Add simple ligature support to Font
authorMikko Rasa <tdb@tdb.fi>
Sun, 16 Jun 2019 08:54:18 +0000 (11:54 +0300)
committerMikko Rasa <tdb@tdb.fi>
Sun, 16 Jun 2019 08:54:18 +0000 (11:54 +0300)
Currently only two-character ligatures are supported.

source/font.cpp
source/font.h

index 54631926e4e1b3ae22da55afff111450fc9719e0..3fd24d8ea0ebde029e262d137dcfaf509b0db5ee 100644 (file)
@@ -44,7 +44,7 @@ void Font::add_glyph(const Glyph &g)
 
 void Font::set_kerning(unsigned l, unsigned r, float d)
 {
-       kerning[KerningKey(l, r)] = d;
+       kerning[CodePair(l, r)] = d;
 }
 
 float Font::get_string_width(const string &str, StringCodec::Decoder &dec) const
@@ -77,9 +77,18 @@ void Font::build_string(const string &str, StringCodec::Decoder &dec, PrimitiveB
        MatrixStack::Push push_mtx(bld.matrix());
 
        unsigned prev = 0;
-       for(string::const_iterator i=str.begin(); i!=str.end();)
+       unsigned next = 0;
+       for(string::const_iterator i=str.begin(); (next || i!=str.end());)
        {
-               unsigned c = dec.decode_char(str, i);
+               unsigned c = (next ? next : dec.decode_char(str, i));
+               next = (i!=str.end() ? dec.decode_char(str, i) : 0);
+
+               if(unsigned lig = get_ligature(c, next))
+               {
+                       c = lig;
+                       next = 0;
+               }
+
                GlyphMap::const_iterator j = glyphs.find(c);
                if(j==glyphs.end())
                        continue;
@@ -116,7 +125,7 @@ float Font::get_glyph_advance(unsigned code, unsigned next) const
 
        if(next)
        {
-               KerningMap::const_iterator j = kerning.find(KerningKey(code, next));
+               KerningMap::const_iterator j = kerning.find(CodePair(code, next));
                if(j!=kerning.end())
                        advance += j->second;
        }
@@ -124,6 +133,12 @@ float Font::get_glyph_advance(unsigned code, unsigned next) const
        return advance;
 }
 
+unsigned Font::get_ligature(unsigned code, unsigned next) const
+{
+       LigatureMap::const_iterator i = ligatures.find(CodePair(code, next));
+       return (i!=ligatures.end() ? i->second : 0);
+}
+
 
 Font::Loader::Loader(Font &f):
        DataFile::CollectionObjectLoader<Font>(f, 0)
@@ -147,6 +162,7 @@ void Font::Loader::init()
        add("texture",     &Loader::texture_ref);
        add("glyph",       &Loader::glyph);
        add("kerning",     &Loader::kerning);
+       add("ligature",    &Loader::ligature);
        add("x_height",    &Font::x_height);
 }
 
@@ -160,7 +176,12 @@ void Font::Loader::glyph(unsigned c)
 
 void Font::Loader::kerning(unsigned l, unsigned r, float d)
 {
-       obj.kerning[KerningKey(l, r)] = d;
+       obj.kerning[CodePair(l, r)] = d;
+}
+
+void Font::Loader::ligature(unsigned l, unsigned r, unsigned g)
+{
+       obj.ligatures[CodePair(l, r)] = g;
 }
 
 void Font::Loader::texture()
index 4eaed9635361ecca51ae5604b84c3c0d533c1109..dab09fa400d3ba0381eda46f5f64fb0e5f823883 100644 (file)
@@ -29,6 +29,7 @@ public:
                void init();
                void glyph(unsigned);
                void kerning(unsigned, unsigned, float);
+               void ligature(unsigned, unsigned, unsigned);
                void texture();
                void texture_ref(const std::string &);
        };
@@ -53,8 +54,9 @@ public:
 
 private:
        typedef std::map<unsigned, Glyph> GlyphMap;
-       typedef std::pair<unsigned, unsigned> KerningKey;
-       typedef std::map<KerningKey, float> KerningMap;
+       typedef std::pair<unsigned, unsigned> CodePair;
+       typedef std::map<CodePair, float> KerningMap;
+       typedef std::map<CodePair, unsigned> LigatureMap;
 
        RefPtr<const Texture2D> texture;
        float native_size;
@@ -64,6 +66,7 @@ private:
        float x_height;
        GlyphMap glyphs;
        KerningMap kerning;
+       LigatureMap ligatures;
 
 public:
        Font();
@@ -133,6 +136,7 @@ public:
 private:
        void create_glyph_quad(const Glyph &, PrimitiveBuilder &) const;
        float get_glyph_advance(unsigned, unsigned = 0) const;
+       unsigned get_ligature(unsigned, unsigned) const;
 };
 
 } // namespace GL