js前端实现多图图片上传预览的两个方法(推荐)

2019-11-19 18:57:02

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一、将图片转成icon码的实现方式

html代码：

<div class="yanzRight">	<input style="margin-top:5px;float: left;" id="st18" name="evidence" onchange="previewImage(this,5)" type="file"/>	<span class="dui" id="imgOrder_dui" style="display: none;"></span></div>	<div id="preview5" style="margin-left:150px;clear:both; padding-top:15px;">	<img src="" alt="" id="imghead5" height="200" width="200" style="display:none;"/></div>

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 ='<img id=imghead'+imgNum+'>';  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 = '<img id=imghead'+imgNum+'>'; 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 = "<div id=divhead"+imgNum+" style='width:"+rect.width+"px;height:"+rect.height+"px;margin-top:"+rect.top+"px;"+sFilter+src+"/"'></div>"; }}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

<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" /><title>测试页面</title><script type="text/javascript"> //下面用于多图片上传预览功能 function setImagePreviews(avalue) {  var docObj = document.getElementById("doc");  var dd = document.getElementById("dd");  dd.innerHTML = "";  var fileList = docObj.files;  for (var i = 0; i < fileList.length; i++) {      dd.innerHTML += "<div style='float:left' > <img id='img" + i + "' /> </div>";   var imgObjPreview = document.getElementById("img"+i);    if (docObj.files && docObj.files[i]) {    //火狐下，直接设img属性    imgObjPreview.style.display = 'block';    imgObjPreview.style.width = '150px';    imgObjPreview.style.height = '180px';    //imgObjPreview.src = docObj.files[0].getAsDataURL();    //火狐7以上版本不能用上面的getAsDataURL()方式获取，需要一下方式    imgObjPreview.src = window.URL.createObjectURL(docObj.files[i]);   }   else {    //IE下，使用滤镜    docObj.select();    var imgSrc = document.selection.createRange().text;    alert(imgSrc)    var localImagId = document.getElementById("img" + i);    //必须设置初始大小    localImagId.style.width = "150px";    localImagId.style.height = "180px";    //图片异常的捕捉，防止用户修改后缀来伪造图片    try {     localImagId.style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale)";     localImagId.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = imgSrc;    }    catch (e) {     alert("您上传的图片格式不正确，请重新选择!");     return false;    }    imgObjPreview.style.display = 'none';    document.selection.empty();   }  }   return true; }</script></head><body><div style="margin :0px auto; width:990px;"><input type="file" name="file" id="doc" multiple="multiple" style="width:150px;" onchange="javascript:setImagePreviews();" accept="image/*" /><div id="dd" style=" width:990px;"></div></div></body></html>

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