From 355e3a068ea4ad6a7d3ab9318b3ce74b7f0b0b15 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sat, 7 Sep 2013 17:09:39 +0300
Subject: [PATCH] Add kerning support to Font

---
 scripts/makefont.py |  3 +++
 source/font.cpp     | 42 +++++++++++++++++++++++++++++++++++++-----
 source/font.h       |  7 ++++++-
 3 files changed, 46 insertions(+), 6 deletions(-)

diff --git a/scripts/makefont.py b/scripts/makefont.py
index 84e9c609..11d83794 100755
--- a/scripts/makefont.py
+++ b/scripts/makefont.py
@@ -23,6 +23,9 @@ def convert_def(fn):
 			result += "\toffset %.3f %.3f;\n"%(float(ox)/fh, float(oy)/fh)
 			result += "\tadvance %.3f;\n"%(float(a)/fh)
 			result += "};\n"
+		elif parts[0]=="kern":
+			l, r, d = map(int, parts[1:])
+			result += "kerning %d %d %.3f;\n"%(l, r, float(d)/fh)
 
 	return result
 
diff --git a/source/font.cpp b/source/font.cpp
index abfe631e..069ecf0f 100644
--- a/source/font.cpp
+++ b/source/font.cpp
@@ -40,12 +40,24 @@ void Font::add_glyph(const Glyph &g)
 	insert_unique(glyphs, g.code, g);
 }
 
+void Font::set_kerning(unsigned l, unsigned r, float d)
+{
+	kerning[KerningKey(l, r)] = d;
+}
+
 float Font::get_string_width(const string &str, StringCodec::Decoder &dec) const
 {
 	float x = 0;
 
+	unsigned prev = 0;
 	for(string::const_iterator i=str.begin(); i!=str.end();)
-		x += get_glyph_advance(dec.decode_char(str, i));
+	{
+		unsigned c = dec.decode_char(str, i);
+		if(prev)
+			x += get_glyph_advance(prev, c);
+		prev = c;
+	}
+	x += get_glyph_advance(prev);
 
 	return x;
 }
@@ -63,14 +75,19 @@ void Font::build_string(const string &str, StringCodec::Decoder &dec, PrimitiveB
 	MatrixStack::Push push_mtx(bld.matrix());
 
 	bld.begin(QUADS);
+	unsigned prev = 0;
 	for(string::const_iterator i=str.begin(); i!=str.end();)
 	{
-		GlyphMap::const_iterator j = glyphs.find(dec.decode_char(str, i));
+		unsigned c = dec.decode_char(str, i);
+		GlyphMap::const_iterator j = glyphs.find(c);
 		if(j==glyphs.end())
 			continue;
 
+		if(prev)
+			bld.matrix() *= Matrix::translation(get_glyph_advance(prev, c), 0, 0);
+
 		create_glyph_vertices(j->second, bld);
-		bld.matrix() *= Matrix::translation(j->second.advance, 0, 0);
+		prev = c;
 	}
 	bld.end();
 }
@@ -87,13 +104,22 @@ void Font::create_glyph_vertices(const Glyph &glyph, VertexBuilder &bld) const
 	bld.vertex(glyph.off_x, glyph.off_y+glyph.h);
 }
 
-float Font::get_glyph_advance(unsigned code) const
+float Font::get_glyph_advance(unsigned code, unsigned next) const
 {
 	GlyphMap::const_iterator i = glyphs.find(code);
 	if(i==glyphs.end())
 		return 0;
 
-	return i->second.advance;
+	float advance = i->second.advance;
+
+	if(next)
+	{
+		KerningMap::const_iterator j = kerning.find(KerningKey(code, next));
+		if(j!=kerning.end())
+			advance += j->second;
+	}
+
+	return advance;
 }
 
 
@@ -117,6 +143,7 @@ void Font::Loader::init()
 	add("texture",     &Loader::texture);
 	add("texture",     &Loader::texture_ref);
 	add("glyph",       &Loader::glyph);
+	add("kerning",     &Loader::kerning);
 }
 
 void Font::Loader::glyph(unsigned c)
@@ -127,6 +154,11 @@ void Font::Loader::glyph(unsigned c)
 	obj.glyphs.insert(GlyphMap::value_type(c, gl));
 }
 
+void Font::Loader::kerning(unsigned l, unsigned r, float d)
+{
+	obj.kerning[KerningKey(l, r)] = d;
+}
+
 void Font::Loader::texture()
 {
 	RefPtr<Texture2D> tex = new Texture2D;
diff --git a/source/font.h b/source/font.h
index fe5a9b34..5fcc63c4 100644
--- a/source/font.h
+++ b/source/font.h
@@ -25,6 +25,7 @@ public:
 	private:
 		void init();
 		void glyph(unsigned);
+		void kerning(unsigned, unsigned, float);
 		void texture();
 		void texture_ref(const std::string &);
 	};
@@ -49,12 +50,15 @@ public:
 
 private:
 	typedef std::map<unsigned, Glyph> GlyphMap;
+	typedef std::pair<unsigned, unsigned> KerningKey;
+	typedef std::map<KerningKey, float> KerningMap;
 
 	RefPtr<const Texture2D> texture;
 	float native_size;
 	float ascent;
 	float descent;
 	GlyphMap glyphs;
+	KerningMap kerning;
 
 public:
 	Font();
@@ -63,6 +67,7 @@ public:
 	void set_texture(const Texture2D &);
 	const Texture2D &get_texture() const;
 	void add_glyph(const Glyph &);
+	void set_kerning(unsigned, unsigned, float);
 	float get_native_size() const { return native_size; }
 	float get_ascent() const { return ascent; }
 	float get_descent() const { return descent; }
@@ -110,7 +115,7 @@ public:
 
 private:
 	void create_glyph_vertices(const Glyph &, VertexBuilder &) const;
-	float get_glyph_advance(unsigned) const;
+	float get_glyph_advance(unsigned, unsigned = 0) const;
 };
 
 } // namespace GL
-- 
2.43.0