Customise Freedesktop file with sbt-native-packager and JDKPackager plugin

Question

I would like to customize the .desktop file created by the javapackager as part of the JDKPackager plugin of sbt-native-packager. It obviously uses a template:

[info]   Using default package resource [Menu shortcut descriptor]
         (add package/linux/Foo.desktop to the class path to customize)

In particular, I want to add the StartupWMClass entry that will be used by Gnome to unify all the windows opened by my application.

Answer 1

The javapackager refers to the target directory of the plugin, i.e. target/jdkpackager. This is created for example when the javafx-ant build-file is written. So we can piggyback here:

// rewrite the task so that after the ant build is created,
// we add package/linux/MyApp.desktop
writeAntBuild in JDKPackager := {
  val res  = (writeAntBuild in JDKPackager).value
  val main = (mainClass     in JDKPackager).value
    .getOrElse(sys.error("No main class specified"))
  val tgt  = (target        in JDKPackager).value
  val n    = (name          in JDKPackager).value
  val wm   = main.replace('.', '-')
  val desktop = 
    s"""[Desktop Entry]
       |Name=APPLICATION_NAME
       |Comment=APPLICATION_SUMMARY
       |Exec=/opt/APPLICATION_FS_NAME/APPLICATION_LAUNCHER_FILENAME
       |Icon=/opt/APPLICATION_FS_NAME/APPLICATION_LAUNCHER_FILENAME.png
       |Terminal=false
       |Type=Application
       |Categories=DEPLOY_BUNDLE_CATEGORY
       |DESKTOP_MIMES
       |StartupWMClass=$wm
       |""".stripMargin
  IO.write(tgt / "package" / "linux" / s"$n.desktop", desktop)
  res
}