[Android] Add support for "setDecibel" feature

android/src/main/java/io/github/mertguner/sound_generator/SoundGenerator.java

@@ -97,6 +97,11 @@ else if (waveType.equals(WaveTypes.SAWTOOTH))
             generator.setGenerator(new sawtoothGenerator());
     }
 
+    public void setDecibel(float decibel) {
+        if (generator != null)
+            generator.setDecibel(decibel);
+    }
+
     public boolean init(int sampleRate) {
         try {
             minSamplesSize = AudioTrack.getMinBufferSize(

android/src/main/java/io/github/mertguner/sound_generator/SoundGeneratorPlugin.java

@@ -79,6 +79,9 @@ public void onMethodCall(@NonNull MethodCall call, @NonNull Result result) {
     }else if (call.method.equals("setVolume")) {
       double volume = call.argument("volume");
       soundGenerator.setVolume((float)volume);
+    }else if (call.method.equals("setDecibel")) {
+        double decibel = call.argument("decibel");
+        soundGenerator.setDecibel((float)decibel);
     }else if (call.method.equals("getSampleRate")) {
       result.success(soundGenerator.getSampleRate());
     }else if (call.method.equals("refreshOneCycleData")) {

android/src/main/java/io/github/mertguner/sound_generator/generators/signalDataGenerator.java

@@ -15,6 +15,8 @@ public class signalDataGenerator {
     private float smoothStep = 1f / (float) sampleRate * 20f;
 
     private float frequency = 50;
+    private float decibel = 20;
+
     private baseGenerator generator = new sinusoidalGenerator();
 
     private short[] backgroundBuffer;
@@ -52,6 +54,10 @@ public void setFrequency(float frequency) {
         createOneCycleData();
     }
 
+    public void setDecibel(float decibel) {
+        this.decibel = decibel;
+    }
+
     public void resetFrequency() {
         oldFrequency = frequency;
     }
@@ -83,9 +89,26 @@ private void updateData() {
                 ph -= _2Pi;
             }
         }
+        float maxAmplitude = findMaxAmplitude(backgroundBuffer);
+        float amplitude = (float) Math.pow(10, decibel / 20.0);
+        for (int i = 0; i < bufferSamplesSize; i++) {
+            backgroundBuffer[i] = (short) (backgroundBuffer[i] * amplitude / maxAmplitude);
+        }
+
         creatingNewData = false;
     }
 
+    private float findMaxAmplitude(short[] waveform) {
+        float maxAmplitude = 0;
+        for (short sample : waveform) {
+            float sampleValue = Math.abs(sample);
+            if (sampleValue > maxAmplitude) {
+                maxAmplitude = sampleValue;
+            }
+        }
+        return maxAmplitude;
+    }
+
     public short[] getData() {
         if (!creatingNewData) {
             System.arraycopy(backgroundBuffer, 0, buffer, 0, bufferSamplesSize);

lib/sound_generator.dart

@@ -122,4 +122,11 @@ class SoundGenerator {
     await _channel
         .invokeMethod("setCleanStart", <String, dynamic>{"cleanStart": cleanStart});
   }
+
+  /// Set Decibel
+  static void setDecibel(double decibel) async {
+    await _channel
+        .invokeMethod("setDecibel", <String, dynamic>{"decibel": decibel});
+  }
+
 }