<div id='wrap'>
  <ul class='justify'>
   <li>
    <a href="javascript:;" class="no_selected"></a>
    <div class='photo_mask'></div>
    <div>
     <div class="dummy"></div>
     <p><img><i></i></p>
    </div>
   </li>
   <li class='justify_fix'></li>
  </ul>
 </div>
inline-block+flex-box+text-align:justify

li{
 margin:0 1%;
 ...
}
#wrap{
 padding:0 1%;
}

li{
 list-style-type: none;
 display:inline-block;
 *display: inline;
 zoom:1;
 max-width: 200px;
 max-height: 200px;
 width: 28%;
 border:1px solid red;
 position: relative;
 overflow: hidden;
 margin:10px 2%;
}
li[class='justify_fix']{
 border:none;
}
.justify {
 display: flex;
 align-items: flex-start;
 flex-flow: row wrap;
 justify-content: space-between;
 text-align: justify;
 text-justify: inter-ideograph;
 *zoom: 1; 
 -moz-text-align-last: justify;
 -webkit-text-align-last: justify;
 text-align-last: justify;
}
@media (-webkit-min-device-pixel-ratio:0) {
 .justify:after {
  content: "";
  display: inline-block;
  width: 100%;
 }
}

<div id='wrap' ms-controller='photo_sort'>
  <ul class='justify'>
   <li ms-repeat='photo_list'>
    <a href="javascript:;" class="no_selected" ms-class-selected_icon='selected_index.indexOf($index)>-1' ms-click='select($index)'></a>
    ...
   </li>
   <li class='justify_fix'></li>
  </ul>
 </div>

var photo_sort=avalon.define({
 selected_index:[],//选中图片的index列表,
 ...
 select:function(i){
  var selected_index=photo_sort.selected_index;
  if(selected_index.indexOf(i)==-1)//选中图片的index列表不存在，添加
   photo_sort.selected_index.ensure(i);
  else
   photo_sort.selected_index.remove(i);
 }
});

<a href="javascript:;" class="no_selected" ms-class-selected_icon='selected_index.indexOf($index)>-1' ms-click='select($index)'></a>
<div class='photo_mask' ms-mousedown='start_drag($event,$index)'></div>
  var photo_sort=avalon.define({
   $id:'photo_sort',
   photo_list:[],//图片列表
   selected_index:[],//选中图片的index列表
   drag_flag:false,
   sort_array:[],//范围列表,
   cell_size:0,//每个单元格尺寸，这里宽高比为1
   target_index:-1,//最终目标位置的index
   col_num:0,//列数
   x_index:-1,//当前拖动位置的x方向index
   ...
  });
start_drag:function(e,index){
 if(photo_sort.selected_index.size()){//有选中的图片
  photo_sort.target_index=index;//避免用户没有拖动图片，但点击了图片，设置默认目标即当前点击图片
  photo_sort.cell_size=this.clientWidth;
  var xx=e.clientX-photo_sort.cell_size/2,yy=e.clientY-photo_sort.cell_size/2;//点下图片，设置代理位置以点击点为中心
  $('drag_proxy').style.top=yy+avalon(window).scrollTop()+'px';
  $('drag_proxy').style.left=xx+'px';
  $('drag_proxy').style.width=photo_sort.cell_size+'px';
  $('drag_proxy').style.height=photo_sort.cell_size+'px';
  drag_proxy.select_num=photo_sort.selected_index.length;//设置代理中选择图片的数量
  if(drag_proxy.select_num>0){
   var drag_img=photo_sort.photo_list[photo_sort.selected_index[drag_proxy.select_num-1]];
   drag_proxy.src=drag_img.src;//将选中的图片中最后一张作为代理对象的"封面"
   photo_sort.drag_flag=true;
   $('drag_proxy').style.display='block';
  }
  //cell_gap:图片间间距,first_gap:第一张图片和外部div间间距
  var wrap_width=avalon($('wrap')).width(),wrap_offset=$('wrap').offsetLeft,first_left=$('wrap_photo0').offsetLeft,
  second_left=$('wrap_photo1').offsetLeft,first_gap=first_left-wrap_offset,cell_gap=second_left-first_left;
  photo_sort.col_num=Math.round((wrap_width-2*first_gap+(cell_gap-photo_sort.cell_size))/cell_gap);
  for(var i=0;i<photo_sort.col_num;i++)//把一行图片里的每张图片中心坐标x方向的值作为分割点，添加到范围列表
   photo_sort.sort_array.push(first_gap+cell_gap*i+photo_sort.cell_size/2);
  var target=this.parentNode;
  avalon.bind(document,'mouseup',function(e){
   onMouseUp(target);
  });
  if(isIE)
   target.setCapture();//让ie下拖动顺滑
  e.stopPropagation();
  e.preventDefault();
 }
}

<div class='photo_mask' ms-class-photo_maskon='drag_flag&&selected_index.indexOf($index)>-1' 
ms-mousedown='start_drag($event,$index)'></div>

drag_move:function(e){
 if(photo_sort.drag_flag){
  var xx=e.clientX,yy=e.clientY,offset=avalon($('wrap')).offset();
  var offsetX=xx-offset.left,offsetY=yy-offset.top;
  photo_sort.sort_array.push(offsetX);//把当前鼠标位置添加的范围列表
  photo_sort.sort_array.sort(function(a,b){//对范围列表排序
   return parseInt(a)-parseInt(b);//转为数值类型,否则会出现'1234'<'333'
  });
  //从已排序的范围列表中找出当前鼠标位置的index,即目标位置水平方向的index
  var x_index=photo_sort.sort_array.indexOf(offsetX),y_index=Math.floor(offsetY/(photo_sort.cell_size+20)),
  size=photo_sort.photo_list.size();
  photo_sort.x_index=x_index;
  photo_sort.target_index=photo_sort.col_num*y_index+x_index;//目标在所有图片中的index
  if(photo_sort.target_index>size)//目标位置越界
   photo_sort.target_index=size;
  photo_sort.sort_array.remove(offsetX);//移除当前位置
  $('drag_proxy').style.top=avalon(window).scrollTop()+yy-photo_sort.cell_size/2+'px';
  $('drag_proxy').style.left=xx-photo_sort.cell_size/2+'px';
 }
 e.stopPropagation();
}

var target;
if(x>50+50){
 if(x>3*100+3*100+50+50){//最后一部分
  target=4;
 }else{
  target=(x-50-50)/(50+100+50);
 }
}else
 target=0;

.prev{
 right: 40px;
}
.next{
 left: 40px;
}
 <div id='wrap' ms-controller='photo_sort'>
  <ul class='justify' ms-mousemove='drag_move($event)'>
   <li ms-repeat='photo_list' ms-attr-id='wrap_photo{{$index}}' ms-class-prev='$index==target_index-1' 
   ms-class-next='$index==target_index'>
   ...
   </li>
   <li class='justify_fix'></li>
  </ul>
 </div>

<li ms-repeat='photo_list' ms-attr-id='wrap_photo{{$index}}' ms-class-prev='$index==target_index-1&&x_index>0' 
ms-class-next='$index==target_index&&x_index<col_num'>
...
</li>

function onMouseUp(target){
   if(photo_sort.drag_flag){
    for(var i=0,len=photo_sort.selected_index.size();i<len;i++){//遍历选中图片
     var item_index=photo_sort.selected_index[i],data=photo_sort.photo_list,
     target_index=photo_sort.target_index,temp;
     if(item_index<target_index){//目标位置在选中图片之后
      temp=data[item_index].src;
      for(var j=item_index;j<target_index;j++)
       data[j].src=data[j+1].src;
      data[target_index-1].src=temp;
     }else{//目标位置在选中图片之前
      temp=data[item_index].src;
      for(var j=item_index;j>target_index;j--)
       data[j].src=data[j-1].src;
      data[target_index].src=temp;
     }
    }
    photo_sort.target_index=-1;//各种重置，初始化
    photo_sort.sort_array=[];
    photo_sort.col_num=0;
    photo_sort.x_index=-1;
    photo_sort.selected_index=[];
    $('drag_proxy').style.display='none';
    photo_sort.drag_flag=false;
    avalon.unbind(document,'mouseup');
    if(isIE)
     target.releaseCapture();
   }
  }