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jQuery implements local preview and upload image function_jquery

WBOY
WBOYOriginal
2016-05-16 15:21:021225browse

This article introduces the example of the image upload preview plug-in based on the JQUERY extension. It is currently compatible with browsers (IE, Google Firefox) and does not support Safari. It is shared with everyone for your reference. The specific content is as follows

HTML code: 

<html>
<head>
<title>图片上传预览演示</title>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js" type="text/javascript"></script>
<script src="16/uploadPreview.js" type="text/javascript"></script>
<script>
$(function () {
$("#up").uploadPreview({ Img: "ImgPr", Width: 120, Height: 120 });
});
</script>
</head>
<body>
<div style="width:500px;margin:0px auto;"><h2>图片上传预览演示</h2>
<a href="# target="_blank">原文</a>

<div><img id="ImgPr" width="120" height="120" /></div>
<input type="file" id="up" />
</div>

</body>
</html>

js code: 

*参数说明: Img:图片ID;Width:预览宽度;Height:预览高度;ImgType:支持文件类型;Callback:选择文件显示图片后回调方法;
*使用方法: 
<div>
<img id="ImgPr" width="120" height="120" /></div>
<input type="file" id="up" />
把需要进行预览的IMG标签外 套一个DIV 然后给上传控件ID给予uploadPreview事件
$("#up").uploadPreview({ Img: "ImgPr", Width: 120, Height: 120, ImgType: ["gif", "jpeg", "jpg", "bmp", "png"], Callback: function () { }});
*/
jQuery.fn.extend({
uploadPreview: function (opts) {
var _self = this,
_this = $(this);
opts = jQuery.extend({
Img: "ImgPr",
Width: 100,
Height: 100,
ImgType: ["gif", "jpeg", "jpg", "bmp", "png"],
Callback: function () {}
}, opts || {});
_self.getObjectURL = function (file) {
var url = null;
if (window.createObjectURL != undefined) {
url = window.createObjectURL(file)
} else if (window.URL != undefined) {
url = window.URL.createObjectURL(file)
} else if (window.webkitURL != undefined) {
url = window.webkitURL.createObjectURL(file)
}
return url
};
_this.change(function () {
if (this.value) {
if (!RegExp("\.(" + opts.ImgType.join("|") + ")$", "i").test(this.value.toLowerCase())) {
alert("选择文件错误,图片类型必须是" + opts.ImgType.join("，") + "中的一种");
this.value = "";
return false
}
if ($.browser.msie) {
try {
$("#" + opts.Img).attr('src', _self.getObjectURL(this.files[0]))
} catch (e) {
var src = "";
var obj = $("#" + opts.Img);
var div = obj.parent("div")[0];
_self.select();
if (top != self) {
window.parent.document.body.focus()
} else {
_self.blur()
}
src = document.selection.createRange().text;
document.selection.empty();
obj.hide();
obj.parent("div").css({
'filter': 'progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale)',
'width': opts.Width + 'px',
'height': opts.Height + 'px'
});
div.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = src
}
} else {
$("#" + opts.Img).attr('src', _self.getObjectURL(this.files[0]))
}
opts.Callback()
}
})
}
});

Go directly to the second piece of code, jquery js implements previewing local images before uploading them 

<style type="text/css">
#preview_wrapper{  
  display:inline-block;  
  width:300px;  
  height:300px;  
  background-color:#CCC;
}  
#preview_fake{  
  filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale);  
}  
#preview_size_fake{  
  filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=image);   
  visibility:hidden;  
}  
#preview{  
  width:300px;  
  height:300px;  
}  
</style>

<script type="text/javascript">
function onUploadImgChange(sender){  
  if( !sender.value.match( /.jpg|.gif|.png|.bmp/i ) ){  
    alert('图片格式无效！');  
    return false;  
  }
  var objPreview = document.getElementByIdx_x('preview');  
  var objPreviewFake = document.getElementByIdx_x('preview_fake');  
  var objPreviewSizeFake = document.getElementByIdx_x('preview_size_fake');
  if( sender.files && sender.files[0] ){  
    objPreview.style.display = 'block';  
    objPreview.style.width = 'auto';  
    objPreview.style.height = 'auto';  
      
    // Firefox 因安全性问题已无法直接通过 input[file].value 获取完整的文件路径  
    objPreview.src = sender.files[0].getAsDataURL();    
  }else if( objPreviewFake.filters ){  
    // IE7,IE8 在设置本地图片地址为 img.src 时出现莫名其妙的后果  
    //（相同环境有时能显示，有时不显示），因此只能用滤镜来解决  
      
    // IE7, IE8因安全性问题已无法直接通过 input[file].value 获取完整的文件路径  
    sender.select();  
    var imgSrc = document.selection.createRange().text;  
      
    objPreviewFake.filters.item(  
      'DXImageTransform.Microsoft.AlphaImageLoader').src = imgSrc;  
    objPreviewSizeFake.filters.item(  
      'DXImageTransform.Microsoft.AlphaImageLoader').src = imgSrc;  
      
    autoSizePreview( objPreviewFake,  
      objPreviewSizeFake.offsetWidth, objPreviewSizeFake.offsetHeight );  
    objPreview.style.display = 'none';  
  }  
}  
 
function onPreviewLoad(sender){  
  autoSizePreview( sender, sender.offsetWidth, sender.offsetHeight );  
}  
 
function autoSizePreview( objPre, originalWidth, originalHeight ){  
  var zoomParam = clacImgZoomParam( 300, 300, originalWidth, originalHeight );  
  objPre.style.width = zoomParam.width + 'px';  
  objPre.style.height = zoomParam.height + 'px';  
  objPre.style.marginTop = zoomParam.top + 'px';  
  objPre.style.marginLeft = zoomParam.left + 'px';  
}  
 
function clacImgZoomParam( maxWidth, maxHeight, width, height ){  
  var param = { width:width, height:height, top:0, left:0 };  
    
  if( width>maxWidth || height>maxHeight ){  
    rateWidth = width / maxWidth;  
    rateHeight = height / maxHeight;  
      
    if( rateWidth > rateHeight ){  
      param.width = maxWidth;  
      param.height = height / rateWidth;  
    }else{  
      param.width = width / rateHeight;  
      param.height = maxHeight;  
    }  
  }  
    
  param.left = (maxWidth - param.width) / 2;  
  param.top = (maxHeight - param.height) / 2;  
    
  return param;  
}
</script>
 
<input name="localfile" type="file" id="localfile" size="28" onchange="onUploadImgChange(this)"/>
 
<!--以下是预览图片用的-->
<div id="preview_wrapper">
<div id="preview_fake">
<img id="preview" src="" onload="onPreviewLoad(this)"/>
</div>
</div>
<br/>
<img id="preview_size_fake" />

The above is the entire content of this article, I hope it will be helpful to everyone’s study.

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