91 lines
2.9 KiB
Python
91 lines
2.9 KiB
Python
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"""
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Theming Dynamic Text
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====================
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Two implementations. The first is based on color brightness obtained from-
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https://www.w3.org/TR/AERT#color-contrast
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The second is based on relative luminance calculation for sRGB obtained from-
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https://www.w3.org/TR/2008/REC-WCAG20-20081211/#relativeluminancedef
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and contrast ratio calculation obtained from-
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https://www.w3.org/TR/2008/REC-WCAG20-20081211/#contrast-ratiodef
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Preliminary testing suggests color brightness more closely matches the
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`Material Design spec` suggested text colors, but the alternative implementation
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is both newer and the current 'correct' recommendation, so is included here
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as an option.
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"""
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def _color_brightness(color):
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# Implementation of color brightness method
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brightness = color[0] * 299 + color[1] * 587 + color[2] * 114
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brightness = brightness
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return brightness
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def _black_or_white_by_color_brightness(color):
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if _color_brightness(color) >= 500:
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return "black"
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else:
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return "white"
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def _normalized_channel(color):
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# Implementation of contrast ratio and relative luminance method
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if color <= 0.03928:
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return color / 12.92
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else:
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return ((color + 0.055) / 1.055) ** 2.4
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def _luminance(color):
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rg = _normalized_channel(color[0])
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gg = _normalized_channel(color[1])
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bg = _normalized_channel(color[2])
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return 0.2126 * rg + 0.7152 * gg + 0.0722 * bg
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def _black_or_white_by_contrast_ratio(color):
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l_color = _luminance(color)
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l_black = 0.0
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l_white = 1.0
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b_contrast = (l_color + 0.05) / (l_black + 0.05)
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w_contrast = (l_white + 0.05) / (l_color + 0.05)
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return "white" if w_contrast >= b_contrast else "black"
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def get_contrast_text_color(color, use_color_brightness=True):
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if use_color_brightness:
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contrast_color = _black_or_white_by_color_brightness(color)
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else:
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contrast_color = _black_or_white_by_contrast_ratio(color)
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if contrast_color == "white":
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return 1, 1, 1, 1
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else:
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return 0, 0, 0, 1
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if __name__ == "__main__":
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from kivy.utils import get_color_from_hex
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from kivymd.color_definitions import colors, text_colors
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for c in colors.items():
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if c[0] in ["Light", "Dark"]:
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continue
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color = c[0]
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print(f"For the {color} color palette:")
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for name, hex_color in c[1].items():
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if hex_color:
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col = get_color_from_hex(hex_color)
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col_bri = get_contrast_text_color(col)
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con_rat = get_contrast_text_color(
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col, use_color_brightness=False
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)
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text_color = text_colors[c[0]][name]
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print(
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f" The {name} hue gives {col_bri} using color "
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f"brightness, {con_rat} using contrast ratio, and "
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f"{text_color} from the MD spec"
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)
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