Responsive Images in Sitecore

By default, when you add an image to a page in Sitecore using the <sc:Image > control it will render height and width attributes on the resulting html. These are based on the images dimensions or any height and width properties you may have set server side.

The benefit of doing this is that when the browser renders the page, it already knows what space the image will take up before the image has loaded. This reduces the number of repaints the browser has to make and ultimately speeds up the page rendering time. If the height and width weren’t specified then a repaint would happen after the image was loaded as the size would now be known.

However this can cause an issue when you are producing a responsive site that changes its layout based on the size of a device or width of a browser window. Because responsive design is done though CSS media tags the server does not know what the height and width of the image will be, unfortunately there’s also no built in way to tell Sitecore to stop rendering the height and width tags. Not very good when you want to size your image to 100% width of an area that can change size.

The solution is to create a Pipeline. Pipelines are Sitecores way of enabling you change how Sitecore works and their not overly complex to implement.

To create a pipeline that will affect the way an Image field is rendered your first need to create a GetImageFieldValueResponsive class as follows. The name of the class can be anything you want but I’ve called it GetImageFieldValueResponsive as it will be called after Sitecores GetImageFieldValue class.

namespace SitecoreCustomization.Pipelines.RenderField
{
    public class GetImageFieldValueResponsive
    {
        public void Process(RenderFieldArgs args)
        {
            if (args.FieldTypeKey != "image")
                return;
            if (args.Parameters.ContainsKey("responsive"))
            {
                string imageTag = args.Result.FirstPart;
                imageTag = Regex.Replace(imageTag, @"(<img[^>]*?)\s+height\s*=\s*\S+", "$1", RegexOptions.IgnoreCase);
                imageTag = Regex.Replace(imageTag, @"(<img[^>]*?)\s+width\s*=\s*\S+", "$1", RegexOptions.IgnoreCase);
                imageTag = Regex.Replace(imageTag, @"(<img[^>]*?)\s+responsive\s*=\s*\S+", "$1", RegexOptions.IgnoreCase);
                args.Result.FirstPart = imageTag;
                
            }
        }
    }
}

The process function in the class is what will get called as the control is rendered. First it will check that the field type is an image and then will look to see if there is a parameter called responsive. This will allow us to control when Sitecore should output height and width tags and when it shouldn’t. Lastly some Regex is used to remove the height, width and responsive properties from the image tag that will already have been generated by this point.

Next we need to tell Sitecore to start using this pipeline. We do this by creating a RenderField.config file and placing it in the App_Config\Include folder of your Sitecore solution.

<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/">
  <sitecore>
    <pipelines>
      <renderField>
        <processor
            patch:after="*[@type='Sitecore.Pipelines.RenderField.GetImageFieldValue, Sitecore.Kernel']"
            type="SitecoreCustomization.Pipelines.RenderField.GetImageFieldValueResponsive, DLLNameOfWhereYouCreatedTheClass"/>
      </renderField>
    </pipelines>
  </sitecore>
</configuration>

Lastly your control will need to have an attribute to say it should be responsive. For an xslt rendering your code will look like this:

<sc:image field="Image" responsive="1" />

And for an ascx sublayout it will look like this:

<sc:Image runat="server" Field="Image" Parameters="responsive=1" />

UI resources for developers

Having a good UI is possibly one of the most important aspects of any development. It doesn’t matter how perfectly the code executes, if the thing looks awful people won’t use it. But it is an area that a lot of developers struggle with.

There have always been things like website skins that you can buy, but I’ve never been a huge fan of these. It’s always seemed odd that you can use an open source CMS for free that has had hundreds of man hours put into it, but a decent skin would cost you £100, and even then would still need a lot of work doing on it.

Thankfully there are some free resources that not only help with the css and making a site responsive, but they also include some fairly decent fonts and layouts.

Bootstrap


Bootstrap is possibly the most popular css framework for building sites with right now. Even Microsoft have adopted it into all the templates that ship with Visual Studio 2013.

One of the main things Bootstrap gives you is a standard set of css classes for doing things like grids and responsive layouts. When people start using a common set of classes to achieve the same thing, things get a lot more compatible and you can already see that starting to happen with Bootstrap.

Bootstraps grid system works on having the illusion that your page is divided up into 12 columns. You then have a set of classes to assign to a div that contain a number, that number is how many columns the div should span over. A bit like a colspan on a table.

These grids are responsive though so as your page shrinks down to a tablet and mobile size it will automatically recognise that the columns won’t fit horizontally and start rearranging them underneath each other.

As a starting point Bootstrap also has some templates of common layouts to get you started.

Bootstrap also has default classes for forms, form fields, headings and lists that will give your site an initial face lift.

Foundation

Foundation in many ways is very similar to Bootstrap. It also has a grid system for layouts and also helps with making a site responsive. There are also default styles for headings, lists and forms but they have also taken things a step further and started to encroach on jQuery UI’s territory with things like tabs and dialog windows.

I haven’t heard of as much industry support but there site is full of documentation and videos on how to use the framework.

Pure

Another CSS framework with yet another grid system. Pure appears to be much simpler than the first two and offers many of the same features. Their site has some good templates that in some ways cover more scenarios that Bootstraps. Personally out of the three I would go with Bootstrap as it appears to have a much higher adoption.

Normalize


If the CSS frameworks seem a little overkill for what you’re after have a look at Normalize. The concept is simple, by including this CSS file in your site as the first CSS file it will overwrite all the default browser styles to create consistency and something that looks a little nicer.

There’s been many incidents where I’ve seen CSS produced that includes a style for every single html element try overcome the differences on browsers, which is a good idea (this is basically what normalize does except someone’s written it for you), but the styles have all been set to the same thing which is generally margin:0, padding:0. On some elements this is fine, on lists though, not so much.

Another option I’ve seen is to define a style on *.* which is equally as bad.

 

Fit Text

Like it or not people are accessing sites from all kinds of devices these days with all kinds of screen sizes. If your site doesn’t scale then you’re going to lose visitors. One issue you will ultimately face at some point is font sizes. These can easily be changed using media queries but another option is to use FitText.

FitText is a really simple bit of JavaScript that will scale your text to fit its containing element. You do have to call a function for each element you want to scale, and it does only work on the width rather than taking the height into account. But it is very cool. Just make sure you have a look at the code because it’s so small this isn’t something you will want in a separate JS file.