function getItemColors (colorLevel) { 
  var colors= []; 
  //默认的最深颜色 
  var red = 134,green = 108, blue = 184; 
  //最浅颜色是239,239,239 比如：最浅颜色的red是 239 则差值为239-134=105 
  var maxRed = 105,maxGreen = 131,maxBlue = 55; 
  var level = colorLevel; 
  while(level--) { 
    colors.push( 'rgb('+red +','+green+','+blue+')'); 
    red += parseInt(maxRed/colorLevel); 
    green += parseInt(maxGreen/colorLevel); 
    blue += parseInt(maxBlue/colorLevel); 
  } 
  return colors; 
}