LENGTH_LONG).show();
}
});
}
// return 4;
} catch (IOException e) {
// TODO Auto-generated catch block
Log.e("TAG", "CmaraHeadService()::takePicture", e);
}
// Get a surface
/*
* sHolder = sv.getHolder(); // tells Android that this surface
* will have its data constantly // replaced if
* (Build.VERSION.SDK_INT < 11)
*
* sHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
*/
}
} else {
// display in long period of time
/*
* Toast.makeText(getApplicationContext(),
* "Your Device dosen't have a Camera !", Toast.LENGTH_LONG)
* .show();
*/
handler.post(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),
"Your Device dosen't have a Camera !",
Toast.LENGTH_LONG).show();
}
});
stopSelf();
}
// return super.onStartCommand(intent, flags, startId);
}
@SuppressWarnings("deprecation")
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
// sv = new SurfaceView(getApplicationContext());
cameraIntent = intent;
Log.d("ImageTakin", "StartCommand()");
pref = getApplicationContext().getSharedPreferences("MyPref", 0);
editor = pref.edit();
windowManager = (WindowManager) getSystemService(WINDOW_SERVICE);
params = new WindowManager.LayoutParams(
WindowManager.LayoutParams.WRAP_CONTENT,
WindowManager.LayoutParams.WRAP_CONTENT,
WindowManager.LayoutParams.TYPE_PHONE,
WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
PixelFormat.TRANSLUCENT);
params.gravity = Gravity.TOP | Gravity.LEFT;
params.width = 1;
params.height = 1;
params.x = 0;
params.y = 0;
sv = new SurfaceView(getApplicationContext());
windowManager.addView(sv, params);
sHolder = sv.getHolder();
sHolder.addCallback(this);
// tells Android that this surface will have its data constantly
// replaced
if (Build.VERSION.SDK_INT < 11)
sHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
return 1;
}
Camera.PictureCallback mCall = new Camera.PictureCallback() {
@Override
public void onPictureTaken(byte[] data, Camera camera) {
// decode the data obtained by the camera into a Bitmap
Log.d("ImageTakin", "Done");
if (bmp != null)
bmp.recycle();
System.gc();
bmp = decodeBitmap(data);
ByteArrayOutputStream bytes = new ByteArrayOutputStream();
if (bmp != null && QUALITY_MODE == 0)
bmp.compress(Bitmap.CompressFormat.JPEG, 70, bytes);
else if (bmp != null && QUALITY_MODE != 0)
bmp.compress(Bitmap.CompressFormat.JPEG, QUALITY_MODE, bytes);
File imagesFolder = new File(
Environment.getExternalStorageDirectory(), "MYGALLERY");
if (!imagesFolder.exists())
imagesFolder.mkdirs(); // <----
File image = new File(imagesFolder, System.currentTimeMillis()
+ ".jpg");
// write the bytes in file
try {
fo = new FileOutputStream(image);
} catch (FileNotFoundException e) {
Log.e("TAG", "FileNotFoundException", e);
// TODO Auto-generated catch block
}
try {
fo.write(bytes.toByteArray());
} catch (IOException e) {
Log.e("TAG", "fo.write::PictureTaken", e);
// TODO Auto-generated catch block
}
// remember close de FileOutput
try {
fo.close();
if (Build.VERSION.SDK_INT < 19)
sendBroadcast(new Intent(
Intent.ACTION_MEDIA_MOUNTED,
Uri.parse("file://"
+ Environment.getExternalStorageDirectory())));
else {
MediaScannerConnection
.scanFile(
getApplicationContext(),
new String[] { image.toString() },
null,
new MediaScannerConnection.OnScanCompletedListener() {
public void onScanCompleted(
String path, Uri uri) {
Log.i("ExternalStorage", "Scanned "
+ path + ":");
Log.i("ExternalStorage", "-> uri="
+ uri);
}
});
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
if (mCamera != null) {
mCamera.stopPreview();
mCamera.release();
mCamera = null;
}
/*
* Toast.makeText(getApplicationContext(),
* "Your Picture has been taken !", Toast.LENGTH_LONG).show();
*/
com.integreight.onesheeld.Log.d("Camera", "Image Taken !");
if (bmp != null) {
bmp.recycle();
bmp = null;
System.gc();
}
mCamera = null;
handler.post(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),
"Your Picture has been taken !", Toast.LENGTH_SHORT)
.show();
}
});
stopSelf();
}
};
@Override
public IBinder onBind(Intent intent) {
return null;
}
public static Camera getCameraInstance() {
Camera c = null;
try {
c = Camera.open(); // attempt to get a Camera instance
} catch (Exception e) {
// Camera is not available (in use or does not exist)
}
return c; // returns null if camera is unavailable
}
@Override
public void onDestroy() {
if (mCamera != null) {
mCamera.stopPreview();
mCamera.release();
mCamera = null;
}
if (sv != null)
windowManager.removeView(sv);
Intent intent = new Intent("custom-event-name");
// You can also include some extra data.
intent.putExtra("message", "This is my message!");
LocalBroadcastManager.getInstance(this).sendBroadcast(intent);
super.onDestroy();
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Auto-generated method stub
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
if (cameraIntent != null)
new TakeImage().execute(cameraIntent);
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
if (mCamera != null) {
mCamera.stopPreview();
mCamera.release();
mCamera = null;
}
}
public static Bitmap decodeBitmap(byte[] data) {
Bitmap bitmap = null;
BitmapFactory.Options bfOptions = new BitmapFactory.Options();
bfOptions.inDither = false; // Disable Dithering mode
bfOptions.inPurgeable = true; // Tell to gc that whether it needs free
// memory, the Bitmap can be cleared
bfOptions.inInputShareable = true; // Which kind of reference will be
// used to recover the Bitmap data
// after being clear, when it will
// be used in the future
bfOptions.inTempStorage = new byte[32 * 1024];
if (data != null)
bitmap = BitmapFactory.decodeByteArray(data, 0, data.length,
bfOptions);
return bitmap;
}
}
答案 1 :(得分：2)
您必须创建一个假的Surface视图，该视图对用户不会显示，然后您可以通过以下代码实现
public class MainActivity extends Activity {
public static final int DONE = 1;
public static final int NEXT = 2;
public static final int PERIOD = 1;
private Camera camera;
private int cameraId = 0;
private ImageView display;
private Timer timer;
SurfaceHolder previewHolder;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
display = (ImageView) findViewById(R.id.imageView1);
// do we have a camera?
if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA))
{
Toast.makeText(this, "No camera on this device", Toast.LENGTH_LONG)
.show();
}
else
{
cameraId = findFrontFacingCamera();
if (cameraId < 0)
{
Toast.makeText(this, "No front facing camera found.",
Toast.LENGTH_LONG).show();
}
else
{
safeCameraOpen(cameraId);
}
}
// THIS IS JUST A FAKE SURFACE TO TRICK THE CAMERA PREVIEW
// http://stackoverflow.com/questions/17859777/how-to-take-pictures-in-android-
// application-without-the-user-interface
SurfaceView dummy = new SurfaceView(this);
previewHolder = dummy.getHolder();
previewHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
try {
camera.setPreviewDisplay(previewHolder);
} catch (IOException e1) {
e1.printStackTrace();
}
/*SurfaceView view = new SurfaceView(this);
try {
// camera.setPreviewDisplay(view.getHolder());
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}*/
Camera.Parameters params = camera.getParameters();
params.setJpegQuality(100);
camera.setParameters(params);
// We need something to trigger periodically the capture of a
// picture to be processed
timer = new Timer(getApplicationContext(), threadHandler);
timer.execute();
}
// thread Handler //
private Handler threadHandler = new Handler() {
public void handleMessage(android.os.Message msg) {
switch (msg.what) {
case DONE:
camera.startPreview();
previewHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
try {
camera.setPreviewDisplay(previewHolder);
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
camera.takePicture(null, null, mCall);
break;
case NEXT:
timer = new Timer(getApplicationContext(), threadHandler);
timer.execute();
break;
}
}
};
Camera.PictureCallback mCall = new Camera.PictureCallback() {
public void onPictureTaken(byte[] data, Camera camera) {
// decode the data obtained by the camera into a Bitmap
// display.setImageBitmap(photo);
Bitmap bitmapPicture = BitmapFactory.decodeByteArray(data, 0,
data.length);
display.setImageBitmap(bitmapPicture);
Message.obtain(threadHandler, MainActivity.NEXT, "").sendToTarget();
// Log.v("MyActivity","Length: "+data.length);
}
};
private int findFrontFacingCamera() {
int cameraId = -1;
// Search for the front facing camera
int numberOfCameras = Camera.getNumberOfCameras();
for (int i = 0; i < numberOfCameras; i++) {
CameraInfo info = new CameraInfo();
Camera.getCameraInfo(i, info);
if (info.facing == CameraInfo.CAMERA_FACING_FRONT) {
Log.v("MyActivity", "Camera found");
cameraId = i;
break;
}
}
return cameraId;
}
@Override
protected void onPause() {
if (timer != null) {
timer.cancel(true);
}
releaseCamera();
super.onPause();
}
// I think Android Documentation recommends doing this in a separate
// task to avoid blocking main UI
private boolean safeCameraOpen(int id) {
boolean qOpened = false;
try {
releaseCamera();
camera = Camera.open(id);
qOpened = (camera != null);
} catch (Exception e) {
Log.e(getString(R.string.app_name), "failed to open Camera");
e.printStackTrace();
}
return qOpened;
}
private void releaseCamera() {
if (camera != null) {
camera.stopPreview();
camera.release();
camera = null;
}
}
}
答案 2 :(得分：0)
如果您使用的是CAMERA2 API（在API 21中添加），请在此处查看我的答案Capture picture without preview using camera2 API
希望有所帮助：）
答案 3 :(得分：-1)
您可以使用 CameraX 做到这一点。它用于创建您自己的相机应用程序，因此您只需省略预览部分即可完成此操作。转到以下链接，获取有关 cameraX https://developer.android.com/codelabs/camerax-getting-started#0 的小教程，您只需复制粘贴代码即可。对于 androidx.camera.view.PreviewView，只需输入 width=0 和 height=0，您就会得到所需的结果。