59 lines
1.5 KiB
Python
59 lines
1.5 KiB
Python
import logging
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import math
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import re
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import matplotlib
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from django.db import models
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from django.utils.safestring import mark_safe
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re_hex = re.compile("^([0-9a-f]{3,6})(\W)?", re.IGNORECASE)
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def hex2rgb(hexval):
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return matplotlib.colors.to_rgb(hexval)
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def light_or_dark(rgbColor, colors: tuple = ('#FFFFFF', '#333333')):
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if isinstance(rgbColor, str):
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rgbColor = hex2rgb(rgbColor)
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[r, g, b] = rgbColor
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val = 0.299 * (r * r) + 0.587 * (g * g) + 0.114 * (b * b)
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hsp = math.sqrt(val)
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# logging.error([rgbColor, val, hsp])
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# if hsp > 127.5:
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if hsp > .5:
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# light
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return colors[1]
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else:
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# dark
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return colors[0]
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def invert_hex(hexval: str):
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def _invert(content):
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text = content.group(1).lower()
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code = {}
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l1 = "0123456789abcdef"
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l2 = "fedcba9876543210"
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for i in range(len(l1)):
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code[l1[i]] = l2[i]
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inverted = ""
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for j in text:
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inverted += code[j]
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return inverted
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prepend_hash = ''
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if hexval.startswith('#'):
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hexval = hexval[1:]
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prepend_hash = '#'
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return prepend_hash + re_hex.sub(_invert, hexval)
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def color_label(instance: models.Model, value:str=None):
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value = value or instance.color
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return mark_safe(f'<div style="padding:.5em 1em;display:inline-block;background-color:{instance.color};border-radius:5px;'
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# f'color:{invert_hex(instance.color)};'
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f'color:{light_or_dark(instance.color)};'
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f'">{value}</div>')
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