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[glyf] Support cubic curves 

https://github.com/harfbuzz/boring-expansion-spec/issues/41
This commit is contained in:
Behdad Esfahbod 2023-02-07 22:19:45 -07:00
parent 64fa5cd482
commit 1d9dafbfd5
2 changed files with 45 additions and 12 deletions
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2
src/OT/glyf/SimpleGlyph.hh
View File

@ -20,7 +20,7 @@ struct SimpleGlyph
FLAG_X_SAME = 0x10,
FLAG_Y_SAME = 0x20,
FLAG_OVERLAP_SIMPLE = 0x40,
FLAG_RESERVED2 = 0x80
FLAG_CUBIC = 0x80
};
const GlyphHeader &header;

55
src/OT/glyf/path-builder.hh
View File

@ -26,13 +26,13 @@ struct path_builder_t
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;
} first_oncurve, first_offcurve, last_offcurve, last_offcurve2;
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 ();
first_oncurve = first_offcurve = last_offcurve = last_offcurve2 = optional_point_t ();
}
/* based on https://github.com/RazrFalcon/ttf-parser/blob/4f32821/src/glyf.rs#L287
@ -42,6 +42,7 @@ struct path_builder_t
void consume_point (const contour_point_t &point)
{
bool is_on_curve = point.flag & glyf_impl::SimpleGlyph::FLAG_ON_CURVE;
bool is_cubic = !is_on_curve && (point.flag & glyf_impl::SimpleGlyph::FLAG_CUBIC);
optional_point_t p (font->em_fscalef_x (point.x), font->em_fscalef_y (point.y));
if (!first_oncurve)
{
@ -69,16 +70,41 @@ struct path_builder_t
{
if (is_on_curve)
{
draw_session->quadratic_to (last_offcurve.x, last_offcurve.y,
p.x, p.y);
if (last_offcurve2)
{
draw_session->cubic_to (last_offcurve2.x, last_offcurve2.y,
last_offcurve.x, last_offcurve.y,
p.x, p.y);
last_offcurve2 = optional_point_t ();
}
else
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;
if (is_cubic && !last_offcurve2)
{
last_offcurve2 = last_offcurve;
last_offcurve = p;
}
else
{
optional_point_t mid = last_offcurve.lerp (p, .5f);
if (is_cubic)
{
draw_session->cubic_to (last_offcurve2.x, last_offcurve2.y,
last_offcurve.x, last_offcurve.y,
mid.x, mid.y);
last_offcurve2 = optional_point_t ();
}
else
draw_session->quadratic_to (last_offcurve.x, last_offcurve.y,
mid.x, mid.y);
last_offcurve = p;
}
}
}
else
@ -105,8 +131,15 @@ struct path_builder_t
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);
{
if (last_offcurve2)
draw_session->cubic_to (last_offcurve2.x, last_offcurve2.y,
last_offcurve.x, last_offcurve.y,
first_oncurve.x, first_oncurve.y);
else
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)
@ -117,7 +150,7 @@ struct path_builder_t
}
/* Getting ready for the next contour */
first_oncurve = first_offcurve = last_offcurve = optional_point_t ();
first_oncurve = first_offcurve = last_offcurve = last_offcurve2 = optional_point_t ();
draw_session->close_path ();
}
}