[Feature] Ability to extract files simultaneously

android/src/main/java/com/ryanheise/just_waveform/JustWaveformPlugin.java

@@ -10,6 +10,7 @@
 import android.os.Handler;
 import java.util.List;
 import io.flutter.plugin.common.PluginRegistry.Registrar;
+import java.util.HashMap;
 
 /** JustWaveformPlugin */
 public class JustWaveformPlugin implements FlutterPlugin, MethodCallHandler {
@@ -18,48 +19,56 @@ public class JustWaveformPlugin implements FlutterPlugin, MethodCallHandler {
 
     @Override
     public void onAttachedToEngine(@NonNull FlutterPluginBinding flutterPluginBinding) {
-        channel = new MethodChannel(flutterPluginBinding.getFlutterEngine().getDartExecutor(), "com.ryanheise.just_waveform");
+        channel = new MethodChannel(flutterPluginBinding.getFlutterEngine().getDartExecutor(),
+                "com.ryanheise.just_waveform");
         channel.setMethodCallHandler(this);
     }
 
     @Override
     public void onMethodCall(@NonNull MethodCall call, @NonNull final Result result) {
         switch (call.method) {
-        case "extract":
-            String audioInPath = call.argument("audioInPath");
-            String waveOutPath = call.argument("waveOutPath");
-            Integer samplesPerPixel = call.argument("samplesPerPixel");
-            Integer pixelsPerSecond = call.argument("pixelsPerSecond");
-            WaveformExtractor waveformExtractor = new WaveformExtractor(audioInPath, waveOutPath, samplesPerPixel, pixelsPerSecond);
-            waveformExtractor.start(new WaveformExtractor.OnProgressListener() {
-                @Override
-                public void onProgress(int progress) {
-                    invokeMethod("onProgress", progress);
-                }
-                @Override
-                public void onComplete() {
-                    handler.post(new Runnable() {
-                        @Override
-                        public void run() {
-                            result.success(null);
-                        }
-                    });
-                }
-                @Override
-                public void onError(final String message) {
-                    invokeMethod("onError", message);
-                    handler.post(new Runnable() {
-                        @Override
-                        public void run() {
-                            result.error(message, null, null);
-                        }
-                    });
-                }
-            });
-            break;
-        default:
-            result.notImplemented();
-            break;
+            case "extract":
+                String audioInPath = call.argument("audioInPath");
+                String waveOutPath = call.argument("waveOutPath");
+                Integer samplesPerPixel = call.argument("samplesPerPixel");
+                Integer pixelsPerSecond = call.argument("pixelsPerSecond");
+                WaveformExtractor waveformExtractor = new WaveformExtractor(audioInPath, waveOutPath, samplesPerPixel,
+                        pixelsPerSecond);
+                waveformExtractor.start(new WaveformExtractor.OnProgressListener() {
+                    @Override
+                    public void onProgress(int progress) {
+                        HashMap<String, Object> args = new HashMap();
+                        args.put("progress", progress);
+                        args.put("waveOutFile", waveOutPath);
+
+                        invokeMethod("onProgress", args);
+                    }
+
+                    @Override
+                    public void onComplete() {
+                        handler.post(new Runnable() {
+                            @Override
+                            public void run() {
+                                result.success(null);
+                            }
+                        });
+                    }
+
+                    @Override
+                    public void onError(final String message) {
+                        invokeMethod("onError", message);
+                        handler.post(new Runnable() {
+                            @Override
+                            public void run() {
+                                result.error(message, null, null);
+                            }
+                        });
+                    }
+                });
+                break;
+            default:
+                result.notImplemented();
+                break;
         }
     }
 

darwin/Classes/JustWaveformPlugin.m

@@ -156,7 +156,7 @@ - (void)handleMethodCall:(FlutterMethodCall*)call result:(FlutterResult)result {
                                     progress = newProgress;
                                     //NSLog(@"Progress: %d percent", progress);
                                     dispatch_async(dispatch_get_main_queue(), ^{
-                                        [_channel invokeMethod:@"onProgress" arguments:@(progress)];
+                                        [_channel invokeMethod:@"onProgress" arguments:@{@"progress" : @(progress), @"waveOutFile" : waveOutPath}];
                                     });
                                 }
                                 //NSLog(@"pixel[%d] %d: %d\t%d", scaledSampleIdx - 2, sampleIdx, minSample, maxSample);

lib/just_waveform.dart

@@ -7,38 +7,43 @@ import 'package:flutter/services.dart';
 /// A utility for extracting a [Waveform] from an audio file suitable for visual
 /// rendering.
 class JustWaveform {
-  static const MethodChannel _channel =
-      MethodChannel('com.ryanheise.just_waveform');
+  static final MethodChannel _channel = MethodChannel('com.ryanheise.just_waveform');
 
   /// Extract a [Waveform] from [audioInFile] and write it to [waveOutFile] at
   /// the specified [zoom] level.
   // XXX: It would be better to return a stream of the actual [Waveform], with
   // progress => wave.data.length / (wave.length*2)
+  static Map<String, StreamController<WaveformProgress>> _map = {};
   static Stream<WaveformProgress> extract({
     required File audioInFile,
     required File waveOutFile,
     WaveformZoom zoom = const WaveformZoom.pixelsPerSecond(100),
   }) {
     final progressController = StreamController<WaveformProgress>.broadcast();
+    _map[waveOutFile.path] = progressController;
+
     progressController.add(WaveformProgress._(0.0, null));
     _channel.setMethodCallHandler((MethodCall call) async {
       switch (call.method) {
         case 'onProgress':
-          // ignore: avoid_print
-          print("received onProgress: ${call.arguments}}");
-          int progress = call.arguments;
-          //print("_progressSubject.add($progress)");
+          final args = call.arguments;
+          int progress = args['progress'];
+          String file = args['waveOutFile'];
           Waveform? waveform;
+
           if (progress == 100) {
-            waveform = await parse(waveOutFile);
+            waveform = await parse(File(file));
           }
-          progressController.add(WaveformProgress._(progress / 100, waveform));
+
+          _map[file]?.add(WaveformProgress._(progress / 100, waveform));
           if (progress == 100) {
-            progressController.close();
+            _map[file]?.close();
+            _map.remove(file);
           }
           break;
       }
     });
+    // print('Started extract $_filename');
     _channel.invokeMethod('extract', {
       'audioInPath': audioInFile.path,
       'waveOutPath': waveOutFile.path,
@@ -54,9 +59,7 @@ class JustWaveform {
     const headerLength = 20;
     final header = Uint32List.view(bytes, 0, headerLength);
     final flags = header[1];
-    final data = flags == 0
-        ? Int16List.view(bytes, headerLength ~/ 2)
-        : Int8List.view(bytes, headerLength);
+    final data = flags == 0 ? Int16List.view(bytes, headerLength ~/ 2) : Int8List.view(bytes, headerLength);
     return Waveform(
       version: header[0],
       flags: flags,
@@ -123,14 +126,12 @@ class Waveform {
   int getPixelMax(int i) => this[2 * i + 1];
 
   /// The duration of audio, inferred from the length of the waveform data.
-  Duration get duration => Duration(
-      microseconds: 1000 * 1000 * length * samplesPerPixel ~/ sampleRate);
+  Duration get duration => Duration(microseconds: 1000 * 1000 * length * samplesPerPixel ~/ sampleRate);
 
   /// Converts an audio position to a pixel position. The returned position is a
   /// [double] for accuracy, but can be converted `toInt` and used to access the
   /// nearest pixel value via [getPixelMin]/[getPixelMax].
-  double positionToPixel(Duration position) =>
-      position.inMicroseconds * sampleRate / (samplesPerPixel * 1000000);
+  double positionToPixel(Duration position) => position.inMicroseconds * sampleRate / (samplesPerPixel * 1000000);
 }
 
 /// The resolution at which a [Waveform] should be generated.