Add Font:getKerning.

Also add a variant of Font:getWidth which accepts a codepoint number.
Fixes #1403

changes.txt

@@ -4,6 +4,8 @@ LOVE 11.4 [Mysterious Mysteries]
 Released: N/A
 
 * Added Body:getLocalPoints.
+* Added Font:getKerning.
+* Added a variant of Font:getWidth which takes a codepoint number argument.
 * Added support for r16, rg16, and rgba16 pixel formats in Canvases.
 * Added Shader:send(name, matrixlayout, data, ...) variant, whose argument order is more consistent than Shader:send(name, data, matrixlayout, ...).
 

src/modules/graphics/Font.cpp

@@ -348,6 +348,24 @@ float Font::getKerning(uint32 leftglyph, uint32 rightglyph)
 	return k;
 }
 
+float Font::getKerning(const std::string &leftchar, const std::string &rightchar)
+{
+	uint32 left = 0;
+	uint32 right = 0;
+
+	try
+	{
+		left = utf8::peek_next(leftchar.begin(), leftchar.end());
+		right = utf8::peek_next(rightchar.begin(), rightchar.end());
+	}
+	catch (utf8::exception &e)
+	{
+		throw love::Exception("UTF-8 decoding error: %s", e.what());
+	}
+
+	return getKerning(left, right);
+}
+
 void Font::getCodepointsFromString(const std::string &text, Codepoints &codepoints)
 {
 	codepoints.reserve(text.size());
@@ -724,9 +742,9 @@ int Font::getWidth(const std::string &str)
 	return max_width;
 }
 
-int Font::getWidth(char character)
+int Font::getWidth(uint32 glyph)
 {
-	const Glyph &g = findGlyph(character);
+	const Glyph &g = findGlyph(glyph);
 	return g.spacing;
 }
 

src/modules/graphics/Font.h

@@ -128,11 +128,9 @@ public:
 	int getWidth(const std::string &str);
 
 	/**
-	 * Returns the width of the passed character.
-	 *
-	 * @param character A character.
+	 * Returns the width of the passed glyph.
 	 **/
-	int getWidth(char character);
+	int getWidth(uint32 glyph);
 
 	/**
 	 * Returns the maximal width of a wrapped string
@@ -169,6 +167,9 @@ public:
 	bool hasGlyph(uint32 glyph) const;
 	bool hasGlyphs(const std::string &text) const;
 
+	float getKerning(uint32 leftglyph, uint32 rightglyph);
+	float getKerning(const std::string &leftchar, const std::string &rightchar);
+
 	void setFallbacks(const std::vector<Font *> &fallbacks);
 
 	float getDPIScale() const;
@@ -206,7 +207,6 @@ private:
 	love::font::GlyphData *getRasterizerGlyphData(uint32 glyph, float &dpiscale);
 	const Glyph &addGlyph(uint32 glyph);
 	const Glyph &findGlyph(uint32 glyph);
-	float getKerning(uint32 leftglyph, uint32 rightglyph);
 	void printv(Graphics *gfx, const Matrix4 &t, const std::vector<DrawCommand> &drawcommands, const std::vector<GlyphVertex> &vertices);
 
 	std::vector<StrongRef<love::font::Rasterizer>> rasterizers;

src/modules/graphics/wrap_Font.cpp

@@ -86,9 +86,16 @@ int w_Font_getHeight(lua_State *L)
 int w_Font_getWidth(lua_State *L)
 {
 	Font *t = luax_checkfont(L, 1);
-	const char *str = luaL_checkstring(L, 2);
-
-	luax_catchexcept(L, [&](){ lua_pushinteger(L, t->getWidth(str)); });
+	if (lua_type(L, 2) == LUA_TSTRING)
+	{
+		const char *str = luaL_checkstring(L, 2);
+		luax_catchexcept(L, [&](){ lua_pushinteger(L, t->getWidth(str)); });
+	}
+	else
+	{
+		uint32 glyph = (uint32) luaL_checknumber(L, 2);
+		luax_catchexcept(L, [&](){ lua_pushinteger(L, t->getWidth(glyph)); });
+	}
 	return 1;
 }
 
@@ -214,6 +221,30 @@ int w_Font_hasGlyphs(lua_State *L)
 	return 1;
 }
 
+int w_Font_getKerning(lua_State *L)
+{
+	Font *t = luax_checkfont(L, 1);
+	float kerning = 0.0f;
+
+	luax_catchexcept(L, [&]() {
+		if (lua_type(L, 2) == LUA_TSTRING)
+		{
+			std::string left = luax_checkstring(L, 2);
+			std::string right = luax_checkstring(L, 3);
+			kerning = t->getKerning(left, right);
+		}
+		else
+		{
+			uint32 left = (uint32) luaL_checknumber(L, 2);
+			uint32 right = (uint32) luaL_checknumber(L, 3);
+			kerning = t->getKerning(left, right);
+		}
+	});
+
+	lua_pushnumber(L, kerning);
+	return 1;
+}
+
 int w_Font_setFallbacks(lua_State *L)
 {
 	Font *t = luax_checkfont(L, 1);
@@ -246,6 +277,7 @@ static const luaL_Reg w_Font_functions[] =
 	{ "getDescent", w_Font_getDescent },
 	{ "getBaseline", w_Font_getBaseline },
 	{ "hasGlyphs", w_Font_hasGlyphs },
+	{ "getKerning", w_Font_getKerning },
 	{ "setFallbacks", w_Font_setFallbacks },
 	{ "getDPIScale", w_Font_getDPIScale },
 	{ 0, 0 }