• 在上传图片前,提供预览功能(Javascript)


    <!-- TWO STEPS TO INSTALL IMAGE UPLOAD PREVIEW:

       1.   Copy the coding into the HEAD of your HTML document
       2.   Add the last code into the BODY of your HTML document   -->

    <!-- STEP ONE: Paste this code into the HEAD of your HTML document   -->

    <HEAD>

    <script type="text/javascript">
    <!-- Begin
    /* This script and many more are available free online at
    The JavaScript Source!!
    http://javascript.internet.com
    Created by: Abraham Joffe :: http://www.abrahamjoffe.com.au/ */

    /***** CUSTOMIZE THESE VARIABLES *****/

       // width to resize large images to
    var maxWidth=100;
       // height to resize large images to
    var maxHeight=100;
       // valid file types
    var fileTypes=["bmp","gif","png","jpg","jpeg"];
       // the id of the preview image tag
    var outImage="previewField";
       // what to display when the image is not valid
    var defaultPic="spacer.gif";

    /***** DO NOT EDIT BELOW *****/

    function preview(what){
       var source=what.value;
       var ext=source.substring(source.lastIndexOf(".")+1,source.length).toLowerCase();
       for (var i=0; i<fileTypes.length; i++) if (fileTypes[i]==ext) break;
       globalPic=new Image();
       if (i<fileTypes.length) globalPic.src=source;
       else {
         globalPic.src=defaultPic;
         alert("THAT IS NOT A VALID IMAGE\nPlease load an image with an extention of one of the following:\n\n"+fileTypes.join(", "));
       }
       setTimeout("applyChanges()",200);
    }
    var globalPic;
    function applyChanges(){
       var field=document.getElementById(outImage);
       var x=parseInt(globalPic.width);
       var y=parseInt(globalPic.height);
       if (x>maxWidth) {
         y*=maxWidth/x;
         x=maxWidth;
       }
       if (y>maxHeight) {
         x*=maxHeight/y;
         y=maxHeight;
       }
       field.style.display=(x<1 || y<1)?"none":"";
       field.src=globalPic.src;
       field.width=x;
       field.height=y;
    }
    // End -->
    </script>
    </HEAD>

    <!-- STEP TWO: Copy this code into the BODY of your HTML document   -->

    <BODY>

    <div align="center" style="line-height: 1.9em;">
    Test it by locating a valid file on your hard drive:
    <br>
    <input type="file" id="picField" onchange="preview(this)">
    <br>
    <img alt="Graphic will preview here" id="previewField" src="spacer.gif">
    <br> <div style="font-size: 7pt;">
    Script submitted by: <a href="
    http://www.abrahamjoffe.com.au/">Sydney Wedding Video / DVD</a></div>
    </div>

    <p><center>
    <font face="arial, helvetica" size"-2">Free JavaScripts provided<br>
    by <a href="
    http://javascriptsource.com">The JavaScript Source</a></font>
    </center><p>

  • 相关阅读:
    火车进出栈问题(卡特兰数)
    HDU 4699 Editor (对顶栈)
    HDU 6430 TeaTree (线段树合并)
    Exam 4895 Crowd Control
    Exam 4894 Booming Business
    8377: Playoff
    hdu 6345 Problem J. CSGO
    HDU 6437 Problem L.Videos
    Making the Grade
    poj2279——Mr. Young's Picture Permutations
  • 原文地址:https://www.cnblogs.com/mqingqing123/p/919025.html
Copyright © 2020-2023  润新知