Add MN Ambulance Service Areas layer

Requested-By: Isaac Swift

layers/mn-ambulance-service-areas/layer.js

@@ -0,0 +1,54 @@
+import GeoJSON from 'ol/format/GeoJSON.js';
+import VectorLayer from 'ol/layer/Vector.js';
+import VectorSource from 'ol/source/Vector.js';
+
+import serviceAreas from './mn-ambulance-service-areas.geojson?url';
+
+import { Fill, Stroke, Style, Text } from 'ol/style.js';
+
+window.chosenColors = {};
+window.chosenColors2 = {};
+
+function style(feature){
+    const name = feature.get('AmbServNam');
+    // // djb2 -- results in very non-uniform distribution
+    // // https://web.archive.org/web/20251011200517/https://www.cse.yorku.ca/~oz/hash.html
+    // let hash = 5381;
+    // for (let i = 0; i < name.length; i++) {
+    //     hash = hash * 33 + name.charCodeAt(i);
+    // }
+    // const colorDeg = hash % 360;
+
+    // erichash -- thanks @villnoweric
+    let hash = 0;
+    for (let i = 0; i < name.length; i++) {
+        hash += name.charCodeAt(i);
+    }
+    let colorDeg = hash % 360;
+
+    return new Style({
+        text: new Text({
+            text: name,
+        }),
+        fill: new Fill({
+            color: `lch(50% 50 ${colorDeg} / 40%)`,
+        }),
+        stroke: new Stroke({
+            color: `lch(50% 50 ${colorDeg})`,
+            width: 1.25,
+        }),
+    });
+}
+
+const layer = {
+    name: "MN Ambulance Service Areas",
+    layer: new VectorLayer({
+        source: new VectorSource({
+            url: serviceAreas,
+            format: new GeoJSON(),
+        }),
+        style: style,
+    }),
+};
+
+export default layer;