Color scheme generation app based on "A Math-Based Approach to Color Theory" by Ethan Gardner

color_scheme_gradio.py

"""
Based on "A Math-Based Approach to Color Theory" by Ethan Gardner
- ethangardner.com/posts/color-theory-math/
"""

import colorsys

import gradio as gr
from PIL import Image, ImageDraw


def complementary_color_scheme(base_color_hsv):
    scheme_colors = [
        base_color_hsv,
        ((base_color_hsv[0] + 0.5) % 1, base_color_hsv[1], base_color_hsv[2])
    ]
    return scheme_colors

def split_complementary_color_scheme(base_color_hsv):
    scheme_colors = [
        base_color_hsv,
        ((base_color_hsv[0] + 0.4) % 1, base_color_hsv[1], base_color_hsv[2]),
        ((base_color_hsv[0] + 0.6) % 1, base_color_hsv[1], base_color_hsv[2])
    ]
    return scheme_colors

def triadic_color_scheme(base_color_hsv):
    scheme_colors = [
        base_color_hsv,
        ((base_color_hsv[0] + 1/3) % 1, base_color_hsv[1], base_color_hsv[2]),
        ((base_color_hsv[0] + 2/3) % 1, base_color_hsv[1], base_color_hsv[2])
    ]
    return scheme_colors

def tetradic_color_scheme(base_color_hsv):
    scheme_colors = [
        base_color_hsv,
        ((base_color_hsv[0] + 0.25) % 1, base_color_hsv[1], base_color_hsv[2]),
        ((base_color_hsv[0] + 0.5) % 1, base_color_hsv[1], base_color_hsv[2]),
        ((base_color_hsv[0] + 0.75) % 1, base_color_hsv[1], base_color_hsv[2])
    ]
    return scheme_colors

def monochrome_color_scheme(base_color_hsv):
    return (base_color_hsv,)

def analogous_color_scheme(base_color_hsv):
    scheme_colors = [
        base_color_hsv,
        ((base_color_hsv[0] + 0.05) % 1, base_color_hsv[1], base_color_hsv[2]),
        ((base_color_hsv[0] - 0.05) % 1, base_color_hsv[1], base_color_hsv[2])
    ]
    return scheme_colors


color_scheme_map = {
    "complementary": complementary_color_scheme,
    "split-complementary": split_complementary_color_scheme,
    "triadic": triadic_color_scheme,
    "tetradic": tetradic_color_scheme,
    "monochrome": monochrome_color_scheme,
    "analogous": analogous_color_scheme
}


def generate_color_scheme(base_color_hsv, scheme_type):
    try:
        scheme_fn = color_scheme_map[scheme_type]
    except KeyError as e:
        raise ValueError("Invalid color scheme") from e
    
    return scheme_fn(base_color_hsv)


def color_scheme_generator(base_color_dropdown, scheme_type_dropdown):
    # Convert hex value to tuple of integers
    base_color = tuple(int(base_color_dropdown.lstrip("#")[i:i + 2], 16) for i in (0, 2, 4))

    # Convert base color from RGB to HSV
    base_color_hsv = colorsys.rgb_to_hsv(*[c / 255.0 for c in base_color])

    # Generate color scheme
    scheme_colors = generate_color_scheme(base_color_hsv, scheme_type_dropdown)

    # Create a color palette image
    palette_width = 400
    palette_height = 300
    n_rows = 6
    palette = Image.new("RGB", (palette_width, palette_height))
    draw = ImageDraw.Draw(palette)

    color_width = palette_width // len(scheme_colors)
    row_height = palette_height // n_rows
    r = 0
    for r in range(n_rows):
        for i, color in enumerate(scheme_colors):
            # Adjust value of color based on row
            color_adj = list(color)
            # Places the base value at the top of the palette
            # color_adj[2] = (1.0 - r / n_rows) if r > 0 else color[2]
            # Ignores base value and generates a range across rows
            color_adj[2] = 1.0 - r / n_rows
            color_adj = tuple(color_adj)

            # Convert scheme colors from HSV to RGB
            color_rgb = tuple(round(c * 255) for c in colorsys.hsv_to_rgb(*color_adj))

            # Draw color rectangle in image
            draw.rectangle(
                [i * color_width, r * row_height,
                 (i + 1) * color_width, (r + 1) * row_height],
                 fill=color_rgb
            )

    return palette


# Define the base color dropdown
base_color_dropdown = gr.ColorPicker(
    label="Select Base Color (RGB)"
)

# Define the color scheme type dropdown
scheme_type_dropdown = gr.Dropdown(
    choices=color_scheme_map.keys(),
    label="Select Color Scheme Type",
    value="complementary"
)

iface = gr.Interface(
    fn=color_scheme_generator,
    inputs=[base_color_dropdown, scheme_type_dropdown],
    outputs="image"
)
iface.launch()