Pillow

Summary

Replace PIL (python-imaging) with Pillow, an actively maintained fork which is also heading for python3 compatibility

Owner

Name: Sandro Mani

Email: manisandro (at) gmail (dot) com

Current status

Targeted release: Fedora 19
Last updated: 2013-03-19
Percentage of completion: 100%

Detailed Description

The PIL project has been rather inactive lately (last release in 2009), and one big issue is the missing python 3 compatibility. There seems to be some general agreement that Pillow [1] is a likely candidate to succeed PIL, and in particular to bring python 3 support, see the discussion at [2]. Pillow describes itself as

 Pillow is the "friendly" PIL fork. PIL is the Python Imaging Library. Pillow was
 started for and is currently maintained by the Plone community. But it is used by
 many other folks in the Python web community, and probably elsewhere too.
 
 The fork author's goal is to foster packaging improvements via:
 
 - Publicized development and solicitation of community support.
 - Exploration of packaging problems within the fork, most noticably
   via adding setuptools support but also via clean up & refactoring
   of packaging code.

Pillow is practically a drop-in replacement for PIL, except one small issue (see below).

For Python 3, there is a fork which offers Py3 compatibility here [3]. The patches are planed for review and merge into Pillow, see [4].

Benefit to Fedora

Actively maintained python imaging library
Python 3 compatibility

Scope

Tasks:

Package Pillow, add obsoletes/provides for python-imaging. Done
Send some patches for python3 compatibility upstream. Done, see here
Wait for RHBZ bug 889784 (python issue 16754) to be fixed (python 3 distutils bug, uses wrong extension when searching for shared objects) Done
Post a new package review process Done, see here
Review finished Done
Notify maintainers of packages depending on PIL Done
- Almost all of the packages have been ported as well (few are waiting on upstream releases)
push package to repositories Done
block python-imaging: Done, see rel-eng ticket

Action needed by other maintainers:

repoquery --whatrequires python-imaging* shows there are 74 packages depending on PIL.
Pillow is a drop-in replacement for PIL, with one detail: The PIL modules now use relative imports between each other, so it is no longer possible to write

 import Image

but one needs to write

 from PIL import Image

The former variant was only made possible by a PIL.pth file in %{python_sitearch}, and actually looks like a hack for backwards compatibility. (100% compatibility between PIL and Pillow could still be achieved by patching away the relative imports in the python2 variant.)

The python-pillow package will Obsolete and Provide python-imaging so there's no need for dependent packages to change their Requires line at this time.

How To Test

Install python-pillow from the rawhide repositories (as of writing, compilation of the python3 variant is disabled due to RHBZ bug 889784), and simply check whether everything still works.

Possibly patch packages to use

 from PIL import <Module>

instead of

 import <Module>

Note that the from PIL import <Module> syntax also works with the legacy python-imaging, so such changes will not break backwards compatibility with PIL.

User Experience

For end-users, nothing should change.
For developers using the python2 variant, next to nothing should change (except the import thing)
For developers wanting a python3 variant, there finally is one available

Dependencies

https://bugzilla.redhat.com/show_bug.cgi?id=894484 - Tracker bug for implementing the switch to pillow

Pillow package needs to be reviewed

https://bugzilla.redhat.com/show_bug.cgi?id=908114

Once done, python-imaging needs to be retired in rawhide.

Problem building pillow for python3

Optional but highly desirable:

RHBZ bug 889784

Packages needing porting to work with pillow

See the tracker:

https://bugzilla.redhat.com/show_bug.cgi?id=894484

Originally, there were 31 packages needing to apply a patch for the changed imports. As of January 16, there are 2. Those two bugs have had the fix sent upstream and are waiting on an upstream release or statement that the patch looks good.

Packages needing evaluation for porting

(Done, all known dependent packages ( found via repoquery --whatrequires python-imaging\* ) have been evaluated. A script to help with finding the places that PIL is used in these packages can be found here: https://fedorahosted.org/fesco/raw-attachment/ticket/985/scan-for-pil.py

Packages not needing porting

python-imaging-devel (obsoleted by pillow)
python-imaging-sane (obsoleted by pillow)
python-imaging-tk (obsoleted by pillow)

Packages that worked unmodified

The following packages are not on the PILLOW tracker because they were coded such that they already worked with the import statement that python-pillow uses.

ReviewBoard
autotest-framework-server
bodhi-server
calibre
django-avatar
dogtail
flumotion(False dep on python-imaging. Bug filed)
gdesklet-SlideShow
griffith
inksmoto(False dep on python-imaging-tk. Bug filed)
libhocr-gtk(requires python-imaging-sane which isn't moving into the PIL directory)
mapnik-python
python-docutils
openerp
openslides(Needed for its use of reportlab)
pkpgcounter
puddletag(False dep. Bug filed)
pympdtouchgui(False dep. Bug filed)
python-djblets
python-pygments
python-django-avatar
python-django-profile
python-django-simple-captcha
python-django-tracking(False dep. Bug filed)
python-fabulous
python-glue
python-qrcode
python-tgcaptcha
python-trml2pdf(need to talk to reportlab about having dep there instead)
python-xhtml2pdf
rapid-photo-downloader
uniconvertor

Contingency Plan

Simply keep shipping the current python-imaging-1.1.7

Documentation

Pillow homepage and discussions:

Initial discussion on fedora-devel:

http://lists.fedoraproject.org/pipermail/devel/2012-December/175621.html

Release Notes

PIL has been replaced with Pillow, an actively maintained fork, which also offers Python 3 compatible modules. Pillow is a drop-in replacement for PIL, except that importing modules now requires the

 from PIL import <Module>

syntax instead of simply

 import <Module>

This change does not break backwards compatibility with the legacy PIL.

Comments and Discussion

See Talk:Features/Pillow

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