Develop Reference

How to update TextureView SurfaceTextureListener

I am developing a camera app and I will use front and back camera. I am using TextureView like this:
<TextureView
android:id="#+id/textureView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="center"
/>
and code behind:
renderer = new CameraRenderer(this, isFrontCamera);
textureView.setSurfaceTextureListener(renderer);
CameraRenderer class implemet SurfaceTextureListener
public class CameraRenderer implements Runnable, TextureView.SurfaceTextureListener{...
and I set camera in onSurfaceTextureAvailable method like this:
public void onSurfaceTextureAvailable(SurfaceTexture surface, int width, int height) {
if (renderThread != null && renderThread.isAlive()) {
renderThread.interrupt();
}
renderThread = new Thread(this);
surfaceTexture = surface;
gwidth = width;
gheight = height;
// Open camera
int cameraId;
if(isFrontCamera)
cameraId = getFrontCamera();
else
cameraId = getBackCamera();
camera = Camera.open(cameraId);
renderThread.start();
}
Problem:
When I want to change camera and click button I am creating a new CameraRenderer instance and set to textureView
textureView.setSurfaceTextureListener(renderer);
but onSurfaceTextureDestroyed method in CameraRenderer class never called, also onSurfaceTextureAvailable method is not called too.
I can call onSurfaceTextureDestroyed method myself but I can't set second camera preview to textureView because onSurfaceTextureAvailable method is not called second time.
Here is my onSurfaceTextureDestroyed method:
#Override
public boolean onSurfaceTextureDestroyed(SurfaceTexture surface) {
if (camera != null) {
camera.stopPreview();
camera.release();
}
if (renderThread != null && renderThread.isAlive()) {
renderThread.interrupt();
}
CameraFilter.release();
return true;
}
Last note: I tried set listener as null but not working.
So How can I re-set textureView Listener. Thanks in advance!

Google GDK: Differences in calling app with voice trigger or menu affecting camera service?

I'm trying to create a Glass GDK app that uses the Camera service to show a preview. Unfortunately, I currently have a bug where a RuntimeException is thrown when trying to open a Camera using Camera.open(). I only encounter this bug when opening the activity through a voice trigger, not by selecting the app from the "launcher" menu.
Is there a difference in how an Activity is launched through this menu versus the voice trigger?
Some of the relevant code is below.
#Override
public void onCreate(Bundle savedInstanceState) {
mGestureDetector = createGestureDetector(this);
super.onCreate(savedInstanceState);
ctx = this;
act = this;
setContentView(R.layout.activity_main);
preview = new Preview(this, (SurfaceView)findViewById(R.id.surfaceView));
((FrameLayout) findViewById(R.id.preview)).addView(preview);
preview.setKeepScreenOn(true);
}
#Override
protected void onResume() {
super.onResume();
try {
if (camera == null) {
Log.d(TAG, "Opening a camera on resume.");
camera = Camera.open();
preview.setCamera(camera);
camera.startPreview();
}
} catch(java.lang.RuntimeException e) {
Log.e(TAG, e.getMessage());
}
}
#Override
protected void onPause() {
if(camera != null) {
camera.stopPreview();
preview.setCamera(null);
Log.d(TAG, "Releasing a camera on pause.");
camera.release();
camera = null;
}
super.onPause();
}
#Override
protected void onDestroy() {
if(camera != null) {
camera.stopPreview();
preview.setCamera(null);
Log.d(TAG, "Releasing a camera on destory.");
camera.release();
camera = null;
}
super.onDestroy();
}

Since it doesn't work when using the voice trigger, it sounds like a possible race condition where the microphone isn't released by the time your activity is displayed on the screen.
Can you try an approach that uses exponential back-off to capture the camera? Basically try to capture the camera and if you get an exception, try again after a short amount of time, increasing the wait time slightly for a fixed number of attempts.
Please also consider filing a bug on the issue tracker, especially if you can reliably find out how much of a delay is needed before the camera/mic can be acquired.

The problem is caused by the delay between the voice recogniser closing event and the camera open event, which is causing a memory overload.
To avoid the problem when launching the app which will be triggered with voice,
pause the app for certain time (1000 Milli seconds will do) from opening the camera soon.
In the below code I am delaying my QR scanner to open from opening for 1000 Milli seconds. This works fine for me. If you want a you can increase the time interval.
Handler handler = new Handler() {
#Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
intent = new Intent("com.google.zxing.client.android.SCAN");
startActivityForResult(intent, 0);
}
};
// sleeper time
handler.sendEmptyMessageDelayed(0, 1000);

OnResume Camera Reinit Black Screen

I have a problem. After initializing the camera for a preview and bringing another app into focus, then back to my app: the preview shows up black. If I continue to take a picture, it takes a picture of where I point the camera normally.
Am I doing something wrong on the OnResume() override? Relative code is below:
public void ReleaseCamera()
{
if (myCamera != null)
{
myCamera.Release();
myCamera = null;
}
}
protected override void OnPause()
{
base.OnPause();
if (myButtonState == ButtonState.CameraActive)
ReleaseCamera();
}
protected override void OnResume()
{
base.OnResume();
if (myButtonState == ButtonState.CameraActive)
InitializeCamera();
}
private void InitializeCamera()
{
SurfaceView mySurfaceView = FindViewById<SurfaceView>(Resource.Id.surfaceView1);
myCamera = Android.Hardware.Camera.Open(cameraNumber);
Android.Hardware.Camera.Parameters p = myCamera.GetParameters();
myCamera.SetDisplayOrientation(90); // Portrait
myCamera.SetPreviewDisplay(mySurfaceView.Holder);
myCamera.StartPreview();
}
Thank you for your help. :)

onResume() gets called too early. You don't have the surface holder ready at this stage. You can try to introduce onPostResume() handler in your Activity, and/or handle the SurfaceHolder.Callback.surfaceChanged() event.

Android Camera Surface View

I am trying to create a surface view for a camera so it renders on the surface whenever is in the view of the camera. At the moment all I can see on my camera view is a black screen view. I have tried to look on Google and here but so far I haven't found what I am looking for. Anyone can suggest me some idea.

I have written a class that can help you.
public class Preview_can_work extends Activity {
private SurfaceView surface_view;
private Camera mCamera;
SurfaceHolder.Callback sh_ob = null;
SurfaceHolder surface_holder = null;
SurfaceHolder.Callback sh_callback = null;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getWindow().setFormat(PixelFormat.TRANSLUCENT);
surface_view = new SurfaceView(getApplicationContext());
addContentView(surface_view, new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
if (surface_holder == null) {
surface_holder = surface_view.getHolder();
}
sh_callback = my_callback();
surface_holder.addCallback(sh_callback);
}
SurfaceHolder.Callback my_callback() {
SurfaceHolder.Callback ob1 = new SurfaceHolder.Callback() {
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
mCamera.stopPreview();
mCamera.release();
mCamera = null;
}
#Override
public void surfaceCreated(SurfaceHolder holder) {
mCamera = Camera.open();
try {
mCamera.setPreviewDisplay(holder);
} catch (IOException exception) {
mCamera.release();
mCamera = null;
}
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
mCamera.startPreview();
}
};
return ob1;
}
}
in your manifest file copy this code for camera permission
<uses-permission android:name="android.permission.CAMERA"/>
Explanation:
SurfaceView is a type of View which contains a SurfaceHolder. SurfaceHolder holds the surface on which we can display our media (generally frames).
mCamera is a Camera object which will contains the camera instance.
When you want to hold default Camera instance then you can simply call Camera.open();
Camera mCamera = Camera.open();
Now you have an open camera or you are having default camera instance. Now you need to capture frames from the camera and display it on a surface. But you cannot display it without any
surface. Here the surfaceView provides surfaceHolder and surfaceHolder provides surface to display camera frames. Now when surface will be created three callback functions will be
called.
1. public void surfaceCreated(SurfaceHolder holder)
2. public void surfaceChanged(SurfaceHolder holder, int format, int width, int height)
3. public void surfaceDestroyed(SurfaceHolder holder)
Note:- Surface will be destroyed when your application will go on pause.
surfaceCreated:
surfaceCreated is a callback function which will be called when your surface will be created. In this, you can open your camera and set other attributes.
surfaceChanged:
This will be called atleast one time when your surface will be created. After that it will be called whenever your surface will change(In device rotation). Here you can
start your preview because your surface have already created.
surfaceDestroyed:
This will be called every time when your surface will destroy. Now if you dont have surface then where you can display you camera frames so I have released camera by using
mCamera.release(). This is very important because if your activity will be on pause and any other activity tries to open camera then it will not able to open it as you have
already open camera. Camera is a shared resource so one time only one application can use it. So remember one thing whenever you open a camera then always release it.
stopPreview:
When you start preview then your camera starts capturing your frames and display it on a surface. Now if your surface have destroyed then you need to stop capturing frames
from camera so you have to call mCamera.stopPreview.

Make shure you added the permission :
<uses-permission android:name="android.permission.CAMERA"/>
Also these window properties:
getWindow().setFormat(PixelFormat.TRANSLUCENT);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN | WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON,
WindowManager.LayoutParams.FLAG_FULLSCREEN | WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
Post some code if that doesn't work in order to help you

recreating camera object after error 100 (camera server died)

I have classic android app with camera preview (common implem that can be found in many tutorials [marakana etc.]) that is supposed to take picture in a given time interval. Threading and killing threads is done, errors such "method called after release" are handled. But sometimes the well-known error 100 occurs. I accepted the fact that it happens and tried to handle it too. I implemented ErrorCallback and its onError method where the current camera object is released and instantiated a new one as written in official documentation.
But (with no surprise) it is not enough. New camera is maybe wrongly allocated because an message "CameraDemo has been exited unexpectedly" appears now.
I've read many docs and examples in hope, that a proper proceeding will be somewhere explained but no one has such problem apparently. So I would like to ask what else should I do beside releasing and creating new camera? Here is the code:
ErrorCallback CEC = new ErrorCallback()
{
public void onError(int error, Camera camera)
{
Log.d("CameraDemo", "camera error detected");
if(error == Camera.CAMERA_ERROR_SERVER_DIED)
{
Log.d("CameraDemo", "attempting to reinstantiate new camera");
camera.stopPreview();
camera.setPreviewCallback(null);
camera.release(); //written in documentation...
camera = null;
camera = Camera.open();
}
}
};
Shortly - if I release and recreate camera in onError callback then RuntimeException Method called after release (takePicture) is raised. So should I somehow assign the surface holder to camera again or recreate the surface holder too?
It would be enough to direct me e.g. to some forums, where it is described or solved, etc. Thanks for any help.

In my app to handle the camere i use this :
public void onResume() {
super.onResume();
if(mCamera == null)
mCamera = getCameraInstance():
}
public static Camera getCameraInstance() {
mCamera = null;
try {
mCamera = Camera.open();
Parameters parameters = mCamera.getParameters();
mCamera.cancelAutoFocus();
mCamera.setPreviewCallback(yourPreviewCb);
mCamera.startPreview();
mCamera.setParameters(parameters);
mCamera.autoFocus(yourAutoFocusCB);
} catch (Exception e) {
//TODO
}
return mCamera;
}
The mCamera = null in the getCameraInstance() is just to be sure there is no camera running at all.
I think you need to recreate a complete camera, not just open it with the
camera.open();
Set this in the onResume or in the error callback, depending on your needs.

This is how I fixed it, here is a sample of code, think you get the idea:
private Camera camera;
// code...
public Camera getCameraInstance() {
Camera camera = Camera.open();
// code...
camera.setErrorCallback(new ErrorCallback() {
#Override
public void onError(int error, Camera camera) {
if(error == Camera.CAMERA_ERROR_SERVER_DIED) {
releaseCamera();
startCamera();
}
}
});
return camera;
}
protected void startCamera() {
if(getCamera() == null)
setCamera(getCameraInstance());
refreshCamera();
}
protected void releaseCamera() {
if (getCamera() != null) {
getCamera().release();
setCamera(null);
}
}
public Camera getCamera() {
return camera;
}
public void setCamera(Camera camera) {
this.camera = camera;
}