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I've looked at all the SO articles I could find on this but none of the solutions work for me.
When called Camera.open(), there is a 3 second (give or take) delay where the UI thread is blocked. I have attempted to put that in a background thread. I'm currently using the solution found here (pasted below) but the 'wait' method is synchronous so it blocks the UI thread too.
What I'm looking to do is load this fragment, show a progress spinner until the camera is good to go, then show the camera on screen, but this delay is killing me and I can't seem to find any really good solution on it.
My fragment:
public class BarcodeFinderFragment extends Fragment implements View.OnClickListener, Camera.AutoFocusCallback, Camera.PreviewCallback {
private static final String CAMERA_THREAD_NAME = "CAMERA_THREAD_NAME";
private Camera mCamera;
private CamViewFinder mPreview;
private Handler autoFocusHandler;
private boolean previewing = true;
private Button noScan;
private Button noBarcode;
private FrameLayout preview;
private BarcodeFinderCallback callBack;
private ImageScanner scanner;
private CameraHandlerThread mThread = null;
private BarcodeFinderCallback dummyCallback = new BarcodeFinderCallback() {
@Override
public void onNoScanClicked() {
}
@Override
public void onNoBarcodeClicked() {
}
@Override
public void finishActivity() {
}
@Override
public void setActivityResult(Bundle bundle) {
}
@Override
public void showProgressDialog(boolean showProgress) {
}
};
public static BarcodeFinderFragment newInstance() {
return new BarcodeFinderFragment();
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
try {
callBack = (BarcodeFinderActivity) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement OnHeadlineSelectedListener");
}
}
@Override
public void onCreate(final Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_barcode_finder, container, false);
noScan = (Button) view.findViewById(R.id.btnNoScan);
noBarcode = (Button) view.findViewById(R.id.btnNobarcode);
preview = (FrameLayout) view.findViewById(R.id.cameraPreview);
noScan.setOnClickListener(this);
noBarcode.setOnClickListener(this);
return view;
}
@Override
public void onResume() {
super.onResume();
autoFocusHandler = new Handler();
//Instance barcode scanner
scanner = new ImageScanner();
scanner.setConfig(0, Config.X_DENSITY, 3);
scanner.setConfig(0, Config.Y_DENSITY, 3);
openCamera();
mPreview = new CamViewFinder(getActivity(), mCamera, BarcodeFinderFragment.this, BarcodeFinderFragment.this);
preview.addView(mPreview);
callBack.showProgressDialog(false);
}
private void getCamera() {
mCamera = null;
try {
mCamera = Camera.open();
} catch (final Exception e) {
Log.d("BarcodeFinderFragment", e.toString());
}
}
private void openCamera() {
if (mThread == null)
mThread = new CameraHandlerThread(CAMERA_THREAD_NAME);
synchronized (mThread) {
mThread.openCamera();
}
}
@Override
public void onPause() {
super.onPause();
releaseCamera();
}
@Override
public void onDetach() {
super.onDetach();
callBack = dummyCallback;
}
private Runnable doAutoFocus() {
return new Runnable() {
@Override
public void run() {
if (previewing) {
mCamera.autoFocus(BarcodeFinderFragment.this);
}
}
};
}
private void releaseCamera() {
if (mCamera != null) {
previewing = false;
mCamera.stopPreview();
mCamera.setPreviewCallback(null);
mCamera.release();
mCamera = null;
}
callBack.finishActivity();
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.btnNoScan:
callBack.onNoScanClicked();
break;
case R.id.btnNobarcode:
callBack.onNoBarcodeClicked();
break;
}
}
@Override
public void onAutoFocus(boolean success, Camera camera) {
autoFocusHandler.postDelayed(doAutoFocus(), 1000);
}
@Override
public void onPreviewFrame(byte[] data, Camera camera) {
final Camera.Parameters parameters = camera.getParameters();
final Camera.Size size = parameters.getPreviewSize();
final Image barcode = new Image(size.width, size.height, "Y800");
barcode.setData(data);
final int result = scanner.scanImage(barcode);
if (result != 0) {
previewing = false;
mCamera.setPreviewCallback(null);
mCamera.stopPreview();
final SymbolSet syms = scanner.getResults();
for (final Symbol sym : syms) {
final Bundle bundle = new Bundle();
bundle.putString("result", sym.getData());
bundle.putString("codeType", "" + sym.getType());
callBack.setActivityResult(bundle);
}
}
}
public interface BarcodeFinderCallback {
void onNoScanClicked();
void onNoBarcodeClicked();
void finishActivity();
void setActivityResult(Bundle bundle);
void showProgressDialog(boolean showProgress);
}
private class CameraHandlerThread extends HandlerThread {
Handler mHandler = null;
public CameraHandlerThread(String name) {
super(name);
callBack.showProgressDialog(true);
start();
mHandler = new Handler(getLooper());
}
synchronized void notifyCameraOpened() {
notify();
}
void openCamera() {
mHandler.post(new Runnable() {
@Override
public void run() {
getCamera();
notifyCameraOpened();
}
});
try {
wait();
} catch (InterruptedException e) {
Log.d("BarcodeFinderFragment", "wait was interrupted");
}
}
}
}
UPDATE
Thanks to MeetTitan, I was able to get this working very smoothly by keeping everything in the background thread and posting to the UI when needed. Here is the working code for anybody who may need it in the future :)
public class BarcodeFinderFragment extends Fragment implements View.OnClickListener {
private static final String CAMERA_THREAD_NAME = "CAMERA_THREAD_NAME";
private Camera mCamera;
private CamViewFinder mPreview;
private Handler autoFocusHandler;
private FrameLayout preview;
private ImageScanner scanner;
private boolean previewing = true;
private CameraHandlerThread mThread = null;
private BarcodeFinderCallback callBack;
private BarcodeFinderCallback dummyCallback = new BarcodeFinderCallback() {
@Override
public void onNoScanClicked() {
}
@Override
public void onNoBarcodeClicked() {
}
@Override
public void finishActivity() {
}
@Override
public void setActivityResult(int resultCode, Bundle bundle) {
}
@Override
public void showProgressDialog(boolean showProgress) {
}
};
public static BarcodeFinderFragment newInstance() {
return new BarcodeFinderFragment();
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
try {
callBack = (BarcodeFinderActivity) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement BarcodeFinderCallback");
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_barcode_finder, container, false);
Button noScan = (Button) view.findViewById(R.id.btnNoScan);
Button noBarcode = (Button) view.findViewById(R.id.btnNobarcode);
preview = (FrameLayout) view.findViewById(R.id.cameraPreview);
noScan.setOnClickListener(this);
noBarcode.setOnClickListener(this);
return view;
}
@Override
public void onResume() {
super.onResume();
autoFocusHandler = new Handler();
//Instance barcode scanner
scanner = new ImageScanner();
scanner.setConfig(0, Config.X_DENSITY, 3);
scanner.setConfig(0, Config.Y_DENSITY, 3);
callBack.showProgressDialog(true);
openCamera();
}
private void openCamera() {
if (mThread == null) {
try {
mThread = new CameraHandlerThread(CAMERA_THREAD_NAME);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
synchronized (mThread) {
mThread.openCamera();
}
}
@Override
public void onPause() {
super.onPause();
releaseCamera();
if (mThread != null && mThread.isAlive())
mThread.interrupt();
}
@Override
public void onDetach() {
super.onDetach();
callBack = dummyCallback;
}
private void releaseCamera() {
if (mCamera != null) {
previewing = false;
mCamera.stopPreview();
mCamera.setPreviewCallback(null);
mCamera.release();
mCamera = null;
}
callBack.finishActivity();
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.btnNoScan:
callBack.onNoScanClicked();
break;
case R.id.btnNobarcode:
callBack.onNoBarcodeClicked();
break;
}
}
public interface BarcodeFinderCallback {
void onNoScanClicked();
void onNoBarcodeClicked();
void finishActivity();
void setActivityResult(int resultCode, Bundle bundle);
void showProgressDialog(boolean showProgress);
}
private class CameraHandlerThread extends HandlerThread implements Camera.AutoFocusCallback, Camera.PreviewCallback {
Handler mHandler = null;
public CameraHandlerThread(String name) throws InterruptedException {
super(name);
callBack.showProgressDialog(true);
start();
mHandler = new Handler(getLooper());
}
void openCamera() {
mHandler.post(new Runnable() {
@Override
public void run() {
mCamera = null;
try {
mCamera = Camera.open();
} catch (final Exception e) {
Log.d("BarcodeFinderFragment", e.toString());
callBack.setActivityResult(Activity.RESULT_CANCELED, null);
interrupt();
}
notifyCameraOpened();
getActivity().runOnUiThread(new Runnable() {
@Override
public void run() {
mPreview = new CamViewFinder(getActivity(), mCamera, CameraHandlerThread.this, CameraHandlerThread.this);
preview.addView(mPreview);
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
callBack.showProgressDialog(false);
}
}, 500);
}
});
}
});
}
synchronized void notifyCameraOpened() {
notify();
}
@Override
public void onAutoFocus(boolean success, Camera camera) {
autoFocusHandler.postDelayed(new Runnable() {
@Override
public void run() {
if (previewing) {
getActivity().runOnUiThread(new Runnable() {
@Override
public void run() {
mCamera.autoFocus(CameraHandlerThread.this);
}
});
}
}
}, 1000);
}
@Override
public void onPreviewFrame(byte[] data, Camera camera) {
final Camera.Parameters parameters = camera.getParameters();
final Camera.Size size = parameters.getPreviewSize();
final Image barcode = new Image(size.width, size.height, "Y800");
barcode.setData(data);
final int result = scanner.scanImage(barcode);
if (result != 0) {
previewing = false;
mCamera.setPreviewCallback(null);
mCamera.stopPreview();
final SymbolSet syms = scanner.getResults();
for (final Symbol sym : syms) {
final Bundle bundle = new Bundle();
bundle.putString("result", sym.getData());
bundle.putString("codeType", "" + sym.getType());
getActivity().runOnUiThread(new Runnable() {
@Override
public void run() {
callBack.setActivityResult(Activity.RESULT_OK, bundle);
}
});
}
}
}
}
}
446
User Interface Thread or UI-Thread in Android is a Thread element responsible for updating the layout elements of the application implicitly or explicitly. This means, to update an element or change its attributes in the application layout ie the front-end of the application, one can make use of the UI-Thread.
If you put long running work on the UI thread, you can get ANR errors. If you have multiple threads and put long running work on the non-UI threads, those non-UI threads can't inform the user of what is happening.
Main Thread: The default, primary thread created anytime an Android application is launched. Also known as a UI thread, it is in charge of handling all user interface and activities, unless otherwise specified. Runnable is an interface meant to handle sharing code between threads. It contains only one method: run() .
UI Thread and Main Thread are same only in Android. The Main thread, that is responsible for handling the UI events like Draw, Listen and receive the UI events. Ans also it is responsible for interact with running components of the UI toolkit for the corresponding application that belongs to.
Could you not continue your thread and call groups of ui commands together with the yourContext.runOnUiThread() method? Then you background any blocking code, wait for the camera to be ready, and update the ui from the background thread.
For example:
private class CameraHandlerThread extends ... {
public void run() {
getCamera();
yourContext.runOnUiThread(new Runnable(){
public void run()
{
...
}
});
}
}
Then you can simply new CameraHandlerThread().start();
165
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