layers: Add Sweden topo map; add script for creating layer cutlines

src/layers.js

@@ -1066,6 +1066,33 @@ class LayerGroupWithOptions extends L.LayerGroup {
                         }
                     )
                 },
+                {
+                    title: 'Sweden topo',
+                    isDefault: false,
+                    layer: L.tileLayer(
+                        'https://minkarta.lantmateriet.se/map/topowebbcache' +
+                        '?layer=topowebb&style=default&tilematrixset=3857&Service=WMTS&Request=GetTile&Version=1.0.0' +
+                        '&Format=image%2Fpng&TileMatrix={z}&TileCol={x}&TileRow={y}',
+                        {
+                            code: 'Se',
+                            isOverlay: true,
+                            tms: false,
+                            print: true,
+                            jnx: true,
+                            scaleDependent: true,
+                            shortName: 'sweden_topo',
+                            isOverlayTransparent: false,
+                            minZoom: 0,
+                            maxNativeZoom: 17,
+                            bounds: [[55.13493, 10.58876], [69.07200, 24.18365]],
+                            noCors: false,
+                            cutline: getCutline('sweden'),
+                            attribution: '<a href="https://minkarta.lantmateriet.se/">' +
+                                'Lantmäteriet</a>'
+                        }
+                    )
+                },
+
     ];
 
     const groupsDefs = [
@@ -1119,6 +1146,7 @@ class LayerGroupWithOptions extends L.LayerGroup {
                 'Topo 250m',
                 'Montenegro topo 250m',
                 'Finland Topo',
+                'Sweden topo',
                 'Great Britain Topo',
                 'Slovakia topo',
                 'Spain topo',
@@ -1190,6 +1218,7 @@ class LayerGroupWithOptions extends L.LayerGroup {
         'Norway paper map',
         'Norway topo',
         'Finland Topo',
+        'Sweden topo',
         'Slovakia topo',
         'Spain topo',
         'Mountains by Alexander Purikov',

src/lib/layers-cutlines/scripts/cutline.py

@@ -0,0 +1,75 @@
+#!/usr/bin/env python3
+import argparse
+import json
+
+from shapely.geometry import MultiPolygon, Point, Polygon, shape
+
+OUTPUT_PRECISION = 5
+
+
+def simplify_line(line, tolerance):
+    return line.simplify(tolerance, preserve_topology=True)
+
+
+def round_coordinates(line, precision):
+    return [(round(x, precision), round(y, precision)) for x, y in line.coords]
+
+
+def main(input_file, output_file, tolerance):
+    with open(input_file, "r") as f:
+        data = json.load(f)
+
+    total_nodes = 0
+    simplified_geometries = []
+    for feature in data["features"]:
+        geom = shape(feature["geometry"])
+        if isinstance(geom, Point):
+            print("Skipping point geometry")
+            continue
+        if isinstance(geom, Polygon):
+            polygons = [geom]
+        elif isinstance(geom, MultiPolygon):
+            polygons = geom.geoms
+        else:
+            print(f"Error: Unsupported geometry type '{geom.geom_type}' encountered.")
+            exit(1)
+
+        for polygon in polygons:
+            if polygon.interiors:
+                print("Error: Polygons with holes not supported")
+                exit(1)
+            linestring = polygon.exterior
+            simplified_linestring = simplify_line(linestring, tolerance)
+            simplified_geometries.append(
+                round_coordinates(simplified_linestring, OUTPUT_PRECISION)
+            )
+
+            polygon_index = len(simplified_geometries)
+            orig_nodes_count = len(linestring.coords)
+            result_nodes_count = len(simplified_linestring.coords)
+
+            print(
+                f"Polygon #{polygon_index}: {orig_nodes_count} -> {result_nodes_count} nodes."
+            )
+            total_nodes += len(simplified_linestring.coords)
+
+    with open(output_file, "w") as f:
+        data = {"cutline": simplified_geometries}
+        json.dump(data, f)
+    print(f"Total nodes: {total_nodes}")
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description="Create boundary from a GeoJSON.")
+    parser.add_argument("input_file", type=str, help="Input GeoJSON file")
+    parser.add_argument("output_file", type=str, help="Output JSON file")
+    parser.add_argument(
+        "-t",
+        "--tolerance",
+        default=0.01,
+        type=float,
+        help="Tolerance for simplifying geometries, default=0.01",
+    )
+    args = parser.parse_args()
+    main(args.input_file, args.output_file, args.tolerance)
+

src/lib/layers-cutlines/scripts/readme.txt

@@ -0,0 +1,11 @@
+How to prepare json cutline for country.
+
+1. On https://www.openstreetmap.org/ find relation id for country border
+2. On https://overpass-turbo.eu/ execute query, replacing ID with actual value:
+rel(ID);
+out body;
+>;
+out skel qt;
+3. Export result as geojson.
+4. Check result at https://geojson.io/
+5. Use script cutline.py to create cutline file.