Introduced fgcolor template filter to render ideal foreground color for any background color

netbox/dcim/tables.py

@@ -29,7 +29,8 @@ SITE_REGION_LINK = """
 """
 
 COLOR_LABEL = """
-<label class="label" style="background-color: #{{ record.color }}">{{ record }}</label>
+{% load helpers %}
+<label class="label" style="color: {{ record.color|fgcolor }}; background-color: #{{ record.color }}">{{ record }}</label>
 """
 
 DEVICE_LINK = """

netbox/utilities/templatetags/helpers.py

@@ -1,11 +1,13 @@
 import datetime
 import json
+import re
 
 from django import template
 from django.utils.safestring import mark_safe
 from markdown import markdown
 
 from utilities.forms import unpack_grouped_choices
+from utilities.utils import foreground_color
 
 
 register = template.Library()
@@ -152,6 +154,17 @@ def tzoffset(value):
     return datetime.datetime.now(value).strftime('%z')
 
 
+@register.filter()
+def fgcolor(value):
+    """
+    Return black (#000000) or white (#ffffff) given an arbitrary background color in RRGGBB format.
+    """
+    value = value.lower().strip('#')
+    if not re.match('^[0-9a-f]{6}$', value):
+        return ''
+    return '#{}'.format(foreground_color(value))
+
+
 #
 # Tags
 #