Wednesday, August 21, 2013

ASP.Net: drag and drop file uploads using HTML5 DND and File API.


Client-Side Script and UI

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Upload.aspx.cs" Inherits="upload.Upload" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <style>
body { padding:10px; font:14px/18px Calibri }
.bold { font-weight:bold }
td { padding:5px; border:1px solid #999 }
p, output { margin:10px 0 0 0 }
#drop_zone 

   margin:10px 0;
   width:40%; 
   min-height:150px; 
   text-align:center;
   text-transform:uppercase;
   font-weight:bold;
   border:8px dashed #898;
                height: 160px;
            }
</style>
    <title></title>
    <script>
        var files;
        function handleDragOver(event) {
            event.stopPropagation();
            event.preventDefault();
            var dropZone = document.getElementById('drop_zone');
            dropZone.innerHTML = "Drop now";
        }

        function handleDnDFileSelect(event) {
            event.stopPropagation();
            event.preventDefault();

            /* Read the list of all the selected files. */
             files = event.dataTransfer.files;

            /* Consolidate the output element. */
             var form = document.getElementById('form1');
             var data = new FormData(form);
           
             for (var i = 0; i < files.length; i++) {
                 data.append(files[i].name, files[i]);
             }
             var xhr = new XMLHttpRequest();
             xhr.onreadystatechange = function () {
                 if (xhr.readyState == 4 && xhr.status == 200 && xhr.responseText) {
                     alert("upload done!");
                 } else {
                     //alert("upload failed!");
                 }
             };
             xhr.open('POST', "Upload.aspx");
            // xhr.setRequestHeader("Content-type", "multipart/form-data");
             xhr.send(data);
            
        }
</script>
</head>
<body>
<form id="form1" runat="server" enctype="multipart/form-data">
        
        <br />
        <div id="drop_zone">Drop files here</div>
</form>
</body>
    <script>
        if (window.File && window.FileList && window.FileReader) {
            /************************************ 
             * All the File APIs are supported. * 
             * Entire code goes here.           *
             ************************************/


            /* Setup the Drag-n-Drop listeners. */
            var dropZone = document.getElementById('drop_zone');
            dropZone.addEventListener('dragover', handleDragOver, false);
            dropZone.addEventListener('drop', handleDnDFileSelect, false);
            
        }
        else {
            alert('Sorry! this browser does not support HTML5 File APIs.');
        }
</script>
</html>

Server-side (Upload.aspx.cs)

using System;
using System.IO;
using System.Web;

namespace upload
{
    public partial class Upload : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
         if (IsPostBack)
         {
             UploadFile(sender,e);
         }
        }
        protected void UploadFile(object sender, EventArgs e)
        {
            HttpFileCollection fileCollection = Request.Files;
            for (int i = 0; i < fileCollection.Count; i++)
            {
                HttpPostedFile upload = fileCollection[i];
                string filename ="c:\\Test\\" +  Path.GetRandomFileName();
                upload.SaveAs(filename);
            }
        }
    }

}

Thanks,
Din.