Develop Reference

Android camera preview freeze when switching the camera?

This error shows "java.lang.RuntimeException: Camera is being used after Camera.release() was called" when me switching camera. Is my way to release the camera is not the correct way? Can someone suggest me the best way to implement this?
This is my CameraActivity.java:
private Camera mCamera;
private CameraPreviewActivity mPreview;
private int cameraId = 0;
private static final int MY_PERMISSIONS_REQUEST_CAMERA = 1;
/**
* 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;
}
}
/**
* A safe way to get an instance of the Camera object.
*/
// attempt to get a Camera instance
public static Camera getCameraInstance() {
Camera c = null;
try {
c = Camera.open();
} catch (Exception e) {
System.out.println("Camera not working.");
}
return c; // returns null if camera is unavailable
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.camerapreview_activity);
// Create our Preview view and set it as the content of our activity.
// Create an instance of Camera
switchCamera();
showCamera();
}
public void switchCamera() {
ToggleButton facingSwitch = (ToggleButton) findViewById(R.id.facingSwitch);
facingSwitch.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
onDestroy();
preview.removeAllViews();
if (isChecked) {
// The toggle is enabled
preview.addView(mPreview);
Camera.open(Camera.CameraInfo.CAMERA_FACING_FRONT);
} else {
// The toggle is disabled
preview.addView(mPreview);
Camera.open(Camera.CameraInfo.CAMERA_FACING_BACK);
}
}
});
}
protected void onDestroy () {
super.onDestroy();
if (mCamera != null){
mCamera.stopPreview();
mCamera.release(); // release the camera for other applications
mCamera = null;
}
}
public void showCamera() {
if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
// Permission is not granted
// Should we show an explanation?
if (ActivityCompat.shouldShowRequestPermissionRationale(this,
Manifest.permission.CAMERA)) {
Toast.makeText(this, "Camera permission is needed to show the camera preview", Toast.LENGTH_SHORT).show();
// Show an explanation to the user *asynchronously* -- don't block
// this thread waiting for the user's response! After the user
// sees the explanation, try again to request the permission.
} else {
// No explanation needed; request the permission
ActivityCompat.requestPermissions(this,
new String[]{Manifest.permission.CAMERA},
MY_PERMISSIONS_REQUEST_CAMERA);
// MY_PERMISSIONS_REQUEST_READ_CONTACTS is an
// app-defined int constant. The callback method gets the
// result of the request.
}
}
else {
// Permission has already been granted
mCamera = getCameraInstance();
mPreview = new CameraPreviewActivity(this, mCamera);
FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
preview.addView(mPreview);
}
}
// Here, thisActivity is the current activity
#Override
public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
switch (requestCode) {
case MY_PERMISSIONS_REQUEST_CAMERA: {
// If request is cancelled, the result arrays are empty.
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
// Create our Preview view and set it as the content of our activity.
// permission was granted, yay! Do the
// contacts-related task you need to do.
showCamera();
} else {
Toast.makeText(this, "Permission was not granted", Toast.LENGTH_SHORT).show();
// permission denied, boo! Disable the
// functionality that depends on this permission.
}
return;
}
}
}
// other 'case' lines to check for other
// permissions this app might request.
And this is my CameraPreviewActivity.java
private SurfaceHolder mHolder;
private Camera mCamera;
public CameraPreviewActivity(Context context, Camera camera) {
super(context);
mCamera = camera;
// Install a SurfaceHolder.Callback so we get notified when the
// underlying surface is created and destroyed.
mHolder = getHolder();
mHolder.addCallback(this);
// deprecated setting, but required on Android versions prior to 3.0
mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
public void surfaceCreated(SurfaceHolder holder) {
// The Surface has been created, now tell the camera where to draw the preview.
try {
mCamera.setPreviewDisplay(holder);
mCamera.startPreview();
} catch (IOException e) {
Log.d(TAG, "Error setting camera preview: " + e.getMessage());
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
// empty. Take care of releasing the Camera preview in your activity.
}
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
// If your preview can change or rotate, take care of those events here.
// Make sure to stop the preview before resizing or reformatting it.
if (mHolder.getSurface() == null){
// preview surface does not exist
return;
}
// stop preview before making changes
try {
mCamera.stopPreview();
} catch (Exception e){
// ignore: tried to stop a non-existent preview
}
// set preview size and make any resize, rotate or
// reformatting changes here
// start preview with new settings
try {
mCamera.setPreviewDisplay(mHolder);
mCamera.startPreview();
} catch (Exception e){
Log.d(TAG, "Error starting camera preview: " + e.getMessage());
}
}
}

Camera.open(1) and Camera.open(0) return a camera instance, use it to replace mCamera. This does not explain the RuntimeException.
This exception happens because your CameraPreviewActivity keeps its separate reference to the Camera instance which you opened in CameraActivity.
The best practice would be to keep the reference only in the CameraPreviewActivity class, and remove the mCamera field from CameraActivity class.

How can I save only the last taken image to directory?

Here I have created an app to take images and save them to external storage of the phone. (Also there is a problem with below code that images are not saved to the given location.) I want only the last taken image to be saved in external memory of the phone.Everytime I take a new picture, I need to delete the previously taken image and save only the last taken image. How can I do it? Also is it possible to take images continously at regular intervals? I searched and I found that I can do it with a Timer(). Is it possible? Thank You.
Edit- Actually what I want is to comapare two images. One is taken at the moment and other is taken immediately before it. (I take images at regular time intervals and I compare new one with the previous one.) Only after comparison, I delete previous one.
public class MyCamera extends Activity {
private Camera mCamera;
private CameraPreview mCameraPreview;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mCamera = getCameraInstance();
mCameraPreview = new CameraPreview(this, mCamera);
FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
preview.addView(mCameraPreview);
Button captureButton = (Button) findViewById(R.id.button_capture);
captureButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
mCamera.takePicture(null, null, mPicture);
}
});
}
/**
* Helper method to access the camera returns null if it cannot get the
* camera or does not exist
*
* #return
*/
private Camera getCameraInstance() {
Camera camera = null;
try {
camera = Camera.open();
} catch (Exception e) {
// cannot get camera or does not exist
}
return camera;
}
PictureCallback mPicture = new PictureCallback() {
#Override
public void onPictureTaken(byte[] data, Camera camera) {
File pictureFile = getOutputMediaFile();
if (pictureFile == null) {
return;
}
try {
FileOutputStream fos = new FileOutputStream(pictureFile);
fos.write(data);
fos.close();
} catch (FileNotFoundException e) {
Log.d(TAG, e.getMessage());
} catch (IOException e) {
Log.d(TAG, e.getMessage());
}
}
};
private static File getOutputMediaFile() {
File mediaStorageDir = new File(
Environment
.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES),
"MyCameraApp");
if (!mediaStorageDir.exists()) {
mediaStorageDir.mkdirs();
if (!mediaStorageDir.mkdirs()) {
Log.d("MyCameraApp", "failed to create directory");
return null;
}
}
// Create a media file name
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss")
.format(new Date());
String fname = "IMG_" + timeStamp + ".jpg";
System.out.println(fname);
File mediaFile;
mediaFile = new File(mediaStorageDir, fname);
return mediaFile;
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.my_camera, menu);
return true;
}
}

You can keep a constant name for your photo file.
String fname = "MyImage.jpg";
You can give some constant name. And about taking image at regular interval, you can use handler.
You can read more about it here.
And make sure your remove your handler when your camera is closed.
EDITED
You can list the files of your directory,mediaStorageDir in your case.
List all the files of the directory, and delete the file which is older by comparing the last modified.

onPreviewCallback wont start android studio

I want to call onPreviewCallback in my app but it wont start. For now there is nothing useufull on onPreviewCallback, i just want it to work. I tried to put callback in Camerapreview.java and still nothing. Can anyone tell me where i made my mistake? Here is my code:
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.example.nikola.camera.MainActivity">
<FrameLayout
android:id="#+id/camera_preview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
/>
</RelativeLayout>
MainActivity.java
package com.example.nikola.camera;
import android.content.Context;
import android.content.pm.PackageManager;
import android.graphics.ImageFormat;
import android.hardware.Camera;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.FrameLayout;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
public Camera mCamera;
private CameraPreview mPreview;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if(checkCameraHardware(this)==false){
Toast.makeText(MainActivity.this, "This device does not have camera", Toast.LENGTH_LONG).show();
finish();
}
mCamera = getCameraInstance();
mCamera.setPreviewCallback(new Camera.PreviewCallback() {
#Override
public void onPreviewFrame(byte[] data, Camera camera) {
Log.d("Camera1","data lenght is:"+data.length);
}
});
if(mCamera==null){
Toast.makeText(MainActivity.this, "Can't access camera", Toast.LENGTH_LONG).show();
finish();
}
Camera.Parameters cameraParametars = mCamera.getParameters();
cameraParametars.setPreviewSize(640,480);
cameraParametars.setPreviewFormat(ImageFormat.RGB_565);
mCamera.setParameters(cameraParametars);
mPreview = new CameraPreview(this, mCamera);
FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
preview.addView(mPreview);
}
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;
}
}
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
}
}
CameraPreview.java
package com.example.nikola.camera;
/**
* Created by Nikola on 8/4/2016.
*/
import android.content.Context;
import android.hardware.Camera;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import java.io.IOException;
/** A basic Camera preview class */
public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
private SurfaceHolder mHolder;
private Camera mCamera;
public CameraPreview(Context context, Camera camera) {
super(context);
mCamera = camera;
// Install a SurfaceHolder.Callback so we get notified when the
// underlying surface is created and destroyed.
mHolder = getHolder();
mHolder.addCallback(this);
// deprecated setting, but required on Android versions prior to 3.0
mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
public void surfaceCreated(SurfaceHolder holder) {
// The Surface has been created, now tell the camera where to draw the preview.
try {
mCamera.setPreviewDisplay(holder);
mCamera.startPreview();
} catch (IOException e) {
Log.d("Camera_app", "Error setting camera preview: " + e.getMessage());
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
// empty. Take care of releasing the Camera preview in your activity.
}
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
// If your preview can change or rotate, take care of those events here.
// Make sure to stop the preview before resizing or reformatting it.
if (mHolder.getSurface() == null){
// preview surface does not exist
return;
}
// stop preview before making changes
try {
mCamera.stopPreview();
} catch (Exception e){
// ignore: tried to stop a non-existent preview
}
// set preview size and make any resize, rotate or
// reformatting changes here
// start preview with new settings
try {
mCamera.setPreviewDisplay(mHolder);
mCamera.startPreview();
} catch (Exception e){
Log.d("Camera_app", "Error starting camera preview: " + e.getMessage());
}
}
}

First permission add for camera and take image in sdcard
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
On click on preview Photo is click and preview You get path in callback
preview.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
mCamera.takePicture(null, null, mPicture);
}
});
Take In class Imagepath your path of image take this in your class
private Camera.PictureCallback mPicture = new Camera.PictureCallback() {
public void onPictureTaken(byte[] data, Camera camera) {
// Replacing the button after a photho was taken.
// File name of the image that we just took.
String fileName = "IMG_" + new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date()).toString() + ".jpg";
// Creating the directory where to save the image. Sadly in older
// version of Android we can not get the Media catalog name
File sdRoot = Environment.getExternalStorageDirectory();
// have the object build the directory structure, if needed.
String dir = "/Capture/path/";
File mkDir = new File(sdRoot, dir);
mkDir.mkdirs();
// Main file where to save the data that we recive from the camera
File pictureFile = new File(sdRoot, dir + fileName);
String imagePath=pictureFile.getPath();
System.out.print("imagePath"+imagePath);
try {
FileOutputStream purge = new FileOutputStream(pictureFile);
purge.write(data);
purge.close();
} catch (FileNotFoundException e) {
Log.d("DG_DEBUG", "File not found: " + e.getMessage());
} catch (IOException e) {
Log.d("DG_DEBUG", "Error accessing file: " + e.getMessage());
}
// Adding Exif data for the orientation. For some strange reason the
// ExifInterface class takes a string instead of a file.
try {
exif = new ExifInterface("/sdcard/" + dir + fileName);
exif.setAttribute(ExifInterface.TAG_ORIENTATION, "" + orientation);
exif.saveAttributes();
} catch (IOException e) {
e.printStackTrace();
}
}
};
But I recommended you the Camera2Basic... Which have tons of example because this is deprecated
I recommeded you to do this example which run in marashmallow or all devices work properly...
https://github.com/googlesamples/android-Camera2Basic
For face Detaction
You must register a FaceDetectionListener and then call camera.startFaceDetection().
Please see the link for face detaction..
https://docs.google.com/open?id=0B2Nu5U2Cz81qZExGQ25sWVdRd21IOExUUTZsZzFoZw

Android App Crashes when paused

I have an android activity which displays a live camera preview using a surfaceview. Everything works fine, however when I press the lock button on my phone and then unlock my phone or when a dialog box from another activity (example bluetooth transfer, or incoming call) overlays my camera preview the app crashes. I suspect this is a problem with my onResume() or onPause() activities as I get an error "method called after release()". However, I am unsure how to fix this.
CAMERA ACTIVITY:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_camera_screen);
setStatusBarColor();
Display display = getWindowManager().getDefaultDisplay();
final int height = display.getHeight();
session = new SessionManager(getApplicationContext());
try {
mCamera = Camera.open();//you can use open(int) to use different cameras
} catch (Exception e) {
Log.d("ERROR", "Failed to get camera: " + e.getMessage());
}
if (mCamera != null) {
mCameraView = new CameraPreview(this, mCamera);//create a SurfaceView to show camera data
FrameLayout camera_view = (FrameLayout) findViewById(R.id.camera_view);
camera_view.addView(mCameraView);//add the SurfaceView to the layout
//rotate preview
mCamera.setDisplayOrientation(90);
//rotate camera
Camera.Parameters p = mCamera.getParameters();
p.setRotation(90);
mCamera.setParameters(p);
}
#Override
protected void onPause() {
super.onPause();
if (mCamera != null) {
mCamera.setPreviewCallback(null);
mCameraView.getHolder().removeCallback(mCameraView);
mCamera.release();
}
}
#Override
public void onResume() {
super.onResume();
// Get the Camera instance as the activity achieves full user focus
if (mCamera == null) {
initializeCamera(); // Local method to handle camera initialization
}
}
protected void initializeCamera(){
// Get an instance of Camera Object
try{
mCamera = Camera.open();//you can use open(int) to use different cameras
} catch (Exception e){
Log.d("ERROR", "Failed to get camera: " + e.getMessage());
}
if(mCamera != null) {
mCameraView = new CameraPreview(this, mCamera);//create a SurfaceView to show camera data
FrameLayout camera_view = (FrameLayout)findViewById(R.id.camera_view);
camera_view.addView(mCameraView);//add the SurfaceView to the layout
}
}

Try adding this line to your onPause():
camera_view.removeView(mCameraView);

onPause(){
...
mCamera.release(); // close mCamera, but not set it to null
//mCamera = null; // you need reset mCamera to trigger init method;
}
onResume(){
...
initializeCamera();// need mCamera == null
}
//If you find other problems.
//Add some codes in the initializeCamera().
{
//mCamera.setPreviewCallback("something");
//mCameraView.getHolder().addCallback(mCameraView);
}
//as onPause do.

Android mediarecorder stop called in an invalid state : 4 [duplicate]

I'm creating a call recording app, when I'm trying to stop call recording the Debug Console in java says that: "MediaRecorder stop called in an invalid state : 4" I've Googled a lot but I can't find anything that can help me! I'm already using RECORD_AUDIO and WRITE_EXTERNAL_STORAGE permissions! Here is part of my code:
private class PhoneCallListener extends PhoneStateListener {
private boolean isPhoneCalling = false;
#SuppressWarnings("deprecation")
#Override
public void onCallStateChanged(int state, final String incomingNumber) {
// TODO Auto-generated method stub
super.onCallStateChanged(state, incomingNumber);
String path = Environment.getExternalStorageDirectory()+"/callrec/";
final MediaRecorder recorder = new MediaRecorder();
recorder.setAudioSource(MediaRecorder.AudioSource.VOICE_CALL);
recorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
recorder.setOutputFile(path+"/TEST00000000011110.M4A");
if (TelephonyManager.CALL_STATE_RINGING == state) {
}
if (TelephonyManager.CALL_STATE_OFFHOOK == state) {
isPhoneCalling = true;
try {
recorder.prepare();
recorder.start();
} catch (Exception e) {
}
}
if (TelephonyManager.CALL_STATE_IDLE == state) {
if (isPhoneCalling) {
try {
recorder.stop();
recorder.reset();
recorder.release();
} catch (Exception e) {
// TODO: handle exception
}
Intent i = getBaseContext().getPackageManager()
.getLaunchIntentForPackage(
getBaseContext().getPackageName());
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(i);
isPhoneCalling = false;
}
}
}
}

finally i found a way to fix my problem !
i created a :
public void Recorder()
in my class and when i want to record audio call it
also i created a function for stop recording !
i hope this work for you !
and also this MediaRecorder API works good on android 2.3.3 to 4.3 !