chromium/third_party/harfbuzz-ng/src/src/hb-subset-instancer-iup.cc

/*
 * 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:
 *
 * https://github.com/fonttools/fonttools/blob/main/Lib/fontTools/varLib/iup.py
 *
 * Where that file returns optimzied deltas vector, we return optimized
 * referenced point indices.
 */

constexpr static unsigned MAX_LOOKBACK = …;

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 */
                                           double tolerance = 0.0)
{ … }

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)
{ … }

static bool rotate_set (const hb_set_t& org_set,
                        int k,
                        unsigned n,
                        hb_set_t& out)
{ … }

/* 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<double>& interp_x_deltas, /* OUT */
                          hb_vector_t<double>& interp_y_deltas /* OUT */)
{ … }

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,
                                 double tolerance)
{ … }

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,
                                      double tolerance,
                                      unsigned lookback,
                                      hb_vector_t<unsigned>& costs, /* OUT */
                                      hb_vector_t<int>& chain /* OUT */)
{ … }

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 */
                                   double tolerance = 0.0)
{ … }

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 */
                         double tolerance)
{ … }