在后台 Android 中使用相机
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【中文标题】在后台 Android 中使用相机【英文标题】：Using the camera in Background Android 【发布时间】：2013-09-09 05:01:17 【问题描述】：我正在尝试将照片从相机中投入使用。
@Override
public void onCreate()
super.onCreate();
//android.os.Debug.waitForDebugger();
myCamera=Camera.open();
SurfaceView dummy=new SurfaceView(getApplicationContext());
try
if(myCamera!=null)
myCamera.setPreviewDisplay(dummy.getHolder());
myCamera.setPreviewCallback(this);
Log.i(TAG,"myCamera is not null");
getFrames();
catch (IOException e)
// TODO Auto-generated catch block
e.printStackTrace();
Log.e(TAG, "setPreviewDisplay " + e);
myCamera.startPreview();
public void getFrames()
new Thread(new Runnable()
public void run()
while(flag)
Log.i(TAG, "getFrames");
try
//method();
takePictureNoPreview();
Thread.sleep(54);
catch (Exception e)
Log.e(TAG, "getFrames thread error: " + e);
myCamera.release();
).start();
public void takePictureNoPreview()
try
Log.i(TAG,"takePictureNoPreview");
myCamera.takePicture(null, null, getJpegCallback())
catch (Exception e)
Log.e(TAG, "takePictureNoPreview " + e);
private PictureCallback getJpegCallback()
PictureCallback jpeg=new PictureCallback()
@Override
public void onPictureTaken(byte[] data, Camera camera)
try
Log.i(TAG,"getJpegCallback");
FileOutputStream(String.format("/sdcard/RealSpeaker/%d.jpg", System.currentTimeMillis()));
FileOutputStream os = new FileOutputStream(String.format("/sdcard/Sample/%d.jpg", System.currentTimeMillis()));
os.write(data);
os.close();
catch (IOException e)
//do something about it
;
return jpeg;
问题是getJpegCallback周围的方法不正确：（文件夹中没有日志和图像）ю 当我调试应用程序时，TAG - getJpegCallback 不会显示在 LogCat 中，但 TAG takePictureNoPreview 会显示。关闭应用程序后，相机不允许（现在没问题）。怎么了？
【问题讨论】：
我的经验是，我需要在布局中使用实际的 SurfaceView 来拍照，所以我添加了一个高度=20dp 和 marginTop=-100dp 的 SurfaceView 或其他东西来“移动它”看不见”，但它仍然存在于布局中。也许你应该尝试这样的事情。另一个思路是：不应该在回调的surfaceCreated/Changed方法中调用setPreviewDisplay和startPreview吗？ 好的。我正在尝试第一个变体 您是否要在后台录制视频 【参考方案1】：我在开发EyeSpy 时遇到了这个问题。即使应用程序在背景或前景中，我也想捕捉图像。我尝试了几个星期，但没有运气。使用相机拍摄照片意味着显示其预览。
From Document(5. 和 6.) 你必须使用SurfaceView 来显示预览。
当您关闭应用程序或您的应用程序进入后台时，SurfaceView 的表面将被破坏。这就是为什么我认为这是不可能的。
如果您发现任何其他方式，请在此处发布。
希望对你有所帮助..
【讨论】：
你尝试过这样的事情吗？ ->从 API 11 开始，您可以使用 SurfaceTexture，而不是使用 SurfaceView 的 SurfaceHolder。然后，您使用Camera.setPreviewTexture 而不是Camera.setPreviewDisplay 进行设置。
在不同设备上的服务对我来说效果很好。
This 回答以及this one 讨论这一点。
【讨论】：
【参考方案3】：public class TakePicture extends Activity implements SurfaceHolder.Callback
// a variable to store a reference to the Image View at the main.xml file
// private ImageView iv_image;
// a variable to store a reference to the Surface View at the main.xml file
private SurfaceView sv;
// a bitmap to display the captured image
private Bitmap bmp;
FileOutputStream fo;
// Camera variables
// a surface holder
private SurfaceHolder sHolder;
// a variable to control the camera
private Camera mCamera;
// the camera parameters
private Parameters parameters;
private String FLASH_MODE;
private boolean isFrontCamRequest = false;
private Camera.Size pictureSize;
/** Called when the activity is first created. */
@SuppressWarnings("deprecation")
@Override
public void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// check if this device has a camera
if (checkCameraHardware(getApplicationContext()))
// get the Image View at the main.xml file
// iv_image = (ImageView) findViewById(R.id.imageView);
// get the Surface View at the main.xml file
Bundle extras = getIntent().getExtras();
String flash_mode = extras.getString("FLASH");
FLASH_MODE = flash_mode;
boolean front_cam_req = extras.getBoolean("Front_Request");
isFrontCamRequest = true;
System.out.println("front_cam_req :"+front_cam_req);
sv = (SurfaceView) findViewById(R.id.camera_preview);
// Get a surface
sHolder = sv.getHolder();
// add the callback interface methods defined below as the Surface
// View
// callbacks
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);
else
// display in long period of time
Toast.makeText(getApplicationContext(),
"Your Device dosen't have a Camera !", Toast.LENGTH_LONG)
.show();
/** 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;
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 surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3)
// get camera parameters
if (mCamera != null)
parameters = mCamera.getParameters();
if (FLASH_MODE == null || FLASH_MODE.isEmpty())
FLASH_MODE = "auto";
parameters.setFlashMode(FLASH_MODE);
pictureSize = getBiggesttPictureSize(parameters);
if (pictureSize != null)
parameters
.setPictureSize(pictureSize.width, pictureSize.height);
// set camera parameters
mCamera.setParameters(parameters);
mCamera.startPreview();
// sets what code should be executed after the picture is taken
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");
bmp = BitmapFactory.decodeByteArray(data, 0, data.length);
ByteArrayOutputStream bytes = new ByteArrayOutputStream();
if (bmp != null)
bmp.compress(Bitmap.CompressFormat.JPEG, 100, bytes);
File imagesFolder = new File(
Environment.getExternalStorageDirectory(),
"OneSheeld");
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)
// TODO Auto-generated catch block
try
fo.write(bytes.toByteArray());
catch (IOException e)
// TODO Auto-generated catch block
// remember close de FileOutput
try
fo.close();
sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED,
Uri.parse("file://"
+ Environment
.getExternalStorageDirectory())));
catch (IOException e)
// TODO Auto-generated catch block
if (mCamera != null)
mCamera.stopPreview();
// release the camera
mCamera.release();
Toast.makeText(getApplicationContext(),
"Your Picture has been taken !", Toast.LENGTH_LONG)
.show();
if (bmp != null)
bmp.recycle();
bmp = null;
System.gc();
TakePicture.this.finish();
;
mCamera.takePicture(null, null, mCall);
@Override
public void surfaceCreated(SurfaceHolder holder)
// The Surface has been created, acquire the camera and tell it where
// to draw the preview.
if (isFrontCamRequest)
//Toast.makeText(getApplicationContext()," isFrontCamRequest()",Toast.LENGTH_LONG).show();
System.out.println("isFrontCamRequest 1");
// 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)
System.out.println("isFrontCamRequest 2");
mCamera = openFrontFacingCameraGingerbread();
try
mCamera.setPreviewDisplay(holder);
catch (IOException exception)
mCamera = null;
Toast.makeText(getApplicationContext(),"API dosen't support front camera",Toast.LENGTH_LONG).show();
TakePicture.this.finish();
else
System.out.println("isFrontCamRequest 3");
if (checkFrontCamera(getApplicationContext()))
mCamera = openFrontFacingCameraGingerbread();
try
mCamera.setPreviewDisplay(holder);
catch (IOException exception)
mCamera = null;
Toast.makeText(getApplicationContext(),
"API dosen't support front camera",
Toast.LENGTH_LONG).show();
TakePicture.this.finish();
/*
* else // API dosen't support front camera or no front camera
* Log.d("Camera",
* "API dosen't support front camera or no front camera");
* Toast.makeText( getApplicationContext(),
* "API dosen't support front camera or no front camera",
* Toast.LENGTH_LONG).show();
*
* finish();
*/
else
System.out.println("isFrontCamRequest 4");
mCamera = getCameraInstance();
try
mCamera.setPreviewDisplay(holder);
catch (Exception exception)
mCamera = null;
@Override
public void surfaceDestroyed(SurfaceHolder holder)
// stop the preview
/*
* mCamera.stopPreview(); // release the camera mCamera.release();
*/
// unbind the camera from this object
mCamera = null;
private Camera openFrontFacingCameraGingerbread()
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;
@Override
protected void onDestroy()
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();
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);
【讨论】：
请提供一些细节。【参考方案4】：似乎解决方案已经晚了，但仍然......实际上我们可以通过在 onCreate() 中使用 WindowManager 并膨胀布局......和 setVisibility(View.INVISIBLE)
@Override public void onCreate()
super.onCreate();
windowManager = (WindowManager) getSystemService(WINDOW_SERVICE);
inflater = (LayoutInflater) getSystemService(LAYOUT_INFLATER_SERVICE);
recording = false;
myview = inflater.inflate(R.layout.service_layout, null);
layout = (FrameLayout) myview.findViewById(R.id.preview);
minimize = (ImageButton) myview.findViewById(R.id.minimize);
minimize.setVisibility(ImageButton.GONE);
start = (Button) myview.findViewById(R.id.record);
start.setVisibility(Button.GONE);
start.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View v)
if(!recording)
if (prepareMediaRecorder())
try
mediaRecorder.start();
Log.e("Camera------>", "working after");
recording = true;
start.setText("STOP");
handler.post(sendUpdates);
catch (Exception e)
Log.getStackTraceString(e);
else
mediaRecorder.stop(); // stop the recording
releaseMediaRecorder();
recording = false;
Log.e("Camera1------>", "working");
start.setText("START");
handler.post(sendUpdates);
);
您也可以参考示例应用程序https://github.com/gauravbspr/Research-Projects/tree/master/Camera%20Service 并在必要时提供帮助
【讨论】：
【参考方案5】：不知道这是否晚了，但对于仍在搜索的任何人，请试试这个Android Background Camerahttps://github.com/YoboZorle/Android-Background-Camera
【讨论】：
【参考方案6】：你可以试试这个
Intent translucent = new Intent(getApplication(),
TakePicture.class);
translucent.putExtra("FLASH", "on");
startActivity(translucent);
Toast.makeText(getApplicationContext(), "Started Capture", 500).show();
<SurfaceView
android:id="@+id/camera_preview"
android:layout_
android:layout_ />
<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
<uses-permission android:name="android.permission.READ_PHONE_STATE"/>
<uses-permission android:name="android.permission.RECORD_VIDEO"/>
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.autofocus" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-feature android:name="android.hardware.camera.front" android:required="false" />
只要这样做对我有用。 希望对您有所帮助。
【讨论】：
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