content: /*
   * Copyright (C) 2015 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package com.example.android.common.midi.synth;
  
  /**
   * Base class for a polyphonic synthesizer voice.
   */
  public abstract class SynthVoice {
      private int mNoteIndex;
      private float mAmplitude;
      public static final int STATE_OFF = 0;
      public static final int STATE_ON = 1;
      private int mState = STATE_OFF;
  
      public SynthVoice() {
          mNoteIndex = -1;
      }
  
      public void noteOn(int noteIndex, int velocity) {
          mState = STATE_ON;
          this.mNoteIndex = noteIndex;
          setAmplitude(velocity / 128.0f);
      }
  
      public void noteOff() {
          mState = STATE_OFF;
      }
  
      /**
       * Add the output of this voice to an output buffer.
       *
       * @param outputBuffer
       * @param samplesPerFrame
       * @param level
       */
      public void mix(float[] outputBuffer, int samplesPerFrame, float level) {
          int numFrames = outputBuffer.length / samplesPerFrame;
          for (int i = 0; i < numFrames; i++) {
              float output = render();
              int offset = i * samplesPerFrame;
              for (int jf = 0; jf < samplesPerFrame; jf++) {
                  outputBuffer[offset + jf] += output * level;
              }
          }
      }
  
      public abstract float render();
  
      public boolean isDone() {
          return mState == STATE_OFF;
      }
  
      public int getNoteIndex() {
          return mNoteIndex;
      }
  
      public float getAmplitude() {
          return mAmplitude;
      }
  
      public void setAmplitude(float amplitude) {
          this.mAmplitude = amplitude;
      }
  
      /**
       * @param scaler
       */
      public void setFrequencyScaler(float scaler) {
      }
  
  }
  