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/*
* Copyright © 2024 Google, Inc.
*
* 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.
*/
#include "hb-subset-instancer-iup.hh"
/* This file is a straight port of the following:
*
*
* Where that file returns optimzied deltas vector, we return optimized
* referenced point indices.
*/
constexpr static unsigned MAX_LOOKBACK = 8;
static void _iup_contour_bound_forced_set (const hb_array_t<const contour_point_t> contour_points,
const hb_array_t<const int> x_deltas,
const hb_array_t<const int> y_deltas,
hb_set_t& forced_set, /* OUT */
float tolerance = 0.f)
{
unsigned len = contour_points.length;
unsigned next_i = 0;
for (int i = len - 1; i >= 0; i--)
{
unsigned last_i = (len + i -1) % len;
for (unsigned j = 0; j < 2; j++)
{
float cj, lcj, ncj;
int dj, ldj, ndj;
if (j == 0)
{
cj = contour_points.arrayZ[i].x;
dj = x_deltas.arrayZ[i];
lcj = contour_points.arrayZ[last_i].x;
ldj = x_deltas.arrayZ[last_i];
ncj = contour_points.arrayZ[next_i].x;
ndj = x_deltas.arrayZ[next_i];
}
else
{
cj = contour_points.arrayZ[i].y;
dj = y_deltas.arrayZ[i];
lcj = contour_points.arrayZ[last_i].y;
ldj = y_deltas.arrayZ[last_i];
ncj = contour_points.arrayZ[next_i].y;
ndj = y_deltas.arrayZ[next_i];
}
float c1, c2;
int d1, d2;
if (lcj <= ncj)
{
c1 = lcj;
c2 = ncj;
d1 = ldj;
d2 = ndj;
}
else
{
c1 = ncj;
c2 = lcj;
d1 = ndj;
d2 = ldj;
}
bool force = false;
if (c1 == c2)
{
if (abs (d1 - d2) > tolerance && abs (dj) > tolerance)
force = true;
}
else if (c1 <= cj && cj <= c2)
{
if (!(hb_min (d1, d2) - tolerance <= dj &&
dj <= hb_max (d1, d2) + tolerance))
force = true;
}
else
{
if (d1 != d2)
{
if (cj < c1)
{
if (abs (dj) > tolerance &&
abs (dj - d1) > tolerance &&
((dj - tolerance < d1) != (d1 < d2)))
force = true;
}
else
{
if (abs (dj) > tolerance &&
abs (dj - d2) > tolerance &&
((d2 < dj + tolerance) != (d1 < d2)))
force = true;
}
}
}
if (force)
{
forced_set.add (i);
break;
}
}
next_i = i;
}
}
template <typename T,
hb_enable_if (hb_is_trivially_copyable (T))>
static bool rotate_array (const hb_array_t<const T>& org_array,
int k,
hb_vector_t<T>& out)
{
unsigned n = org_array.length;
if (!n) return true;
if (unlikely (!out.resize (n, false)))
return false;
unsigned item_size = hb_static_size (T);
if (k < 0)
k = n - (-k) % n;
else
k %= n;
hb_memcpy ((void *) out.arrayZ, (const void *) (org_array.arrayZ + n - k), k * item_size);
hb_memcpy ((void *) (out.arrayZ + k), (const void *) org_array.arrayZ, (n - k) * item_size);
return true;
}
static bool rotate_set (const hb_set_t& org_set,
int k,
unsigned n,
hb_set_t& out)
{
if (!n) return false;
k %= n;
if (k < 0)
k = n + k;
if (k == 0)
{
out.set (org_set);
}
else
{
for (auto v : org_set)
out.add ((v + k) % n);
}
return !out.in_error ();
}
/* Given two reference coordinates (start and end of contour_points array),
* output interpolated deltas for points in between */
static bool _iup_segment (const hb_array_t<const contour_point_t> contour_points,
const hb_array_t<const int> x_deltas,
const hb_array_t<const int> y_deltas,
const contour_point_t& p1, const contour_point_t& p2,
int p1_dx, int p2_dx,
int p1_dy, int p2_dy,
hb_vector_t<float>& interp_x_deltas, /* OUT */
hb_vector_t<float>& interp_y_deltas /* OUT */)
{
unsigned n = contour_points.length;
if (unlikely (!interp_x_deltas.resize (n, false) ||
!interp_y_deltas.resize (n, false)))
return false;
for (unsigned j = 0; j < 2; j++)
{
float x1, x2, d1, d2;
float *out;
if (j == 0)
{
x1 = p1.x;
x2 = p2.x;
d1 = p1_dx;
d2 = p2_dx;
out = interp_x_deltas.arrayZ;
}
else
{
x1 = p1.y;
x2 = p2.y;
d1 = p1_dy;
d2 = p2_dy;
out = interp_y_deltas.arrayZ;
}
if (x1 == x2)
{
if (d1 == d2)
{
for (unsigned i = 0; i < n; i++)
out[i] = d1;
}
else
{
for (unsigned i = 0; i < n; i++)
out[i] = 0.f;
}
continue;
}
if (x1 > x2)
{
hb_swap (x1, x2);
hb_swap (d1, d2);
}
float scale = (d2 - d1) / (x2 - x1);
for (unsigned i = 0; i < n; i++)
{
float x = j == 0 ? contour_points.arrayZ[i].x : contour_points.arrayZ[i].y;
float d;
if (x <= x1)
d = d1;
else if (x >= x2)
d = d2;
else
d = d1 + (x - x1) * scale;
out[i] = d;
}
}
return true;
}
static bool _can_iup_in_between (const hb_array_t<const contour_point_t> contour_points,
const hb_array_t<const int> x_deltas,
const hb_array_t<const int> y_deltas,
const contour_point_t& p1, const contour_point_t& p2,
int p1_dx, int p2_dx,
int p1_dy, int p2_dy,
float tolerance)
{
hb_vector_t<float> interp_x_deltas, interp_y_deltas;
if (!_iup_segment (contour_points, x_deltas, y_deltas,
p1, p2, p1_dx, p2_dx, p1_dy, p2_dy,
interp_x_deltas, interp_y_deltas))
return false;
unsigned num = contour_points.length;
for (unsigned i = 0; i < num; i++)
{
float dx = x_deltas.arrayZ[i] - interp_x_deltas.arrayZ[i];
float dy = y_deltas.arrayZ[i] - interp_y_deltas.arrayZ[i];
if (sqrtf ((float)dx * dx + (float)dy * dy) > tolerance)
return false;
}
return true;
}
static bool _iup_contour_optimize_dp (const contour_point_vector_t& contour_points,
const hb_vector_t<int>& x_deltas,
const hb_vector_t<int>& y_deltas,
const hb_set_t& forced_set,
float tolerance,
unsigned lookback,
hb_vector_t<unsigned>& costs, /* OUT */
hb_vector_t<int>& chain /* OUT */)
{
unsigned n = contour_points.length;
if (unlikely (!costs.resize (n, false) ||
!chain.resize (n, false)))
return false;
lookback = hb_min (lookback, MAX_LOOKBACK);
for (unsigned i = 0; i < n; i++)
{
unsigned best_cost = (i == 0 ? 1 : costs.arrayZ[i-1] + 1);
costs.arrayZ[i] = best_cost;
chain.arrayZ[i] = (i == 0 ? -1 : i - 1);
if (i > 0 && forced_set.has (i - 1))
continue;
int lookback_index = hb_max ((int) i - (int) lookback + 1, -1);
for (int j = i - 2; j >= lookback_index; j--)
{
unsigned cost = j == -1 ? 1 : costs.arrayZ[j] + 1;
/* num points between i and j */
unsigned num_points = i - j - 1;
unsigned p1 = (j == -1 ? n - 1 : j);
if (cost < best_cost &&
_can_iup_in_between (contour_points.as_array ().sub_array (j + 1, num_points),
x_deltas.as_array ().sub_array (j + 1, num_points),
y_deltas.as_array ().sub_array (j + 1, num_points),
contour_points.arrayZ[p1], contour_points.arrayZ[i],
x_deltas.arrayZ[p1], x_deltas.arrayZ[i],
y_deltas.arrayZ[p1], y_deltas.arrayZ[i],
tolerance))
{
best_cost = cost;
costs.arrayZ[i] = best_cost;
chain.arrayZ[i] = j;
}
if (j > 0 && forced_set.has (j))
break;
}
}
return true;
}
static bool _iup_contour_optimize (const hb_array_t<const contour_point_t> contour_points,
const hb_array_t<const int> x_deltas,
const hb_array_t<const int> y_deltas,
hb_array_t<bool> opt_indices, /* OUT */
float tolerance = 0.f)
{
unsigned n = contour_points.length;
if (opt_indices.length != n ||
x_deltas.length != n ||
y_deltas.length != n)
return false;
bool all_within_tolerance = true;
for (unsigned i = 0; i < n; i++)
{
int dx = x_deltas.arrayZ[i];
int dy = y_deltas.arrayZ[i];
if (sqrtf ((float)dx * dx + (float)dy * dy) > tolerance)
{
all_within_tolerance = false;
break;
}
}
/* If all are within tolerance distance, do nothing, opt_indices is
* initilized to false */
if (all_within_tolerance)
return true;
/* If there's exactly one point, return it */
if (n == 1)
{
opt_indices.arrayZ[0] = true;
return true;
}
/* If all deltas are exactly the same, return just one (the first one) */
bool all_deltas_are_equal = true;
for (unsigned i = 1; i < n; i++)
if (x_deltas.arrayZ[i] != x_deltas.arrayZ[0] ||
y_deltas.arrayZ[i] != y_deltas.arrayZ[0])
{
all_deltas_are_equal = false;
break;
}
if (all_deltas_are_equal)
{
opt_indices.arrayZ[0] = true;
return true;
}
/* else, solve the general problem using Dynamic Programming */
hb_set_t forced_set;
_iup_contour_bound_forced_set (contour_points, x_deltas, y_deltas, forced_set, tolerance);
if (!forced_set.is_empty ())
{
int k = n - 1 - forced_set.get_max ();
if (k < 0)
return false;
hb_vector_t<int> rot_x_deltas, rot_y_deltas;
contour_point_vector_t rot_points;
hb_set_t rot_forced_set;
if (!rotate_array (contour_points, k, rot_points) ||
!rotate_array (x_deltas, k, rot_x_deltas) ||
!rotate_array (y_deltas, k, rot_y_deltas) ||
!rotate_set (forced_set, k, n, rot_forced_set))
return false;
hb_vector_t<unsigned> costs;
hb_vector_t<int> chain;
if (!_iup_contour_optimize_dp (rot_points, rot_x_deltas, rot_y_deltas,
rot_forced_set, tolerance, n,
costs, chain))
return false;
hb_set_t solution;
int index = n - 1;
while (index != -1)
{
solution.add (index);
index = chain.arrayZ[index];
}
if (solution.is_empty () ||
forced_set.get_population () > solution.get_population ())
return false;
for (unsigned i : solution)
opt_indices.arrayZ[i] = true;
hb_vector_t<bool> rot_indices;
const hb_array_t<const bool> opt_indices_array (opt_indices.arrayZ, opt_indices.length);
rotate_array (opt_indices_array, -k, rot_indices);
for (unsigned i = 0; i < n; i++)
opt_indices.arrayZ[i] = rot_indices.arrayZ[i];
}
else
{
hb_vector_t<int> repeat_x_deltas, repeat_y_deltas;
contour_point_vector_t repeat_points;
if (unlikely (!repeat_x_deltas.resize (n * 2, false) ||
!repeat_y_deltas.resize (n * 2, false) ||
!repeat_points.resize (n * 2, false)))
return false;
unsigned contour_point_size = hb_static_size (contour_point_t);
for (unsigned i = 0; i < n; i++)
{
hb_memcpy ((void *) repeat_x_deltas.arrayZ, (const void *) x_deltas.arrayZ, n * sizeof (float));
hb_memcpy ((void *) (repeat_x_deltas.arrayZ + n), (const void *) x_deltas.arrayZ, n * sizeof (float));
hb_memcpy ((void *) repeat_y_deltas.arrayZ, (const void *) y_deltas.arrayZ, n * sizeof (float));
hb_memcpy ((void *) (repeat_y_deltas.arrayZ + n), (const void *) y_deltas.arrayZ, n * sizeof (float));
hb_memcpy ((void *) repeat_points.arrayZ, (const void *) contour_points.arrayZ, n * contour_point_size);
hb_memcpy ((void *) (repeat_points.arrayZ + n), (const void *) contour_points.arrayZ, n * contour_point_size);
}
hb_vector_t<unsigned> costs;
hb_vector_t<int> chain;
if (!_iup_contour_optimize_dp (repeat_points, repeat_x_deltas, repeat_y_deltas,
forced_set, tolerance, n,
costs, chain))
return false;
unsigned best_cost = n + 1;
int len = costs.length;
hb_set_t best_sol;
for (int start = n - 1; start < len; start++)
{
hb_set_t solution;
int i = start;
int lookback = start - (int) n;
while (i > lookback)
{
solution.add (i % n);
i = chain.arrayZ[i];
}
if (i == lookback)
{
unsigned cost_i = i < 0 ? 0 : costs.arrayZ[i];
unsigned cost = costs.arrayZ[start] - cost_i;
if (cost <= best_cost)
{
best_sol.set (solution);
best_cost = cost;
}
}
}
for (unsigned i = 0; i < n; i++)
if (best_sol.has (i))
opt_indices.arrayZ[i] = true;
}
return true;
}
bool iup_delta_optimize (const contour_point_vector_t& contour_points,
const hb_vector_t<int>& x_deltas,
const hb_vector_t<int>& y_deltas,
hb_vector_t<bool>& opt_indices, /* OUT */
float tolerance)
{
if (!opt_indices.resize (contour_points.length))
return false;
hb_vector_t<unsigned> end_points;
unsigned count = contour_points.length;
if (unlikely (!end_points.alloc (count)))
return false;
for (unsigned i = 0; i < count - 4; i++)
if (contour_points.arrayZ[i].is_end_point)
end_points.push (i);
/* phantom points */
for (unsigned i = count - 4; i < count; i++)
end_points.push (i);
if (end_points.in_error ()) return false;
unsigned start = 0;
for (unsigned end : end_points)
{
unsigned len = end - start + 1;
if (!_iup_contour_optimize (contour_points.as_array ().sub_array (start, len),
x_deltas.as_array ().sub_array (start, len),
y_deltas.as_array ().sub_array (start, len),
opt_indices.as_array ().sub_array (start, len),
tolerance))
return false;
start = end + 1;
}
return true;
}