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  • html 图片上传预览

    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
    <html xmlns="http://www.w3.org/1999/xhtml" >
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title>本地图片预览</title>
    <style type="text/css">
    #_preview{100px;height:100px;border:1px solid #000;overflow:hidden;}
    #_imghead {filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=image);}
    </style>
    <script type="text/javascript">
    function previewImage(file) {
        //默认的image
        var MAXWIDTH  = 100;
        var MAXHEIGHT = 100;
    
        var div = document.getElementById('_preview');
        div.innerHTML = '<img id=_imghead>';
        img = document.getElementById('_imghead');
      
        if (file.files && file.files[0]) {
            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;
            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 style='"+rect.width+"px;height:"+rect.height+"px;margin-top:"+rect.top+"px;margin-left:"+rect.left+"px;"+sFilter+src+""'></div>";
        }
    }
    function clacImgZoomParam( maxWidth, maxHeight, width, height ){
        var param = {top:0, left:0, 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;
    }
    </script>
    </head>
    <body>
        <div id="_preview">
            <img id="_imghead" style=' 100px; height: 100' border=0 src='http://www.baidu.com/img/bdlogo.gif'>
        </div>
        <br/>
        <input type="file" onchange="previewImage(this)" />
    </body>
    </html>
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  • 原文地址:https://www.cnblogs.com/hzm112567/p/3757185.html
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