harfbuzz/src/hb-draw-embolden.hh

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/*
* Copyright © 2023 Behdad Esfahbod
*
* This is part of HarfBuzz, a text shaping library.
*
* Permission is hereby granted, without written agreement and without
* license or royalty fees, to use, copy, modify, and distribute this
* software and its documentation for any purpose, provided that the
* above copyright notice and the following two paragraphs appear in
* all copies of this software.
*
* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*
* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*/
#ifndef HB_DRAW_EMBOLDEN_HH
#define HB_DRAW_EMBOLDEN_HH
#include "hb.hh"
#include "hb-draw.hh"
struct hb_contour_point_t
{
enum class type_t
{
MOVE_TO,
LINE_TO,
QUADRATIC_TO,
CUBIC_TO,
};
hb_contour_point_t (float x, float y, type_t type) :
x (x), y (y), type (type) {}
float x, y;
type_t type;
};
using hb_contour_t = hb_vector_t<hb_contour_point_t>;
template <typename context_t>
struct hb_filter_outline_t
{
void replay (hb_draw_funcs_t *pen, void *pen_data)
{
hb_draw_state_t st = HB_DRAW_STATE_DEFAULT;
unsigned first = 0;
for (unsigned contour : contours)
{
auto it = points.as_array ().sub_array (first, contour - first);
while (it)
{
hb_contour_point_t p1 = *it++;
switch (p1.type)
{
case hb_contour_point_t::type_t::MOVE_TO:
{
pen->move_to (pen_data, st,
p1.x, p1.y);
}
break;
case hb_contour_point_t::type_t::LINE_TO:
{
pen->line_to (pen_data, st,
p1.x, p1.y);
}
break;
case hb_contour_point_t::type_t::QUADRATIC_TO:
{
hb_contour_point_t p2 = *it++;
pen->quadratic_to (pen_data, st,
p1.x, p1.y,
p2.x, p2.y);
}
break;
case hb_contour_point_t::type_t::CUBIC_TO:
{
hb_contour_point_t p2 = *it++;
hb_contour_point_t p3 = *it++;
pen->cubic_to (pen_data, st,
p1.x, p1.y,
p2.x, p2.y,
p3.x, p3.y);
}
break;
}
}
pen->close_path (pen_data, st);
first = contour;
}
}
hb_vector_t<hb_contour_point_t> points;
hb_vector_t<unsigned> contours;
};
template <typename context_t>
static void
hb_filter_outline_move_to (hb_draw_funcs_t *dfuncs HB_UNUSED,
void *data,
hb_draw_state_t *st,
float to_x, float to_y,
void *user_data HB_UNUSED)
{
context_t *c = (context_t *) data;
c->points.push (hb_contour_point_t {to_x, to_y, hb_contour_point_t::type_t::MOVE_TO});
}
template <typename context_t>
static void
hb_filter_outline_line_to (hb_draw_funcs_t *dfuncs HB_UNUSED,
void *data,
hb_draw_state_t *st,
float to_x, float to_y,
void *user_data HB_UNUSED)
{
context_t *c = (context_t *) data;
c->points.push (hb_contour_point_t {to_x, to_y, hb_contour_point_t::type_t::LINE_TO});
}
template <typename context_t>
static void
hb_filter_outline_quadratic_to (hb_draw_funcs_t *dfuncs HB_UNUSED,
void *data,
hb_draw_state_t *st,
float control_x, float control_y,
float to_x, float to_y,
void *user_data HB_UNUSED)
{
context_t *c = (context_t *) data;
c->points.push (hb_contour_point_t {control_x, control_y, hb_contour_point_t::type_t::QUADRATIC_TO});
c->points.push (hb_contour_point_t {to_x, to_y, hb_contour_point_t::type_t::QUADRATIC_TO});
}
template <typename context_t>
static void
hb_filter_outline_cubic_to (hb_draw_funcs_t *dfuncs HB_UNUSED,
void *data,
hb_draw_state_t *st,
float control1_x, float control1_y,
float control2_x, float control2_y,
float to_x, float to_y,
void *user_data HB_UNUSED)
{
context_t *c = (context_t *) data;
c->points.push (hb_contour_point_t {control1_x, control1_y, hb_contour_point_t::type_t::CUBIC_TO});
c->points.push (hb_contour_point_t {control2_x, control2_y, hb_contour_point_t::type_t::CUBIC_TO});
c->points.push (hb_contour_point_t {to_x, to_y, hb_contour_point_t::type_t::CUBIC_TO});
}
template <typename context_t>
static void
hb_filter_outline_close_path (hb_draw_funcs_t *dfuncs HB_UNUSED,
void *data,
hb_draw_state_t *st,
void *user_data HB_UNUSED)
{
context_t *c = (context_t *) data;
c->contours.push (c->points.length);
}
struct hb_draw_embolden_context_t : hb_filter_outline_t<hb_draw_embolden_context_t>
{
void operator () (float x_strength, float y_strength)
{
if (!x_strength && !y_strength) return;
if (!points) return;
x_strength /= 2.f;
y_strength /= 2.f;
bool orientation_negative = false;
struct vector_t
{
float normalize_len ()
{
float len = hypotf (x, y);
if (len)
{
x /= len;
y /= len;
}
return len;
}
float x, y;
};
signed first = 0;
for (unsigned c = 0; c < contours.length; c++)
{
vector_t in, out, anchor, shift;
float l_in, l_out, l_anchor = 0, l, q, d;
l_in = 0;
signed last = (int) contours[c] - 1;
/* pacify compiler */
in.x = in.y = anchor.x = anchor.y = 0;
/* Counter j cycles though the points; counter i advances only */
/* when points are moved; anchor k marks the first moved point. */
for ( signed i = last, j = first, k = -1;
j != i && i != k;
j = j < last ? j + 1 : first )
{
if ( j != k )
{
out.x = points[j].x - points[i].x;
out.y = points[j].y - points[i].y;
l_out = out.normalize_len ();
if ( l_out == 0 )
continue;
}
else
{
out = anchor;
l_out = l_anchor;
}
if ( l_in != 0 )
{
if ( k < 0 )
{
k = i;
anchor = in;
l_anchor = l_in;
}
d = in.x * out.x + in.y * out.y;
/* shift only if turn is less than ~160 degrees */
if ( d > -15.f/16.f )
{
d = d + 1.f;
/* shift components along lateral bisector in proper orientation */
shift.x = in.y + out.y;
shift.y = in.x + out.x;
if ( orientation_negative )
shift.x = -shift.x;
else
shift.y = -shift.y;
/* restrict shift magnitude to better handle collapsing segments */
q = out.x * in.y - out.y * in.x;
if ( orientation_negative )
q = -q;
l = hb_min (l_in, l_out);
/* non-strict inequalities avoid divide-by-zero when q == l == 0 */
if (x_strength * q <= l * d)
shift.x = shift.x * x_strength / d;
else
shift.x = shift.x * l / q;
if (y_strength * q <= l * d)
shift.y = shift.y * y_strength / d;
else
shift.y = shift.y * l / q;
}
else
shift.x = shift.y = 0;
for ( ;
i != j;
i = i < last ? i + 1 : first )
{
points[i].x += x_strength + shift.x;
points[i].y += y_strength + shift.y;
}
}
else
i = j;
in = out;
l_in = l_out;
}
first = last + 1;
}
}
hb_draw_funcs_t *pen;
void *pen_data;
float x_strength, y_strength;
};
static inline void free_static_draw_embolden_funcs ();
static struct hb_draw_embolden_funcs_lazy_loader_t : hb_draw_funcs_lazy_loader_t<hb_draw_embolden_funcs_lazy_loader_t>
{
static hb_draw_funcs_t *create ()
{
hb_draw_funcs_t *funcs = hb_draw_funcs_create ();
using t = hb_draw_embolden_context_t;
hb_draw_funcs_set_move_to_func (funcs, hb_filter_outline_move_to<t>, nullptr, nullptr);
hb_draw_funcs_set_line_to_func (funcs, hb_filter_outline_line_to<t>, nullptr, nullptr);
hb_draw_funcs_set_quadratic_to_func (funcs, hb_filter_outline_quadratic_to<t>, nullptr, nullptr);
hb_draw_funcs_set_cubic_to_func (funcs, hb_filter_outline_cubic_to<t>, nullptr, nullptr);
hb_draw_funcs_set_close_path_func (funcs, hb_filter_outline_close_path<t>, nullptr, nullptr);
hb_draw_funcs_make_immutable (funcs);
hb_atexit (free_static_draw_embolden_funcs);
return funcs;
}
} static_draw_embolden_funcs;
static inline
void free_static_draw_embolden_funcs ()
{
static_draw_embolden_funcs.free_instance ();
}
static hb_draw_funcs_t *
hb_draw_embolden_get_funcs ()
{
return static_draw_embolden_funcs.get_unconst ();
}
#endif /* HB_DRAW_EMBOLDEN_HH */