Develop Reference

EventChannel not being called every time

I am very new to flutter+dart framework. I am trying to understand how EventChannel works. I have set up EventChannel to capture the number of an incoming call.
On the android side, I have set up an BroadcastReceiver as follows.
public class CallEventHandler extends BroadcastReceiver implements EventChannel.StreamHandler {
private static final String TAG = "[SAMPLE]";
private static final int NUMBER_LEN = 10;
private EventChannel.EventSink eventSink = null;
private Activity activity = null;
public CallEventHandler(Activity activity) {
this.activity = activity;
}
#Override
public void onListen(Object arguments, EventChannel.EventSink events) {
Log.i(TAG, "[onListen] setting up events");
eventSink = events;
}
#Override
public void onCancel(Object arguments) {
Log.i(TAG, "[onCancel] cancel events");
eventSink = null;
activity = null;
}
#Override
public void onReceive(Context context, Intent intent) {
try {
String state = intent.getStringExtra(TelephonyManager.EXTRA_STATE);
String incomingNumber = intent.getStringExtra(TelephonyManager.EXTRA_INCOMING_NUMBER);
if(state.equals(TelephonyManager.EXTRA_STATE_RINGING)) {
if(incomingNumber != null) {
Log.i(TAG, "[CallEventHandler] Incoming number : " + incomingNumber);
if(incomingNumber.length() > NUMBER_LEN) {
incomingNumber = incomingNumber.substring(incomingNumber.length() - NUMBER_LEN, incomingNumber.length());
Log.i(TAG, "[CallEventHandler] Incoming number after : " + incomingNumber);
if(activity != null) {
String finalIncomingNumber = incomingNumber;
activity.runOnUiThread(new Runnable() {
#Override
public void run() {
if(eventSink != null) {
Log.i(TAG, "[CallEventHandler] HERESSSSS : " + finalIncomingNumber);
eventSink.success(finalIncomingNumber);
}
}
});
}
}
}
}
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
In the onReceive method, I am getting the incoming number and I am sending it to EventSink.
In my MainActivity I am setting up the CallEventHandler as follows:
private final String eventId = "SAMPLE_ID";
private CallEventHandler handler = new CallEventHandler(this);
#Override
public void onStart() {
super.onStart();
...
registerReceiver(handler, filter);
}
#Override
public void onStop() {
super.onStop();
unregisterReceiver(handler);
}
#Override
public void configureFlutterEngine(#NonNull FlutterEngine flutterEngine) {
super.configureFlutterEngine(flutterEngine);
new EventChannel(flutterEngine.getDartExecutor().getBinaryMessenger(), eventId)
.setStreamHandler(handler);
}
On the Flutter side, the code is as follows:
class EventHandler {
static const String TAG = "[SAMPLE]";
final String _eventId = "SAMPLE_ID";
EventChannel? _evtChannel;
Stream<String>? _evtStream;
EventHandler() {
debugPrint(TAG + " Setting up EventHandler");
_evtChannel = EventChannel(_eventId);
_evtStream = _evtChannel?.receiveBroadcastStream().distinct().map((dynamic
event) => getString(event as String));
}
void startListening(void Function(String data)? onData) {
debugPrint(TAG + " starting listening");
_evtStream?.listen((data) {
debugPrint(TAG + " In listening");
onData!(data);
});
}
}
In my UI code, I have a StatefulWidget (MySamplePage) where I am registering my callback when the call is received
void initState() {
widget.handler.startListening((incomingNumber) {
debugPrint(_tag + " data : $incomingNumber");
...
});
}
In my stateful home page build method, I initialize the handler in initState and added a route in build method
class _HomeScreenState extends State<HomeScreen> {
#override
void initState() {
super.initState();
debugPrint(_tag + "initState");
_handler = EventHandler();
}
#override
Widget build(BuildContext context) {
return MaterialApp(
routes: {
'/caller': (context) => MySamplePage(
handler: _handler
),
},
...
);
}
}
The issue I am facing is that, when the widget is opened I am receiving the first incoming call, as expected. But if I make another call, then that second call is not captured by the stream. If I press the back button, and reopen the Widget everything works as expected, the first incoming call is printed in the console. I know the the Android code is sending the event from the onReceive method (The `HERESSSSS' line is printed every time), but the flutter stream is not getting the values. I am not sure what I am doing wrong here. Can anyone please help?
My log is
I/flutter (11836): [SAMPLE][HomeScreen]initState
I/flutter (11836): [SAMPLE][EventHandler] Setting up EventHandler
V/AutofillManager(11836): requestHideFillUi(null): anchor = null
I/flutter (11836): [SAMPLE][EventHandler] starting listening
I/[SAMPLE] (11836): [onListen] setting up events
I/[SAMPLE] (11836): [CallEventHandler] Receiver start
I/[SAMPLE] (11836): [CallEventHandler] Receiver start
I/[SAMPLE] (11836): [CallEventHandler] Incoming number : +91XXXXXXXXXX
I/[SAMPLE] (11836): [CallEventHandler] Incoming number after : XXXXXXXXXX
I/[SAMPLE] (11836): [CallEventHandler] HERESSSSS : XXXXXXXXXX
I/flutter (11836): [SAMPLE][EventHandler] In listening
I/flutter (11836): [SAMPLE] data : XXXXXXXXXX
In the subsequent incoming calls, the last line is not printed
Thank you

Ok, I have managed to resolve it, but don't know if this is the correct approach. The issue is that MySamplePage is a StatefulWidget, And I am calling setState in its State object. That might be the reason it's unable to listen to the stream anymore. I have called startListening is the setState method and changed the code accordingly (remove the previous subscription and re-listen to the stream)
void startListening(void Function(String data)? onData) {
debugPrint(TAG + " starting listening");
if(_subscription != null) {
_subscription?.cancel();
_subscription = null;
}
_subscription ??= _evtStream?.listen((data) {
debugPrint(TAG + " In listening");
onData!(data);
});
}
Here _subscription is a variable of type StreamSubscription<String>?. Hope this answer is helpful. And I should have posted complete code earlier.

Send string from thread bluetooth service to textView in main activity

I want to send value from string (distance to obstacle) to my TextView in main activity.
I tried to use Handler, but still not working (crash) or receive nothing.
A part code which receive data from HC-05 (screen where you see in debug value assignet to variable)
enter image description here
#Override
public void run() {
byte[] buffer = new byte[1024];
int bytes;
while(true){
try {
bytes = inputStream.read(buffer);
final String comingMsg = new String(buffer,0,bytes);
Log.d(TAG,"InputStream: " + comingMsg);
/*mHandler2.post(new Runnable() {
#Override
public void run() {
Message message = new Message();
message.obj = comingMsg;
mHandler2.sendMessage(message);
}
});*/
}catch (IOException e){
Log.e(TAG,"Write: Error reading input." + e.getMessage());
active=false;
break;
}
}
}
Here It's parts of code from MainActivity where I tried put something to get values from service.
[I add, that for this moment i want to see something values from bluetooth in textView. Later I want to create parse string and send custom text to custom TextView - example: FL: (Front Left)- to one textView, FR: (Front Right) - to second textView]
There is method implementThreads(), because I wanted to do 6 Threads to 6 TextView which every time is refreshing value from string in Services (there I tried get value from Bluetooth Service)
Log.d(TAG,"Check intent - result");
if(getIntent().getIntExtra("result",0)==RESULT_OK){
mDevice = getIntent().getExtras().getParcelable("bonded device");
myBluetoothService = new MyBluetoothService(getApplicationContext());
startConnection(mDevice,MY_UUID);
Log.d(TAG,"Check is active service");
checkIfActive();
}
Log.d(TAG,"Check intent - connect_to_paired");
if(getIntent().getIntExtra("connect_to_paired",0)==RESULT_OK){
mDevice = getIntent().getExtras().getParcelable("bonded_paired_device");
myBluetoothService = new MyBluetoothService(getApplicationContext());
startConnection(mDevice,MY_UUID);
Log.d(TAG,"Check is active service");
checkIfActive();
}
}
#Override
public void onStart(){
super.onStart();
myBluetoothService = new MyBluetoothService(getApplicationContext());
}
public void checkIfActive(){
Log.d(TAG,"CheckIfActive: Started");
if(myBluetoothService.active){
Log.d(TAG,"CheckIfActive: Running method implementThreads()");
implementThreads();
}
}
public void implementThreads(){
Log.d(TAG,"ImplementThreads: Started");
Thread thread = new Thread(){
#Override
public void run() {
try{
sleep(100);
}catch (InterruptedException e){
e.printStackTrace();
}
}
};
thread.start();
}
public void startConnection(BluetoothDevice device,UUID uuid){
Log.d(TAG,"StartConnection: Initializing connection");
myBluetoothService.startClient(device,uuid);
}
Thanks all for help, because It's very important for me !

Use this to interect with UI Thread for operations like updating textviews etc.
new Handler(Looper.getMainLooper()).post(new Runnable() {
#Override
public void run() {
//YOUR CODE HERE
Message message = new Message();
message.obj = comingMsg;
mHandler2.sendMessage(message);
}
});

ConnectSDK doesn't try to find Chromecast

all.
I try to create an android cast application with google chromecast. So I tryied to find chromecast with this code:
public void startDiscoveringDevices() {
DiscoveryManager.init(mContext);
mDiscoveryManager = DiscoveryManager.getInstance();
mDiscoveryManager.registerDeviceService(CastService.class, CastDiscoveryProvider.class);
mDiscoveryManager.setPairingLevel(DiscoveryManager.PairingLevel.ON);
mDiscoveryManager.setCapabilityFilters(new CapabilityFilter(
MediaPlayer.Any,
MediaControl.Any,
VolumeControl.Any
));
mDiscoveryManager.addListener(this);
mDiscoveryManager.start();
Log.wtf("CastDeviceManager", "discovery manager was started");
}
After this I listen DiscoveryManagerListener:
// ********************* My DiscoveryManagerListener ********************************** //
#Override
public void onDeviceAdded(DiscoveryManager manager, ConnectableDevice device) {
Log.wtf("DiscoveryManagerListener", "Device added");
device.addListener(...); // Here I pass implementation of ConnectableDeviceListener interface.
device.connect(); // connect to device
}
#Override
public void onDeviceUpdated(DiscoveryManager manager, ConnectableDevice device) {
Log.wtf("DiscoveryManagerListener", "Device updated");
device.addListener(...); // Here I pass implementation of ConnectableDeviceListener interface.
// try to connect to device, if it not connected yet
if (device.isConnected()) {
device.disconnect();
}
else {
device.connect();
}
}
#Override
public void onDeviceRemoved(DiscoveryManager manager, ConnectableDevice device) {
Log.wtf("DiscoveryManagerListener", "Device removed");
mCastDevices.remove(device.hashCode()); // remove device from list of devices
}
#Override
public void onDiscoveryFailed(DiscoveryManager manager, ServiceCommandError error) {
Log.wtf("DiscoveryManagerListener", "Device(s) not found", error);
destroyDiscoveryManager();
}
// ************************************************************************************ //
// ************************** My ConnectableDeviceListener **************************** //
#Override
public void onDeviceReady(ConnectableDevice device) {
Log.wtf("ConnectableDeviceListener", "device ready");
outDeviceInfo(device, "ConnectableDeviceListener");
// put to map with devices new connected device
mCastDevices.put(device.hashCode(), new CastDevice(device, mCastLifecycleListener));
Log.wtf("ConnectableDeviceListener", "Count cast devices: " + mCastDevices.size());
}
#Override
public void onDeviceDisconnected(ConnectableDevice device) {
Log.wtf("ConnectableDeviceListener", "device disconnected");
destroyDiscoveryManager();
}
#Override
public void onPairingRequired(ConnectableDevice device, DeviceService service, PairingType pairingType) {
Log.wtf("ConnectableDeviceListener", "device paring required");
}
#Override
public void onCapabilityUpdated(ConnectableDevice device, List<String> added, List<String> removed) {
Log.wtf("ConnectableDeviceListener", "capability updated");
}
#Override
public void onConnectionFailed(ConnectableDevice device, ServiceCommandError error) {
Log.wtf("ConnectableDeviceListener", "connection failed");
destroyDiscoveryManager();
}
// ************************************************************************************ //
// this method I use to disconnect from devices in map and stop discovering new devices
public void destroyDiscoveryManager() {
mDiscoveryManager.stop();
DiscoveryManager.destroy();
Log.wtf("CastDeviceManager", "discovery manager was stopped");
for (Map.Entry<Integer, CastDevice> castDeviceEntry: mCastDevices.entrySet()) {
castDeviceEntry.getValue().stopCast();
castDeviceEntry.getValue().disconnect();
Log.wtf("CastDevice", "device.isConnected(): " + castDeviceEntry.getValue().isConnected());
}
mCastDevices.clear();
}
In my Activity I call startDiscoveringDevices() and destroyDiscoveryManager() by buttons. And all was fine, but in one time it stop finding devices. I wasn't change anything in code.
Maybe I made something with bugs and it worked, but now something happened and it doesn't work now? What I doing wrong?

Libgdx and Google In-App-Purchase result

I followed these instructions to integrate both Libgdx and native android code using ActionResolver interface. I have no problem calling the Android method from the Libgdx part of my code. But I am hitting a dead end when I am trying to intergrate Google IAP with Libgdx. According to TrivialDrive example, it uses mPurchaseFinishedListener (outside of calling method).
My question is: how do I pass this IAP resultcode back to Libgdx since the listener is outside the calling method? Currently, purchase process went through, but the libgdx part of my code is not being "informed" of the purchase status/result.
This is my code:
Any help is much appreciated.
ActionResolver:
public interface IActionResolver {
public int requestIabPurchase(int product);
}
MainActivity:
public class MainActivity extends AndroidApplication implements IActionResolver {
// Debug tag, for logging
static final String TAG = "greatgame";
// Does the user have the premium upgrade?
boolean mIsUpgraded = false;
// SKUs for our products: the cat, all, or pow
static final String SKU_UPGRADE = "android.test.purchased";
// (arbitrary) request code for the purchase flow
static final int RC_REQUEST = 10001;
// The helper object
IabHelper mHelper;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
getWindow().clearFlags(WindowManager.LayoutParams.FLAG_FORCE_NOT_FULLSCREEN);
getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
AndroidApplicationConfiguration cfg = new AndroidApplicationConfiguration();
cfg.useGL20 = false;
initialize(new Catland(this), cfg);
}
void iAbStartup() {
String base64EncodedPublicKey = "some key";
// Create the helper, passing it our context and the public key to verify signatures with
Log.d(TAG, "Creating IAB helper.");
mHelper = new IabHelper(this, base64EncodedPublicKey);
// enable debug logging (for a production application, you should set this to false).
mHelper.enableDebugLogging(true);
// Start setup. This is asynchronous and the specified listener
// will be called once setup completes.
Log.d(TAG, "Starting setup.");
mHelper.startSetup(new IabHelper.OnIabSetupFinishedListener() {
public void onIabSetupFinished(IabResult result) {
Log.d(TAG, "Setup finished.");
if (!result.isSuccess()) {
// Oh noes, there was a problem.
Log.d(TAG, "Problem setting up in-app billing: " + result);
return;
}
// Have we been disposed of in the meantime? If so, quit.
if (mHelper == null) {
return;
}
// IAB is fully set up. Now, let's get an inventory of stuff we own.
Log.d(TAG, "Setup successful. Querying inventory.");
mHelper.queryInventoryAsync(mGotInventoryListener);
}
});
}
// Listener that's called when we finish querying the items and subscriptions we own
IabHelper.QueryInventoryFinishedListener mGotInventoryListener = new IabHelper.QueryInventoryFinishedListener() {
public void onQueryInventoryFinished(IabResult result, Inventory inventory) {
Log.d(TAG, "Query inventory finished.");
// Have we been disposed of in the meantime? If so, quit.
if (mHelper == null) {
return;
}
// Is it a failure?
if (result.isFailure()) {
Log.d(TAG, "Failed to query inventory: " + result);
return;
}
Log.d(TAG, "Query inventory was successful.");
// Do we have the SKU_UPGRADE upgrade?
Purchase thisUpgrade = inventory.getPurchase(SKU_UPGRADE);
mIsUpgraded = (thisUpgrade != null && verifyDeveloperPayload(thisUpgrade));
Log.d(TAG, "User is " + (mIsUpgraded ? "Upgraded" : "Free"));
Log.d(TAG, "Initial inventory query finished; enabling main UI.");
runPurchaseFlow(submitProduct);
}
};
// Run real purchase flow
public void runPurchaseFlow(int product) {
Log.d(TAG, "runPurchaseFlow");
/* TODO: for security, generate your payload here for verification. See the comments on
* verifyDeveloperPayload() for more info. Since this is a SAMPLE, we just use
* an empty string, but on a production app you should carefully generate this. */
String payload = "";
if (product == 1)
mHelper.launchPurchaseFlow(this, SKU_UPGRADE, RC_REQUEST, mPurchaseFinishedListener, payload);
}
// Callback for when a purchase is finished
IabHelper.OnIabPurchaseFinishedListener mPurchaseFinishedListener = new IabHelper.OnIabPurchaseFinishedListener() {
public void onIabPurchaseFinished(IabResult result, Purchase purchase) {
Log.d(TAG, "Purchase finished: " + result + ", purchase: " + purchase);
// if we were disposed of in the meantime, quit.
if (mHelper == null) return;
if (result.isFailure()) {
Log.d(TAG, "Error purchasing: " + result);
return;
}
if (!verifyDeveloperPayload(purchase)) {
Log.d(TAG, "Error purchasing. Authenticity verification failed.");
return;
}
Log.d(TAG, "Purchase successful.");
if (purchase.getSku().equals(SKU_CAT)) {
// bought the upgrade!
Log.d(TAG, "Purchase Upgrade. Congratulating user.");
mIsUpgraded = true;
// how do i pass this result to the libgdx?
}
}
};
/** Verifies the developer payload of a purchase. */
boolean verifyDeveloperPayload(Purchase p) {
String payload = p.getDeveloperPayload();
return true;
}
#Override
public int requestIabPurchase(int product) {
iAbStartup();
return 0; // how do i get the result from mPurchaseFinishedListener?
}
}
PurchaseScreen
result = greatgame.actionResolver.requestIabPurchase(1);

You won't be able to return the result from requestIabPurchase() - the only methods of doing so would block for a long time. The best way, in my opinion, would be to create a listener interface of your own that your LibGdx project implements, and pass that into your request interface. For example:
In your libGdx project somewhere:
interface PurchaseCallback {
public int setPurchaseResult(int result);
}
ActionResolver:
public interface IActionResolver {
public int requestIabPurchase(int product, PurchaseCallback callback);
}
In PurchaseScreen, implement PurchaseCallback:
#override
public int setPurchaseResult(int result) {
// Yay! I have a result from a purchase! Maybe you want a boolean instead of an int? I don't know. Maybe an int (for the product code) and a boolean.
}
...and pass whatever is implementing PurchaseCallback (I'm assuming your PurchaseScreen does itself):
result = greatgame.actionResolver.requestIabPurchase(1, this);
Finally, hook it all up in MainActivity:
PurchaseCallback mCallback = null;
mPurchaseFinishedListener = ... etc. etc.
.
.
.
if (mCallback != null) {
mCallback.setPurchaseResult(0);
}
.
.
.
#Override
public int requestIabPurchase(int product, PurchaseCallback callback) {
mCallback = callback; // save this for later
iAbStartup();
return 0;
}
Note that you should call PurchaseCallback.setPurchaseResult() everywhere that mPurchaseFinishedListener has return, not only at the line // how do i pass this result to the libgdx? - otherwise, you will never know if a purchase failed or is just taking a really long time.

Receive data from TI CC2540 Bluetooth Low Energy kit

I have a CC2540 BLE kit and i want to see the battery level of the kit in my smartphone app. I have made the code, which gets the battery level from the kit. The battery level is called BodySensor in this case:
First, i will go into the characteristic value of the battery service part for the kit. So i use the Service and Characteristic UUID's for the battery service:
public void getBodySensorLoc(BluetoothDevice device)
{
Log.i(TAG, "getBodySensorLoc");
BluetoothGattService mHRP = mBluetoothGatt.getService(device, HRP_SERVICE);
if (mHRP == null)
{
Log.e(TAG, "getBodySensorLoc: mHRP = null");
return;
}
BluetoothGattCharacteristic mBSLcharac = mHRP.getCharacteristic(BODY_SENSOR_LOCATION);
if (mBSLcharac == null) {
Log.e(TAG, "getBodySensorLoc: mBSLcharac = null");
return;
}
mBluetoothGatt.readCharacteristic(mBSLcharac);
}
My purpose is to read the battery level, when pressing a button in my application. So i implement this button in my Activity class:
((Button) findViewById(R.id.btn_BSL)).setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v)
{
mService.getBodySensorLoc(mDevice);
}
});
This kit will automatically send the battery level back to the smartphone. So i will set focus on onCharacteristicRead method of BluetoothGattCallback part in my code:
private BluetoothGattCallback mGattCallbacks = new BluetoothGattCallback()
{
public void onCharacteristicRead(BluetoothGattCharacteristic charac, int status)
{
UUID charUuid = charac.getUuid();
Bundle mBundle = new Bundle();
Message msg = Message.obtain(mActivityHandler, HRP_VALUE_MSG);
Log.i(TAG, "onCharacteristicRead");
if (charUuid.equals(BODY_SENSOR_LOCATION))
mBundle.putByteArray(BSL_VALUE, charac.getValue());
msg.setData(mBundle);
msg.sendToTarget();
}
};
I want the application to show the received battery level in a textview. The kit sends the battery level as a integer, so if the level is 70%, it sends "70". The code includes a Handler in the Activity class:
private Handler mHandler = new Handler()
{
#Override
public void handleMessage(Message msg)
{
switch (msg.what)
{
case HRPService.HRP_VALUE_MSG:
Log.d(TAG, "mHandler.HRP_VALUE_MSG");
Bundle data1 = msg.getData();
final byte[] bslval = data1.getByteArray(HRPService.BSL_VALUE);
runOnUiThread(new Runnable()
{
public void run()
{
if (bslval != null)
{
try {
Log.i(TAG, "BYTE BSL VAL =" + bslval[0]);
TextView bsltv = (TextView) findViewById(R.id.BodySensorLocation);
bsltv.setText("\t" + mContext.getString(R.string.BodySensorLocation)
+ getBodySensorLocation(bslval[0]));
} catch (Exception e)
{
Log.e(TAG, e.toString());
}
}
}
});
default:
super.handleMessage(msg);
}
}
};
The problem is that the textview doesn't show anything, when i press this button in my application after i connected my smartphone with the kit. Can anyone tell me, where the problem is ?.
Thanks in advance

Unsure what exact kit you have. Unsure if they all have battery level measuring hardware on board. Maybe this is the reason.