when the jpeg encoder sees the flags optimize or progressive (or progression)
it will write the full image in one shot.
The bufsize needs to be big enough to hold the entire image. The current heuristic
is that the entire compressed image will fit in width * height bytes, but this
heuristic is only applied to save operations with the flag "optimize" and not to
save operations with the flag "progressive".
This patch fixes this oversight.
(Btw, it will probably be a good idea to have a loop that retries with a bigger
bufsize in case this guess is not big enough.)
There are two main issues fixed with this commit:
* bytes vs. str: All file, image, and palette data are now handled as
bytes. A new _binary module consolidates the hacks needed to do this
across Python versions. tostring/fromstring methods have been renamed to
tobytes/frombytes, but the Python 2.6/2.7 versions alias them to the old
names for compatibility. Users should move to tobytes/frombytes.
One other potentially-breaking change is that text data in image files
(such as tags, comments) are now explicitly handled with a specific
character encoding in mind. This works well with the Unicode str in
Python 3, but may trip up old code expecting a straight byte-for-byte
translation to a Python string. This also required a change to Gohlke's
tags tests (in Tests/test_file_png.py) to expect Unicode strings from
the code.
* True div vs. floor div: Many division operations used the "/" operator
to do floor division, which is now the "//" operator in Python 3. These
were fixed.
As of this commit, on the first pass, I have one failing test (improper
handling of a slice object in a C module, test_imagepath.py) in Python 3,
and three that that I haven't tried running yet (test_imagegl,
test_imagegrab, and test_imageqt). I also haven't tested anything on
Windows. All but the three skipped tests run flawlessly against Pythons
2.6 and 2.7.
This is, I guess, a few things the Python devs were just fed up with.
* "while 1" is now "while True"
* Types are compared with isinstance instead of ==
* Sort a list in one go with sorted()
My own twist is to also replace type('') with str, type(()) with tuple,
type([]) with list, type(1) with int, and type(5000.0) with float.
In py3k, imports are absolute unless using the "from . import" syntax.
This commit also solves a recursive import between Image, ImageColor, and
ImagePalette by delay-importing ImagePalette in Image.
I'm not too keen on this commit because the syntax is ugly. I might go back
and prefer the prettier "from PIL import".
y.has_key(x) is gone (use x in y), and keys(), values(), items(), and
range() all return views.
Some iterables needed to be packed into lists, either because the code
expected a list (such as "range(256) * 3") or because the original
collection was being modified (automatic global declarations).
The Tiff ImageFileDictionary is a special case and will be dealt with in
another commit.
