title: ReplacementSpan's draw() method isn't called
body: <p>I set background in string like that:</p>
  
  <pre><code>spanString.setSpan(new BackgroundColorSpan(color), 0, 3, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
  </code></pre>
  
  <p>But I would like to increase left and right padding in this background so I created custom span</p>
  
  <pre><code>public class PaddingBackgroundSpan extends ReplacementSpan {
  private int mBackgroundColor;
  private int mForegroundColor;
  
  public PaddingBackgroundSpan(int backgroundColor, int foregroundColor) {
      this.mBackgroundColor = backgroundColor;
      this.mForegroundColor = foregroundColor;
  }
  
  @Override
  public int getSize(Paint paint, CharSequence text, int start, int end, Paint.FontMetricsInt fm) {
      return Math.round(measureText(paint, text, start, end));
  
  }
  
  @Override
  public void draw(Canvas canvas, CharSequence text, int start, int end, float x, int top, int y, int bottom, Paint paint) {
      RectF rect = new RectF(x, top, x + measureText(paint, text, start, end), bottom);
      paint.setColor(mBackgroundColor);
      canvas.drawRect(rect, paint);
      paint.setColor(mForegroundColor);
      canvas.drawText(text, start, end, x, y, paint);
  }
  
  private float measureText(Paint paint, CharSequence text, int start, int end) {
      return paint.measureText(text, start, end);
  }
  </code></pre>
  
  <p>I use my span by:</p>
  
  <pre><code>spanString.setSpan(new PaddingBackgroundSpan(color1, color2), 0, 3, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
  </code></pre>
  
  <p>Unfortunately, my draw() method isn't called. getSize() is called correctly.</p>