android vision ORC java.lang.RuntimeException: takePicture failed when call mCameraSource.takePicture inside Handler -

i using android vision orc api develop example. example is: after text recognized in ocrdetectorprocessor.receivedetections() send handler message in ui activity. inside handler, want take picture, there error in case

11-06 00:12:43.932 15916-15916/com.google.android.gms.samples.vision.barcodereader e/androidruntime: fatal exception: main                                                                                                  process: com.google.android.gms.samples.vision.barcodereader, pid: 15916                                                                                                  java.lang.runtimeexception: takepicture failed                                                                                                      @ android.hardware.camera.native_takepicture(native method)                                                                                                      @ android.hardware.camera.takepicture(camera.java:1523)                                                                                                      @ com.google.android.gms.samples.vision.ocrreader.ui.camera.camerasource.takepicture(camerasource.java:517)                                                                                                      @ com.google.android.gms.samples.vision.ocrreader.ocrcaptureactivity$6.handlemessage(ocrcaptureactivity.java:464)                                                                                                      @ android.os.handler.dispatchmessage(handler.java:102)                                                                                                      @ android.os.looper.loop(looper.java:158)                                                                                                      @ android.app.activitythread.main(activitythread.java:7224)                                                                                                      @ java.lang.reflect.method.invoke(native method)                                                                                                      @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:1230)                                                                                                      @ com.android.internal.os.zygoteinit.main(zygoteinit.java:1120) 

below code using ocrcaptureactivity

@override public void oncreate(bundle icicle) {     super.oncreate(icicle);     setcontentview(r.layout.ocr_capture);      mpreview = (camerasourcepreview) findviewbyid(r.id.preview);     mgraphicoverlay = (graphicoverlay<ocrgraphic>) findviewbyid(r.id.graphicoverlay);      // read parameters intent used launch activity.     boolean autofocus = getintent().getbooleanextra(autofocus, false);     boolean useflash = getintent().getbooleanextra(useflash, false);     mhandler = new handler() {         @override         public void handlemessage(message msg) {             switch (msg.what) {                 case 1:                     mcamerasource.takepicture(null, new camerasource.picturecallback() {                         @override                         public void onpicturetaken(byte[] bytes) {                             bitmap bmp = bitmapfactory.decodebytearray(bytes, 0, bytes.length);                             log.d("bitmap", bmp.getwidth() + "x" + bmp.getheight());                         }                     });                     break;             }         }     };      // check camera permission before accessing camera.  if     // permission not granted yet, request permission.     int rc = activitycompat.checkselfpermission(this, manifest.permission.camera);     if (rc == packagemanager.permission_granted) {         createcamerasource(autofocus, useflash);     } else {         requestcamerapermission();     }      int rcexternalstorage = activitycompat.checkselfpermission(this, manifest.permission.write_external_storage);     if(rcexternalstorage != packagemanager.permission_granted){         requestwritestoragepermission();     }      gesturedetector = new gesturedetector(this, new capturegesturelistener());     scalegesturedetector = new scalegesturedetector(this, new scalelistener());      snackbar.make(mgraphicoverlay, "tap capture. pinch/stretch zoom",             snackbar.length_long)             .show();     ....      }      @suppresslint("inlinedapi") private void createcamerasource(boolean autofocus, boolean useflash) {     context context = getapplicationcontext();      // text recognizer created find text.  associated processor instance     // set receive text recognition results , display graphics each text block     // on screen.     textrecognizer textrecognizer = new textrecognizer.builder(context).build();     textrecognizer.setprocessor(new ocrdetectorprocessor(mgraphicoverlay, this, mhandler));      if (!textrecognizer.isoperational()) {         // note: first time app using vision api installed on         // device, gms download native libraries device in order detection.         // completes before app run first time.  if         // download has not yet completed, above call not detect text,         // barcodes, or faces.         //         // isoperational() can used check if required native libraries         // available.  detectors automatically become operational once library         // downloads complete on device.         log.w(tag, "detector dependencies not yet available.");          // check low storage.  if there low storage, native library not         // downloaded, detection not become operational.         intentfilter lowstoragefilter = new intentfilter(intent.action_device_storage_low);         boolean haslowstorage = registerreceiver(null, lowstoragefilter) != null;          if (haslowstorage) {             toast.maketext(this, r.string.low_storage_error, toast.length_long).show();             log.w(tag, getstring(r.string.low_storage_error));         }     }      // creates , starts camera.  note uses higher resolution in comparison     // other detection examples enable text recognizer detect small pieces of text.     mcamerasource =             new camerasource.builder(getapplicationcontext(), textrecognizer)                     .setfacing(camerasource.camera_facing_back)                     .setrequestedpreviewsize(1280, 1024)                     .setrequestedfps(2.0f)                     .setflashmode(useflash ? camera.parameters.flash_mode_torch : null)                     .setfocusmode(autofocus ? camera.parameters.focus_mode_continuous_picture : null)                     .build(); } 

in ocrdetectorprocessor

@override public void receivedetections(detector.detections<textblock> detections) {     mgraphicoverlay.clear();     sparsearray<textblock> items = detections.getdetecteditems();     (int = 0; < items.size(); ++i) {         textblock item = items.valueat(i);         ocrgraphic graphic = new ocrgraphic(mgraphicoverlay, item);         mgraphicoverlay.add(graphic);         mhandler.sendemptymessage(1);     }  } 

note: there no problem when take picture button click can me ?