Bitmap font to custom font conversion

include/library/customfont.hpp

@@ -28,6 +28,7 @@ struct custom_font
 public:
 	custom_font();
 	custom_font(const std::string& file);
+	custom_font(struct bitmap_font& bfont);
 	void add(const std::u32string& key, const font_glyph_data& glyph) throw(std::bad_alloc);
 	std::u32string best_ligature_match(const std::u32string& codepoints, size_t start) const
 		throw(std::bad_alloc);

include/library/framebuffer.hpp

@@ -5,6 +5,7 @@
 #include <cstdlib>
 #include <vector>
 #include <map>
+#include <set>
 
 template<bool X> struct framebufferelem {};
 template<> struct framebufferelem<false> { typedef uint32_t t; };
@@ -513,6 +514,14 @@ struct bitmap_font
  * Returns: String layout.
  */
 	std::vector<layout> dolayout(const std::string& string) throw(std::bad_alloc);
+/**
+ * Get set of all glyph numbers.
+ */
+	std::set<uint32_t> get_glyphs_set();
+/**
+ * Get bad glyph.
+ */
+	const glyph& get_bad_glyph() throw();
 /**
  * Render string to framebuffer.
  *

lua.lyx

@@ -1633,11 +1633,12 @@ gui.loadfont: Load a font file
 \end_layout
 
 \begin_layout Itemize
-Syntax: CUSTOMFONT gui.loadfont(string filename)
+Syntax: CUSTOMFONT gui.loadfont([string filename])
 \end_layout
 
 \begin_layout Standard
 Loads font from specified file (CUSTOMFONT object).
+ If filename is not given, loads the system default font.
 \end_layout
 
 \begin_layout Subsection

src/library/customfont.cpp

@@ -236,6 +236,36 @@ custom_font::custom_font(const std::string& file)
 	}
 }
 
+custom_font::custom_font(struct bitmap_font& bfont)
+{
+	auto s = bfont.get_glyphs_set();
+	for(auto i = s.begin();;i++) {
+		const bitmap_font::glyph& j = (i != s.end()) ? bfont.get_glyph(*i) : bfont.get_bad_glyph();
+		font_glyph_data k;
+		k.width = j.wide ? 16 : 8;
+		k.height = 16;
+		k.stride = 1;
+		k.glyph.resize(16);
+		for(size_t y = 0; y < 16; y++) {
+			k.glyph[y] = 0;
+			uint32_t r = j.data[y / (j.wide ? 2 : 4)];
+			if(j.wide)
+				r >>= 16 - ((y & 1) << 4);
+			else
+				r >>= 24 - ((y & 3) << 3);
+			for(size_t x = 0; x < k.width; x++) {
+				uint32_t b = (j.wide ? 15 : 7) - x;
+				if(((r >> b) & 1) != 0)
+					k.glyph[y] |= 1UL << (31 - x);
+			}
+		}
+		std::u32string key = (i != s.end()) ? std::u32string(1, *i) : std::u32string();
+		glyphs[key] = k;
+		if(i == s.end()) break;
+	}
+	rowadvance = 16;
+}
+
 std::ostream& operator<<(std::ostream& os, const std::u32string& lkey)
 {
 	if(!lkey.length())

src/library/framebuffer.cpp

@@ -687,6 +687,19 @@ const bitmap_font::glyph& bitmap_font::get_glyph(uint32_t glyph) throw()
 		return bad_glyph;
 }
 
+std::set<uint32_t> bitmap_font::get_glyphs_set()
+{
+	std::set<uint32_t> out;
+	for(auto& i : glyphs)
+		out.insert(i.first);
+	return out;
+}
+
+const bitmap_font::glyph& bitmap_font::get_bad_glyph() throw()
+{
+	return bad_glyph;
+}
+
 std::pair<size_t, size_t> bitmap_font::get_metrics(const std::string& string) throw()
 {
 	size_t commit_width = 0;

src/lua/gui-text-cf.cpp

@@ -13,14 +13,17 @@ namespace
 	{
 	public:
 		lua_customfont(lua_state& L, const std::string& filename);
+		lua_customfont(lua_state& L);
 		~lua_customfont() throw();
 		int draw(lua_state& L, const std::string& fname);
 		const custom_font& get_font() { return font; }
 		std::string print()
 		{
-			return "";
+			return orig_filename;
 		}
 	private:
+		void init(lua_state& L);
+		std::string orig_filename;
 		custom_font font;
 	};
 }
@@ -89,14 +92,27 @@ namespace
 		lua_obj_pin<lua_customfont> font;
 	};
 
-	lua_customfont::lua_customfont(lua_state& L, const std::string& filename)
-		: font(filename)
+	void lua_customfont::init(lua_state& L)
 	{
 		objclass<lua_customfont>().bind_multi(L, {
 			{"__call", &lua_customfont::draw},
 		});
 	}
 
+	lua_customfont::lua_customfont(lua_state& L, const std::string& filename)
+		: font(filename)
+	{
+		orig_filename = filename;
+		init(L);
+	}
+
+	lua_customfont::lua_customfont(lua_state& L)
+		: font(main_font)
+	{
+		orig_filename = "<builtin>";
+		init(L);
+	}
+
 	lua_customfont::~lua_customfont() throw()
 	{
 		render_kill_request(this);
@@ -125,6 +141,10 @@ namespace
 
 	function_ptr_luafun gui_text_cf(lua_func_misc, "gui.loadfont", [](lua_state& L, const std::string& fname)
 		-> int {
+		if(L.type(1) == LUA_TNONE || L.type(1) == LUA_TNIL) {
+			lua_class<lua_customfont>::create(L);
+			return 1;
+		}
 		std::string filename = L.get_string(1, fname.c_str());
 		lua_class<lua_customfont>::create(L, filename);
 		return 1;