Introduction
Here I will explain how to generate thumbnails from uploaded images and how to bind thumbnails to datalist using asp.net.
Description:
In previous post I explained clearly how to bind images from folder to datalist
. Now I will explain how to generate thumbnails from uploaded images
and how to bind those thumbnails to datalist using asp.net. In website
development sometimes we get requirement like generating thumbnails from
images without losing quality of image and it’s same like original
image. For that first create one new website after that right click on
that website select New Folder give name as Images because
here I am using same name if you want to use another name you need to
change the name in code also. After completion of adding Images folder to your website Design your aspx page like this
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title>Generate a Thumbnails from Uploaded Image</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:FileUpload ID="fileupload1" runat="server" />
<asp:Button ID="btnsave" runat="server" Text="Upload" onclick="btnsave_Click" />
</div>
<div>
<asp:DataList ID="dtlist" runat="server" RepeatColumns="3" CellPadding="5">
<ItemTemplate>
<asp:Image ID="Image1" ImageUrl='<%# Bind("Name", "~/Images/{0}") %>' runat="server" />
<br />
<asp:HyperLink ID="HyperLink1" Text='<%# Bind("Name") %>' NavigateUrl='<%# Bind("Name", "~/Images/{0}") %>' runat="server"/>
</ItemTemplate>
<ItemStyle BorderColor="Brown" BorderStyle="dotted" BorderWidth="3px" HorizontalAlign="Center"
VerticalAlign="Bottom" />
</asp:DataList>
</div>
</form>
</body>
</html>
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After that add following namespaces in code behind
using System.Collections;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.IO;
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After completion of adding namespaces write the following code
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
BindDataList();
}
}
protected void BindDataList()
{
DirectoryInfo dir = new DirectoryInfo(MapPath("Images"));
FileInfo[] files = dir.GetFiles();
ArrayList listItems = new ArrayList();
foreach (FileInfo info in files)
{
listItems.Add(info);
}
dtlist.DataSource = listItems;
dtlist.DataBind();
}
protected void btnsave_Click(object sender, EventArgs e)
{
string filename = Path.GetFileName(fileupload1.PostedFile.FileName);
string targetPath = Server.MapPath("Images/" + filename);
Stream strm = fileupload1.PostedFile.InputStream;
var targetFile = targetPath;
//Based on scalefactor image size will vary
GenerateThumbnails(0.07, strm, targetFile);
BindDataList();
}
private void GenerateThumbnails(double scaleFactor, Stream sourcePath, string targetPath)
{
using (var image = Image.FromStream(sourcePath))
{
var newWidth = (int)(image.Width * scaleFactor);
var newHeight = (int)(image.Height * scaleFactor);
var thumbnailImg = new Bitmap(newWidth, newHeight);
var thumbGraph = Graphics.FromImage(thumbnailImg);
thumbGraph.CompositingQuality = CompositingQuality.HighQuality;
thumbGraph.SmoothingMode = SmoothingMode.HighQuality;
thumbGraph.InterpolationMode = InterpolationMode.HighQualityBicubic;
var imageRectangle = new Rectangle(0, 0, newWidth, newHeight);
thumbGraph.DrawImage(image, imageRectangle);
thumbnailImg.Save(targetPath, image.RawFormat);
}
}
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Demo
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Download sample code attached
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