Create the map WKT behavior.

modules/core/map/config/install/farm_map.map_behavior.wkt.yml

@@ -0,0 +1,11 @@
+langcode: en
+status: true
+dependencies:
+  enforced:
+    module:
+      - farm_map
+id: wkt
+label: WKT
+description: 'Displays WKT as a map layer.'
+library: 'farm_map/behavior_wkt'
+settings: { }

modules/core/map/farm_map.libraries.yml

@@ -19,3 +19,9 @@ farm_map:
     js/farm_map.js: { }
   dependencies:
     - farm_map/farmOS-map
+behavior_wkt:
+  js:
+    js/farmOS.map.behaviors.wkt.js: { }
+  dependencies:
+    - core/drupalSettings
+    - farm_map/farm_map

modules/core/map/js/farmOS.map.behaviors.wkt.js

@@ -0,0 +1,44 @@
+(function () {
+  farmOS.map.behaviors.wkt = {
+    attach: function (instance) {
+
+      // If WKT was set, create a layer.
+      if (drupalSettings.farm_map[instance.target].wkt) {
+        var wkt = drupalSettings.farm_map[instance.target].wkt;
+        var type = 'vector';
+        var opts = {
+          title: 'Geometry',
+          color: 'orange',
+        };
+        if (wkt !== '' && wkt !== 'GEOMETRYCOLLECTION EMPTY') {
+          type = 'wkt';
+          opts.wkt = wkt;
+        }
+        var layer = instance.addLayer(type, opts);
+      }
+
+      // If edit is true, enable drawing controls.
+      if (drupalSettings.farm_map[instance.target].behaviors.wkt.edit) {
+        if (layer !== undefined) {
+          instance.addBehavior('edit', { layer: layer });
+        } else {
+          instance.addBehavior('edit');
+          var layer = instance.edit.layer;
+        }
+
+        // Add the snappingGrid behavior.
+        instance.addBehavior('snappingGrid');
+      }
+
+      // Enable the line/polygon measure behavior.
+      instance.addBehavior('measure', { layer: layer });
+
+      // If zoom is true and the layer has features, zoom to them.
+      // Otherwise, zoom to all vectors.
+      if (drupalSettings.farm_map[instance.target].behaviors.wkt.zoom && layer !== undefined) {
+        instance.zoomToLayer(layer);
+      }
+    },
+    weight: 100,
+  };
+}());