make_hill_chart_emojis.py

"""
Generate a set of emoji images depicting various points on a hill.

Assumes pillow is available
https://pypi.org/project/pillow/

Image size is based on the size recommended by Notion
"""
import math
import sys

from PIL import Image, ImageDraw


def hill_curve_func(width: int, height: int, x: float) -> float:
    x_center = width // 2
    bottom_margin = width // 6
    # Primary Gaussian curve
    primary_curve_height = width * 1.2
    primary_curve_bell_width = width // 6
    # Subtract a smaller Gaussian curve to flatten the primary curve a bit
    damper_curve_height = width // 2
    damper_curve_bell_width = width // 8

    return (
        height
        - bottom_margin
        - (
            primary_curve_height * math.e ** (-(((x - x_center) ** 2 / (2 * primary_curve_bell_width**2))))
            - damper_curve_height * math.e ** (-(((x - x_center) ** 2 / (2 * damper_curve_bell_width**2))))
        )
    )


def draw_hill_curve(d: ImageDraw.ImageDraw):
    width, height = d.im.size
    for x1 in range(1, width):
        x0 = x1 - 1
        y0 = hill_curve_func(width, height, x0)
        y1 = hill_curve_func(width, height, x1)
        d.line((x0, y0, x1, y1), fill=0, width=width // 30)


def draw_progress_dot(d: ImageDraw.ImageDraw, progress: float):
    """
    :param progress: A float between 0 and 1, inclusive.
    """
    width, height = d.im.size
    x = width * progress
    y = hill_curve_func(width, height, x)
    radius = width // 9
    d.circle((x, y), radius, fill=(0, 168, 211), outline=None, width=0)


def make_emoji(width: int, height: int, progress: float):
    """
    :param progress: A float between 0 and 1, inclusive.
    """
    # To draw a smooth hill curve, we draw on a bigger image and scale it down
    scale = 8
    upscaled_width, upscaled_height = width * scale, height * scale
    image = Image.new("RGB", (upscaled_width, upscaled_height), (255, 255, 255))
    draw_upscaled = ImageDraw.Draw(image)
    draw_hill_curve(draw_upscaled)

    # Draw the progress dot
    final_image = image.resize((width, height), resample=Image.LANCZOS)
    draw_final = ImageDraw.Draw(final_image)
    draw_progress_dot(draw_final, progress=progress)

    return final_image


def main():
    emoji_width = 280
    emoji_height = 280
    dot_count = 7

    for i in range(dot_count):
        progress = (1 + i) / (dot_count + 1)
        emoji = make_emoji(emoji_width, emoji_height, progress)

        with open(f"hill_{i + 1}.png", "wb") as f:
            emoji.save(f, "PNG")


if __name__ == "__main__":
    main()