Implement a mechanism for a special node picker to affect two fields

Use it for the MSG_PAIR picker and the PIC_NONE picker.

src/scenario/special.cpp

@@ -762,7 +762,7 @@ node_builder_t& node_builder_t::sdf() {
 }
 
 node_builder_t& node_builder_t::msg() {
-	return msg1(eSpecPicker::MSG_PAIR).msg2(eSpecPicker::NONE);
+	return field_pair(eSpecField::MSG1, eSpecField::MSG2, eSpecPicker::MSG_PAIR);
 };
 
 node_builder_t& node_builder_t::rect() {
@@ -772,7 +772,7 @@ node_builder_t& node_builder_t::rect() {
 };
 
 node_builder_t& node_builder_t::pic() {
-	return pict(eSpecPicker::PICTURE).ptyp(STRT_PICT);
+	return field_pair(eSpecField::PICT, eSpecField::PTYP, eSpecPicker::PICTURE).ptyp(STRT_PICT);
 }
 
 node_builder_t& node_builder_t::sdf1(node_function_t picker) {
@@ -838,8 +838,9 @@ node_builder_t& node_builder_t::field(eSpecField field, node_function_t picker)
 }
 
 node_builder_t& node_builder_t::field_pair(eSpecField main, eSpecField extra, node_function_t picker) {
-	// Not implemented yet, so just assign the picker to the main field and NONE to the extra field.
+	field(main, picker).field(extra, eSpecPicker::NONE);
-	return field(main, picker).field(extra, eSpecPicker::NONE);
+	(node.*fields().map[main]).continuation = extra;
+	return *this;
 }
 
 node_builder_t& node_builder_t::sdf(eSpecField a, eSpecField b) {

src/scenario/special.hpp

@@ -160,7 +160,7 @@ enum class eSpecPicker {
 	POINTER,
 };
 
-enum class eSpecField { SDF1, SDF2, MSG1, MSG2, MSG3, PICT, PTYP, EX1A, EX1B, EX1C, EX2A, EX2B, EX2C, JUMP };
+enum class eSpecField { NONE, SDF1, SDF2, MSG1, MSG2, MSG3, PICT, PTYP, EX1A, EX1B, EX1C, EX2A, EX2B, EX2C, JUMP };
 
 struct node_function_t {
 	eSpecPicker button = eSpecPicker::NONE;
@@ -172,6 +172,7 @@ struct node_function_t {
 	};
 	bool augmented = false; // only for eSpecPicker::FIELD and eSpecPicker::STRING with certain string types
 	int adjust = 0; // only for eSpecPicker::STRING
+	eSpecField continuation = eSpecField::NONE;
 	std::string label() const;
 	std::string help() const; // maybe we don't need this though? I guess it would be for a hypothetical help button next to each field to give addition info on how that one field works.
 	node_function_t();

src/scenedit/scen.keydlgs.cpp

@@ -855,18 +855,44 @@ static node_function_t get_field_function(const cSpecial& spec, const std::strin
 	return node_function_t();
 }
 
+static std::string get_control_for_field(eSpecField field) {
+	switch(field) {
+		case eSpecField::SDF1: return "sdf1";
+		case eSpecField::SDF2: return "sdf2";
+		case eSpecField::MSG1: return "msg1";
+		case eSpecField::MSG2: return "msg2";
+		case eSpecField::MSG3: return "msg3";
+		case eSpecField::PICT: return "pict";
+		case eSpecField::PTYP: return "pictype";
+		case eSpecField::EX1A: return "x1a";
+		case eSpecField::EX1B: return "x1b";
+		case eSpecField::EX1C: return "x1c";
+		case eSpecField::EX2A: return "x2a";
+		case eSpecField::EX2B: return "x2b";
+		case eSpecField::EX2C: return "x2c";
+		case eSpecField::JUMP: return "jump";
+		case eSpecField::NONE: break;
+	}
+	return "num";
+}
+
 static bool edit_spec_enc_value(cDialog& me, std::string item_hit, node_stack_t& edit_stack) {
 	std::string field = item_hit.substr(0, item_hit.find_first_of('-'));
 	const cSpecial& spec = edit_stack.top().node;
 	node_function_t fcn = get_field_function(spec, field);
 	short val = me[field].getTextAsNum(), store;
 	switch(fcn.button) {
-		case eSpecPicker::MSG_PAIR:
+		case eSpecPicker::MSG_PAIR: {
-			store = me["msg2"].getTextAsNum();
+			if(fcn.continuation == eSpecField::NONE) {
+				store = val;
+				break;
+			}
+			auto otherField = get_control_for_field(fcn.continuation);
+			store = me[otherField].getTextAsNum();
 			edit_spec_text(fcn.force_global ? STRS_SCEN : eStrMode(edit_stack.top().mode), &val, &store, &me);
-			me["msg2"].setTextToNum(store);
+			me[otherField].setTextToNum(store);
 			store = val;
-			break;
+		} break;
 		case eSpecPicker::MSG_SINGLE:
 			edit_spec_text(fcn.force_global ? STRS_SCEN : eStrMode(edit_stack.top().mode), &val, nullptr, &me);
 			store = val;
@@ -958,9 +984,10 @@ static bool edit_spec_enc_value(cDialog& me, std::string item_hit, node_stack_t&
 		case eSpecPicker::PICTURE: {
 			ePicType type = fcn.pic_type;
 			if(type == PIC_NONE) {
-				short pictype = me["pictype"].getTextAsNum();
+				auto otherField = get_control_for_field(fcn.continuation);
+				short pictype = me[otherField].getTextAsNum();
 				if(pictype < 0) {
-					me["pictype"].setTextToNum(PIC_DLOG);
+					me[otherField].setTextToNum(PIC_DLOG);
 					type = PIC_DLOG;
 				} else type = ePicType(pictype);
 			}