Imaging module

The Imaging module simplifies working with images. You don’t need to resize and crop each image by hand as the imaging engine generate variations on the fly. Administrators create the rules that determine the sizes of derivatives. Editors save time as they can select an image from the DAM or upload one, and it will be automatically adapted to match the rule.

Please note that the artifact IDs (Maven groupId and artifactId) have changed since Magnolia 5.5.

If you have custom Java code relying on this module, you need to install a compatibility module too.

To be sure, please check the module on our Bitbucket server.

Edition CE

License

MLA, GPL

Issues

MGNLIMG

Maven site

Imaging

Latest

3.4.4

Installing with Maven

Maven is the easiest way to install the module. Add the following to your bundle:

<dependency>
  <groupId>info.magnolia.imaging</groupId>
  <artifactId>magnolia-imaging</artifactId>
  <version>3.4.4</version>
</dependency>

Note the changes in groupId and artifactId since the 3.4 release.

Compatibility module

With Magnolia 5.6 we’ve begun removing the old Content API from our modules. If you have custom code relying on classes from the old imaging module then you must do one of two things:

  • Update your code for the new version of the imaging module.

  • Or you can use the magnolia-imaging-compatibility module together with the magnolia-core-compatibility module.

Add the following snippet to your POM file:

<dependency>
  <groupId>info.magnolia.imaging</groupId>
  <artifactId>magnolia-imaging-compatibility</artifactId>
  <version>3.4.4</version>
</dependency>

Image request processing

The diagram shows the elements of the Imaging module and how they interrelate (credit: Richard Unger).

image

Imaging servlet

ImagingServlet is registered in the Magnolia servlet filter chain in /server/filters/servlets/ImagingServlet. The servlet is responsible for generating images.

image

Image generators

ImageGenerator is a component that generates variants from a source image based on configuration. Generators are used by image provider classes to render images in the UI and on pages.

Generators are configured in {/modules/imaging/config/generators.

Example: Generator configurations

image

Property Description

generators

required

Generators configuration.

     <generator name>

required

The name of the image generator.

large, portrait and thumbnail are used in the UI to generate images in apps. mte generates image variations in a theme.

         class

required

The image generator class:

  • DefaultImageGenerator: Default image generator with provided OutputFormat and ImageOperation defaults.

  • ImageOperationChain: Image generator that delegates to a list of ImageOperation instances. This is the most commonly used generator class. It executes an operation chain and is used by large, portrait and thumbnail generators.

  • ThemeAwareImageGenerator: Theme-aware generator that handles image variations in a theme. Extends ImageOperationChain.

         outputFormat

required

Output format configuration.

         parameterProviderFactory

required

         operations

required (for ImageOperationChain only)

See the Image operation chains configuration.

Output format

The output format is the format or file type the generator produces, such as JPEG or PNG. Supported formats are bmp, gif, jpeg, jpg, png, and wbmp. The module also supports these formats and tiff as input formats . You can verify the available formats on your system by installing the Imaging Tools JAR file.

The Image I/O plugins app displays a list of supported file extensions.

The output format is configured in /modules/imaging/generators/<generator name>/outputFormat.

Example: Output format configurations

image

Property Description

outputFormat

required

Output format configuration. Defines the format the generator produces, such as jpg or png.

     quality

required

Image quality as a percentage.

     formatName

required (for ImageOperationChain only)

The file extension of the generated images.

ThemeAwareImageGenerator generates images in the same format as the source image. If you upload a jpg, this generator will produce a jpg.

Parameter provider factory

Parameters are instructions passed to an operation, such as where to load a source image or what text to lay over it. Registering a ParameterProviderFactory allows you to pass parameters from different sources:

The parameter provider factory is configured in /modules/imaging/generators/<generator name>/parameterProviderFactory.

image

Parameter provider classes:

info.magnolia.imaging.parameters.BinaryNodeIdentifierParameterProviderFactory

Node-based ParameterProviderFactory that tries to determine the Node by its identifier.

info.magnolia.imaging.parameters.BinaryNodePathParameterProviderFactory

Node-based ParameterProviderFactory that will tries to determine the Node by its path.

info.magnolia.templating.imaging.parameters.ThemeAwareParameterProviderFactory

Theme -aware ParameterProviderFactory.

info.magnolia.imaging.parameters.AbstractWorkspaceAndPathParameterProviderFactory

Superclass for parameter provider factories based on workspace and path.

info.magnolia.imaging.parameters.AbstractWorkspaceAndIdentifierParameterProviderFactory

Extracts workspace and identifier from the path. Everything after the identifier is ignored. This allows you, for example, to pass a properly named file name, to the image.

info.magnolia.imaging.parameters.AbstractWorkspaceAndUuidParameterProviderFactory

Extracts workspace and UUID from the path. Everything after the UUID is ignored. This allows you, for example to pass a properly named file name to the image.

Image operation chains

The Imaging module can resize and crop images, overlay text and apply image filters. These are called image operations and are configured in /modules/imaging/config/generators/<generator name>/operations. Image operations can also be configured in a theme.

An image operation chain consists of one or more operations. A simple chain could add only fixed text, while a more complex chain could load an image from a remote source, apply filters, add multiple text fields and style them differently.

Example: Image operation chain configuration

image

Property Description

<generator name>

required

Name of the image generator.

     operations

required

Operations node.

         <operation names>

required

One node for each operation in the chain, for example load, resize and overlay. The chain is executed from top to bottom.

             class

required

Operation class

             <properties>

required/optional

Other properties supported by the operation class.

The first operation in an operation chain is typically a load operation. Use load class FromBinaryNode to load an image from the DAM.

ParameterProviderFactory and load operation class typing

Note that ParameterProviderFactory and ParameterProvider implementations are typed. Let’s have a look at the interfaces:

ParameterProviderFactory

ParameterProvider

Return type of ParameterProviderFactory#newParameterProviderFor and the method argument in the class used for a load operation must have the same type!

For instance BinaryNodePathParameterProviderFactory (as ParameterProviderFactory) and FromBinaryNode work nicely together.

Creating a custom generator

You can create a custom image generator If the defaults do not meet your requirements:

  • Subclass ImageOperationChain.

  • Override getOutputFormat() method.

  • Set the value of the class node in configuration to your class name.

Imaging workspace

The imaging engine stores generated images in the imaging workspace.

The path where generated images are stored depends on the CachingStrategy. The default path is:

/<generatorName>
  /<workspaceName>
    /<path of node or property (nodedata)>

For the MTE generator, the path is:

/mte
  /<themeName>
    /<variationName>
      /<path of node or property (nodedata)>

For example:

/mte
  /travel-demo-theme
    /960x720
      /dam
        /tours
          /shark_brian_warrick_0824.JPG
            /jcr:content
             /generated image

When the image is rendered on a page, the URL to the generated image is:

/<CATALINA_HOME, contextPath>
  /.imaging (which is the Imaging servlet default path)
    /<generatorName>
      /<path to the cached image>

Here’s the same image generated by the portrait and mte generators in the JCR Browser app. The 960x720 variation is configured in the travel-demo-theme.

image

Viewing generated images

The syntax for the URL to request a generated image depends on the used ParameterProviderFactory. However, it usually has the following pattern:

<protocol>://<context>/.imaging/<generator name>/<specific parameters ...>

Here is an example of a path when using BinaryNodePathParameterProviderFactory:

<protocol>:<context>/.imaging/<generator-name>/<jcr-workspace-name>/<path-to-binary-node>.<suffix-according-to-output-type>

Caching

Magnolia caches image resources to improve performance. Any dynamic images generated by the Imaging module are cached at two levels: in the imaging workspace and in the actual cache like any other page or document. This means that once the system generates an image, you keep getting the same cached image on subsequent requests.

During testing, you can disable caching of generated images completely. In /modules/imaging/config, create a new property named storeGeneratedImages and set the value to false.

image

There is still a small delay between configuration changes and a new image being available. Magnolia’s observation mechanism intentionally waits a couple of seconds before reading a changed configuration.

Imaging support

Imaging support is enabled by 3 Magnolia modules:

magnolia-imaging-support

ImagingSupport

The support interface for imaging.

magnolia-dam-imaging

ImagingBasedAssetRenderer

Asset renderer that uses ImagingSupport to generate renditions.

magnolia-templating-essentials-imaging

ThemeDelegatingImagingSupport

ImagingSupport that delegates to a Theme.

Image variations in a theme

A variation is a theme-specific configuration that defines the size of the target image and tells the imaging engine whether cropping is allowed. Variations are configured in a theme which allows you to configure image look and feel in the same place as CSS.

Configuring an image operation in a variation

Example: /modules/site/config/themes/travel-demo-theme/imaging/variations

image

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