code: private float getScaleForZoom(int zoomFactor){
  
  		if ( zoomFactor > 100)
  			zoomFactor = 100;
  		if ( zoomFactor < 1)
  			zoomFactor = 1;
  
  
  		int DEFAULT_X_START
  		= SequenceScalePanel.DEFAULT_X_START;
  		int DEFAULT_X_RIGHT_BORDER = SequenceScalePanel.DEFAULT_X_RIGHT_BORDER;
  
  		int seqLength = getMaxSequenceLength();
  		// the maximum width depends on the size of the parent Component
  
  		int width=getWidth();
  
  
  		float s = width / (float) ( seqLength + DEFAULT_X_START + DEFAULT_X_RIGHT_BORDER );
  		//logger.info("scale for 100% " + s + " " + seqLength + " " + zoomFactor);
  
  		s = (100) * s / ( zoomFactor * 1.0f) ;
  
  		if ( s > MAX_SCALE)
  			s = MAX_SCALE;
  
  		//logger.info("but changed to " + s);
  		return s;
  	}
docs: calculate the float that is used for display.
  1 * scale = size of 1 amino acid (in pixel).
  maximum @see MAX_SCALE
  @param zoomFactor
  @return a float that is the display "scale" - an internal value required for paintin.
  user should only interact with the zoomfactor ...