From 895c0b254e0ac9911ccf2a1d954bb00a76a4d961 Mon Sep 17 00:00:00 2001
From: Peter Nelson <peter1138@openttd.org>
Date: Sat, 15 Jun 2024 21:11:16 +0100
Subject: [PATCH] Add: FontSearcher interface.

---
 src/fontcache.cpp   | 16 ++++++++++++++++
 src/fontdetection.h | 41 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+)

diff --git a/src/fontcache.cpp b/src/fontcache.cpp
index 93d56416ae..954f38d5ed 100644
--- a/src/fontcache.cpp
+++ b/src/fontcache.cpp
@@ -230,6 +230,22 @@ void UninitFontCache()
 #endif /* WITH_FREETYPE */
 }
 
+/**
+ * Register the FontSearcher instance. There can be only one font searcher, which depends on platform.
+ */
+FontSearcher::FontSearcher()
+{
+	FontSearcher::instance = this;
+}
+
+/**
+ * Deregister this FontSearcher.
+ */
+FontSearcher::~FontSearcher()
+{
+	FontSearcher::instance = nullptr;
+}
+
 #if !defined(_WIN32) && !defined(__APPLE__) && !defined(WITH_FONTCONFIG) && !defined(WITH_COCOA)
 
 bool SetFallbackFont(FontCacheSettings *, const std::string &, int, MissingGlyphSearcher *) { return false; }
diff --git a/src/fontdetection.h b/src/fontdetection.h
index 2a316da505..43a5f4731d 100644
--- a/src/fontdetection.h
+++ b/src/fontdetection.h
@@ -39,4 +39,45 @@ FT_Error GetFontByFaceName(const char *font_name, FT_Face *face);
  */
 bool SetFallbackFont(struct FontCacheSettings *settings, const std::string &language_isocode, int winlangid, class MissingGlyphSearcher *callback);
 
+struct FontFamily {
+	std::string family;
+	std::string style;
+	int32_t slant;
+	int32_t weight;
+
+	FontFamily(std::string_view family, std::string_view style, int32_t slant, int32_t weight) : family(family), style(style), slant(slant), weight(weight) {}
+};
+
+class FontSearcher {
+public:
+	FontSearcher();
+	virtual ~FontSearcher();
+
+	/**
+	 * Get the active FontSearcher instance.
+	 * @return FontSearcher instance, or nullptr if not present.
+	 */
+	static inline FontSearcher *GetFontSearcher() { return FontSearcher::instance; }
+
+	/**
+	 * List available fonts.
+	 * @param language_isocode the language, e.g. en_GB.
+	 * @param winlangid the language ID windows style.
+	 * @return vector containing font family names.
+	 */
+	virtual std::vector<std::string> ListFamilies(const std::string &language_isocode, int winlangid) = 0;
+
+	/**
+	 * List available styles for a font family.
+	 * @param language_isocode the language, e.g. en_GB.
+	 * @param winlangid the language ID windows style.
+	 * @param font_family The font family to list.
+	 * @return vector containing style information for the family.
+	 */
+	virtual std::vector<FontFamily> ListStyles(const std::string &language_isocode, int winlangid, std::string_view font_family) = 0;
+
+private:
+	static inline FontSearcher *instance = nullptr;
+};
+
 #endif