Attracted by virtual constructs

June 18, 2014

Thumbnails & previews for your Geo Data files (KML, GPX, OSM, …)

Filed under: Calligra,KDE,Marble — by frinring @ 10:02 pm

Almost two years ago (uh, already?) I went to Prague for a developer sprint of the team of Marble, the virtual globe and world atlas. My goal was to work on a proper maps shape plugin for Calligra.

We are ready to render, or? … Or?

Just, it showed that Marble at that time was not properly supporting the needs such a plugin has. Biggest showstopper was that Marble did not expose the information if and when all external data needed for rendering was available. Think e.g. of map pieces (so called tiles) still having to be downloaded from a server like OpenStreetMap‘s one. Not knowing the state is not good e.g. if a document with a map is to be rendered to a real printer.

Telling the File Manager some more about Marble and Geo Data Files

At that sprint then I worked instead on making sure that there are proper mime-types registered for the types of geo data files that Marble can read and display (like OSM data files, ESRI shapefiles and GPX files). So that such files are nicely displayed in the file manager with matching icon & type description and can get Marble assigned as handler. And:

[...]
Next step is to finish the thumbnail plugin, so one can also have nice previews of the content of these filetypes.
[...]

The thumbnailer was started in the train back from Prague, but Dresden was arrived before it was properly working. Then… the code went out of focus and mind, that step frozen in the middle of the air…

Getting ready to render!

These days, Calligra still has no maps shape plugin. Now and then I nag^Wbeg the Marble developers for the issue (how lame, indeed), as there are other interesting use cases for rendering of map stills, like:

  • Creating a jigsaw puzzle for Palapeli, the jigsaw puzzle gaming program
  • Creating an animation for a movie in Kdenlive, the video editor
  • Yes, even creating the thumbnails for geo data files, if not using the simple installed map theme

Last week luckily earthwings found some personal interest to draft code for renderer state. Time to add a bit of momentum, by reviving the thumbnailer code, to serve as a use case. Still found in its old place, after some bit-rot cleanup and finally solving the problems of last time (different mindset, and things seem so obvious) it works now good enough for serious usage:

Thumbnails for Geo Data files

Thumbnails for Geo Data files

Some things need some more thinking (which map theme to use when, how to properly detect the sky object the data is for, how to deal with thumbnail generation in offline-state), but it’s a good first complete step :) It does not yet use the new render state feature, but should be soon.

So look forward to Marble 1.9, bringing previews for geo data files to your filemanager and in the file dialogs! (And do not forget to enable them in Dolphin > Settings > Configure Dolphin… > General > Previews, disabled for all types by default).

And perhaps, perhaps, one day we finally also will have a maps shape plugin for Calligra…

BTW, if you want to help development of Marble, other KDE Edu projects and more, consider to donate for enabling the Randa Meetings 2014. Every little amount will help, as it sums up. Best do it now! :)

5 Comments »

  1. […] Attracted by virtual constructs […]

    Pingback by Links 19/6/2014: New Mir, Dalvik Changes, X.org Turns 30 | Techrights — June 20, 2014 @ 12:02 am |Reply

  2. Very cool! I’ve always wanted previews in Dolphin of .kml files, and now here it is! I just wish that the previews were enabled by default because it is so easy to assume that there’s nothing to preview unless you’re a gearhead and like to look in settings dialogs, like I do. Yet my friends don’t and I have to configure their KDE systems and enable all these every time.

    Comment by Michael Lutynski — June 21, 2014 @ 8:09 am |Reply

  3. Does it wor in Gnomes Nautilus too?

    Comment by tobias — June 22, 2014 @ 8:45 pm |Reply

  4. Hi, just wanted to inform you about a free conversion tool that turns gpx to kml files, when needed. Simple and easy to use, converted files can be easily downloaded.

    Comment by Julliana — August 28, 2014 @ 9:33 am |Reply

  5. http://gpx2kml.com/ that’s the tool. I forget mentioning it.

    Comment by Julliana — August 28, 2014 @ 9:34 am |Reply


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