[glyf] Adopt a state machine like style for the path builder

Toward making glyf path reader alloc free at least on gvar absence.
This commit is contained in:
Ebrahim Byagowi 2020-02-17 23:44:31 +03:30
parent 60f8f384f9
commit 11f5f7c59c
1 changed files with 166 additions and 155 deletions

View File

@ -1031,174 +1031,185 @@ struct glyf
add_gid_and_children (item.glyphIndex, gids_to_retain, depth); add_gid_and_children (item.glyphIndex, gids_to_retain, depth);
} }
static void struct path_builder_t
_normal_quadratic_to_call (hb_font_t *font, const hb_draw_funcs_t *funcs,
float from_x HB_UNUSED, float from_y HB_UNUSED,
float control_x, float control_y,
float to_x, float to_y,
void *user_data)
{ {
funcs->quadratic_to (font->em_scalef_x (control_x), font->em_scalef_y (control_y), hb_font_t *font;
font->em_scalef_x (to_x), font->em_scalef_y (to_y), const hb_draw_funcs_t *funcs;
user_data); void *user_data;
} void (*quad_to) (hb_font_t *, const hb_draw_funcs_t *,
float, float, float, float, float, float,
void *);
float last_x, last_y;
static void struct optional_point_t
_translate_quadratic_to_cubic (hb_font_t *font, const hb_draw_funcs_t *funcs, {
float from_x, float from_y, optional_point_t () { is_null = true; }
float control_x, float control_y, optional_point_t (float x_, float y_) { x = x_; y = y_; is_null = false; }
float to_x, float to_y,
void *user_data)
{
funcs->cubic_to (font->em_scalef_x ((from_x + 2.f * control_x) / 3.f),
font->em_scalef_y ((from_y + 2.f * control_y) / 3.f),
font->em_scalef_x ((to_x + 2.f * control_x) / 3.f),
font->em_scalef_y ((to_y + 2.f * control_y) / 3.f),
font->em_scalef_x (to_x),
font->em_scalef_y (to_y),
user_data);
}
struct optional_point_t bool is_null;
{ float x;
optional_point_t () { is_null = true; } float y;
optional_point_t (float x_, float y_) { x = x_; y = y_; is_null = false; }
bool is_null; optional_point_t lerp (optional_point_t p, float t)
float x; { return optional_point_t (x + t * (p.x - x), y + t * (p.y - y)); }
float y; } first_oncurve, first_offcurve, last_offcurve;
optional_point_t lerp (optional_point_t p, float t) path_builder_t (hb_font_t *font_, const hb_draw_funcs_t *funcs_, void *user_data_)
{ return optional_point_t (x + t * (p.x - x), y + t * (p.y - y)); } {
font = font_;
funcs = funcs_;
user_data = user_data_;
quad_to = funcs->quadratic_to ? _normal_quadratic_to_call : _translate_quadratic_to_cubic;
last_x = last_y = 0;
end_of_contour ();
}
void end_of_contour () { first_oncurve = first_offcurve = last_offcurve = optional_point_t (); }
static void
_normal_quadratic_to_call (hb_font_t *font, const hb_draw_funcs_t *funcs,
float from_x HB_UNUSED, float from_y HB_UNUSED,
float control_x, float control_y,
float to_x, float to_y,
void *user_data)
{
funcs->quadratic_to (font->em_scalef_x (control_x), font->em_scalef_y (control_y),
font->em_scalef_x (to_x), font->em_scalef_y (to_y),
user_data);
}
static void
_translate_quadratic_to_cubic (hb_font_t *font, const hb_draw_funcs_t *funcs,
float from_x, float from_y,
float control_x, float control_y,
float to_x, float to_y,
void *user_data)
{
funcs->cubic_to (font->em_scalef_x ((from_x + 2.f * control_x) / 3.f),
font->em_scalef_y ((from_y + 2.f * control_y) / 3.f),
font->em_scalef_x ((to_x + 2.f * control_x) / 3.f),
font->em_scalef_y ((to_y + 2.f * control_y) / 3.f),
font->em_scalef_x (to_x),
font->em_scalef_y (to_y),
user_data);
}
/* based on https://github.com/RazrFalcon/ttf-parser/blob/master/src/glyf.rs#L292 */
void consume_point (contour_point_t &point)
{
/* Skip empty contours */
if (unlikely (point.is_end_point && first_oncurve.is_null && first_offcurve.is_null))
return;
bool is_on_curve = point.flag & Glyph::FLAG_ON_CURVE;
optional_point_t p (point.x, point.y);
if (first_oncurve.is_null)
{
if (is_on_curve)
{
first_oncurve = p;
last_x = p.x; last_y = p.y;
funcs->move_to (font->em_scalef_x (last_x), font->em_scalef_y (last_y),
user_data);
}
else
{
if (!first_offcurve.is_null)
{
optional_point_t mid = first_offcurve.lerp (p, .5f);
first_oncurve = mid;
last_offcurve = p;
last_x = mid.x; last_y = mid.y;
funcs->move_to (font->em_scalef_x (last_x), font->em_scalef_y (last_y),
user_data);
}
else
first_offcurve = p;
}
}
else
{
if (!last_offcurve.is_null)
{
if (is_on_curve)
{
quad_to (font, funcs, last_x, last_y, last_offcurve.x, last_offcurve.y, p.x, p.y, user_data);
last_x = p.x;
last_y = p.y;
last_offcurve = optional_point_t ();
}
else
{
optional_point_t mid = last_offcurve.lerp (p, .5f);
quad_to (font, funcs, last_x, last_y, last_offcurve.x, last_offcurve.y, mid.x, mid.y, user_data);
last_x = mid.x;
last_y = mid.y;
last_offcurve = p;
}
}
else
{
if (is_on_curve)
{
last_x = p.x;
last_y = p.y;
funcs->line_to (font->em_scalef_x (last_x), font->em_scalef_y (last_y),
user_data);
}
else
{
last_offcurve = p;
}
}
}
if (point.is_end_point)
{
while (true)
{
if (!first_offcurve.is_null && !last_offcurve.is_null)
{
optional_point_t mid = last_offcurve.lerp (first_offcurve, .5f);
quad_to (font, funcs, last_x, last_y, last_offcurve.x, last_offcurve.y, mid.x, mid.y, user_data);
last_x = mid.x;
last_y = mid.y;
last_offcurve = optional_point_t ();
}
else if (!first_offcurve.is_null && last_offcurve.is_null)
{
if (!first_oncurve.is_null)
quad_to (font, funcs, last_x, last_y, first_offcurve.x, first_offcurve.y, first_oncurve.x, first_oncurve.y, user_data);
break;
}
else if (first_offcurve.is_null && !last_offcurve.is_null)
{
if (!first_oncurve.is_null)
quad_to (font, funcs, last_x, last_y, last_offcurve.x, last_offcurve.y, first_oncurve.x, first_oncurve.y, user_data);
break;
}
else /* first_offcurve.is_null && last_offcurve.is_null */
{
if (!first_oncurve.is_null)
funcs->line_to (font->em_scalef_x (first_oncurve.x), font->em_scalef_y (first_oncurve.y),
user_data);
break;
}
}
end_of_contour ();
funcs->close_path (user_data);
}
}
}; };
bool bool
get_path (hb_font_t *font, hb_codepoint_t gid, get_path (hb_font_t *font, hb_codepoint_t gid,
const hb_draw_funcs_t *funcs, void *user_data) const const hb_draw_funcs_t *funcs, void *user_data) const
{ {
/* Making this completely alloc free is not that easy path_builder_t builder (font, funcs, user_data);
https://github.com/harfbuzz/harfbuzz/issues/2095
mostly because of gvar handling in VF fonts,
perhaps a separate path can be considered */
contour_point_vector_t all_points; contour_point_vector_t all_points;
if (unlikely (!get_points (font, gid, all_points))) return false; if (unlikely (!get_points (font, gid, all_points))) return false;
hb_array_t<contour_point_t> points = all_points.sub_array (0, all_points.length - 4); for (unsigned point_index = 0; point_index < all_points.length - 4; ++point_index)
builder.consume_point (all_points[point_index]);
void (*quad_to) (hb_font_t *, const hb_draw_funcs_t *,
float, float, float, float, float, float,
void *) = funcs->quadratic_to ? _normal_quadratic_to_call : _translate_quadratic_to_cubic;
/* based on https://github.com/RazrFalcon/ttf-parser/blob/master/src/glyf.rs#L292 which is base on font-rs */
unsigned point_index = 0;
while (point_index < points.length)
{
/* Skip empty contours */
if (points[point_index].is_end_point)
{
++point_index;
continue;
}
optional_point_t first_oncurve = optional_point_t ();
optional_point_t first_offcurve = optional_point_t ();
optional_point_t last_offcurve = optional_point_t ();
float last_x = 0, last_y = 0;
do
{
bool is_on_curve = points[point_index].flag & Glyph::FLAG_ON_CURVE;
optional_point_t p (points[point_index].x, points[point_index].y);
if (first_oncurve.is_null)
{
if (is_on_curve)
{
first_oncurve = p;
last_x = p.x; last_y = p.y;
funcs->move_to (font->em_scalef_x (last_x), font->em_scalef_y (last_y),
user_data);
}
else
{
if (!first_offcurve.is_null)
{
optional_point_t mid = first_offcurve.lerp (p, .5f);
first_oncurve = mid;
last_offcurve = p;
last_x = mid.x; last_y = mid.y;
funcs->move_to (font->em_scalef_x (last_x), font->em_scalef_y (last_y),
user_data);
}
else
first_offcurve = p;
}
}
else
{
if (!last_offcurve.is_null)
{
if (is_on_curve)
{
quad_to (font, funcs, last_x, last_y, last_offcurve.x, last_offcurve.y, p.x, p.y, user_data);
last_x = p.x;
last_y = p.y;
last_offcurve = optional_point_t ();
}
else
{
optional_point_t mid = last_offcurve.lerp (p, .5f);
quad_to (font, funcs, last_x, last_y, last_offcurve.x, last_offcurve.y, mid.x, mid.y, user_data);
last_x = mid.x;
last_y = mid.y;
last_offcurve = p;
}
}
else
{
if (is_on_curve)
{
last_x = p.x;
last_y = p.y;
funcs->line_to (font->em_scalef_x (last_x), font->em_scalef_y (last_y),
user_data);
}
else
{
last_offcurve = p;
}
}
}
} while (!points[point_index++].is_end_point);
while (true)
{
if (!first_offcurve.is_null && !last_offcurve.is_null)
{
optional_point_t mid = last_offcurve.lerp (first_offcurve, .5f);
quad_to (font, funcs, last_x, last_y, last_offcurve.x, last_offcurve.y, mid.x, mid.y, user_data);
last_x = mid.x;
last_y = mid.y;
last_offcurve = optional_point_t ();
}
else if (!first_offcurve.is_null && last_offcurve.is_null)
{
if (!first_oncurve.is_null)
quad_to (font, funcs, last_x, last_y, first_offcurve.x, first_offcurve.y, first_oncurve.x, first_oncurve.y, user_data);
break;
}
else if (first_offcurve.is_null && !last_offcurve.is_null)
{
if (!first_oncurve.is_null)
quad_to (font, funcs, last_x, last_y, last_offcurve.x, last_offcurve.y, first_oncurve.x, first_oncurve.y, user_data);
break;
}
else /* first_offcurve.is_null && last_offcurve.is_null */
{
if (!first_oncurve.is_null)
funcs->line_to (font->em_scalef_x (first_oncurve.x), font->em_scalef_y (first_oncurve.y),
user_data);
break;
}
}
funcs->close_path (user_data);
}
return true; return true;
} }