At Rover we are upgrading our codebase to python3.6 while maintaining compatibility with python2.7.

We are running into a problem where imgix isn't compatible with both python 2.7 and 3.6 at the same time.

The reason is that the behavior of string literals in the imgix-python library is not consistent between python versions.

For example, take URLBuilder.create_url(path, opts). If path is explicitly unicode in python 2, this will result in the following error:

  File "/usr/local/lib/python2.7/dist-packages/imgix/urlhelper.py", line 188, in __str__
    "", ])
  File "/usr/local/lib/python2.7/dist-packages/future/backports/urllib/parse.py", line 387, in urlunparse
    _coerce_args(*components))
  File "/usr/local/lib/python2.7/dist-packages/future/backports/urllib/parse.py", line 115, in _coerce_args
    raise TypeError("Cannot mix str and non-str arguments")
TypeError: Cannot mix str and non-str arguments

This will fail in the same way if path is explicitly a byte string in python 3. The only way that it can be expected to work at all between the two versions is if the path variable is a string literal with no explicit type and from __future__ import unicode_literals is not present.

In order to ease our transition of hundreds of thousands of lines of code to python3 we need to include all future imports in all our files which means that path will be explicitly unicode in both python2 and python3.

The issue can be fixed by making string literals be either explicitly unicode or bytestring regardless of what version of python was being run. This can be done by adding from __future__ import unicode_literals to all the files in this library.

One way to automatically do this would be to use futurize

When signing a url with a + encoded as %20 for a web proxy secure source, the signing fails.

Try encoding:
http://www.brookings.edu/~/media/research/images/l/lk%20lo/london_bigben_flags001/london_bigben_flags001_16x9.jpg

>>> import imgix
>>> image_url_builder = imgix.UrlBuilder(IMGIX_URL, sign_key=IMGIX_SIGN_KEY, use_https=True)
>>> image_url = 'http://www.brookings.edu/~/media/research/images/l/lk%20lo/london_bigben_flags001/london_bigben_flags001_16x9.jpg'
>>> options = {'w': 260, 'fit': 'crop', 'crop': 'entropy'}
>>> image_url_builder.create_url(image_url, options)
'https://factr-url.imgix.net/http%3A%2F%2Fwww.brookings.edu%2F%7E%2Fmedia%2Fresearch%2Fimages%2Fl%2Flk%2520lo%2Flondon_bigben_flags001%2Flondon_bigben_flags001_16x9.jpg?crop=entropy&fit=crop&ixlib=python-1.1.0&w=260&s=473639e97d47f1b991e46ba670042358'

The signed url throws a 401.

Description

Related to https://github.com/imgix/js-core#fixed-image-rendering

Add a device_pixel_ratios option to the https://github.com/imgix/imgix-python#fixed-width-images function to allow users to customize the target device pixel ratio(s) (dpr) when generating a fixed image. This will allow users to have more granular control over the fixed-size srcset values generated.

The value is named SRCSET_INCREMENT_PERCENTAGE, consider making it one.

It's only other use is 13 lines down here,

where the conversion to a percentage actually occurs.

Reasons to Consider:

• truth, the value is named to be a percentage, so it should be a percentage
• demonstrate consistent semantics for ourselves and users

Operative line to update: https://github.com/imgix/imgix-python/blob/master/imgix/__init__.py#L79

See also the case in the blueprint: https://github.com/imgix/imgix-blueprint#fully-qualified-urls-with-imgix-url-api-parameters

import imgix

b = imgix.url.Builder("demos.imgix.net")
b.create("/bridge.png", w=100, h=100)

Is Helper needed? It's not currently exposed in the docs.

The library is encoding the space in the dl as %20, but if you put a signed url in an anchor <a href="url"> it gets changed by the browser to a +, resulting in the error message "URI signature match failed".

There are many settings that can be used with Imgix. These have a range of types, but most are integers, floats, or strings that define an enumeration.

It would be great to get a more type-safe API using Python enums and/or mypy types. This would also give some basis to further safety in APIs provided using this library (such as a GraphQL API backed by this).

Description

Related PR: imgix/js-core#314

Add disablePathEncoding functionality to the URL building logic in create_url and create_srcset. This way, users can decide to opt-out of path encoding.

Probably a good way of handling this would be to add a new constructor option, disablePathEncoding, that can be referenced in any of the instance methods.

Description

Related to https://github.com/imgix/js-core#variable-qualities

Add a variable_qualities option to the https://github.com/imgix/imgix-python#fixed-width-images function to allow users to override the mapping of the quality parameter (q) to each device pixel ratio (dpr). This will allow users to have more granular control over the fixed-size srcset values generated.