Mime Types/Category

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The hildon-mime-category API

This document describes how the hildon_mime_category_* API works in the system.

Note: This document assumes familiarity with adding MIME types to the system, using the shared-mime-info specification.

The utility that is used when working with MIME categories is: 

hildon-update-category-database

Categories

The platform has a notion of file categories for the user's data files. The available categories are:

  • Bookmarks
  • Contacts
  • Documents
  • Emails
  • Images
  • Audio
  • Video
  • Other

A mapping is setup between categories and MIME types, so that the MIME type of a file decides which category it is in. The MIME type setup is handled by the shared-mime-info infrastructure, and the category information is added to that same framework.

There is also a category API in libhildonmime that is used to get the category of a certain MIME type and a list of MIME types in a certain category.

See the API documentation for libhildonmime for more details on this.


Adding mappings

Adding a mapping between a category and a number of MIME types is done much like adding or editing the supported MIME types in the system.

Each application or library that adds a category mapping should add a file in: 

 $(prefix)/share/mime/packages/

The file format is the same XML format used for MIME types, with an added tag "<osso:category>". An example follows: 


 <mime-info xmlns="http://www.freedesktop.org/standards/shared-mime-info"
            xmlns:osso="http://nokia.com/osso/mime-categories">
   <mime-type type="application/pdf">
     <osso:category name="documents"/>
   </mime-type>
   <mime-type type="image/jpeg">
     <osso:category name="images"/>
   </mime-type>
   <mime-type type="image/png">
     <osso:category name="images"/>
   </mime-type>
 </mime-info>


The example sets up three mappings, between PDF files and the Document category, and between JPEG and PNG images and the Images category.

The valid category names are: audio, bookmarks, contacts, documents, emails, images, video

MIME types that does not have a category set up automatically are treated as members in the category Other.

If the application also adds the MIME type in question, the MIME information and category information can be put in the same file: 

   <mime-type type="image/png">
     <comment>PNG image</comment>
     <magic priority="50">
       <match value="\x89PNG" type="string" offset="0"/>
     </magic>
     <glob pattern="*.png"/>
     <osso:category name="images"/>
   </mime-type>


As when adding MIME types, a special program needs to be run to update the MIME information, for example: 

 hildon-update-category-database /usr/share/mime

Like update-mime-database, this is usually done in the post-inst phase in a Debian package, in addition to "make install" in the makefile target.

Retrieved from "http://wiki.maemo.org/Mime_Types/Category"