feat: add feature cache to GeoFeatureLayer to ensure signal propagation

Previously, signals called on one feature would not be triggered on another feature from the same layer loaded by a different call (e.g. two separate "get_features_near_position" calls) since they were entirely different objects.

Now, the two features are the same object and therefore signals propagate between them.

This should have no effects on thread safety as the underlying GDAL feature was already cached and identical, this just makes the wrapper cached as well.

src/geodata.cpp

@@ -145,7 +145,15 @@ Vector3 GeoFeatureLayer::get_center() {
 }
 
 // Utility function for converting a Processing Library Feature to the appropriate GeoFeature
-Ref<GeoFeature> get_specialized_feature(std::shared_ptr<Feature> raw_feature) {
+Ref<GeoFeature> GeoFeatureLayer::get_specialized_feature(std::shared_ptr<Feature> raw_feature) {
+    if (feature_cache.count(raw_feature)) {
+        return feature_cache[raw_feature];
+    }
+
+    // Not cached -> instantiate and cache
+
+    Ref<GeoFeature> new_feature;
+
     // Check which geometry this feature has, and cast it to the according
     // specialized class
     if (raw_feature->geometry_type == raw_feature->POINT) {
@@ -156,7 +164,7 @@ Ref<GeoFeature> get_specialized_feature(std::shared_ptr<Feature> raw_feature) {
 
         point->set_gdal_feature(point_feature);
 
-        return point;
+        new_feature = point;
     } else if (raw_feature->geometry_type == raw_feature->LINE) {
         Ref<GeoLine> line;
         line.instantiate();
@@ -165,7 +173,7 @@ Ref<GeoFeature> get_specialized_feature(std::shared_ptr<Feature> raw_feature) {
 
         line->set_gdal_feature(line_feature);
 
-        return line;
+        new_feature = line;
     } else if (raw_feature->geometry_type == raw_feature->POLYGON) {
         Ref<GeoPolygon> polygon;
         polygon.instantiate();
@@ -174,16 +182,20 @@ Ref<GeoFeature> get_specialized_feature(std::shared_ptr<Feature> raw_feature) {
 
         polygon->set_gdal_feature(polygon_feature);
 
-        return polygon;
+        new_feature = polygon;
     } else {
         // Geometry type is NONE or unknown
         Ref<GeoFeature> feature;
         feature.instantiate();
 
         feature->set_gdal_feature(raw_feature);
 
-        return feature;
+        new_feature = feature;
     }
+
+    feature_cache[raw_feature] = new_feature;
+
+    return new_feature;
 }
 
 Ref<GeoFeature> GeoFeatureLayer::get_feature_by_id(int id) {

src/geodata.h

@@ -83,6 +83,9 @@ class EXPORT GeoFeatureLayer : public RefCounted {
     /// Note that syntax errors are printed to the console by GDAL.
     Array get_features_by_attribute_filter(String filter);
 
+    /// Returns the (cached) specialized feature of the given raw feature
+    Ref<GeoFeature> get_specialized_feature(std::shared_ptr<Feature> raw_feature);
+
     /// Set the OGRLayer object directly.
     /// Not exposed to Godot since Godot doesn't know about GDALDatasets - this
     /// is only for internal use.
@@ -96,6 +99,7 @@ class EXPORT GeoFeatureLayer : public RefCounted {
 
   private:
     std::shared_ptr<NativeLayer> layer;
+    std::map<std::shared_ptr<Feature>, Ref<GeoFeature>> feature_cache;
     Ref<GeoDataset> origin_dataset;
     ExtentData extent_data;
 };