Serve blank tiles with the z/x/y address labelled

serve-blanks.py

import io

from fastapi import FastAPI, Response
from PIL import Image, ImageDraw, ImageFont

app = FastAPI()


@app.get("/tiles/{z}/{x}/{y}.png")
async def get_debug_tile(z: int, x: int, y: int):
    img = Image.new("RGB", (256, 256), "white")

    draw = ImageDraw.Draw(img)
    draw.rectangle([0, 0, 255, 255], outline="black", width=1)

    font = ImageFont.load_default()
    text = f"{z}/{x}/{y}"

    # Calculate text size and position for centering
    bbox = draw.textbbox((0, 0), text, font=font)
    text_width = bbox[2] - bbox[0]
    text_height = bbox[3] - bbox[1]
    x_pos = (256 - text_width) // 2
    y_pos = (256 - text_height) // 2

    # Draw it
    draw.text((x_pos, y_pos), text, fill="black", font=font)

    # Save to bytes
    img_byte_arr = io.BytesIO()
    img.save(img_byte_arr, format="PNG")
    img_byte_arr.seek(0)

    return Response(content=img_byte_arr.getvalue(), media_type="image/png")


if __name__ == "__main__":
    import uvicorn

    uvicorn.run(app, host="0.0.0.0", port=8080)