上一张下一张

/*
* 改变灰度图索引，下一张，上一张
* */
function GrayImageChangeIndex(type) {
  if(type=='up'){
    GrayImagePlayIndex--;
    if(GrayImagePlayIndex<0){
      GrayImagePlayIndex=GrayImagePlayLength-1;
    }
  }else{
    GrayImagePlayIndex++;
    if(GrayImagePlayIndex>=GrayImagePlayLength){
      GrayImagePlayIndex=0;
    }
  }
  GrayImageLayerLayer.getSource().setPlayIndexWithAnimation(GrayImagePlayIndex);

}