Don't populate sdf_names needlessly

src/scenario/scenario.cpp

@@ -605,3 +605,11 @@ std::string cScenario::get_feature_flag(std::string flag) {
 	if(iter == this->feature_flags.end()) return "";
 	return iter->second;
 }
+
+std::string cScenario::get_sdf_name(int col, int row) {
+	if(sdf_names.find(col) == sdf_names.end())
+		return "";
+	if(sdf_names[col].find(row) == sdf_names[col].end())
+		return "";
+	return sdf_names[col][row];
+}

src/scenario/scenario.hpp

@@ -104,6 +104,8 @@ class cScenario {
 	std::vector<std::string> ic_names;
 	std::vector<std::string> itf_names;
 	std::map<int, std::map<int, std::string>> sdf_names;
+	std::string get_sdf_name(int col, int row);
+
 	bool adjust_diff;
 	bool is_legacy;
 	fs::path scen_file; // transient

src/scenedit/scen.fileio.cpp

@@ -417,7 +417,7 @@ void writeScenarioToXml(ticpp::Printer&& data, cScenario& scenario) {
 	}
 	for(int x = 0; x < SDF_COLUMNS; x++) {
 		for(int y = 0; y < SDF_ROWS; y++) {
-			if(scenario.sdf_names[x][y].empty()) continue;
+			if(scenario.get_sdf_name(x, y).empty()) continue;
 			data.OpenElement("sdf");
 			data.PushAttribute("row", x);
 			data.PushAttribute("col", y);

src/scenedit/scen.sdfpicker.cpp

@@ -119,7 +119,7 @@ void cStuffDonePicker::fill_names() {
 			location sdf = viewport;
 			sdf.x += x;
 			sdf.y += y;
-			field.setText(scenario.sdf_names[sdf.x][sdf.y]);
+			field.setText(scenario.get_sdf_name(sdf.x, sdf.y));
 			if(x == 0) {
 				// Add row labels
 				row_labels->getChild("row", 0, y).setTextToNum(sdf.y);
@@ -139,7 +139,8 @@ void cStuffDonePicker::save_names() {
 			location sdf = viewport;
 			sdf.x += x;
 			sdf.y += y;
-			scenario.sdf_names[sdf.x][sdf.y] = field.getText();
+			if(!field.getText().empty())
+				scenario.sdf_names[sdf.x][sdf.y] = field.getText();
 		}
 	}
 }