[RTL] Adds "lang" tag to allow overriding language specific text rendering without starting a new paragraph.

doc/classes/RichTextLabel.xml

@@ -380,6 +380,13 @@
 				Adds a [code][font][/code] tag with an italics font to the tag stack. This is the same as adding an [code][i][/code] tag if not currently in a [code][b][/code] tag.
 			</description>
 		</method>
+		<method name="push_language">
+			<return type="void" />
+			<param index="0" name="language" type="String" />
+			<description>
+				Adds language code used for text shaping algorithm and Open-Type font features.
+			</description>
+		</method>
 		<method name="push_list">
 			<return type="void" />
 			<param index="0" name="level" type="int" />

scene/gui/rich_text_label.cpp

@@ -2564,7 +2564,10 @@ String RichTextLabel::_find_language(Item *p_item) {
 	Item *item = p_item;
 
 	while (item) {
-		if (item->type == ITEM_PARAGRAPH) {
+		if (item->type == ITEM_LANGUAGE) {
+			ItemLanguage *p = static_cast<ItemLanguage *>(item);
+			return p->language;
+		} else if (item->type == ITEM_PARAGRAPH) {
 			ItemParagraph *p = static_cast<ItemParagraph *>(item);
 			return p->language;
 		}
@@ -3441,6 +3444,17 @@ void RichTextLabel::push_meta(const Variant &p_meta) {
 	_add_item(item, true);
 }
 
+void RichTextLabel::push_language(const String &p_language) {
+	_stop_thread();
+	MutexLock data_lock(data_mutex);
+
+	ERR_FAIL_COND(current->type == ITEM_TABLE);
+	ItemLanguage *item = memnew(ItemLanguage);
+
+	item->language = p_language;
+	_add_item(item, true);
+}
+
 void RichTextLabel::push_hint(const String &p_string) {
 	_stop_thread();
 	MutexLock data_lock(data_mutex);
@@ -4222,6 +4236,11 @@ void RichTextLabel::append_text(const String &p_bbcode) {
 			push_indent(indent_level);
 			pos = brk_end + 1;
 			tag_stack.push_front(tag);
+		} else if (tag.begins_with("lang=")) {
+			String lang = tag.substr(5, tag.length()).unquote();
+			push_language(lang);
+			pos = brk_end + 1;
+			tag_stack.push_front("lang");
 		} else if (tag == "p") {
 			push_paragraph(HORIZONTAL_ALIGNMENT_LEFT);
 			pos = brk_end + 1;
@@ -5607,6 +5626,7 @@ void RichTextLabel::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("push_list", "level", "type", "capitalize", "bullet"), &RichTextLabel::push_list, DEFVAL(String::utf8("•")));
 	ClassDB::bind_method(D_METHOD("push_meta", "data"), &RichTextLabel::push_meta);
 	ClassDB::bind_method(D_METHOD("push_hint", "description"), &RichTextLabel::push_hint);
+	ClassDB::bind_method(D_METHOD("push_language", "language"), &RichTextLabel::push_language);
 	ClassDB::bind_method(D_METHOD("push_underline"), &RichTextLabel::push_underline);
 	ClassDB::bind_method(D_METHOD("push_strikethrough"), &RichTextLabel::push_strikethrough);
 	ClassDB::bind_method(D_METHOD("push_table", "columns", "inline_align", "align_to_row"), &RichTextLabel::push_table, DEFVAL(INLINE_ALIGNMENT_TOP), DEFVAL(-1));

scene/gui/rich_text_label.h

@@ -77,7 +77,8 @@ public:
 		ITEM_HINT,
 		ITEM_DROPCAP,
 		ITEM_CUSTOMFX,
-		ITEM_CONTEXT
+		ITEM_CONTEXT,
+		ITEM_LANGUAGE,
 	};
 
 	enum MenuItems {
@@ -237,6 +238,11 @@ private:
 		ItemHint() { type = ITEM_HINT; }
 	};
 
+	struct ItemLanguage : public Item {
+		String language;
+		ItemLanguage() { type = ITEM_LANGUAGE; }
+	};
+
 	struct ItemParagraph : public Item {
 		HorizontalAlignment alignment = HORIZONTAL_ALIGNMENT_LEFT;
 		String language;
@@ -615,6 +621,7 @@ public:
 	void push_outline_color(const Color &p_color);
 	void push_underline();
 	void push_strikethrough();
+	void push_language(const String &p_language);
 	void push_paragraph(HorizontalAlignment p_alignment, Control::TextDirection p_direction = Control::TEXT_DIRECTION_INHERITED, const String &p_language = "", TextServer::StructuredTextParser p_st_parser = TextServer::STRUCTURED_TEXT_DEFAULT, BitField<TextServer::JustificationFlag> p_jst_flags = TextServer::JUSTIFICATION_WORD_BOUND | TextServer::JUSTIFICATION_KASHIDA | TextServer::JUSTIFICATION_SKIP_LAST_LINE | TextServer::JUSTIFICATION_DO_NOT_SKIP_SINGLE_LINE, const PackedFloat32Array &p_tab_stops = PackedFloat32Array());
 	void push_indent(int p_level);
 	void push_list(int p_level, ListType p_list, bool p_capitalize, const String &p_bullet = String::utf8("•"));