[Evolution-hackers] Archive integration project

[藍挺瑋 <lantw44 gmail com>]

Hi, I am Ting-Wei Lan. I am working on the Google Summer of Code 
project to integrate archives support into GNOME.

There is some information about the project:
1. wiki.gnome.org
https://wiki.gnome.org/SummerOfCode2013/Projects/TingWeiLan_GnomeArchives
2. Google Melange project page:
http://www.google-melange.com/gsoc/project/google/gsoc2013/lantw44/22001


I have written some code to integrate archives support into Evolution.

I added options to the attachment saving dialog, so users can choose
whether they want to extract the attachments if the attachments are
archives. Users can also save both original attachments and extracted
files, and these two works will be started at the same time.

Archive creation support is always enabled. If users choose an directory
in the attachment loading dialog, an archive will be automatically
created for the directory. Users can choose their preferred archive
format in the dialog.


However, there are some known problems in these code.

1. If users decide to save both original attachments and extracted
files, both works will call attachment_progress_cb to report progress on
the same EAttachment object. This may be a problem, but I did not find
bad user interface changes related to this.

2. If an attachment is saved as an directory because of automatic
extraction, users cannot know the name of the directory in Evolution.
This may not be a problem because the name of the directory will be
similar to file name that users provide.

3. When users want to upload a directory, the archive will be created
under ~/.cache/evolution/tmp/. Files in this directory are not removed
after Evolution exits.

4. There is no progress report when an archive is creating. Users can
still know whether archive creating is completed by the icon change in
the attachment bar.


All code related to Evolution are available at the following sites:
(All modification is in the branch `archive-integration')
1. http://www.tfcis.org/~lantw44/cgit/cgit.cgi/gsoc2013-evolution
2. http://master.lant.com.tw/~lantw44/cgit/cgit.cgi/gsoc2013-evolution
3. https://github.com/lantw44/gsoc2013-evolution

I have written a shared library in order to integrate archives into
different GNOME programs. I called it `gnome-autoar', and it is
available at https://git.gnome.org/gnome-autoar. Build Evolution with
archive integration will require gnome-autoar to be installed.