There's a KImageFormats plugin for EPS files, so we can just load them easily as QImage
OTOH this will not work if kimageformats is not installed, and the thumbnailer gives no hint about that.
But it will return false if the creation failed. Not sure if the PreviewJob keeps chugging along or says "you claimed you can handle it and now you cant, screw you, aborting"
Then just ship a desktop file for that format in kimageformats:
- if kio-extras is not installed, that desktop file will be unused (although just a couple of kilobytes on disk)
- if ko-extras is installed, it will register PS as thumbnail format using imagethumbnail
The same change can IMHO be done for all the formats currently in MimeType, and that provided by kimageformats.