advent22/api/advent22_api/routers/days.py

import colorsys
import random
from datetime import date
from io import BytesIO

import numpy as np
from fastapi import APIRouter, Depends
from fastapi.responses import StreamingResponse
from PIL import Image, ImageDraw, ImageFont

router = APIRouter(prefix="/days", tags=["days"])

loesungswort = "ABCDEFGHIJKLMNOPQRSTUVWX"


async def shuffle(string: str) -> str:
    rnd = random.Random(loesungswort)
    return "".join(rnd.sample(string, len(string)))


@router.on_event("startup")
async def narf() -> None:
    print(loesungswort)
    print(await shuffle(loesungswort))


@router.get("/letter/{index}")
async def get_letter(
    index: int,
) -> str:
    return (await shuffle(loesungswort))[index]


@router.get("/date")
def get_date() -> int:
    return date.today().day


@router.get(
    "/picture",
    response_class=StreamingResponse,
)
async def get_picture():
    img = Image.open("hand.png").convert("RGBA")
    d1 = ImageDraw.Draw(img)
    font = ImageFont.truetype("Lena.ttf", 50)
    d1.text((260, 155), "W", font=font, fill=(0, 0, 255))
    # d1.text(xy=(400, 210), text="Deine Hände auch?",
    #         font=Font, fill=(255, 0, 0))
    img_buffer = BytesIO()
    img.save(img_buffer, format="PNG", quality=85)
    img_buffer.seek(0)

    return StreamingResponse(
        content=img_buffer,
        media_type="image/png",
    )


async def load_picture_standard() -> Image.Image:
    """
    Bild laden und einen quadratischen Ausschnitt
    aus der Mitte nehmen
    """

    # Bild laden
    img = Image.open("lena2.jpg")

    # Größen bestimmen
    width, height = img.size
    square = min(width, height)

    # Bild zuschneiden und skalieren
    img = img.crop(box=(
        int((width - square)/2),
        int((height - square)/2),
        int((width + square)/2),
        int((height + square)/2),
    ))

    img = img.resize(
        size=(400, 400),
        resample=Image.ANTIALIAS,
    )

    # Farbmodell festlegen
    return img.convert("RGB")


async def get_text_box(
    img: Image.Image,
    xy: tuple[float, float],
    text: str | bytes,
    font: "ImageFont._Font",
    anchor: str | None = "mm",
    **text_kwargs,
) -> tuple[int, int, int, int] | None:
    """
    Koordinaten (links, oben, rechts, unten) des betroffenen
    Rechtecks bestimmen, wenn das Bild `img` mit einem Text
    versehen wird
    """

    # Neues 1-Bit Bild, gleiche Größe
    mask = Image.new(mode="1", size=img.size, color=0)

    # Text auf Maske auftragen
    ImageDraw.Draw(mask).text(
        xy=xy,
        text=text,
        font=font,
        anchor=anchor,
        fill=1,
        **text_kwargs,
    )

    # betroffenen Pixelbereich bestimmen
    return mask.getbbox()


async def get_average_color(
    img: Image.Image,
    box: tuple[int, int, int, int],
) -> tuple[int, int, int]:
    """
    Durchschnittsfarbe eines rechteckigen Ausschnitts in
    einem Bild `img` berechnen
    """

    pixel_data = img.crop(box).getdata()
    mean_color: np.ndarray = np.mean(pixel_data, axis=0)

    return tuple(mean_color.astype(int).tolist())


@router.get(
    "/picture/{index}",
    response_class=StreamingResponse,
)
async def get_picture_for_day(
    index: int,
    letter: str = Depends(get_letter),
    img: Image.Image = Depends(load_picture_standard),
) -> StreamingResponse:
    """
    Bild für einen Tag erstellen
    """

    # Font laden
    font = ImageFont.truetype("Lena.ttf", 50)

    # Position des Buchstaben bestimmen
    rnd = random.Random(f"{loesungswort}{index}")
    xy = tuple(rnd.choices(range(30, 370), k=2))

    # betroffenen Bildbereich bestimmen
    text_box = await get_text_box(
        img=img,
        xy=xy,
        text=letter,
        font=font,
    )

    if text_box is not None:
        # Durchschnittsfarbe bestimmen
        text_color = await get_average_color(
            img=img,
            box=text_box,
        )

        # etwas heller/dunkler machen
        tc_h, tc_s, tc_v = colorsys.rgb_to_hsv(*text_color)
        tc_v = int((tc_v - 127) * 0.97) + 127

        if tc_v < 127:
            tc_v += 3

        else:
            tc_v -= 3

        text_color = colorsys.hsv_to_rgb(tc_h, tc_s, tc_v)
        text_color = tuple(int(val) for val in text_color)

        # Buchstaben verstecken
        ImageDraw.Draw(img).text(
            xy=xy,
            text=letter,
            font=font,
            anchor="mm",
            fill=text_color,
        )

    # Bilddaten in Puffer laden
    img_buffer = BytesIO()
    img.save(img_buffer, format="JPEG", quality=85)
    img_buffer.seek(0)

    return StreamingResponse(
        content=img_buffer,
        media_type="image/jpeg",
    )