Merge pull request #27 from xPutnikx/use-nfc-stream

use stream to be able to read nfc details without interruptions
dotintent · Feb 23, 2019 · 5469452 · 5469452
2 parents b23039a + e989191
commit 5469452
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Showing 4 changed files with 44 additions and 28 deletions.
diff --git a/android/build.gradle b/android/build.gradle
@@ -31,7 +31,7 @@ android {
         main.java.srcDirs += 'src/main/kotlin'
     }
     defaultConfig {
-        minSdkVersion 19
+        minSdkVersion 18
         testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
     }
     lintOptions {

diff --git a/android/src/main/kotlin/it/matteocrippa/flutternfcreader/FlutterNfcReaderPlugin.kt b/android/src/main/kotlin/it/matteocrippa/flutternfcreader/FlutterNfcReaderPlugin.kt
@@ -7,6 +7,9 @@ import android.nfc.NfcManager
 import android.nfc.Tag
 import android.nfc.tech.Ndef
 import android.os.Build
+import io.flutter.plugin.common.EventChannel
+import io.flutter.plugin.common.EventChannel.StreamHandler
+import io.flutter.plugin.common.EventChannel.EventSink
 import io.flutter.plugin.common.MethodCall
 import io.flutter.plugin.common.MethodChannel
 import io.flutter.plugin.common.MethodChannel.MethodCallHandler
@@ -17,15 +20,15 @@ import java.nio.charset.Charset
 
 const val PERMISSION_NFC = 1007
 
-class FlutterNfcReaderPlugin(val registrar: Registrar) : MethodCallHandler,  NfcAdapter.ReaderCallback {
+class FlutterNfcReaderPlugin(val registrar: Registrar) : MethodCallHandler, EventChannel.StreamHandler, NfcAdapter.ReaderCallback {
 
     private val activity = registrar.activity()
 
     private var isReading = false
     private var nfcAdapter: NfcAdapter? = null
     private var nfcManager: NfcManager? = null
 
-    private var resulter: Result? = null
+    private var eventSink: EventChannel.EventSink? = null
 
     private var kId = "nfcId"
     private var kContent = "nfcContent"
@@ -37,8 +40,12 @@ class FlutterNfcReaderPlugin(val registrar: Registrar) : MethodCallHandler,  Nfc
     companion object {
         @JvmStatic
         fun registerWith(registrar: Registrar): Unit {
-            val channel = MethodChannel(registrar.messenger(), "flutter_nfc_reader")
-            channel.setMethodCallHandler(FlutterNfcReaderPlugin(registrar))
+            val messenger = registrar.messenger()
+            val channel = MethodChannel(messenger, "flutter_nfc_reader")
+            val eventChannel = EventChannel(messenger, "it.matteocrippa.flutternfcreader.flutter_nfc_reader")
+            val plugin = FlutterNfcReaderPlugin(registrar)
+            channel.setMethodCallHandler(plugin)
+            eventChannel.setStreamHandler(plugin)
         }
     }
 
@@ -59,15 +66,14 @@ class FlutterNfcReaderPlugin(val registrar: Registrar) : MethodCallHandler,  Nfc
                     )
                 }
 
-                resulter = result
                 startNFC()
 
                 if (!isReading) {
-                    val data = mapOf(kId to "", kContent to "", kError to "NFC Hardware not found", kStatus to "error")
-                    result.success(data)
-                    resulter = null
+                    result.error("404", "NFC Hardware not found", null)
+                    return
                 }
 
+                result.success(null)
             }
             "NfcStop" -> {
                 stopNFC()
@@ -80,6 +86,16 @@ class FlutterNfcReaderPlugin(val registrar: Registrar) : MethodCallHandler,  Nfc
         }
     }
 
+    // EventChannel.StreamHandler methods
+    override fun onListen(arguments: Any?, eventSink: EventChannel.EventSink?) {
+      this.eventSink = eventSink
+    }
+
+    override fun onCancel(arguments: Any?) {
+      eventSink = null
+      stopNFC()
+    }
+
     private fun startNFC(): Boolean {
         isReading = if (nfcAdapter?.isEnabled == true) {
 
@@ -98,8 +114,8 @@ class FlutterNfcReaderPlugin(val registrar: Registrar) : MethodCallHandler,  Nfc
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
             nfcAdapter?.disableReaderMode(registrar.activity())
         }
-        resulter = null
         isReading = false
+        eventSink = null
     }
 
     // handle discovered NDEF Tags
@@ -117,7 +133,7 @@ class FlutterNfcReaderPlugin(val registrar: Registrar) : MethodCallHandler,  Nfc
         ndef?.close()
         if (message != null) {
             val data = mapOf(kId to id, kContent to message, kError to "", kStatus to "read")
-            resulter?.success(data)
+            eventSink?.success(data)
         }
     }
 

diff --git a/example/lib/main.dart b/example/lib/main.dart
@@ -1,6 +1,6 @@
-import 'package:flutter/material.dart';
 import 'dart:async';
 
+import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter_nfc_reader/flutter_nfc_reader.dart';
 
@@ -20,23 +20,18 @@ class _MyAppState extends State<MyApp> {
   }
 
   Future<void> startNFC() async {
-    NfcData response;
-
     setState(() {
       _nfcData = NfcData();
       _nfcData.status = NFCStatus.reading;
     });
 
     print('NFC: Scan started');
 
-    try {
-      print('NFC: Scan readed NFC tag');
-      response = await FlutterNfcReader.read;
-    } on PlatformException {
-      print('NFC: Scan stopped exception');
-    }
-    setState(() {
-      _nfcData = response;
+    print('NFC: Scan readed NFC tag');
+    FlutterNfcReader.read.listen((response) {
+      setState(() {
+        _nfcData = response;
+      });
     });
   }
 

diff --git a/lib/flutter_nfc_reader.dart b/lib/flutter_nfc_reader.dart
@@ -1,4 +1,5 @@
 import 'dart:async';
+
 import 'package:flutter/services.dart';
 
 enum NFCStatus {
@@ -54,13 +55,17 @@ class NfcData {
 class FlutterNfcReader {
   static const MethodChannel _channel =
       const MethodChannel('flutter_nfc_reader');
+  static const stream =
+      const EventChannel('it.matteocrippa.flutternfcreader.flutter_nfc_reader');
 
-  static Future<NfcData> get read async {
-    final Map data = await _channel.invokeMethod('NfcRead');
-
-    final NfcData result = NfcData.fromMap(data);
-
-    return result;
+  static Stream<NfcData> get read {
+    final resultStream = _channel
+        .invokeMethod('NfcRead')
+        .asStream()
+        .asyncExpand((_) => stream
+            .receiveBroadcastStream()
+            .map((result) => NfcData.fromMap(result)));
+    return resultStream;
   }
 
   static Future<NfcData> get stop async {