android mapsforge overlay doesn't show in view - dictionary

I need a little help. I wrote an android app using "org.mapsforge.android.maps".
There I create a custom overlay wich I wanna show in the map. The map is shown but without my Overlay. I see that "mapView.getOverlays().add(myOverlay)" adds myOverlay to mapView but on the screen nothing happens.
Does someone has an idea why not?
Thanks a lot
Tom
#Override
public void onCreate(Bundle savedInstanceState) {
try
{
res= this.getResources();
context=this;
requestWindowFeature(Window.FEATURE_CUSTOM_TITLE);
super.onCreate(savedInstanceState);
setContentView(R.layout.openstreet);
getWindow().setFeatureInt(Window.FEATURE_CUSTOM_TITLE, R.layout.main_title_back);
// get the pointers to different system services
this.locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
this.myLocationListener = new MyLocationListener(this);
if(getIntent().hasExtra("comingfrom") == true)
comingfrom = getIntent().getExtras().getString("comingfrom");
if(getIntent().hasExtra("latitude") == true)
mlatitude = getIntent().getExtras().getDouble("latitude");
if(getIntent().hasExtra("longitude") == true)
mlongitude = getIntent().getExtras().getDouble("longitude");
initMapView();
Log.i(Properties.getProgramname(), "OpenStreetActivity->onCreate: Übergebene Koordinate Lat=" + mlatitude + " Lon=" + mlongitude);
if (comingfrom.equals("ButtonArea"))
{
LoadData();
}
else
{
}
if (this.locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
initMyLocation(true);
} else {
Toast.makeText(this,"GPS Provider not enabled",Toast.LENGTH_LONG).show();
}
// create a GeoPoint with the latitude and longitude coordinates
GeoPoint geoPoint = new GeoPoint(mlatitude, mlongitude);
mapController.setCenter(geoPoint);
mapController.setZoom(16);
}
catch (Exception ex)
{
Log.e(Properties.getProgramname(), "Fehler in OpenStreetActivity->onCreate: " + ex.getLocalizedMessage());
Toast.makeText(this,"UI problem " + ex.getMessage(),Toast.LENGTH_LONG).show();
}
}
/**
* Initialize the OSM
*
*/
private void initMapView()
{
settingsLayer = new TJHookerSettingsLayer(this);
Cursor cur = settingsLayer.ladeSettings();
String filename =cur.getString(cur.getColumnIndex(TJHookerSettingsTables.MAPFILE));
cur.close();
mapView = (MapView) this.findViewById(R.id.openmapview);
this.mapView.setClickable(true);
this.mapView.setBuiltInZoomControls(true);
this.mapView.setFocusable(true);
if (!this.mapView.getMapGenerator().requiresInternetConnection() ) {
File file = new File(filename);
if (file.exists())
mapView.setMapFile(new File(filename));
else
Toast.makeText(this,"Problem: Mapfile not found. Please correct the path of your mapfile",Toast.LENGTH_LONG).show();
}
mapController = this.mapView.getController();
}
/**
* Show the current location of my position
*
*/
private void initMyLocation(boolean centerAtFirstFix)
{
try
{
Criteria criteria = new Criteria();
criteria.setAccuracy(Criteria.ACCURACY_FINE);
String bestProvider = this.locationManager.getBestProvider(criteria, true);
this.itemizedMyLocationOverlay = new ArrayItemizedOverlay(null);
this.overlayMyLocationItem = new OverlayItem();
this.overlayMyLocationItem.setMarker(ItemizedOverlay.boundCenter(getResources().getDrawable(R.drawable.my_location)));
this.itemizedMyLocationOverlay.addItem(this.overlayMyLocationItem);
this.mapView.getOverlays().add(this.itemizedMyLocationOverlay);
this.myLocationListener.setCenterAtFirstFix(centerAtFirstFix);
this.locationManager.requestLocationUpdates(bestProvider, 1000, 0, this.myLocationListener);
}
catch(Exception ex)
{
Log.e(Properties.getProgramname(), "Fehler in OpenStreetActivity->initMyLocation: " + ex.getLocalizedMessage());
Toast.makeText(OpenStreetActivity.this, "!initMyLocation: " + ex.getMessage(), Toast.LENGTH_LONG).show();
}
}
// neuen Thread starten
private void LoadData()
{
if(mlongitude > 0 && mlatitude > 0)
{
SystemInformation sys = new SystemInformation();
if(sys.isNetworkAvailable(this))
{
// Neuen Thread startenn der die Kontakte laden soll. Activity wir schon angezeigt
prog = ProgressDialog.show(this, res.getString(R.string.gc40_progtitle), "", true, false);
prog.setMessage(Html.fromHtml("<font color='white'>" + res.getString(R.string.gc40_progtext) + "</font>"));
pdIsShow=true;
Thread thread = new Thread(this);
thread.start();
}
}
}
#Override
public void run() {
GCApiRequests _apiRequests= new GCApiRequests();
try {
lc = _apiRequests.GetCacheByArea(Properties.getGCAccessToken(), mlongitude, mlatitude,"5000", GeocachingConstants.maxCachesPerPage);
handler.sendEmptyMessage(0);
} catch (Exception e) {
Log.e(Properties.getProgramname(), "KartenAnzeigenActivity->Fehler in run: " + e.getLocalizedMessage());
handler.sendEmptyMessage(1);
}
}
// Wenn Thread alle Kontakte geladen hat, dann in ListView anzeigen
private Handler handler = new Handler() {
#Override
public void handleMessage(Message msg) {
if (pdIsShow)
prog.dismiss();
setOverlayCaches();
}
};
private void setOverlayCaches()
{
try {
CacheType typ = new CacheType();
lc.trimToSize();
Log.i(Properties.getProgramname(), "OpenStreetActivity->setOverlayCache: Anzahlgefundener Caches=" +lc.size());
/** So, jetzt gehen wir erstmal durch alle Logs von geocaching.com durch */
// create an ItemizedOverlay with the default marker
CacheOpenStreetMapItemizedOverlay myOverlay= new CacheOpenStreetMapItemizedOverlay(getResources().getDrawable(typ.getCacheType(2)), context);
for(Geocache cache: lc)
{
// create a GeoPoint with the latitude and longitude coordinates
int lat = (int) (Double.parseDouble(cache.GetLatitude()) * 1e6);
int lon = (int) (Double.parseDouble(cache.GetLongitude()) * 1e6);
GeoPoint geoPoint = new GeoPoint(lat,lon);
// create an OverlayItem with title and description
OverlayItem item = new OverlayItem(geoPoint, cache.GetCacheName(), cache.GetGCCode(),
getResources().getDrawable(typ.getCacheType(Integer.parseInt(cache.GetCacheType()))));
myOverlay.addOverlay(item);
}
myOverlay.requestRedraw();
// add the ArrayItemizedOverlay to the MapView
//if (traditionellOverlay != null)
Log.i(Properties.getProgramname(), "OpenStreetActivity->setOverlayCache: Anzahl Overlay items=" + myOverlay.size());
Log.i(Properties.getProgramname(), "OpenStreetActivity->setOverlayCache: Anzahl MapView Overlays=" + mapView.getOverlays().size());
mapView.getOverlays().add(myOverlay);
Log.i(Properties.getProgramname(), "OpenStreetActivity->setOverlayCache: Anzahl MapView Overlays=" + mapView.getOverlays().size());
} catch (Exception e) {
Log.e(Properties.getProgramname(), "KartenAnzeigenActivity->Fehler in setOverlayCaches: " + e.getLocalizedMessage());
}
}
/** Back-Button in Titlebar wurde gedrückt */
public void PressTitleBackButton_Click(View view)
{
/** Durch ein finish() wird der Back-Button Effekt ausgelöst. */
finish();
}

Solved!
You have to rewrite the code to:
int cachetyp = typ.getCacheType(Integer.parseInt(cache.GetCacheType()));
Drawable itemMarker = getResources().getDrawable(cachetyp);
// Without that the icons aren't displayed. So you NEED it
itemMarker.setBounds(0, 0, itemMarker.getIntrinsicWidth(), itemMarker.getIntrinsicHeight());
The item need the bounds.....

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How to save current location?

I have a question. I am working on mobile app where my user can store experience from trip by loggin current location.
I am connected to SQLite fo now and I am just exploring the Geolocator nuget from James Monemagno. SO far I can get the pin on map with current location, but I am unsure how to store the location in databse. I guess it wont be"position" and it must be Latitude and Longitude but then how will i get again the picture with the pin displayed under my post? Do you guys have some experience?
Public clas NoteViewMode : BaseViewModel
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/////
private string _location;
public string Location
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get { return _location; }
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you can programmatically add a Pin to a Map
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Long tap and drop pin in xamarin forms maps

I used Xamarin.Forms.Maps nuget package and displayed map on the device. I am able to show the pin on external button tap with the help of following code, but unable to achieve same on map tap to drop a pin on a specific location.
public void addPin(double latitude, double longitude, string labelName)
{
Position position = new Position(latitude, longitude);
_assignedPin = new Pin
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Type = PinType.Place,
Position = position,
Label = labelName,
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};
map.Pins.Add(_assignedPin);
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I followed this blog to get lat long on map, but map does not display the pin on the map.
We need to add the code in renderer itself to drop pin using xamarin.forms.maps
In Android: Renderer class:
private void googleMap_MapClick(object sender, GoogleMap.MapClickEventArgs e)
{
Map.Pins.Add(new Pin
{
Label = "Pin from tap",
Position = new Position(e.Point.Latitude, e.Point.Longitude))
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And in iOS Renderer class:
[assembly: ExportRenderer(typeof(ExtMap), typeof(ExtMapRenderer))]
namespace Xamarin.iOS.CustomRenderers
{
/// <summary>
/// Renderer for the xamarin ios map control
/// </summary>
public class ExtMapRenderer : MapRenderer
{
private readonly UITapGestureRecognizer _tapRecogniser;
public ExtMapRenderer()
{
_tapRecogniser = new UITapGestureRecognizer(OnTap)
{
NumberOfTapsRequired = 1,
NumberOfTouchesRequired = 1
};
}
protected override IMKAnnotation CreateAnnotation(Pin pin)
{
return base.CreateAnnotation(pin);
}
class BasicMapAnnotation : MKAnnotation
{
CLLocationCoordinate2D coord;
string title, subtitle;
public override CLLocationCoordinate2D Coordinate { get { return coord; } }
public override void SetCoordinate(CLLocationCoordinate2D value)
{
coord = value;
}
public override string Title { get { return title; } }
public override string Subtitle { get { return subtitle; } }
public BasicMapAnnotation(CLLocationCoordinate2D coordinate, string title, string subtitle)
{
this.coord = coordinate;
this.title = title;
this.subtitle = subtitle;
}
}
protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
{
base.OnElementPropertyChanged(sender, e);
}
private async void OnTap(UITapGestureRecognizer recognizer)
{
var cgPoint = recognizer.LocationInView(Control);
var nativeMap = Control as MKMapView;
var location = ((MKMapView)Control).ConvertPoint(cgPoint, Control);
((ExtMap)Element).OnTap(new Position(location.Latitude, location.Longitude));
try
{
var lat = location.Latitude;
var lon = location.Longitude;
var placemarks = await Geocoding.GetPlacemarksAsync(lat, lon);
var placemark = placemarks?.FirstOrDefault();
if (placemark != null)
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var geocodeAddress =
$"AdminArea: {placemark.AdminArea}\n" +
$"CountryCode: {placemark.CountryCode}\n" +
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nativeMap.AddAnnotation(annotation);
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catch (FeatureNotSupportedException fnsEx)
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// Feature not supported on device
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catch (Exception ex)
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// Handle exception that may have occurred in geocoding
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if (Control != null)
Control.RemoveGestureRecognizer(_tapRecogniser);
base.OnElementChanged(e);
if (Control != null)
Control.AddGestureRecognizer(_tapRecogniser);
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How do you print TextArea to a USB Thermal Printer 58mm?(JAVAFX)

So I'm trying to make a billing system in which I want to print a receipt.I was able to do it with some code that I found online,but the font size is too big to print in the 58mm wide paper.I'm not able to adjust the font size.Any kind of help with this issue will be highly appreciated.Thank You.
Here is The Code :
public class PrinterService implements Printable {
public List<String> getPrinters(){
DocFlavor flavor = DocFlavor.BYTE_ARRAY.AUTOSENSE;
PrintRequestAttributeSet pras = new HashPrintRequestAttributeSet();
PrintService printServices[] = PrintServiceLookup.lookupPrintServices(
flavor, pras);
List<String> printerList = new ArrayList<String>();
for(PrintService printerService: printServices){
printerList.add( printerService.getName());
}
return printerList;
}
#Override
public int print(Graphics g, PageFormat pf, int page)
throws PrinterException {
if (page > 0) { /* We have only one page, and 'page' is zero-based */
return NO_SUCH_PAGE;
}
/*
* User (0,0) is typically outside the imageable area, so we must
* translate by the X and Y values in the PageFormat to avoid clipping
*/
Graphics2D g2d = (Graphics2D) g;
g2d.translate(pf.getImageableX(), pf.getImageableY());
/* Now we perform our rendering */
g.setFont(new Font("Roman", 0, 8));
g.drawString("Hello world !", 0, 10);
return PAGE_EXISTS;
}
public void printString(String printerName, String text) {
// find the printService of name printerName
DocFlavor flavor = DocFlavor.BYTE_ARRAY.AUTOSENSE;
PrintRequestAttributeSet pras = new HashPrintRequestAttributeSet();
PrintService printService[] = PrintServiceLookup.lookupPrintServices(
flavor, pras);
PrintService service = findPrintService(printerName, printService);
DocPrintJob job = service.createPrintJob();
try {
byte[] bytes;
// important for umlaut chars
bytes = text.getBytes("CP437");
Doc doc = new SimpleDoc(bytes, flavor, null);
job.print(doc, null);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void printBytes(String printerName, byte[] bytes) {
DocFlavor flavor = DocFlavor.BYTE_ARRAY.AUTOSENSE;
PrintRequestAttributeSet pras = new HashPrintRequestAttributeSet();
PrintService printService[] = PrintServiceLookup.lookupPrintServices(
flavor, pras);
PrintService service = findPrintService(printerName, printService);
DocPrintJob job = service.createPrintJob();
try {
Doc doc = new SimpleDoc(bytes, flavor, null);
job.print(doc, null);
} catch (Exception e) {
e.printStackTrace();
}
}
private PrintService findPrintService(String printerName,
PrintService[] services) {
for (PrintService service : services) {
if (service.getName().equalsIgnoreCase(printerName)) {
return service;
}
}
return null;
}
}
#FXML
public void printit(ActionEvent actionEvent)
{
PrinterService printerService = new PrinterService();
System.out.println(printerService.getPrinters());
//print some stuff
printerService.printString("POS-58-Series", area.getText());
}

Fail to connect to camera service at sometimes

Am calling my camera function as separate fragment during first 2 times of calling the class camera is opening but if am calling the class third time app is crashing.
private int findFrontFacingCamera() {
int cameraId = 0;
// Search for the front facing camera
int numberOfCameras = Camera.getNumberOfCameras();
for (int i = 0; i < numberOfCameras; i++) {
CameraInfo info = new CameraInfo();
Camera.getCameraInfo(i, info);
if (info.facing == CameraInfo.CAMERA_FACING_FRONT) {
cameraId = i;
cameraFront = true;
break;
}
}
return cameraId;
}
private int findBackFacingCamera() {
int cameraId = -1;
//Search for the back facing camera
//get the number of cameras
int numberOfCameras = Camera.getNumberOfCameras();
//for every camera check
for (int i = 0; i < numberOfCameras; i++) {
CameraInfo info = new CameraInfo();
Camera.getCameraInfo(i, info);
if (info.facing == CameraInfo.CAMERA_FACING_BACK) {
cameraId = i;
cameraFront = false;
break;
}
}
return cameraId;
}
public void onResume() {
super.onResume();
if (!hasCamera(myContext)) {
Toast toast = Toast.makeText(myContext, "Sorry, your phone does not have a camera!", Toast.LENGTH_LONG);
toast.show();
finish();
}
if (mCamera == null) {
//if the front facing camera does not exist
if (findFrontFacingCamera() < 0) {
Toast.makeText(getActivity().getApplicationContext(), "No front facing camera found.", Toast.LENGTH_LONG).show();
switchCamera.setVisibility(View.GONE);
}
mCamera = Camera.open(findFrontFacingCamera());
mPicture = getPictureCallback();
mPreview.refreshCamera(mCamera);
}
}
logcat
01-19 10:56:15.164 11477-11477/com.example.siva.prep E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.siva.prep, PID: 11477
java.lang.RuntimeException: Fail to connect to camera service
at android.hardware.Camera.native_setup(Native Method)
at android.hardware.Camera.<init>(Camera.java:393)
at android.hardware.Camera.open(Camera.java:347)
at com.example.siva.prep.Selfie.onResume(Selfie.java:146)
It's showing error on the following line in "onResume()" method:
mCamera = Camera.open(findFrontFacingCamera());
Here is the full my code am using:
public class Selfie extends Fragment implements OnClickListener {
private Camera mCamera;
private CameraPreview mPreview;
private PictureCallback mPicture;
private Button capture, switchCamera;
private Context myContext;
private LinearLayout cameraPreview;
private boolean cameraFront = false;
Bitmap bmp;
ImageView iv;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_selfie, container, false);
// getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
iv=(ImageView) view.findViewById(R.id.image);
myContext = getActivity().getApplicationContext();
getActivity().setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
cameraPreview = (LinearLayout) view.findViewById(R.id.camera_preview);
mPreview = new CameraPreview(myContext, mCamera);
cameraPreview.addView(mPreview);
ImageView capture = (ImageView) view.findViewById(R.id.button_capture);
capture.setOnClickListener(captrureListener);
ImageView switchCamera = (ImageView) view.findViewById(R.id.button_ChangeCamera);
switchCamera.setOnClickListener(switchCameraListener);
ImageView button1 = (ImageView) view.findViewById(R.id.back);
button1.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
FreeFragment fragment2 = new FreeFragment();
FragmentManager fragmentManager = getFragmentManager();
android.support.v4.app.FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.container, fragment2);
fragmentTransaction.commit();
}
});
getSupportActionBar().hide();
return view;
}
private ActionBar getSupportActionBar() {
return ((AppCompatActivity) getActivity()).getSupportActionBar();
}
#Override
public void onClick(View v) {
}
private int findFrontFacingCamera() {
int cameraId = 0;
// Search for the front facing camera
int numberOfCameras = Camera.getNumberOfCameras();
for (int i = 0; i < numberOfCameras; i++) {
CameraInfo info = new CameraInfo();
Camera.getCameraInfo(i, info);
if (info.facing == CameraInfo.CAMERA_FACING_FRONT) {
cameraId = i;
cameraFront = true;
break;
}
}
return cameraId;
}
private int findBackFacingCamera() {
int cameraId = -1;
//Search for the back facing camera
//get the number of cameras
int numberOfCameras = Camera.getNumberOfCameras();
//for every camera check
for (int i = 0; i < numberOfCameras; i++) {
CameraInfo info = new CameraInfo();
Camera.getCameraInfo(i, info);
if (info.facing == CameraInfo.CAMERA_FACING_BACK) {
cameraId = i;
cameraFront = false;
break;
}
}
return cameraId;
}
public void onResume() {
super.onResume();
if (!hasCamera(myContext)) {
Toast toast = Toast.makeText(myContext, "Sorry, your phone does not have a camera!", Toast.LENGTH_LONG);
toast.show();
finish();
}
if (mCamera == null) {
//if the front facing camera does not exist
if (findFrontFacingCamera() < 0) {
Toast.makeText(getActivity().getApplicationContext(), "No front facing camera found.", Toast.LENGTH_LONG).show();
switchCamera.setVisibility(View.GONE);
}
mCamera = Camera.open(findFrontFacingCamera());
mPicture = getPictureCallback();
mPreview.refreshCamera(mCamera);
}
}
private void finish() {
}
OnClickListener switchCameraListener = new OnClickListener() {
#Override
public void onClick(View v) {
//get the number of cameras
int camerasNumber = Camera.getNumberOfCameras();
if (camerasNumber >= 1) {
//release the old camera instance
//switch camera, from the front and the back and vice versa
releaseCamera();
chooseCamera();
} else {
Toast toast = Toast.makeText(myContext, "Sorry, your phone has only one camera!", Toast.LENGTH_LONG);
toast.show();
}
}
};
public void chooseCamera() {
// if the camera preview is the front
if (cameraFront) {
int cameraId = findBackFacingCamera();
if (cameraId <= 0) {
//open the backFacingCamera
//set a picture callback
//refresh the preview
mCamera = Camera.open(cameraId);
mPicture = getPictureCallback();
mPreview.refreshCamera(mCamera);
}
} else
{
int cameraId = findFrontFacingCamera();
if (cameraId >= 0) {
//open the backFacingCamera
//set a picture callback
//refresh the preview
mCamera = Camera.open(cameraId);
mPicture = getPictureCallback();
mPreview.refreshCamera(mCamera);
}
}
}
#Override
public void onPause() {
super.onPause();
//when on Pause, release camera in order to be used from other applications
releaseCamera();
}
private boolean hasCamera(Context context) {
//check if the device has camera
if (context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)) {
return true;
} else {
return false;
}
}
private PictureCallback getPictureCallback() {
PictureCallback picture = new PictureCallback() {
#Override
public void onPictureTaken(byte[] data, Camera camera) {
//make a new picture file
File pictureFile = getOutputMediaFile();
if (pictureFile == null) {
return;
}
try {
//write the file
FileOutputStream fos = new FileOutputStream(pictureFile);
fos.write(data);
fos.close();
Toast toast = Toast.makeText(myContext, "Picture saved: " + pictureFile.getName(), Toast.LENGTH_LONG);
iv.setImageURI(Uri.fromFile(pictureFile));
//Intent intent = new Intent(AndroidCameraExample.this,Fina.class);
String stringUri;
stringUri = pictureFile.toString();
//intent.putExtra("imagePath", stringUri);
//startActivity(intent);
FreeFragment ldf = new FreeFragment ();
Bundle args = new Bundle();
args.putString("Image", stringUri);
ldf.setArguments(args);
Log.d("Passing image", String.valueOf(args));
getFragmentManager().beginTransaction().add(R.id.container, ldf).commit();
toast.show();
} catch (FileNotFoundException e) {
} catch (IOException e) {
}
//refresh camera to continue preview
mPreview.refreshCamera(mCamera);
}
};
return picture;
}
//make picture and save to a folder
public static File getOutputMediaFile() {
//make a new file directory inside the "sdcard" folder
File mediaStorageDir = new File("/sdcard/", "JCG Camera");
//if this "JCGCamera folder does not exist
if (!mediaStorageDir.exists()) {
//if you cannot make this folder return
if (!mediaStorageDir.mkdirs()) {
return null;
}
}
//take the current timeStamp
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
File mediaFile;
//and make a media file:
mediaFile = new File(mediaStorageDir.getPath() + File.separator + "IMG_" + timeStamp + ".jpg");
return mediaFile;
}
OnClickListener captrureListener = new OnClickListener() {
#Override
public void onClick(View v) {
mCamera.takePicture(null, null, mPicture);
}
};
private void releaseCamera() {
// stop and release camera
if (mCamera != null) {
mCamera.release();
mCamera = null;
}
}
}
Irrespective of the reason, not obtaining Camera handle is a case that needs to be handled with proper error handling. In the current case in your Pause handler, is the Camera instance being released ? Check for proper usage at http://developer.android.com/training/basics/activity-lifecycle/pausing.html

Huge amount of packet drops and latency faced in netty

I am using netty 3.5.11 with Jdk 1.7 on Ubuntu to receive a large amount of updates of stocks rates at a very high frequency. The message format being sent is JSON. The data is subscribed from topic on a redis server. There is a Subscriber for each symbol. The channel object is passed to multiple Subscribers and on receiving the data it is written to the client.
Now the amount of data received is around 25,000 records in 2 minutes. Each record size is on an average around 500 bytes long.
During test runs around 7500/8000 records were dropped because the channel was not writable.
How do i avoid this. ?
I also noticed that the latency increases systematically leading to updates being received after a long period. This happened when i I used Bufferedwritehandler to avoid packet drops.
Here are the options that i set on bootstrap.
executionHandler = new ExecutionHandler(
new OrderedMemoryAwareThreadPoolExecutor(Runtime.getRuntime().availableProcessors() * 2, 1000000, 10000000, 100,
TimeUnit.MILLISECONDS));
serverBootStrap.setPipelineFactory(new ChannelPipelineFactory()
{
#Override
public ChannelPipeline getPipeline() throws Exception
{
return Channels.pipeline(new PortUnificationServerHandler(getConfiguration(), executionHandler));
}
});
serverBootStrap.setOption("child.tcpNoDelay", true);
serverBootStrap.setOption("tcpNoDelay", true);
serverBootStrap.setOption("child.keepAlive", true);
serverBootStrap.setOption("child.reuseAddress", true);
//setting buffer size can improve I/O
serverBootStrap.setOption("child.sendBufferSize", 16777216);
serverBootStrap.setOption("receiveBufferSize", 16777216);//1048576);
// better to have an receive buffer predictor
serverBootStrap.setOption("receiveBufferSizePredictorFactory", new AdaptiveReceiveBufferSizePredictorFactory(1024, 1024 * 16, 16777216));//1048576));
//if the server is sending 1000 messages per sec, optimum write buffer water marks will
//prevent unnecessary throttling, Check NioSocketChannelConfig doc
serverBootStrap.setOption("backlog", 1000);
serverBootStrap.setOption("sendBufferSize", 16777216);//1048576);
serverBootStrap.setOption("writeBufferLowWaterMark", 1024 * 1024 * 25);
serverBootStrap.setOption("writeBufferHighWaterMark", 1024 * 1024 * 50);
The pipeline and handlers class
public class PortUnificationServerHandler extends FrameDecoder
{
private AppConfiguration appConfiguration;
private final ExecutionHandler executionHandler;
public PortUnificationServerHandler(AppConfiguration pAppConfiguration, ExecutionHandler pExecutionHandler)
{
appConfiguration = pAppConfiguration;
this.executionHandler = pExecutionHandler;
}
#Override
protected Object decode(ChannelHandlerContext ctx, Channel channel, ChannelBuffer buffer) throws Exception
{
String lRequest = buffer.toString(CharsetUtil.UTF_8);
if (ConnectionServiceHelper.isValidJSON(lRequest))
{
ObjectMapper lObjectMapper = new ObjectMapper();
StringReader lStringReader = new StringReader(lRequest);
JsonNode lNode = lObjectMapper.readTree(lStringReader);
if (lNode.get(Constants.REQUEST_TYPE).asText().trim().equalsIgnoreCase(Constants.LOGIN_REQUEST))
{
JsonNode lDataNode1 = lNode.get(Constants.REQUEST_DATA);
LoginRequest lLogin = lObjectMapper.treeToValue(lDataNode1, LoginRequest.class);
if (lLogin.getCompress() != null)
{
if (lLogin.getCompress().trim().equalsIgnoreCase(Constants.COMPRESS_FLAG_TRUE))
{
enableJSON(ctx);
enableGzip(ctx);
ctx.getPipeline().remove(this);
}
else
{
enableJSON(ctx);
ctx.getPipeline().remove(this);
}
}
else
{
enableJSON(ctx);
ctx.getPipeline().remove(this);
}
}
}
// Forward the current read buffer as is to the new handlers.
return buffer.readBytes(buffer.readableBytes());
}
private void enableJSON(ChannelHandlerContext ctx)
{
ChannelPipeline pipeline = ctx.getPipeline();
boolean lHandlerExists = pipeline.getContext("bufferedwriter") != null;
if (!lHandlerExists)
{
pipeline.addFirst("bufferedwriter", new MyBufferedWriteHandler()); // 80960
}
boolean lHandlerExists = pipeline.getContext("framer") != null;
if (!lHandlerExists)
{
pipeline.addLast("framer", new DelimiterBasedFrameDecoder(65535,
new ChannelBuffer[]
{
ChannelBuffers.wrappedBuffer(
new byte[]
{
'\n'
})
}));
}
lHandlerExists = pipeline.getContext("decoder") != null;
if (!lHandlerExists)
{
pipeline.addLast("decoder", new StringDecoder(CharsetUtil.UTF_8));
}
lHandlerExists = pipeline.getContext("encoder") != null;
if (!lHandlerExists)
{
pipeline.addLast("encoder", new StringEncoder(CharsetUtil.UTF_8));
}
lHandlerExists = pipeline.getContext("executor") != null;
if (!lHandlerExists)
{
pipeline.addLast("executor", executionHandler);
}
lHandlerExists = pipeline.getContext("handler") != null;
if (!lHandlerExists)
{
pipeline.addLast("handler", new ConnectionServiceUpStreamHandler(appConfiguration));
}
lHandlerExists = pipeline.getContext("unite") != null;
if (!lHandlerExists)
{
pipeline.addLast("unite", new PortUnificationServerHandler(appConfiguration, executionHandler));
}
}
private void enableGzip(ChannelHandlerContext ctx)
{
ChannelPipeline pipeline = ctx.getPipeline();
//pipeline.remove("decoder");
//pipeline.addLast("decoder", new MyStringDecoder(CharsetUtil.UTF_8, true));
//pipeline.addLast("compress", new CompressionHandler(80, "gzipdeflater"));
boolean lHandlerExists = pipeline.getContext("encoder") != null;
if (lHandlerExists)
{
pipeline.remove("encoder");
}
lHandlerExists = pipeline.getContext("gzipdeflater") != null;
if (!lHandlerExists)
{
pipeline.addBefore("executor", "gzipdeflater", new ZlibEncoder(ZlibWrapper.GZIP));
}
lHandlerExists = pipeline.getContext("lengthprepender") != null;
if (!lHandlerExists)
{
pipeline.addAfter("gzipdeflater", "lengthprepender", new LengthFieldPrepender(4));
}
}
}
The BufferedWriterHandler
public class MyBufferedWriteHandler extends BufferedWriteHandler
{
private final AtomicLong bufferSize = new AtomicLong();
final Logger logger = LoggerFactory.getLogger(getClass());
public MyBufferedWriteHandler() {
// Enable consolidation by default.
super(true);
}
#Override
public void writeRequested(ChannelHandlerContext ctx, MessageEvent e) throws Exception
{
ChannelBuffer data = (ChannelBuffer) e.getMessage();
if (e.getChannel().isWritable())
{
long newBufferSize = bufferSize.get();
// Flush the queue if it gets larger than 8KiB.
if (newBufferSize > 0)
{
flush();
bufferSize.set(0);
}
ctx.sendDownstream(e);
}
else
{
logger.warn( "Buffering data for : " + e.getChannel().getRemoteAddress() );
super.writeRequested(ctx, e);
bufferSize.addAndGet(data.readableBytes());
}
}
#Override
public void channelInterestChanged(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception
{
if (e.getChannel().isWritable())
{
flush();
}
}
The function used in the Subscriber class to write data
public void writeToClient(Channel pClientChannel, String pMessage) throws IOException
{
String lMessage = pMessage;
if (pClientChannel.isWritable())
{
lMessage += Constants.RESPONSE_DELIMITER;
pClientChannel.write(lMessage);
}
else
{
logger.warn(DroppedCounter++ + " droppped : " + pMessage);
}
}
I have implemented some of the suggestions that i read on stackoverflow and other sites. But i have not been successfull in resolving this issue.
Kindly suggest or advice as to what am i missing ?
Thanks

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