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How to change renderer for ImageData



I'm trying to figure out how to change the markup that's rendered for an image. Alloy templates has a renderer registered for the type ImageFile, which is a content type that inherits from ImageData. That renderer tries to render a title and alt attribute, but unfortunately it doesn't work.

The property type is actually ContentReference, so should we register a renderer for that type instead?

This article mentions templates in the heading, but nothing in the article. The article says how to write a handler for the BLOB though, but not how to change the markup.

So, how do we do this?

Feb 27, 2014 18:29

It occured to me that you might be using webforms. In that case:

The ImageControl is used when an image is rendered in an content area. If you need to change the markup for an image property (ContentReference with UiHint set to "Image"), you should be able to create a new user control, and use a template descriptor with the image tag:


    [TemplateDescriptor(TagString = "Image")]
    public partial class Image : PropertyControlBase<ContentReference>



Much like how it is done with the "StringList"

Edited, Feb 27, 2014 19:40

Thank you Per!

But my code is never hit by the debugger, not even in the constructor. The url to the images changes in the markup though, so something is happening. The url becomes the url to the content data and not the actual url that the handler needs to serve the BLOB.

My code looks like this:

[TemplateDescriptor(TagString = UIHint.Image)]
public partial class ImageControl : PropertyControlBase<ContentReference>
    public ImageControl()
        var hitMe = true;



Feb 27, 2014 22:47

I'm seeing some inconsistent behavior when trying this out myself. Sometimes it uses the default renderer, and sometimes it uses the one I have defined. However, could you try changing tag/UiHint to "Image2"? That seem to work for me. Not a great solution though

Feb 27, 2014 23:11

My control is not chosen, even if I change the tag in the control and then in the rendering settings on the property control. But when I do, this is rendered instead:

<span><a href="/Views/Blocks/Promos/13">13</a></span>


Feb 27, 2014 23:19

Which is not the image url or the url to the image data. The url is to the block where the image property is defined.

Feb 27, 2014 23:20

Ok, the url thing seems to be a caching issue. Removed the images from the properties and re-added them. Then the urls are correct, but are rendered as a link. And not still able to use my custom control.

Edited, Feb 27, 2014 23:28

That is strange. This seem to work for me:

In a standard alloy 7.5 web forms site:

1. Modifed JumbotronBlock:

        public virtual ContentReference Image { get; set; }


2. Add new user control "Image.ascx"

 Control Language="C#" AutoEventWireup="true" CodeBehind="Image.ascx.cs" Inherits="EPiServer.Templates.Alloy.Views.Properties.Image" %>

<p>I can render anything here</p>


code behind:  

    [TemplateDescriptor(TagString = "Image2")]
    public partial class Image : PropertyControlBase<ContentReference>



3. "I can render anything here" is now rendered instead of the image. To render the Image I would have used the CurrentData object in the page load method, or something like that.


Feb 27, 2014 23:35

I think the reason why it wont work with the "image" tag is because of the PropertyImageReferenceControl, (EPiServer.Web.PropertyControls), which has a template descriptor set with the image tag.

Feb 27, 2014 23:36

Hmm I added the tag to the property control instead, if you add it to the content type, the editor can chose pages and other files as well. But it should pick up the tag from the property control.

I will do a test with another UIHint in the content model.

Feb 27, 2014 23:43

Alright, this is embarrassing. There was a merge issue and the property type was changed to Url instead of ContentReference! Now is my controled loaded!!! And it seems to work with the standard tag, UIHint.Image.

Feb 27, 2014 23:52

Ah. Great! Not sure why I had some inconsistent behavior when using the standard image tag though. It seemed the ordering of the registering of the built in property control and the custom property control changed from one restart of the site to another.

Feb 28, 2014 10:27
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