Theme

A theme is a collection of resource files that gives a site its visual identity through the use of colors and typography. A theme consists of Cascading Style Sheets (CSS), Javascript files and an imaging configuration which tells the Imaging module what to do with images for a particular page or component.

What is a theme?

A theme is a module or part of a module composed of CSS, JS, and images.

When to use a theme

The Site module provides theme functionality. You can only create a theme if you use this module and have configured a site definition.

Themes and modules

Theme resources can be stored in light (YAML) or Maven modules. Themes can reside in a dedicated theme module or form part of another module. A special module version handler is not necessary.

Resource loading

All Magnolia resources, including theme resources, are loaded under the /.resources ("dot resources") path.

• In a Maven module the resources are located in /src/main/resources/<moduleName> and any subfolder.
• In a light module resources can be located any subfolder of your module, for example, /<moduleName>/webresources/

Theme resources can also be loaded from an external source by specifying the full URL. This is very useful if you use a CDN to store, cache and deliver your static resources.

See Resources and Module structure for more.

Benefits of using a theme

Themes offer a number of benefits:

• Theme resources are applied to the entire site.
• Resources are all in one place.
• Themes are an easy way to work with resources without having to modify the head section of your HTML
• You can define more than one theme and switch between them, or apply a different theme to a variation of your site. For example, you could use a different theme for pages targeted at U.S. users and European users, or a seasonal theme for different times of the year.
• You can still use different or additional overriding resources on a page-template level.

Configuring a theme

Themes are configured in the Themes tab of the Site app.

Example: Travel demo theme.

Three configuration nodes define the individual elements of a theme:

CSS files

Links to CSS resources are configured in the cssFiles node of the theme.

CSS defines the presentation semantics of an HTML document, and creates the look and feel of the site. 

Example: cssFiles configurations.

Properties:

<!--[if lte IE9]>
	//inclusion of the stylesheet or javascript resource
<![endif]-->

This simple theme example uses only the default Bootstrap minimized CSS with no customizations.

JavaScript files

Links to JavaScripts are configured in the jsFiles node of the theme.

JavaScript is responsible for client-side functionality such as carousel paging, AJAX, menu animations, trees, embedded video player, mouse wheel support, Google Analytics and much more.

Example: jsFiles configuration.

Properties:

Here's an example JavaScript alert box using JQuery and the default Bootstrap minimized CSS.

Image variations

Themes can make use of the Imaging module to preconfigure image variations. A variation is a specific configuration that defines features of a target image. Variations can range from complex operations, such as applying filters and overlays, to simple resizing of the target image. 

Variations are an effective alternative to resizing images with CSS:

• Image size is reduced and less data transferred.
• Editors can upload images of any size which will automatically be resized to fit the template.
• Image sizes are uniform throughout the site.

Variations are configured in the imaging node of the theme.

Example: Travel demo theme.

Properties:

Configuring a simple resize

The SimpleResizeVariation class is suitable for most resize variations. It resizes the original image to a defined size in pixels.

Properties:

Behavior:

• Although both the width and height properties are optional you must configure at least one. If you omit both the renderer intentionally throws an internal ImagingException and the image displays in it's original uploaded size.
• If you define both width and height the image is sized down to the lower of the two and the rest is cropped, if necessary. Cropping starts from the middle, so the image is either cropped on top and bottom, or left and right.
• If you define only width or height, the omitted property is calculated using the aspect ratio of the original image.
• if you set crop to false, the image is resized to the specified size, and may be distorted (stretched).

See damfn and How to work with images using damfn for how to use variations in your scripts.

Assigning a theme to a site

Themes are assigned to a site in the theme node of the site definition in the Site Definitions tabl of the Site app. You can, for example, assign different themes to all defined variations of a site.

Example: Travel Demo Site Definition (CE)

Properties:

Using theme resources in template scripts

Theme resources are typically added to the <head> element of a page template.

• Retrieve the configured theme configured over the sitefn function class:

  [#assign site =
  sitefn.site()!]
  
  [#assign theme =
  sitefn.theme(site)!]

• Iterate over the theme configuration and include the configured resources:

  [#list theme.cssFiles as cssFile] 
      <link rel="stylesheet" href="${cssFile.link}" media="${cssFile.media}" />
  [/#list]
  
  [#list theme.jsFiles as jsFile]
      <script src="${jsFile.link}"></script>
  [/#list]