Based on Miguel Sousa's original PR and the following discussion:
https://github.com/googlei18n/cu2qu/pull/114
Instead of raising an error at the first incompatible glyph, we
let it continue (keeping the original contours unmodified when
that happens), and use logging to print error messages.
A new `IncompatibleFontsError` exception is raised at the end of
`fonts_to_quadratic` if any glyph has incompatible number or types
of segments. The exception instance has a `glyph_errors` attribute
(dict) which collects all the individual IncompatibleGlyphsError
keyed by glyph name.
When the 'max_err_em' argument is a float, we multiply it
by the font.info.unitsPerEm. However we were not doing it when
the argument is a list of floats...
We dropped robofab support. There is no reason to arbitrarily
drop any contour points. Anchors are handled as anchors in
latest ufoLib+defcon, also for UFO2. No more need to special-case.
This was needed for when we were supporting the old robofab.ufoLib
where anchors were represented as single-point-with-a-name contours.
With latest ufoLib, even when glif format is 1, anchors are
stored separately and are not drawn with pens (only proper contours
and components are passed on in the draw method).
So there is no longer need to special-case single points.
It's not the job of the cu2qu pens to filter those out.
otherwise, pytest test collection fails to import ufo_benchmark mode, as defcon/robofab are not specified as install requirements, thus may not be present when running the test suite.
The test suite is installed as a sub-package, so the test data must also be installed along with it.
The `__file__` attribute can be missing when importing a zipped package, so we load test files with `pkg_resources.resource_filename()`.
`random.randint`, which is used in `cu2qu.benchmark.generate_curve` function, yields
different results when run in Python 2.7 or 3, despite using the same `random.seed(1)`.
For this reason, the `test_results_unchanged` and `test_results_unchanged_multiple` tests
in `cu2qu_test` module fail when run under Python 2.
Backward compatibility was broken with Python 3.2 `random` module, as a side effect of
fixing a non-uniformity bug. For mor info see:
https://groups.google.com/forum/#!topic/comp.lang.python/KwALjKjF6Y4http://bugs.python.org/issue9025
To work around this, I dumped the result of generate_curve (running from Python 3.5.2 on
OSX) to a json file, and use that to run the tests.
I also stripped the white space to reduce the file size.
```python
import random
import json
from cu2qu.benchmark import generate_curve
random.seed(1)
curves = [generate_curve() for i in range(1000)]
with open("Lib/cu2qu/test/data/curves.json", "w") as fp:
fp.write(json.dumps(curves).replace(" ", ""))
```
fixup
otherwise, the direction would only flipped if the glyph contains at least one cubic curve; whereas, we want to reverse the contour direction of all the glyphs in the font, even if they are just made of straight lines.
Don't use zip(*fonts) as defcon fonts are dictionary-like objects and the ordering of the glyphs returned by __iter__ method is undefined.
Should fix#48
This was requested in https://github.com/googlei18n/cu2qu/issues/26
Plus:
- do not modify input glyphs unless they contain one cubic curve;
- make public functions return True/False to signal that the input
was modified or not (eg. no curves, or all quadratic)
