Feature: Help and manuals access window

src/textfile_gui.h

@@ -22,9 +22,6 @@ struct TextfileWindow : public Window, MissingGlyphSearcher {
 	TextfileType file_type;          ///< Type of textfile to view.
 	Scrollbar *vscroll;              ///< Vertical scrollbar.
 	Scrollbar *hscroll;              ///< Horizontal scrollbar.
-	uint search_iterator;            ///< Iterator for the font check search.
-
-	uint max_length;                 ///< Maximum length of unwrapped text line.
 
 	TextfileWindow(TextfileType file_type);
 
@@ -33,33 +30,81 @@ struct TextfileWindow : public Window, MissingGlyphSearcher {
 	void DrawWidget(const Rect &r, int widget) const override;
 	void OnResize() override;
 	void OnInvalidateData(int data = 0, bool gui_scope = true) override;
+	void OnDropdownSelect(int widget, int index) override;
 
 	void Reset() override;
 	FontSize DefaultSize() override;
 	std::optional<std::string_view> NextString() override;
 	bool Monospace() override;
 	void SetFontNames(FontCacheSettings *settings, const char *font_name, const void *os_data) override;
+	void ScrollToLine(size_t line);
 
 	virtual void LoadTextfile(const std::string &textfile, Subdirectory dir);
 
 protected:
-	void LoadText(std::string_view buf);
-
-private:
 	struct Line {
-		int top;               ///< Top scroll position.
-		int bottom;            ///< Bottom scroll position.
-		std::string_view text; ///< Pointer to text buffer.
+		int top{0};                  ///< Top scroll position in visual lines.
+		int bottom{0};               ///< Bottom scroll position in visual lines.
+		std::string text{};          ///< Contents of the line.
+		TextColour colour{TC_WHITE}; ///< Colour to render text line in.
 
 		Line(int top, std::string_view text) : top(top), bottom(top + 1), text(text) {}
+		Line() {}
 	};
 
-	std::string text;                ///< Lines of text from the NewGRF's textfile.
-	std::vector<Line> lines;         ///< #text, split into lines in a table with lines.
+	struct Hyperlink {
+		size_t line;             ///< Which line the link is on.
+		size_t begin;            ///< Character position on line the link begins.
+		size_t end;              ///< Character position on line the link end.
+		std::string destination; ///< Destination for the link.
+	};
+
+	struct HistoryEntry {
+		std::string filepath;    ///< File the history entry is in.
+		int scrollpos;           ///< Scrolling position the file was at at navigation time.
+	};
+
+	std::string filename{};              ///< Filename of the textfile.
+	std::string filepath{};              ///< Full path to the filename.
+
+	std::vector<Line> lines;             ///< #text, split into lines in a table with lines.
+	std::vector<size_t> jumplist;        ///< Table of contents list, line numbers.
+	std::vector<Hyperlink> links;        ///< Clickable links in lines.
+	std::vector<Hyperlink> link_anchors; ///< Anchor names of headings that can be linked to.
+	std::vector<HistoryEntry> history;   ///< Browsing history in this window.
+	size_t history_pos{0};               ///< Position in browsing history (for forward movement).
+	bool trusted{false};                 ///< Whether the content is trusted (read: not from content like NewGRFs, etc).
+
+	void LoadText(std::string_view buf);
+	void FindHyperlinksInMarkdown(Line &line, size_t line_index);
+
+	/**
+	 * Handle the clicking on a hyperlink.
+	 *
+	 * @param link The link that is clicked on.
+	 */
+	virtual void OnHyperlinkClick(const Hyperlink &link);
+
+	/**
+	 * Post-processing after the text is loaded.
+	 */
+	virtual void AfterLoadText();
+
+	void NavigateToFile(std::string newfile, size_t line);
+	void AppendHistory(const std::string &filepath);
+	void UpdateHistoryScrollpos();
+	void NavigateHistory(int delta);
+
+private:
+	uint search_iterator{0};     ///< Iterator for the font check search.
+	uint max_length{0};          ///< Maximum length of unwrapped text line.
 
 	uint ReflowContent();
 	uint GetContentHeight();
 	void SetupScrollbars(bool force_reflow);
+	void CheckHyperlinkClick(Point pt);
+
+	void AfterLoadMarkdown();
 };
 
 #endif /* TEXTFILE_GUI_H */