Many years ago, when koffice was fresh and with few users, I
-decided to test its presentation tool when making the slides for a
-talk I was giving for NUUG on Japhar, a free Java virtual machine. I
-wrote the first draft of the slides, saved the result and went to bed
-the day before I would give the talk. The next day I took a plane to
-the location where the meeting should take place, and on the plane I
-started up koffice again to polish the talk a bit, only to discover
-that kpresenter refused to load its own data file. I cursed a bit and
-started making the slides again from memory, to have something to
-present when I arrived. I tested that the saved files could be
-loaded, and the day seemed to be rescued. I continued to polish the
-slides until I suddenly discovered that the saved file could no longer
-be loaded into kpresenter. In the end I had to rewrite the slides
-three times, condensing the content until the talk became shorter and
-shorter. After the talk I was able to pinpoint the problem –
-kpresenter wrote inline images in a way itself could not understand.
-Eventually that bug was fixed and kpresenter ended up being a great
-program to make slides. The point I'm trying to make is that we
-expect a program to be able to load its own data files, and it is
-embarrassing to its developers if it can't.
-
-
Did you ever experience a program failing to load its own data
-files from the desktop file browser? It is not a uncommon problem. A
-while back I discovered that the screencast recorder
-gtk-recordmydesktop would save an Ogg Theora video file the KDE file
-browser would refuse to open. No video player claimed to understand
-such file. I tracked down the cause being file --mime-type
-returning the application/ogg MIME type, which no video player I had
-installed listed as a MIME type they would understand. I asked for
-file to change its
-behavour and use the MIME type video/ogg instead. I also asked
-several video players to add video/ogg to their desktop files, to give
-the file browser an idea what to do about Ogg Theora files. After a
-while, the desktop file browsers in Debian started to handle the
-output from gtk-recordmydesktop properly.
-
-
But history repeats itself. A few days ago I tested the music
-system Rosegarden again, and I discovered that the KDE and xfce file
-browsers did not know what to do with the Rosegarden project files
-(*.rg). I've reported the
-rosegarden problem to BTS and a fix is commited to git and will be
-included in the next upload. To increase the chance of me remembering
-how to fix the problem next time some program fail to load its files
-from the file browser, here are some notes on how to fix it.
-
-
The file browsers in Debian in general operates on MIME types.
-There are two sources for the MIME type of a given file. The output from
-file --mime-type mentioned above, and the content of the
-shared MIME type registry (under /usr/share/mime/). The file MIME
-type is mapped to programs supporting the MIME type, and this
-information is collected from
-the
-desktop files available in /usr/share/applications/. If there is
-one desktop file claiming support for the MIME type of the file, it is
-activated when asking to open a given file. If there are more, one
-can normally select which one to use by right-clicking on the file and
-selecting the wanted one using 'Open with' or similar. In general
-this work well. But it depend on each program picking a good MIME
-type (preferably
-a
-MIME type registered with IANA), file and/or the shared MIME
-registry recognizing the file and the desktop file to list the MIME
-type in its list of supported MIME types.
-
-
The /usr/share/mime/packages/rosegarden.xml entry for
-the
-Shared MIME database look like this:
-
-
-<?xml version="1.0" encoding="UTF-8"?>
-<mime-info xmlns="http://www.freedesktop.org/standards/shared-mime-info">
- <mime-type type="audio/x-rosegarden">
- <sub-class-of type="application/x-gzip"/>
- <comment>Rosegarden project file</comment>
- <glob pattern="*.rg"/>
- </mime-type>
-</mime-info>
-
-
-
This states that audio/x-rosegarden is a kind of application/x-gzip
-(it is a gzipped XML file). Note, it is much better to use an
-official MIME type registered with IANA than it is to make up ones own
-unofficial ones like the x-rosegarden type used by rosegarden.
-
-
The desktop file of the rosegarden program failed to list
-audio/x-rosegarden in its list of supported MIME types, causing the
-file browsers to have no idea what to do with *.rg files:
-
-
-% grep Mime /usr/share/applications/rosegarden.desktop
-MimeType=audio/x-rosegarden-composition;audio/x-rosegarden-device;audio/x-rosegarden-project;audio/x-rosegarden-template;audio/midi;
-X-KDE-NativeMimeType=audio/x-rosegarden-composition
-%
-
-
-
The fix was to add "audio/x-rosegarden;" at the end of the
-MimeType= line.
-
-
If you run into a file which fail to open the correct program when
-selected from the file browser, please check out the output from
-file --mime-type for the file, ensure the file ending and
-MIME type is registered somewhere under /usr/share/mime/ and check
-that some desktop file under /usr/share/applications/ is claiming
-support for this MIME type. If not, please report a bug to have it
-fixed. :)
-
