Android Open Source - Backyard-Brains-Android-App Oscilloscope Renderer

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License

The source code is released under:
GNU General Public License
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Java Source Code

/*
 * Backyard Brains Android App/*from w w w.j a  v a 2  s  .co m*/
 * Copyright (C) 2011 Backyard Brains
 * by Nathan Dotz <nate (at) backyardbrains.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package com.backyardbrains.drawing;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import java.text.DecimalFormat;

import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;

import android.content.Intent;
import android.opengl.GLSurfaceView;
import android.os.SystemClock;
import android.util.Log;

import com.backyardbrains.BackyardAndroidActivity;

public class OscilloscopeRenderer implements GLSurfaceView.Renderer {

  private static final String TAG = OscilloscopeRenderer.class
      .getCanonicalName();
  public static final int PCM_MAXIMUM_VALUE = (Short.MAX_VALUE * 3 / 2);

  protected int glWindowHorizontalSize = 4000;
  private float minimumDetectedPCMValue = -5000000f;
  protected int glWindowVerticalSize = 10000;
  private boolean autoScaled = false;
  protected BackyardAndroidActivity context;
  protected short[] mBufferToDraws;
  protected boolean mAudioServiceIsBound;
  protected int height;
  protected int width;
  private long firstBufferDrawn = 0;

  public OscilloscopeRenderer(BackyardAndroidActivity backyardAndroidActivity) {
    context = backyardAndroidActivity;
  }

  @Override
  public void onDrawFrame(GL10 gl) {
    // grab current audio from audioservice
    if (context.getmAudioService() == null)
      return;

    getCurrentAudio();

    if (!isValidAudioBuffer())
      return;

    preDrawingHandler();
    glClear(gl);
    drawingHandler(gl);
    postDrawingHandler(gl);
  }

  @Override
  public void onSurfaceChanged(GL10 gl, int width, int height) {
    this.width = width;
    this.height = height;
    setMillivoltLabelPosition(height);
  }

  @Override
  public void onSurfaceCreated(GL10 gl, EGLConfig config) {
    gl.glDisable(GL10.GL_DITHER);
    gl.glHint(GL10.GL_LINE_SMOOTH_HINT, GL10.GL_NICEST);
    gl.glEnable(GL10.GL_DEPTH_TEST);
  }

  private void glClear(GL10 gl) {
    gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
  }

  protected void preDrawingHandler() {
    // scale the right side to the number of data points we have
    if (mBufferToDraws.length < glWindowHorizontalSize) {
      setGlWindowHorizontalSize(mBufferToDraws.length);
    }
    setLabels(glWindowHorizontalSize);
  }

  protected void postDrawingHandler(GL10 gl) {
    // stub
  }

  private void drawingHandler(GL10 gl) {
    setGlWindow(gl, glWindowHorizontalSize, mBufferToDraws.length);
    FloatBuffer mVertexBuffer = getWaveformBuffer(mBufferToDraws);

    firstBufferDrawnCheck();
    autoScaleCheck();

    gl.glMatrixMode(GL10.GL_MODELVIEW);
    gl.glLoadIdentity();

    gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
    gl.glLineWidth(1f);
    gl.glColor4f(0f, 1f, 0f, 1f);
    gl.glVertexPointer(2, GL10.GL_FLOAT, 0, mVertexBuffer);
    gl.glDrawArrays(GL10.GL_LINE_STRIP, 0, mVertexBuffer.limit() / 2);
    gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
  }

  private void firstBufferDrawnCheck() {
    if (firstBufferDrawn == 0) {
      firstBufferDrawn = SystemClock.currentThreadTimeMillis();
    }
  }

  private void autoScaleCheck() {
    if (!isAutoScaled()
        && firstBufferDrawn != 0
        && (SystemClock.currentThreadTimeMillis() - firstBufferDrawn) > 100) {
      autoSetFrame(mBufferToDraws);
    }
  }

  private void autoSetFrame(short[] arrayToScaleTo) {
    int theMax = 0;
    int theMin = 0;

    for (int i = 0; i < arrayToScaleTo.length; i++) {
      if (theMax < arrayToScaleTo[i])
        theMax = arrayToScaleTo[i];
      if (theMin > arrayToScaleTo[i])
        theMin = arrayToScaleTo[i];
    }

    int newyMax;
    if (theMax != 0 && theMin != 0) {

      if (Math.abs(theMax) >= Math.abs(theMin)) {
        newyMax = Math.abs(theMax) * 2;
      } else {
        newyMax = Math.abs(theMin) * 2;
      }
      if (-newyMax > getMinimumDetectedPCMValue()) {
        Log.d(TAG, "Scaling window to " + -newyMax + " < y < "
            + newyMax);
        setGlWindowVerticalSize(newyMax * 2);
      }

    }
    setAutoScaled(true);
  }

  protected FloatBuffer getWaveformBuffer(short[] shortArrayToDraw) {
    int micSize = context.getmAudioService().getMicListenerBufferSizeInSamples();
    float[] arr = new float[(glWindowHorizontalSize + micSize) * 2];
    int j = 0; // index of arr
    try {
      for (int i = shortArrayToDraw.length - glWindowHorizontalSize
          - micSize; i < shortArrayToDraw.length; i++) {
        arr[j++] = i;
        arr[j++] = shortArrayToDraw[i];
      }
    } catch (ArrayIndexOutOfBoundsException e) {
      Log.e(TAG, "Array size out of sync while building new waveform buffer");
    }
    return getFloatBufferFromFloatArray(arr);
  }

  FloatBuffer getFloatBufferFromFloatArray(final float[] array) {
    final ByteBuffer temp = ByteBuffer.allocateDirect(array.length * 4);
    temp.order(ByteOrder.nativeOrder());
    final FloatBuffer buf = temp.asFloatBuffer();
    buf.put(array);
    buf.position(0);
    return buf;
  }

  protected boolean isValidAudioBuffer() {
    return mBufferToDraws != null && mBufferToDraws.length > 0;
  }

  protected void setLabels(int samplesToShow) {
    setmVText();
    final float millisecondsInThisWindow = samplesToShow / 44100.0f * 1000 / 3;
    setMsText(millisecondsInThisWindow);
  }

  protected void setmVText() {
    float yPerDiv = (float) getGlWindowVerticalSize() / 4.0f / 24.5f / 1000;
    setmVText(yPerDiv);
  }

  public void setMsText(Float ms) {
    String msString = new DecimalFormat("#.#").format(ms);
    broadcastTextUpdate("BYBUpdateMillisecondsReciever",
        "millisecondsDisplayedString", msString + " ms");
  }

  public void setmVText(Float ms) {
    String msString = new DecimalFormat("#.##").format(ms);
    broadcastTextUpdate("BYBUpdateMillivoltReciever",
        "millivoltsDisplayedString", msString + " mV");
  }

  private void setMillivoltLabelPosition(int height) {
    Intent i = new Intent();
    i.setAction("BYBMillivoltsViewSize");
    i.putExtra("millivoltsViewNewSize", height / 2);
    context.sendBroadcast(i);
  }
  
  private void broadcastTextUpdate(String action, String name, String data) {
    Intent i = new Intent();
    i.setAction(action);
    i.putExtra(name, data);
    context.sendBroadcast(i);
  }

  /*
  private long samplesToMs(long samps) {
    return Math.round(samps / 44.1);
  }
  */

  private long msToSamples(long timeSince) {
    return Math.round(44.1 * timeSince);
  }

  protected void setGlWindow(GL10 gl, final int samplesToShow,
      final int lengthOfSampleSet) {
    
    final int micBufferSize = context.getmAudioService().getMicListenerBufferSizeInSamples();
    final long lastTimestamp = context.getmAudioService().getLastSamplesReceivedTimestamp();
    final long timeSince = System.currentTimeMillis() - lastTimestamp;
    
    long xEnd = Math.min(lengthOfSampleSet, lengthOfSampleSet - micBufferSize + msToSamples(timeSince));
    long xBegin = Math.min(lengthOfSampleSet - glWindowHorizontalSize, xEnd - glWindowHorizontalSize);
    xBegin = Math.max(0, xBegin);
    initGL(gl, xBegin,
        xEnd, -getGlWindowVerticalSize() / 2,
        getGlWindowVerticalSize() / 2);
  }

  void initGL(GL10 gl, float xBegin, float xEnd, float scaledYBegin,
      float scaledYEnd) {
    // set viewport
    gl.glViewport(0, 0, width, height);

    glClear(gl);
    gl.glMatrixMode(GL10.GL_PROJECTION);
    gl.glLoadIdentity();
    gl.glOrthof(xBegin, xEnd, scaledYBegin, scaledYEnd, -1f, 1f);
    gl.glRotatef(0f, 0f, 0f, 1f);

    // Blackout, then we're ready to draw! \o/
    // mGL.glEnable(GL10.GL_TEXTURE_2D);
    gl.glClearColor(0f, 0f, 0f, 0.5f);
    gl.glClearDepthf(1.0f);
    gl.glEnable(GL10.GL_DEPTH_TEST);
    gl.glDepthFunc(GL10.GL_LEQUAL);
    gl.glEnable(GL10.GL_LINE_SMOOTH);
    gl.glHint(GL10.GL_LINE_SMOOTH_HINT, GL10.GL_NICEST);
    // Enable Blending
    gl.glEnable(GL10.GL_BLEND);
    // Specifies pixel arithmetic
    gl.glBlendFunc(GL10.GL_SRC_ALPHA, GL10.GL_ONE_MINUS_SRC_ALPHA);
    gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_NICEST);
  }

  public void setGlWindowHorizontalSize(final int newSize) {
    int maxlength = 0;
    if (mBufferToDraws != null)
      maxlength = mBufferToDraws.length;
    if (newSize < 16 || (maxlength > 0 && newSize > maxlength))
      return;
    this.glWindowHorizontalSize = newSize;
  }

  public void setGlWindowVerticalSize(int y) {
    if (y < 800 || y > PCM_MAXIMUM_VALUE * 2)
      return;

    glWindowVerticalSize = y;
  }

  public float getMinimumDetectedPCMValue() {
    return minimumDetectedPCMValue;
  }

  public int getGlWindowVerticalSize() {
    return glWindowVerticalSize;
  }

  public int getGlWindowHorizontalSize() {
    return glWindowHorizontalSize;
  }

  protected void getCurrentAudio() {
    mBufferToDraws = context.getmAudioService().getAudioBuffer();
  }

  public boolean isAutoScaled() {
    return autoScaled;
  }

  public void setAutoScaled(boolean isScaled) {
    autoScaled = isScaled;
  }

}
Java Source Code List
