strgen: Allow using another string as a default translation source

src/lang/extra/english.txt

@@ -15,7 +15,6 @@ STR_TIMETABLE_TOTAL_TIME                                        :{BLACK}This tim
 STR_TIMETABLE_TOTAL_TIME_INCOMPLETE                             :{BLACK}This timetable will take at least {STRING3} to complete (not all timetabled)
 STR_TIMETABLE_STATUS_LATE                                       :{BLACK}This vehicle is currently running {STRING3} late
 STR_TIMETABLE_STATUS_EARLY                                      :{BLACK}This vehicle is currently running {STRING3} early
-STR_SCREENSHOT_WORLD_SCREENSHOT                                 :{BLACK}Whole map default zoom screenshot
 ##override off
 
 ##after STR_CONFIG_SETTING_TREE_PLACER_IMPROVED
@@ -1647,7 +1646,10 @@ STR_CARGO_TYPE_UNLOAD_ORDERS_DROP_TOOLTIP                       :{BLACK}Change t
 STR_CARGO_TYPE_ORDERS_SET_TO_ALL_LABEL                          :{BLACK}Set all to:
 STR_CARGO_TYPE_ORDERS_SET_TO_ALL_TOOLTIP                        :{BLACK}Set all cargo type orders to the one selected by the dropdown
 
+##default-translation STR_SCREENSHOT_WORLD_SCREENSHOT
+STR_SCREENSHOT_WORLD_SCREENSHOT_DEFAULT_ZOOM                    :{BLACK}Whole map default zoom screenshot
 STR_SCREENSHOT_WORLD_SCREENSHOT_CURRENT_ZOOM                    :{BLACK}Whole map current zoom screenshot
+
 STR_SCREENSHOT_TOPOGRAPHY_SCREENSHOT                            :{BLACK}Topography screenshot
 STR_SCREENSHOT_INDUSTRY_SCREENSHOT                              :{BLACK}Industries screenshot
 

src/lang/extra/korean.txt

@@ -1614,7 +1614,9 @@ STR_CARGO_TYPE_UNLOAD_ORDERS_DROP_TOOLTIP                       :{BLACK}이 화
 STR_CARGO_TYPE_ORDERS_SET_TO_ALL_LABEL                          :{BLACK}모두 설정:
 STR_CARGO_TYPE_ORDERS_SET_TO_ALL_TOOLTIP                        :{BLACK}모든 화물의 승/하차 설정을 한 번에 변경합니다.
 
+STR_SCREENSHOT_WORLD_SCREENSHOT_DEFAULT_ZOOM                    :{BLACK}기본 확대 지도 전체 스크린 샷
 STR_SCREENSHOT_WORLD_SCREENSHOT_CURRENT_ZOOM                    :{BLACK}현재 확대 지도 전체 스크린 샷
+
 STR_SCREENSHOT_TOPOGRAPHY_SCREENSHOT                            :{BLACK}지형 스크린 샷
 STR_SCREENSHOT_INDUSTRY_SCREENSHOT                              :{BLACK}산업시설 스크린 샷
 

src/screenshot_gui.cpp

@@ -57,7 +57,7 @@ static const NWidgetPart _nested_screenshot[] = {
 		NWidget(WWT_PUSHTXTBTN, COLOUR_GREY, WID_SC_TAKE), SetFill(1, 1), SetDataTip(STR_SCREENSHOT_SCREENSHOT, 0), SetMinimalTextLines(2, 0),
 		NWidget(WWT_PUSHTXTBTN, COLOUR_GREY, WID_SC_TAKE_ZOOMIN), SetFill(1, 1), SetDataTip(STR_SCREENSHOT_ZOOMIN_SCREENSHOT, 0), SetMinimalTextLines(2, 0),
 		NWidget(WWT_PUSHTXTBTN, COLOUR_GREY, WID_SC_TAKE_DEFAULTZOOM), SetFill(1, 1), SetDataTip(STR_SCREENSHOT_DEFAULTZOOM_SCREENSHOT, 0), SetMinimalTextLines(2, 0),
-		NWidget(WWT_PUSHTXTBTN, COLOUR_GREY, WID_SC_TAKE_WORLD), SetFill(1, 1), SetDataTip(STR_SCREENSHOT_WORLD_SCREENSHOT, 0), SetMinimalTextLines(2, 0),
+		NWidget(WWT_PUSHTXTBTN, COLOUR_GREY, WID_SC_TAKE_WORLD), SetFill(1, 1), SetDataTip(STR_SCREENSHOT_WORLD_SCREENSHOT_DEFAULT_ZOOM, 0), SetMinimalTextLines(2, 0),
 		NWidget(WWT_PUSHTXTBTN, COLOUR_GREY, WID_SC_TAKE_WORLD_ZOOM), SetFill(1, 1), SetDataTip(STR_SCREENSHOT_WORLD_SCREENSHOT_CURRENT_ZOOM, 0), SetMinimalTextLines(2, 0),
 		NWidget(WWT_PUSHTXTBTN, COLOUR_GREY, WID_SC_TAKE_HEIGHTMAP), SetFill(1, 1), SetDataTip(STR_SCREENSHOT_HEIGHTMAP_SCREENSHOT, 0), SetMinimalTextLines(2, 0),
 		NWidget(WWT_PUSHTXTBTN, COLOUR_GREY, WID_SC_TAKE_MINIMAP), SetFill(1, 1), SetDataTip(STR_SCREENSHOT_MINIMAP_SCREENSHOT, 0), SetMinimalTextLines(2, 0),

src/strgen/strgen.cpp

@@ -250,6 +250,14 @@ void FileStringReader::HandlePragma(char *str)
 	} else if (!memcmp(str, "end-after", 10)) {
 		if (this->translation) error("Insert after is only allowed in the base translation.");
 		this->data.insert_after = nullptr;
+	} else if (!memcmp(str, "default-translation ", 20)) {
+		if (this->translation) error("Default translation is only allowed in the base translation.");
+		LangString *ent = this->data.Find(str + 20);
+		if (ent != nullptr) {
+			this->data.default_translation = ent;
+		} else {
+			error("Can't find string to use as default translation: '%s'", str + 20);
+		}
 	} else {
 		StringReader::HandlePragma(str);
 	}

src/strgen/strgen.h

@@ -36,6 +36,7 @@ struct LangString {
 	int line;              ///< Line of string in source-file.
 	Case *translated_case; ///< Cases of the translation.
 	std::unique_ptr<LangString> chain_next;
+	LangString *default_translation = nullptr;
 
 	LangString(const char *name, const char *english, size_t index, int line);
 	void ReplaceDefinition(const char *name, const char *english, int line);
@@ -54,6 +55,7 @@ struct StringData {
 	std::vector<std::unique_ptr<LangString>> string_store;
 	LangString *insert_after = nullptr;
 	bool override_mode = false;
+	LangString *default_translation = nullptr;
 
 	StringData(size_t tabs);
 	~StringData();

src/strgen/strgen_base.cpp

@@ -782,6 +782,11 @@ void StringReader::HandleString(char *str)
 		this->data.next_string_id = -1;
 		this->data.Add(str, ls.get());
 
+		if (this->data.default_translation != nullptr) {
+			ls->default_translation = this->data.default_translation;
+			this->data.default_translation = nullptr;
+		}
+
 		if (this->data.insert_after != nullptr) {
 			LangString *cur = ls.get();
 			this->data.insert_after->chain_next = std::move(ls);
@@ -1017,7 +1022,9 @@ void LanguageWriter::WriteLang(const StringData &data)
 
 		for (uint j = 0; j != in_use[tab]; j++) {
 			const LangString *ls = data.strings[(tab * TAB_SIZE) + j];
-			if (ls != nullptr && ls->translated == nullptr) _lang.missing++;
+			if (ls != nullptr && ls->translated == nullptr && ls->default_translation == nullptr) {
+				_lang.missing++;
+			}
 		}
 	}
 
@@ -1064,6 +1071,9 @@ void LanguageWriter::WriteLang(const StringData &data)
 			} else {
 				casep = nullptr;
 				cmdp = ls->english;
+				if (ls->default_translation != nullptr && ls->default_translation->translated != nullptr) {
+					cmdp = ls->default_translation->translated;
+				}
 			}
 
 			_translated = cmdp != ls->english;