From 49287507321fcba5cfbc1b33cadc23846f874c80 Mon Sep 17 00:00:00 2001
From: Clemens Wolff <clewolff@microsoft.com>
Date: Wed, 9 Oct 2019 11:04:37 -0400
Subject: [PATCH] Replace Color class with colour library

---
 app/api/tests/test_utils.py | 36 ++++++-------------------
 app/api/utils.py            | 52 +++++--------------------------------
 requirements.txt            |  1 +
 3 files changed, 15 insertions(+), 74 deletions(-)

diff --git a/app/api/tests/test_utils.py b/app/api/tests/test_utils.py
index 34d0e9ac86..e12a0917dd 100644
--- a/app/api/tests/test_utils.py
+++ b/app/api/tests/test_utils.py
@@ -6,26 +6,7 @@
 
 from ..models import Label, Document
 from ..utils import BaseStorage, ClassificationStorage, SequenceLabelingStorage, Seq2seqStorage, CoNLLParser
-from ..utils import Color, iterable_to_io
-
-
-class TestColor(TestCase):
-    def test_random_color(self):
-        color = Color.random()
-        self.assertTrue(0 <= color.red <= 255)
-        self.assertTrue(0 <= color.green <= 255)
-        self.assertTrue(0 <= color.blue <= 255)
-
-    def test_hex(self):
-        color = Color(red=255, green=192, blue=203)
-        self.assertEqual(color.hex, '#ffc0cb')
-
-    def test_contrast_color(self):
-        color = Color(red=255, green=192, blue=203)
-        self.assertEqual(color.contrast_color.hex, '#000000')
-
-        color = Color(red=199, green=21, blue=133)
-        self.assertEqual(color.contrast_color.hex, '#ffffff')
+from ..utils import iterable_to_io
 
 
 class TestBaseStorage(TestCase):
@@ -48,15 +29,14 @@ def test_to_serializer_format(self):
         labels = ['positive']
         created = {}
 
-        actual = BaseStorage.to_serializer_format(labels, created, random_seed=123)
+        actual = BaseStorage.to_serializer_format(labels, created)
 
-        self.assertEqual(actual, [{
-            'text': 'positive',
-            'prefix_key': None,
-            'suffix_key': 'p',
-            'background_color': '#0d1668',
-            'text_color': '#ffffff',
-        }])
+        self.assertEqual(len(actual), 1)
+        self.assertEqual(actual[0]['text'], 'positive')
+        self.assertIsNone(actual[0]['prefix_key'])
+        self.assertEqual(actual[0]['suffix_key'], 'p')
+        self.assertIsNotNone(actual[0]['background_color'])
+        self.assertIsNotNone(actual[0]['text_color'])
 
     def test_get_shortkey_without_existing_shortkey(self):
         label = 'positive'
diff --git a/app/api/utils.py b/app/api/utils.py
index cac7a249f2..90ed2a97d7 100644
--- a/app/api/utils.py
+++ b/app/api/utils.py
@@ -4,11 +4,11 @@
 import json
 import re
 from collections import defaultdict
-from random import Random
 
 import conllu
 from django.db import transaction
 from django.conf import settings
+from colour import Color
 import pyexcel
 from rest_framework.renderers import JSONRenderer
 from seqeval.metrics.sequence_labeling import get_entities
@@ -65,7 +65,7 @@ def exclude_created_labels(cls, labels, created):
         return [label for label in labels if label not in created]
 
     @classmethod
-    def to_serializer_format(cls, labels, created, random_seed=None):
+    def to_serializer_format(cls, labels, created):
         existing_shortkeys = {(label.suffix_key, label.prefix_key)
                               for label in created.values()}
 
@@ -80,9 +80,10 @@ def to_serializer_format(cls, labels, created, random_seed=None):
                 serializer_label['prefix_key'] = shortkey[1]
                 existing_shortkeys.add(shortkey)
 
-            color = Color.random(seed=random_seed)
-            serializer_label['background_color'] = color.hex
-            serializer_label['text_color'] = color.contrast_color.hex
+            background_color = Color(pick_for=label)
+            text_color = Color('white') if background_color.get_luminance() < 0.5 else Color('black')
+            serializer_label['background_color'] = background_color.hex
+            serializer_label['text_color'] = text_color.hex
 
             serializer_labels.append(serializer_label)
 
@@ -445,47 +446,6 @@ def paint(self, documents):
         return res
 
 
-class Color:
-    def __init__(self, red, green, blue):
-        self.red = red
-        self.green = green
-        self.blue = blue
-
-    @property
-    def contrast_color(self):
-        """Generate black or white color.
-
-        Ensure that text and background color combinations provide
-        sufficient contrast when viewed by someone having color deficits or
-        when viewed on a black and white screen.
-
-        Algorithm from w3c:
-        * https://www.w3.org/TR/AERT/#color-contrast
-        """
-        return Color.white() if self.brightness < 128 else Color.black()
-
-    @property
-    def brightness(self):
-        return ((self.red * 299) + (self.green * 587) + (self.blue * 114)) / 1000
-
-    @property
-    def hex(self):
-        return '#{:02x}{:02x}{:02x}'.format(self.red, self.green, self.blue)
-
-    @classmethod
-    def white(cls):
-        return cls(red=255, green=255, blue=255)
-
-    @classmethod
-    def black(cls):
-        return cls(red=0, green=0, blue=0)
-
-    @classmethod
-    def random(cls, seed=None):
-        rgb = Random(seed).choices(range(256), k=3)
-        return cls(*rgb)
-
-
 def iterable_to_io(iterable, buffer_size=io.DEFAULT_BUFFER_SIZE):
     """See https://stackoverflow.com/a/20260030/3817588."""
     class IterStream(io.RawIOBase):
diff --git a/requirements.txt b/requirements.txt
index 6625b265f6..824e1cc958 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,5 +1,6 @@
 apache-libcloud==2.4.0
 applicationinsights==0.11.7
+colour==0.1.5
 coverage==4.5.3
 dj-database-url==0.5.0
 Django==2.1.7