Visualize sound to show in Bar Graph

Question

I have created sound visualization using felixpalmer library. Now i have to modify his code to look like this.How could i achieve empty spaces between bars. like

I will handle the color scheme but don't know how to add empty spaces in bars and shadow effect.

BarGraphRender

public class BarGraphRenderer extends Renderer
{
  private int mDivisions;
  private Paint mPaint;
  private boolean mTop;

  /**
   * Renders the FFT data as a series of lines, in histogram form
   * @param divisions - must be a power of 2. Controls how many lines to draw
   * @param paint - Paint to draw lines with
   * @param top - whether to draw the lines at the top of the canvas, or the bottom
   */
  public BarGraphRenderer(int divisions , Paint paint , boolean top)
  {
    super();
    mDivisions = divisions;
    mPaint = paint;
    mTop = top;
  }

  @Override
  public void onRender(Canvas canvas, AudioData data, Rect rect)
  {
    // Do nothing, we only display FFT data
  }

  @Override
  public void onRender(Canvas canvas, FFTData data, Rect rect)
  {
        for (int i = 0; i < data.bytes.length / mDivisions; i++) 
        {
            mFFTPoints[i * 4] = i * 4 * mDivisions;
            mFFTPoints[i * 4 + 2] = i * 4 * mDivisions;
            byte rfk = data.bytes[mDivisions * i];
            byte ifk = data.bytes[mDivisions * i + 1];
            float magnitude = (rfk * rfk + ifk * ifk);
            int dbValue = (int) (10 * Math.log10(magnitude));

            if(mTop)
            {
              mFFTPoints[i * 4 + 1] = 0;
              mFFTPoints[i * 4 + 3] = (dbValue * 2 - 10);  
            }
            else
            {
              mFFTPoints[i * 4 + 1] = rect.height();
              mFFTPoints[i * 4 + 3] = rect.height() - (dbValue * 2 - 10);
            }
        }
          canvas.drawLines(mFFTPoints, mPaint);
  }
}