js前端实现多图图片上传预览的两个方法(推荐)

一、将图片转成icon码的实现方式

html代码：

js代码

//图片预览功能
function previewImage(file,imgNum)
{
 var MAXWIDTH = 200; 
 var MAXHEIGHT = 200;
 var div = document.getElementById('preview'+imgNum);
 if (file.files && file.files[0])
 {
  div.innerHTML ='';
  var img = document.getElementById('imghead'+imgNum+'');
  img.onload = function(){
  var rect = clacImgZoomParam(MAXWIDTH, MAXHEIGHT, img.offsetWidth, img.offsetHeight);
  img.width = rect.width;
  img.height = rect.height;
//   img.style.marginLeft = rect.left+'px';
  img.style.marginTop = rect.top+'px';
  }
  var reader = new FileReader();
  reader.onload = function(evt){img.src = evt.target.result;}
  reader.readAsDataURL(file.files[0]);
 }
 else //
 {
 var sFilter='filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale,src="';
 file.select();
 var src = document.selection.createRange().text;
 div.innerHTML = '';
 var img = document.getElementById('imghead2');
 img.filters.item('DXImageTransform.Microsoft.AlphaImageLoader').src = src;
 var rect = clacImgZoomParam(MAXWIDTH, MAXHEIGHT, img.offsetWidth, img.offsetHeight);
 status =('rect:'+rect.top+','+rect.left+','+rect.width+','+rect.height);
 div.innerHTML = "";
 }
}
function clacImgZoomParam( maxWidth, maxHeight, width, height ){
 var param = {top:0, left:0, width:width, height:height};
 if( width>maxWidth || height>maxHeight )
 {
  rateWidth = width / maxWidth;
  rateHeight = height / maxHeight;

  if( rateWidth > rateHeight )
  {
   param.width = maxWidth;
   param.height = Math.round(height / rateWidth);
  }else
  {
   param.width = Math.round(width / rateHeight);
   param.height = maxHeight;
  }
 }
 param.left = Math.round((maxWidth - param.width) / 2);
 param.top = Math.round((maxHeight - param.height) / 2);
 return param;
}

二、使用js的另一种方法一次选中多个图片预览展示

以上这篇js前端实现多图图片上传预览的两个方法(推荐)就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持考高分网。