update: divide polygon into tiles

server/map/get_relation.py

-import string
 import json
 import geopandas as gpd
-from server.map.get_markers import get_all_markers
-from shapely.geometry import Polygon, LineString, Point
+from shapely.geometry import Polygon
 
 
-# get_relation returns the geojson data for a selected body of water
-def get_relation(self, body_of_water: string):
+def get_relation(self, body_of_water: str):
     # Load GeoJSON data using geopandas
     geo_data = gpd.read_file("server/map/mjosa.geojson")
 
-    # Filter only polygons, exclude points
+    # Filter only polygons, exclude points and other feature types
     polygon_data = geo_data[geo_data['geometry'].geom_type == 'Polygon']
 
-    # Convert GeoDataFrame to dictionary
-    geojson_dict = json.loads(polygon_data.to_json())
+    # Extract coordinates from polygons and create polygon objects
+    polygons = [Polygon(polygon.exterior) for polygon in polygon_data['geometry']]
+
+    if len(polygons) <= 1:
+        print("Failed to convert to polygons")
+
+    tiles = []
+
+    for polygon in polygons:
+        tiles.extend(divide_relation(polygon))  # Divide each polygon from relation and append to tiles
+
+    # Convert polygon coordinates to lists
+    tiles_json = [list(tile.exterior.coords) for tile in tiles]
 
     # Convert response data to JSON string
-    response_json = json.dumps(divide_relation(self, polygon_data))
+    response_json = json.dumps(tiles_json)
 
     # Set headers
     self.send_response(200)
@@ -28,54 +36,30 @@ def get_relation(self, body_of_water: string):
     self.wfile.write(response_json.encode('utf-8'))
 
 
-def divide_relation(self, polygon):
-    # Fetch measurements from database
-    measurements = get_all_markers(self.cursor, False, 'Mjosa')
-
-    # Temporary hardcoded point at which relation is split, should be
-    splitting_points = [(60.6853, 10.9571), (60.7018, 11.1058)]
-
-    # Lists to hold new polygons
-    divided_relation = []
-    temp_seg_1 = []
-    temp_seg_2 = []
-
-    # Loop through polygon coordinates and split at defined coordinates
-    for i in range(len(polygon)):
-
-        closest_point = []
-
-        # Find the closest point on the polygon to the splitting point
-        for point in splitting_points:
-            closest_point = polygon.exterior.interpolate(polygon.exterior.project(Point(point)),normalized=True)
-
-        # Check if the closest point is already in the polygon coordinates
-        if closest_point.coords[0] not in polygon:
-            # If not, add it to the polygon coordinates
-            polygon.append(closest_point.coords[0])
-        # Add the splitting point (either the original or the closest) to the splitting points list
-        splitting_points.append(closest_point.coords[0])
-
-        current_point = polygon[i]
-        next_point = polygon[(i + 1) % len(polygon)]  # Circular index
-
-        # Check if the current segment crosses any splitting point
-        for splitting_point in splitting_points:
-            if (current_point != splitting_point and
-                    next_point != splitting_point and
-                    LineString([current_point, next_point]).intersects(Point(splitting_point))):
-                # Split the segment at the splitting point
-                temp_seg_1.append(current_point)
-                temp_seg_2.append(splitting_point)
-                temp_seg_1.append(splitting_point)
-                temp_seg_2.append(next_point)
-                break
-        else:
-            # If the segment doesn't cross any splitting point, add it to both lists
-            temp_seg_1.append(current_point)
-            temp_seg_2.append(current_point)
-
-    # Return a list containing all the created polygons
-    divided_relation = [Polygon(temp_seg_1), Polygon(temp_seg_2)]
-
-    return divided_relation
+def divide_relation(polygon):
+    # Define tile size
+    tile_size = 0.01
+
+    x_min, y_min, x_max, y_max = polygon.bounds
+    rows = int((y_max - y_min) / tile_size)
+    cols = int((x_max - x_min) / tile_size)
+
+    tiles = []
+
+    if rows == 0 or cols == 0:  # Return if the polygon is too small
+        return []
+
+    for row in range(rows):
+        for col in range(cols):
+            tile_bbox = Polygon([
+                (x_min + col * tile_size, y_min + row * tile_size),
+                (x_min + (col + 1) * tile_size, y_min + row * tile_size),
+                (x_min + (col + 1) * tile_size, y_min + (row + 1) * tile_size),
+                (x_min + col * tile_size, y_min + (row + 1) * tile_size)
+            ])
+            tiles.append(tile_bbox)
+
+    if len(tiles) <= 1:
+        print("Failed to divide polygon into tiles")
+
+    return tiles