[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
parent
60f8f384f9
commit
11f5f7c59c
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@ -1031,174 +1031,185 @@ struct glyf
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add_gid_and_children (item.glyphIndex, gids_to_retain, depth);
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}
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static void
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_normal_quadratic_to_call (hb_font_t *font, const hb_draw_funcs_t *funcs,
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float from_x HB_UNUSED, float from_y HB_UNUSED,
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float control_x, float control_y,
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float to_x, float to_y,
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void *user_data)
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struct path_builder_t
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{
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funcs->quadratic_to (font->em_scalef_x (control_x), font->em_scalef_y (control_y),
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font->em_scalef_x (to_x), font->em_scalef_y (to_y),
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user_data);
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}
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hb_font_t *font;
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const hb_draw_funcs_t *funcs;
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void *user_data;
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void (*quad_to) (hb_font_t *, const hb_draw_funcs_t *,
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float, float, float, float, float, float,
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void *);
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float last_x, last_y;
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static void
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_translate_quadratic_to_cubic (hb_font_t *font, const hb_draw_funcs_t *funcs,
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float from_x, float from_y,
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float control_x, float control_y,
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float to_x, float to_y,
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void *user_data)
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{
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funcs->cubic_to (font->em_scalef_x ((from_x + 2.f * control_x) / 3.f),
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font->em_scalef_y ((from_y + 2.f * control_y) / 3.f),
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font->em_scalef_x ((to_x + 2.f * control_x) / 3.f),
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font->em_scalef_y ((to_y + 2.f * control_y) / 3.f),
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font->em_scalef_x (to_x),
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font->em_scalef_y (to_y),
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user_data);
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}
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struct optional_point_t
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{
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optional_point_t () { is_null = true; }
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optional_point_t (float x_, float y_) { x = x_; y = y_; is_null = false; }
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struct optional_point_t
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{
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optional_point_t () { is_null = true; }
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optional_point_t (float x_, float y_) { x = x_; y = y_; is_null = false; }
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bool is_null;
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float x;
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float y;
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bool is_null;
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float x;
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float y;
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optional_point_t lerp (optional_point_t p, float t)
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{ return optional_point_t (x + t * (p.x - x), y + t * (p.y - y)); }
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} first_oncurve, first_offcurve, last_offcurve;
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optional_point_t lerp (optional_point_t p, float t)
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{ return optional_point_t (x + t * (p.x - x), y + t * (p.y - y)); }
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path_builder_t (hb_font_t *font_, const hb_draw_funcs_t *funcs_, void *user_data_)
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{
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font = font_;
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funcs = funcs_;
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user_data = user_data_;
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quad_to = funcs->quadratic_to ? _normal_quadratic_to_call : _translate_quadratic_to_cubic;
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last_x = last_y = 0;
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end_of_contour ();
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}
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void end_of_contour () { first_oncurve = first_offcurve = last_offcurve = optional_point_t (); }
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static void
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_normal_quadratic_to_call (hb_font_t *font, const hb_draw_funcs_t *funcs,
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float from_x HB_UNUSED, float from_y HB_UNUSED,
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float control_x, float control_y,
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float to_x, float to_y,
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void *user_data)
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{
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funcs->quadratic_to (font->em_scalef_x (control_x), font->em_scalef_y (control_y),
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font->em_scalef_x (to_x), font->em_scalef_y (to_y),
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user_data);
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}
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static void
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_translate_quadratic_to_cubic (hb_font_t *font, const hb_draw_funcs_t *funcs,
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float from_x, float from_y,
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float control_x, float control_y,
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float to_x, float to_y,
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void *user_data)
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{
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funcs->cubic_to (font->em_scalef_x ((from_x + 2.f * control_x) / 3.f),
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font->em_scalef_y ((from_y + 2.f * control_y) / 3.f),
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font->em_scalef_x ((to_x + 2.f * control_x) / 3.f),
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font->em_scalef_y ((to_y + 2.f * control_y) / 3.f),
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font->em_scalef_x (to_x),
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font->em_scalef_y (to_y),
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user_data);
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}
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/* based on https://github.com/RazrFalcon/ttf-parser/blob/master/src/glyf.rs#L292 */
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void consume_point (contour_point_t &point)
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{
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/* Skip empty contours */
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if (unlikely (point.is_end_point && first_oncurve.is_null && first_offcurve.is_null))
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return;
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bool is_on_curve = point.flag & Glyph::FLAG_ON_CURVE;
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optional_point_t p (point.x, point.y);
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if (first_oncurve.is_null)
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{
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if (is_on_curve)
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{
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first_oncurve = p;
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last_x = p.x; last_y = p.y;
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funcs->move_to (font->em_scalef_x (last_x), font->em_scalef_y (last_y),
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user_data);
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}
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else
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{
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if (!first_offcurve.is_null)
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{
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optional_point_t mid = first_offcurve.lerp (p, .5f);
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first_oncurve = mid;
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last_offcurve = p;
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last_x = mid.x; last_y = mid.y;
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funcs->move_to (font->em_scalef_x (last_x), font->em_scalef_y (last_y),
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user_data);
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}
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else
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first_offcurve = p;
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}
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}
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else
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{
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if (!last_offcurve.is_null)
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{
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if (is_on_curve)
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{
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quad_to (font, funcs, last_x, last_y, last_offcurve.x, last_offcurve.y, p.x, p.y, user_data);
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last_x = p.x;
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last_y = p.y;
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last_offcurve = optional_point_t ();
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}
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else
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{
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optional_point_t mid = last_offcurve.lerp (p, .5f);
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quad_to (font, funcs, last_x, last_y, last_offcurve.x, last_offcurve.y, mid.x, mid.y, user_data);
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last_x = mid.x;
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last_y = mid.y;
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last_offcurve = p;
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}
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}
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else
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{
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if (is_on_curve)
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{
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last_x = p.x;
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last_y = p.y;
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funcs->line_to (font->em_scalef_x (last_x), font->em_scalef_y (last_y),
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user_data);
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}
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else
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{
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last_offcurve = p;
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}
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}
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}
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if (point.is_end_point)
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{
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while (true)
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{
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if (!first_offcurve.is_null && !last_offcurve.is_null)
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{
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optional_point_t mid = last_offcurve.lerp (first_offcurve, .5f);
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quad_to (font, funcs, last_x, last_y, last_offcurve.x, last_offcurve.y, mid.x, mid.y, user_data);
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last_x = mid.x;
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last_y = mid.y;
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last_offcurve = optional_point_t ();
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}
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else if (!first_offcurve.is_null && last_offcurve.is_null)
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{
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if (!first_oncurve.is_null)
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quad_to (font, funcs, last_x, last_y, first_offcurve.x, first_offcurve.y, first_oncurve.x, first_oncurve.y, user_data);
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break;
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}
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else if (first_offcurve.is_null && !last_offcurve.is_null)
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{
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if (!first_oncurve.is_null)
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quad_to (font, funcs, last_x, last_y, last_offcurve.x, last_offcurve.y, first_oncurve.x, first_oncurve.y, user_data);
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break;
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}
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else /* first_offcurve.is_null && last_offcurve.is_null */
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{
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if (!first_oncurve.is_null)
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funcs->line_to (font->em_scalef_x (first_oncurve.x), font->em_scalef_y (first_oncurve.y),
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user_data);
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break;
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}
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}
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end_of_contour ();
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funcs->close_path (user_data);
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}
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}
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};
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bool
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get_path (hb_font_t *font, hb_codepoint_t gid,
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const hb_draw_funcs_t *funcs, void *user_data) const
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{
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/* Making this completely alloc free is not that easy
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https://github.com/harfbuzz/harfbuzz/issues/2095
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mostly because of gvar handling in VF fonts,
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perhaps a separate path can be considered */
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path_builder_t builder (font, funcs, user_data);
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contour_point_vector_t all_points;
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if (unlikely (!get_points (font, gid, all_points))) return false;
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hb_array_t<contour_point_t> points = all_points.sub_array (0, all_points.length - 4);
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void (*quad_to) (hb_font_t *, const hb_draw_funcs_t *,
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float, float, float, float, float, float,
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void *) = funcs->quadratic_to ? _normal_quadratic_to_call : _translate_quadratic_to_cubic;
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/* based on https://github.com/RazrFalcon/ttf-parser/blob/master/src/glyf.rs#L292 which is base on font-rs */
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unsigned point_index = 0;
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while (point_index < points.length)
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{
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/* Skip empty contours */
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if (points[point_index].is_end_point)
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{
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++point_index;
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continue;
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}
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optional_point_t first_oncurve = optional_point_t ();
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optional_point_t first_offcurve = optional_point_t ();
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optional_point_t last_offcurve = optional_point_t ();
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float last_x = 0, last_y = 0;
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do
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{
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bool is_on_curve = points[point_index].flag & Glyph::FLAG_ON_CURVE;
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optional_point_t p (points[point_index].x, points[point_index].y);
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if (first_oncurve.is_null)
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{
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if (is_on_curve)
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{
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first_oncurve = p;
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last_x = p.x; last_y = p.y;
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funcs->move_to (font->em_scalef_x (last_x), font->em_scalef_y (last_y),
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user_data);
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}
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else
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{
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if (!first_offcurve.is_null)
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{
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optional_point_t mid = first_offcurve.lerp (p, .5f);
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first_oncurve = mid;
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last_offcurve = p;
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last_x = mid.x; last_y = mid.y;
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funcs->move_to (font->em_scalef_x (last_x), font->em_scalef_y (last_y),
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user_data);
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}
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else
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first_offcurve = p;
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}
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}
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else
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{
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if (!last_offcurve.is_null)
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{
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if (is_on_curve)
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{
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quad_to (font, funcs, last_x, last_y, last_offcurve.x, last_offcurve.y, p.x, p.y, user_data);
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last_x = p.x;
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last_y = p.y;
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last_offcurve = optional_point_t ();
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}
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else
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{
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optional_point_t mid = last_offcurve.lerp (p, .5f);
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quad_to (font, funcs, last_x, last_y, last_offcurve.x, last_offcurve.y, mid.x, mid.y, user_data);
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last_x = mid.x;
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last_y = mid.y;
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last_offcurve = p;
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}
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}
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else
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{
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if (is_on_curve)
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{
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last_x = p.x;
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last_y = p.y;
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funcs->line_to (font->em_scalef_x (last_x), font->em_scalef_y (last_y),
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user_data);
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}
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else
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{
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last_offcurve = p;
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}
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}
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}
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} while (!points[point_index++].is_end_point);
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while (true)
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{
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if (!first_offcurve.is_null && !last_offcurve.is_null)
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{
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optional_point_t mid = last_offcurve.lerp (first_offcurve, .5f);
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quad_to (font, funcs, last_x, last_y, last_offcurve.x, last_offcurve.y, mid.x, mid.y, user_data);
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last_x = mid.x;
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last_y = mid.y;
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last_offcurve = optional_point_t ();
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}
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else if (!first_offcurve.is_null && last_offcurve.is_null)
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{
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if (!first_oncurve.is_null)
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quad_to (font, funcs, last_x, last_y, first_offcurve.x, first_offcurve.y, first_oncurve.x, first_oncurve.y, user_data);
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break;
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}
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else if (first_offcurve.is_null && !last_offcurve.is_null)
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{
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if (!first_oncurve.is_null)
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quad_to (font, funcs, last_x, last_y, last_offcurve.x, last_offcurve.y, first_oncurve.x, first_oncurve.y, user_data);
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break;
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}
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else /* first_offcurve.is_null && last_offcurve.is_null */
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{
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if (!first_oncurve.is_null)
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funcs->line_to (font->em_scalef_x (first_oncurve.x), font->em_scalef_y (first_oncurve.y),
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user_data);
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break;
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}
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}
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funcs->close_path (user_data);
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}
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for (unsigned point_index = 0; point_index < all_points.length - 4; ++point_index)
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builder.consume_point (all_points[point_index]);
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return true;
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}
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