overlayLib.py

import geopandas
import urllib
import shapely
import matplotlib.pyplot as plt
from math import sin, cos, sqrt, atan2, radians
import json
from PIL import Image
import os


def getDistance(lat1, lon1, lat2, lon2):
    R = 6373.0
    lat1 = radians(lat1)
    lon1 = radians(lon1)
    lat2 = radians(lat2)
    lon2 = radians(lon2)

    dlon = lon2 - lon1
    dlat = lat2 - lat1

    a = sin(dlat / 2)**2 + cos(lat1) * cos(lat2) * sin(dlon / 2)**2
    c = 2 * atan2(sqrt(a), sqrt(1 - a))

    distance = R * c
    return distance


def getCitySize(cityBounds):
    lat1, lon1, lat2, lon2 = cityBounds
    return getDistance(lat1, lon1, lat2, lon2)


def getCityOutline(query: str):
    openStreetMap_base_url = "https://nominatim.openstreetmap.org/search"
    url = openStreetMap_base_url + '?' + urllib.parse.urlencode({
        "q": query,
        "format": "json",
        "polygon_geojson": 1
    })

    # filename should not have things like "," or whitespaces
    fileName = query.lower().replace(", ", "_").replace(",", "_")
    # If json for that query already exists --> get it
    if os.path.exists(f"cache/{fileName}.json"):
        with open(f"cache/{fileName}.json", "r") as f:
            responseJson = json.loads(f.read())
    # else get it from the web
    else:
        response = urllib.request.urlopen(url).read()
        responseJson = json.loads(response)
        # save file
        os.makedirs("cache", exist_ok=True)
        with open(f"cache/{fileName}.json", "w") as f:
            json.dump(responseJson, f)

    # find first multipolygon/polygon result (most likely the correct one)
    for shape in responseJson:
        # Included this try if shape has no geojson. Now just goes to next entry
        try:
            if isinstance(shapely.geometry.shape(shape["geojson"]), shapely.geometry.MultiPolygon):
                cityShape = shapely.geometry.shape(shape["geojson"])
                lat1, long1, lat2, long2 = cityShape.bounds
                bounds = [lat1, long1, lat2, long2]
                # check if size is way too big or too small. If so --> kick out
                size = getCitySize(bounds)
                if size > 200 or size < 5:
                    continue
                cityGDF = geopandas.GeoDataFrame({
                    "geometry": cityShape
                })
                return cityGDF, bounds
            elif isinstance(shapely.geometry.shape(shape["geojson"]), shapely.geometry.Polygon):
                cityShape = shapely.geometry.shape(shape["geojson"])
                lat1, long1, lat2, long2 = cityShape.bounds
                bounds = [lat1, long1, lat2, long2]
                # check if size is way too big or too small. If so --> kick out
                size = getCitySize(bounds)
                if size > 200 or size < 5:
                    continue
                cityGDF = geopandas.GeoDataFrame({
                    "geometry": cityShape
                }, index=[0])
                return cityGDF, bounds
        except:
            continue
    # If nothing found return None
    return None, None


def overlayCities(city1, size1, city2, size2):
    if size1 > size2:
        bigCity = city1
        bigSize = size1
        smallCity = city2
        smallSize = size2
    else:
        bigCity = city2
        bigSize = size2
        smallCity = city1
        smallSize = size1
    # Save the cities as images
    bigCity.plot(color="red")
    plt.axis("off")
    plt.savefig("static/images/BigCity.png", transparent=True)
    plt.close()
    smallCity.plot(alpha=0.7)
    plt.axis("off")
    plt.savefig("static/images/SmallCity.png", transparent=True)
    plt.close()
    # Load images with Pillow
    bigCityIm = Image.open("static/images/BigCity.png")
    smallCityIm = Image.open("static/images/SmallCity.png")
    oldWidth, oldHeight = smallCityIm.size
    newWidth = int(oldWidth * smallSize / bigSize)
    newHeight = int(oldHeight * smallSize / bigSize)
    # Scale down the smaller city
    smallCityImScaled = smallCityIm.resize((newWidth, newHeight))
    # Find center of bigger city
    bigCityWidth, bigCityHeight = bigCityIm.size
    bigCenterW = int(bigCityWidth / 2)
    bigCenterH = int(bigCityHeight / 2)
    topLeftX = bigCenterW - int(newWidth / 2)
    topLeftY = bigCenterH - int(newHeight / 2)
    botRightX = bigCenterW + (newWidth - int(newWidth / 2))
    botRightY = bigCenterH + (newHeight - int(newHeight / 2))
    # Paste the small city onto the bigger one (the mask key-word reserves the transparency of the png)
    bigCityIm.paste(smallCityImScaled, (topLeftX, topLeftY, botRightX, botRightY), mask=smallCityImScaled)
    bigCityIm.save("static/images/Overlay.png", "png")
    #     bigCityIm.show()
    return bigCityIm