CODEWITHSUNDEEP
asp.netinternet-explorer-6ajax.netimage-caching
youwhut
youwhut

Reputation: 948

Migrated Web Forms Application .NET 2.0 -> 3.5, new infrastructure - Images Not Caching in IE 6

I have been migrating a .NET 2.0 web forms application to use .NET 3.5 and a new infrastructure. There is a GridView inside an UpdatePanel, with an Actions column which contains icons to perform an action for that row. A problem that I am having in IE 6 is that images are not caching. This is particularly noticeable on the Actions column because there are 9 icons x 100 rows = 900 icons to load. Internet Explorer counts down these images from 900 until they are all loaded.

This problem does not appear to be limited to the images inside the GridView which is inside an UpdatePanel because I can see header images being reloaded each time there is a page refresh.

I have done my research:

Please let me know if I can provide other information.

UPDATE 1

Workarounds which have already been attempted with no success:

UPDATE 2

Some of the other solutions may have worked here but I have gone with the code provided by @Afshin Gh.

Upvotes: 2

Views: 247

Answers (4)

Aristos
Aristos

Reputation: 66641

I suggest to set this cache parameters on header.

Response.Cache.AppendCacheExtension("post-check=900, pre-check=3600");

You can read more about here http://www.rdlt.com/cache-control-post-check-pre-check.html or google it.

Check it out and tell me if this solve your issue.

Upvotes: 1

Drew Freyling
Drew Freyling

Reputation: 1258

Does fiddler show cache control: private for other browsers as well? If so they won't be cached either. Are you using a custom control to serve up the images in the grid? If so you probably aren't handling the cache headers correctly (including 304 responses etc).

Upvotes: 1

Afshin Gh
Afshin Gh

Reputation: 8198

Use this handler: 

Public NotInheritable Class ImageHandler
    Implements IHttpHandler

    Private Const REQUEST_KEY As String = "pic"

    Public ReadOnly Property IsReusable() As Boolean Implements System.Web.IHttpHandler.IsReusable
        Get
            Return False
        End Get
    End Property

    Public Sub ProcessRequest(ByVal context As System.Web.HttpContext) Implements System.Web.IHttpHandler.ProcessRequest
        If Not String.IsNullOrEmpty(context.Request.QueryString(REQUEST_KEY)) Then
            Dim fileName As String = context.Request.QueryString(REQUEST_KEY)

            Try

                Dim fileInfo As New IO.FileInfo(context.Server.MapPath(fileName))

                If fileInfo.Exists Then
                    context.Response.Cache.SetCacheability(HttpCacheability.Public)
                    context.Response.Cache.SetExpires(Date.Now.AddYears(1))

                    Dim fileExt As String = fileInfo.Extension.Remove(0, 1).ToUpperInvariant

                    If fileExt = "JPG" Then
                        context.Response.ContentType = "image/jpeg"
                    Else
                        context.Response.ContentType = "image/" & fileExt
                    End If

                    context.Response.TransmitFile(fileInfo.FullName)

                End If

            Catch ex As Exception
            End Try

        End If
    End Sub

End Class

Register it in your web.config:

    <httpHandlers>
        <add verb="*" path="image.axd" type="MyApp.ImageHandler, MyApp" validate="false"/>
    </httpHandlers>

Use it like this:

<img src="image.axd?pic=/App_Themes/Modern/Logo.jpg" />

Upvotes: 1

David
David

Reputation: 430

Have you tried adding the 9 images to the top of your page (outside the update panel) but set to hidden?

<asp:Image ID="Image1" ImageUrl = "images/img1.jpg" runat="server" style = "visibility:hidden" />
<asp:Image ID="Image2" ImageUrl = "images/img2.jpg" runat="server" style = "visibility:hidden" />
<asp:Image ID="Image3" ImageUrl = "images/img3.jpg" runat="server" style = "visibility:hidden" />
...
<asp:Image ID="Image9" ImageUrl = "images/img9.jpg" runat="server" style = "visibility:hidden" />

Upvotes: 0

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