src/OT/glyf/path-builder.hh

   1 #ifndef OT_GLYF_PATH_BUILDER_HH
   2 #define OT_GLYF_PATH_BUILDER_HH
   3
   4
   5 #include "../../hb.hh"
   6
   7
   8 namespace OT {
   9 namespace glyf_impl {
  10
  11
  12 struct path_builder_t
  13 {
  14   hb_font_t *font;
  15   hb_draw_session_t *draw_session;
  16
  17   struct optional_point_t
  18   {
  19     optional_point_t () {}
  20     optional_point_t (float x_, float y_) : has_data (true), x (x_), y (y_) {}
  21     operator bool () const { return has_data; }
  22
  23     bool has_data = false;
  24     float x;
  25     float y;
  26
  27     optional_point_t mid (optional_point_t p)
  28     { return optional_point_t ((x + p.x) * 0.5f, (y + p.y) * 0.5f); }
  29   } first_oncurve, first_offcurve, first_offcurve2, last_offcurve, last_offcurve2;
  30
  31   path_builder_t (hb_font_t *font_, hb_draw_session_t &draw_session_) :
  32     font (font_), draw_session (&draw_session_) {}
  33
  34   /* based on https://github.com/RazrFalcon/ttf-parser/blob/4f32821/src/glyf.rs#L287
  35      See also:
  36      * https://developer.apple.com/fonts/TrueType-Reference-Manual/RM01/Chap1.html
  37      * https://stackoverflow.com/a/20772557
  38      *
  39      * Cubic support added. */
  40   HB_ALWAYS_INLINE
  41   void consume_point (const contour_point_t &point)
  42   {
  43     bool is_on_curve = point.flag & glyf_impl::SimpleGlyph::FLAG_ON_CURVE;
  44 #ifdef HB_NO_CUBIC_GLYF
  45     bool is_cubic = false;
  46 #else
  47     bool is_cubic = !is_on_curve && (point.flag & glyf_impl::SimpleGlyph::FLAG_CUBIC);
  48 #endif
  49     optional_point_t p (font->em_fscalef_x (point.x), font->em_fscalef_y (point.y));
  50     if (unlikely (!first_oncurve))
  51     {
  52       if (is_on_curve)
  53       {
  54         first_oncurve = p;
  55         draw_session->move_to (p.x, p.y);
  56       }
  57       else
  58       {
  59         if (is_cubic && !first_offcurve2)
  60         {
  61           first_offcurve2 = first_offcurve;
  62           first_offcurve = p;
  63         }
  64         else if (first_offcurve)
  65         {
  66           optional_point_t mid = first_offcurve.mid (p);
  67           first_oncurve = mid;
  68           last_offcurve = p;
  69           draw_session->move_to (mid.x, mid.y);
  70         }
  71         else
  72           first_offcurve = p;
  73       }
  74     }
  75     else
  76     {
  77       if (last_offcurve)
  78       {
  79         if (is_on_curve)
  80         {
  81           if (last_offcurve2)
  82           {
  83             draw_session->cubic_to (last_offcurve2.x, last_offcurve2.y,
  84                                     last_offcurve.x, last_offcurve.y,
  85                                     p.x, p.y);
  86             last_offcurve2 = optional_point_t ();
  87           }
  88           else
  89             draw_session->quadratic_to (last_offcurve.x, last_offcurve.y,
  90                                        p.x, p.y);
  91           last_offcurve = optional_point_t ();
  92         }
  93         else
  94         {
  95           if (is_cubic && !last_offcurve2)
  96           {
  97             last_offcurve2 = last_offcurve;
  98             last_offcurve = p;
  99           }
 100           else
 101           {
 102             optional_point_t mid = last_offcurve.mid (p);
 103
 104             if (is_cubic)
 105             {
 106               draw_session->cubic_to (last_offcurve2.x, last_offcurve2.y,
 107                                       last_offcurve.x, last_offcurve.y,
 108                                       mid.x, mid.y);
 109               last_offcurve2 = optional_point_t ();
 110             }
 111             else
 112               draw_session->quadratic_to (last_offcurve.x, last_offcurve.y,
 113                                          mid.x, mid.y);
 114             last_offcurve = p;
 115           }
 116         }
 117       }
 118       else
 119       {
 120         if (is_on_curve)
 121           draw_session->line_to (p.x, p.y);
 122         else
 123           last_offcurve = p;
 124       }
 125     }
 126
 127     if (unlikely (point.is_end_point))
 128     {
 129       if (first_offcurve && last_offcurve)
 130       {
 131         optional_point_t mid = last_offcurve.mid (first_offcurve2 ?
 132                                                   first_offcurve2 :
 133                                                   first_offcurve);
 134         if (last_offcurve2)
 135           draw_session->cubic_to (last_offcurve2.x, last_offcurve2.y,
 136                                   last_offcurve.x, last_offcurve.y,
 137                                   mid.x, mid.y);
 138         else
 139           draw_session->quadratic_to (last_offcurve.x, last_offcurve.y,
 140                                      mid.x, mid.y);
 141         last_offcurve = optional_point_t ();
 142       }
 143       /* now check the rest */
 144
 145       if (first_offcurve && first_oncurve)
 146       {
 147         if (first_offcurve2)
 148           draw_session->cubic_to (first_offcurve2.x, first_offcurve2.y,
 149                                   first_offcurve.x, first_offcurve.y,
 150                                   first_oncurve.x, first_oncurve.y);
 151         else
 152           draw_session->quadratic_to (first_offcurve.x, first_offcurve.y,
 153                                      first_oncurve.x, first_oncurve.y);
 154       }
 155       else if (last_offcurve && first_oncurve)
 156       {
 157         if (last_offcurve2)
 158           draw_session->cubic_to (last_offcurve2.x, last_offcurve2.y,
 159                                   last_offcurve.x, last_offcurve.y,
 160                                   first_oncurve.x, first_oncurve.y);
 161         else
 162           draw_session->quadratic_to (last_offcurve.x, last_offcurve.y,
 163                                      first_oncurve.x, first_oncurve.y);
 164       }
 165       else if (first_oncurve)
 166         draw_session->line_to (first_oncurve.x, first_oncurve.y);
 167       else if (first_offcurve)
 168       {
 169         float x = first_offcurve.x, y = first_offcurve.y;
 170         draw_session->move_to (x, y);
 171         draw_session->quadratic_to (x, y, x, y);
 172       }
 173
 174       /* Getting ready for the next contour */
 175       first_oncurve = first_offcurve = last_offcurve = last_offcurve2 = optional_point_t ();
 176       draw_session->close_path ();
 177     }
 178   }
 179   void points_end () {}
 180
 181   bool is_consuming_contour_points () { return true; }
 182   contour_point_t *get_phantoms_sink () { return nullptr; }
 183 };
 184
 185
 186 } /* namespace glyf_impl */
 187 } /* namespace OT */
 188
 189
 190 #endif /* OT_GLYF_PATH_BUILDER_HH */