Difference between revisions of "Desktop entries"

From ArchWiki
Jump to: navigation, search
(Application entry)
m (Application entry)
Line 12: Line 12:
 
==Application entry==
 
==Application entry==
  
Desktop entries for applications or {{ic|.desktop}} files are generally a combination of meta information resources and a shortcut of an application. These files usually reside in {{ic|/usr/share/applications}} for systemwide installed applications or {{ic|~/.local/shar/applications}} for user specific applications.  
+
Desktop entries for applications or {{ic|.desktop}} files are generally a combination of meta information resources and a shortcut of an application. These files usually reside in {{ic|/usr/share/applications}} for systemwide installed applications or {{ic|~/.local/share/applications}} for user specific applications.  
  
 
===File example===
 
===File example===

Revision as of 19:56, 5 July 2013

Desktop entries is a freedesktop.org standard for specifying the behaviour of programs running on X Window Systems. It is a configuration file that describe how an application is launched and how it appears in a menu with an icon. The most common desktop entries are the .desktop and .directory files. This article explains briefly how to create useful and standard compliant desktop entries. It is mainly intended for package contributors and maintainers, but may also be useful for software developers and others.

Note: A lot of applications do not have a desktop entry by default or they have one that could be improved. To participate in creating and maintaining desktop entries, please join the Arch Desktop Project.

There are roughly three types of desktop entries:

Application 
a shortcut to an application
Link 
a shortcut to a web link.
Directory 
a container of meta data of a menu entry

The following sections will roughly explain how these are created and validated.

Application entry

Desktop entries for applications or .desktop files are generally a combination of meta information resources and a shortcut of an application. These files usually reside in /usr/share/applications for systemwide installed applications or ~/.local/share/applications for user specific applications.

File example

Following is an example of its structure with additional comments. The example is only meant to give a quick impression, and does not show how to utilize all possible entry keys. The complete list of keys can be found in the freedesktop.org specification.

[Desktop Entry]
Type=Application                          # Indicates the type as listed above
Version=1.0                               # The version of the desktop entry specification to which this file complies
Name=jMemorize                            # The name of the application
Comment=Flash card based learning tool    # A comment which can/will be used as a tooltip
Exec=jmemorize                            # The executable of the application.
Icon=jmemorize                            # The name of the icon that will be used to display this entry
Terminal=false                            # Describes whether this application needs to be run in a terminal or not
Categories=Education;Languages;Java;      # Describes the categories in which this entry should be shown

Key definition

All Desktop recognized desktop entries can be found on the site of the project Freedesktop.org site on the following link. For example the Type key defines 3 types of desktop entries: Application (type 1), Link (type 2) and Directory (type 3).

  • Version key does not stand for the version of the application, but for the version of the desktop entry specification to which this file complies.
  • Name, GenericName and Comment often contain redundant values in the form of combinations of them, like:
Name=Pidgin Internet Messenger
GenericName=Internet Messenger

or

Name=NoteCase notes manager
Comment=Notes Manager 

This should be avoided, as it will only be confusing to users. The Name key should only contain the name, or maybe an abbreviation/acronym if available.

  • GenericName should state what you would generally call an application that does what this specific application offers (i.e. Firefox is a "Web Browser").
  • Comment is intended to contain any usefull additional information.

Deprecation

There are quite some keys that have become deprecated over time as the standard has matured. The best/simplest way is to use the tool desktop-file-validate which is part of the package desktop-file-utils. To validate, run

$ desktop-file-validate <your desktop file>

This will give you very verbose and useful warnings and error messages.

Icons

Common image formats

Here is a short overview of image formats commonly used for icons.

Support for image formats for icons as specified by the freedesktop.org standard.
Extension Full Name and/or Description Graphics Type Container Format Supported
.png Portable Network Graphics Raster no yes
.svg(z) Scalable Vector Graphics Vector no yes (optional)
.xpm X PixMap Raster no yes (deprecated)
.gif Graphics Interchange Format Raster no no
.ico MS Windows Icon Format Raster yes no
.icns Apple Icon Image Raster yes no

Converting icons

If you stumble across an icon which is in a format that is not supported by the freedesktop.org standard (like gif or ico), you can convert (which is part of the imagemagick package) it to a supported/recommended format, e.g.:

$ convert <icon name>.gif <icon name>.png             /* Converts from gif to png */

If you convert from a container format like ico, you will get all images that were encapsulated in the ico file in the form <icon name>-<number>.png. If you want to know the size of the image, or the number of images in a container file like ico you can use identify (also part of the imagemagick package)

$ identify /usr/share/vlc/vlc48x48.ico
/usr/share/vlc/vlc48x48.ico[0] ICO 32x32 32x32+0+0 8-bit DirectClass 84.3kb
/usr/share/vlc/vlc48x48.ico[1] ICO 16x16 16x16+0+0 8-bit DirectClass 84.3kb
/usr/share/vlc/vlc48x48.ico[2] ICO 128x128 128x128+0+0 8-bit DirectClass 84.3kb
/usr/share/vlc/vlc48x48.ico[3] ICO 48x48 48x48+0+0 8-bit DirectClass 84.3kb
/usr/share/vlc/vlc48x48.ico[4] ICO 32x32 32x32+0+0 8-bit DirectClass 84.3kb
/usr/share/vlc/vlc48x48.ico[5] ICO 16x16 16x16+0+0 8-bit DirectClass 84.3kb

As you can see, the example ico file, although its name might suggest a single image of size 48x48, contains no less than 6 different sizes, of which one is even greater than 48x48, namely 128x128. And to give a bit of motivation on this subject, at the point of writing this section (2008-10-27), the 128x128 size was missing in the vlc package (0.9.4-2). So the next step would be to look at the vlc PKGBUILD and check whether this icon format was not in the source package to begin with (in that case we would inform the vlc developers), or whether this icon was somehow omitted from the Arch-specific package (in that case we can file a bug report at the Arch Linux bug tracker). (Update: this bug has now been fixed, so as you can see, your work will not be in vain.)

Obtaining icons

Although packages that already ship with a .desktop-file most certainly contain an icon or a set of icons, there is sometimes the case when a developer has not created a .desktop-file, but may ship icons, nonetheless. So a good start is to look for icons in the source package. You can i.e. first filter for the extension with find and then use grep to filter further for certain buzzwords like the package name, "icon", "logo", etc, if there are quite a lot of images in the source package.

$ find /path/to/source/package -regex ".*\.\(svg\|png\|xpm\|gif\|ico\)$"      /* this filters for common extensions */

If the developers of an application do not include icons in their source packages, the next step would be to search on their web sites. Some projects, like i.e. tvbrowser have an artwork/logo page where additional icons may be found. If a project is multi-platform, there may be the case that even if the linux/unix package does not come with an icon, the Windows package might provide one. If the project uses a Version control system like CVS/SVN/etc. and you have some experience with it, you also might consider browsing it for icons. If everything fails, the project might simple have no icon/logo yet.

Tools

gendesk

gendesk is a Arch Linux-specific tool for generating .desktop files from PKGBUILD files. Most of the information is fetched directly from the PKGBUILD.

Icons are downloaded from fedora, if available. The source for icons can easily be changed in the future.

How to use

  • Add gendesk to makedepends
  • Start the build() function with:
cd "$srcdir"
gendesk $SRCDEST/PKGBUILD
# And then the rest
  • Add _name=('Program Name') to the PKGBUILD to choose a name for the menu entry. There are other options available too, like _exec=('someapp --with-ponies').
  • Use gendesk -n if you wish to generate a .desktop file, but not download any icon
  • See the gendesk source for more information. (Patches and pull requests are welcome).

More resources