Add colour contrast filter

Make colours on images yoinkable

onlylegs/filters.py

@@ -0,0 +1,22 @@
+"""
+OnlyLegs filters
+Custom Jinja2 filters
+"""
+from flask import Blueprint
+from onlylegs.utils import contrast
+
+
+blueprint = Blueprint('filters', __name__)
+
+
+@blueprint.app_template_filter()
+def colour_contrast(colour):
+    """
+    Pass in the colour of the background and will return
+    a css variable based on the contrast of text required to be readable
+    "color: var(--fg-white);" or "color: var(--fg-black);"
+    """
+    bright = "var(--fg-white)"
+    dark = "var(--fg-black)"
+    
+    return "color: RGB(" + contrast.contrast(colour, dark, bright) + ");"