kc3-lang/harfbuzz/src/OT/glyf/path-builder.hh

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• Hash : cf57f04d
  Author :
  Date : 2022-06-26T16:26:17
  

  [glyf/path-builder] Optimize scaling code
  
  Scale each point once upon entry to function.
  
  This makes our shape fetching code as fast as FreeType for all
  benchmark cases now.
  

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• src/OT/glyf/path-builder.hh

• #ifndef OT_GLYF_PATH_BUILDER_HH
  #define OT_GLYF_PATH_BUILDER_HH
  
  
  #include "../../hb.hh"
  
  
  namespace OT {
  namespace glyf_impl {
  
  
  struct path_builder_t
  {
    hb_font_t *font;
    hb_draw_session_t *draw_session;
  
    struct optional_point_t
    {
      optional_point_t () {}
      optional_point_t (float x_, float y_) : has_data (true), x (x_), y (y_) {}
      operator bool () const { return has_data; }
  
      bool has_data = false;
      float x = 0.;
      float y = 0.;
  
      optional_point_t lerp (optional_point_t p, float t)
      { return optional_point_t (x + t * (p.x - x), y + t * (p.y - y)); }
    } first_oncurve, first_offcurve, last_offcurve;
  
    path_builder_t (hb_font_t *font_, hb_draw_session_t &draw_session_)
    {
      font = font_;
      draw_session = &draw_session_;
      first_oncurve = first_offcurve = last_offcurve = optional_point_t ();
    }
  
    /* based on https://github.com/RazrFalcon/ttf-parser/blob/4f32821/src/glyf.rs#L287
       See also:
       * https://developer.apple.com/fonts/TrueType-Reference-Manual/RM01/Chap1.html
       * https://stackoverflow.com/a/20772557 */
    void consume_point (const contour_point_t &point)
    {
      bool is_on_curve = point.flag & glyf_impl::SimpleGlyph::FLAG_ON_CURVE;
      optional_point_t p (font->em_fscalef_x (point.x), font->em_fscalef_y (point.y));
      if (!first_oncurve)
      {
        if (is_on_curve)
        {
  	first_oncurve = p;
  	draw_session->move_to (p.x, p.y);
        }
        else
        {
  	if (first_offcurve)
  	{
  	  optional_point_t mid = first_offcurve.lerp (p, .5f);
  	  first_oncurve = mid;
  	  last_offcurve = p;
  	  draw_session->move_to (mid.x, mid.y);
  	}
  	else
  	  first_offcurve = p;
        }
      }
      else
      {
        if (last_offcurve)
        {
  	if (is_on_curve)
  	{
  	  draw_session->quadratic_to (last_offcurve.x, last_offcurve.y,
  				     p.x, p.y);
  	  last_offcurve = optional_point_t ();
  	}
  	else
  	{
  	  optional_point_t mid = last_offcurve.lerp (p, .5f);
  	  draw_session->quadratic_to (last_offcurve.x, last_offcurve.y,
  				     mid.x, mid.y);
  	  last_offcurve = p;
  	}
        }
        else
        {
  	if (is_on_curve)
  	  draw_session->line_to (p.x, p.y);
  	else
  	  last_offcurve = p;
        }
      }
  
      if (point.is_end_point)
      {
        if (first_offcurve && last_offcurve)
        {
  	optional_point_t mid = last_offcurve.lerp (first_offcurve, .5f);
  	draw_session->quadratic_to (last_offcurve.x, last_offcurve.y,
  				   mid.x, mid.y);
  	last_offcurve = optional_point_t ();
  	/* now check the rest */
        }
  
        if (first_offcurve && first_oncurve)
  	draw_session->quadratic_to (first_offcurve.x, first_offcurve.y,
  				   first_oncurve.x, first_oncurve.y);
        else if (last_offcurve && first_oncurve)
  	draw_session->quadratic_to (last_offcurve.x, last_offcurve.y,
  				   first_oncurve.x, first_oncurve.y);
        else if (first_oncurve)
  	draw_session->line_to (first_oncurve.x, first_oncurve.y);
        else if (first_offcurve)
        {
  	float x = first_offcurve.x, y = first_offcurve.y;
  	draw_session->move_to (x, y);
  	draw_session->quadratic_to (x, y, x, y);
        }
  
        /* Getting ready for the next contour */
        first_oncurve = first_offcurve = last_offcurve = optional_point_t ();
        draw_session->close_path ();
      }
    }
    void points_end () {}
  
    bool is_consuming_contour_points () { return true; }
    contour_point_t *get_phantoms_sink () { return nullptr; }
  };
  
  
  } /* namespace glyf_impl */
  } /* namespace OT */
  
  
  #endif /* OT_GLYF_PATH_BUILDER_HH */
  

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