533 lines
16 KiB
C++
533 lines
16 KiB
C++
/*
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* Copyright © 2024 Google, Inc.
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*
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* This is part of HarfBuzz, a text shaping library.
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*
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* Permission is hereby granted, without written agreement and without
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* license or royalty fees, to use, copy, modify, and distribute this
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* software and its documentation for any purpose, provided that the
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* above copyright notice and the following two paragraphs appear in
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* all copies of this software.
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*
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* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
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* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
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* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
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* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
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* DAMAGE.
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*
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* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
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* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
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* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
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* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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*/
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#include "hb-subset-instancer-iup.hh"
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/* This file is a straight port of the following:
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*
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* https://github.com/fonttools/fonttools/blob/main/Lib/fontTools/varLib/iup.py
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*
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* Where that file returns optimzied deltas vector, we return optimized
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* referenced point indices.
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*/
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constexpr static unsigned MAX_LOOKBACK = 8;
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static void _iup_contour_bound_forced_set (const hb_array_t<const contour_point_t> contour_points,
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const hb_array_t<const int> x_deltas,
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const hb_array_t<const int> y_deltas,
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hb_set_t& forced_set, /* OUT */
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double tolerance = 0.0)
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{
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unsigned len = contour_points.length;
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unsigned next_i = 0;
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for (int i = len - 1; i >= 0; i--)
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{
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unsigned last_i = (len + i -1) % len;
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for (unsigned j = 0; j < 2; j++)
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{
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double cj, lcj, ncj;
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int dj, ldj, ndj;
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if (j == 0)
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{
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cj = static_cast<double> (contour_points.arrayZ[i].x);
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dj = x_deltas.arrayZ[i];
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lcj = static_cast<double> (contour_points.arrayZ[last_i].x);
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ldj = x_deltas.arrayZ[last_i];
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ncj = static_cast<double> (contour_points.arrayZ[next_i].x);
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ndj = x_deltas.arrayZ[next_i];
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}
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else
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{
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cj = static_cast<double> (contour_points.arrayZ[i].y);
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dj = y_deltas.arrayZ[i];
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lcj = static_cast<double> (contour_points.arrayZ[last_i].y);
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ldj = y_deltas.arrayZ[last_i];
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ncj = static_cast<double> (contour_points.arrayZ[next_i].y);
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ndj = y_deltas.arrayZ[next_i];
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}
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double c1, c2;
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int d1, d2;
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if (lcj <= ncj)
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{
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c1 = lcj;
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c2 = ncj;
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d1 = ldj;
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d2 = ndj;
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}
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else
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{
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c1 = ncj;
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c2 = lcj;
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d1 = ndj;
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d2 = ldj;
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}
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bool force = false;
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if (c1 == c2)
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{
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if (abs (d1 - d2) > tolerance && abs (dj) > tolerance)
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force = true;
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}
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else if (c1 <= cj && cj <= c2)
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{
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if (!(hb_min (d1, d2) - tolerance <= dj &&
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dj <= hb_max (d1, d2) + tolerance))
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force = true;
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}
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else
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{
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if (d1 != d2)
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{
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if (cj < c1)
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{
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if (abs (dj) > tolerance &&
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abs (dj - d1) > tolerance &&
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((dj - tolerance < d1) != (d1 < d2)))
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force = true;
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}
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else
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{
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if (abs (dj) > tolerance &&
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abs (dj - d2) > tolerance &&
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((d2 < dj + tolerance) != (d1 < d2)))
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force = true;
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}
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}
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}
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if (force)
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{
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forced_set.add (i);
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break;
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}
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}
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next_i = i;
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}
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}
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template <typename T,
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hb_enable_if (hb_is_trivially_copyable (T))>
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static bool rotate_array (const hb_array_t<const T>& org_array,
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int k,
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hb_vector_t<T>& out)
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{
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unsigned n = org_array.length;
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if (!n) return true;
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if (unlikely (!out.resize (n, false)))
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return false;
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unsigned item_size = hb_static_size (T);
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if (k < 0)
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k = n - (-k) % n;
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else
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k %= n;
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hb_memcpy ((void *) out.arrayZ, (const void *) (org_array.arrayZ + n - k), k * item_size);
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hb_memcpy ((void *) (out.arrayZ + k), (const void *) org_array.arrayZ, (n - k) * item_size);
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return true;
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}
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static bool rotate_set (const hb_set_t& org_set,
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int k,
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unsigned n,
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hb_set_t& out)
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{
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if (!n) return false;
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k %= n;
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if (k < 0)
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k = n + k;
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if (k == 0)
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{
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out.set (org_set);
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}
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else
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{
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for (auto v : org_set)
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out.add ((v + k) % n);
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}
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return !out.in_error ();
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}
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/* Given two reference coordinates (start and end of contour_points array),
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* output interpolated deltas for points in between */
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static bool _iup_segment (const hb_array_t<const contour_point_t> contour_points,
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const hb_array_t<const int> x_deltas,
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const hb_array_t<const int> y_deltas,
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const contour_point_t& p1, const contour_point_t& p2,
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int p1_dx, int p2_dx,
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int p1_dy, int p2_dy,
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hb_vector_t<double>& interp_x_deltas, /* OUT */
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hb_vector_t<double>& interp_y_deltas /* OUT */)
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{
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unsigned n = contour_points.length;
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if (unlikely (!interp_x_deltas.resize (n, false) ||
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!interp_y_deltas.resize (n, false)))
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return false;
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for (unsigned j = 0; j < 2; j++)
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{
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double x1, x2, d1, d2;
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double *out;
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if (j == 0)
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{
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x1 = static_cast<double> (p1.x);
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x2 = static_cast<double> (p2.x);
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d1 = p1_dx;
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d2 = p2_dx;
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out = interp_x_deltas.arrayZ;
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}
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else
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{
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x1 = static_cast<double> (p1.y);
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x2 = static_cast<double> (p2.y);
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d1 = p1_dy;
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d2 = p2_dy;
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out = interp_y_deltas.arrayZ;
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}
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if (x1 == x2)
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{
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if (d1 == d2)
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{
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for (unsigned i = 0; i < n; i++)
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out[i] = d1;
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}
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else
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{
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for (unsigned i = 0; i < n; i++)
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out[i] = 0.0;
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}
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continue;
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}
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if (x1 > x2)
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{
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hb_swap (x1, x2);
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hb_swap (d1, d2);
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}
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double scale = (d2 - d1) / (x2 - x1);
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for (unsigned i = 0; i < n; i++)
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{
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double x = (j == 0 ? static_cast<double> (contour_points.arrayZ[i].x) : static_cast<double> (contour_points.arrayZ[i].y));
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double d;
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if (x <= x1)
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d = d1;
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else if (x >= x2)
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d = d2;
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else
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d = d1 + (x - x1) * scale;
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out[i] = d;
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}
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}
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return true;
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}
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static bool _can_iup_in_between (const hb_array_t<const contour_point_t> contour_points,
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const hb_array_t<const int> x_deltas,
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const hb_array_t<const int> y_deltas,
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const contour_point_t& p1, const contour_point_t& p2,
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int p1_dx, int p2_dx,
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int p1_dy, int p2_dy,
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double tolerance)
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{
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hb_vector_t<double> interp_x_deltas, interp_y_deltas;
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if (!_iup_segment (contour_points, x_deltas, y_deltas,
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p1, p2, p1_dx, p2_dx, p1_dy, p2_dy,
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interp_x_deltas, interp_y_deltas))
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return false;
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unsigned num = contour_points.length;
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for (unsigned i = 0; i < num; i++)
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{
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double dx = static_cast<double> (x_deltas.arrayZ[i]) - interp_x_deltas.arrayZ[i];
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double dy = static_cast<double> (y_deltas.arrayZ[i]) - interp_y_deltas.arrayZ[i];
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if (sqrt (dx * dx + dy * dy) > tolerance)
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return false;
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}
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return true;
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}
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static bool _iup_contour_optimize_dp (const contour_point_vector_t& contour_points,
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const hb_vector_t<int>& x_deltas,
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const hb_vector_t<int>& y_deltas,
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const hb_set_t& forced_set,
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double tolerance,
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unsigned lookback,
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hb_vector_t<unsigned>& costs, /* OUT */
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hb_vector_t<int>& chain /* OUT */)
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{
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unsigned n = contour_points.length;
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if (unlikely (!costs.resize (n, false) ||
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!chain.resize (n, false)))
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return false;
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lookback = hb_min (lookback, MAX_LOOKBACK);
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for (unsigned i = 0; i < n; i++)
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{
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unsigned best_cost = (i == 0 ? 1 : costs.arrayZ[i-1] + 1);
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costs.arrayZ[i] = best_cost;
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chain.arrayZ[i] = (i == 0 ? -1 : i - 1);
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if (i > 0 && forced_set.has (i - 1))
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continue;
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int lookback_index = hb_max ((int) i - (int) lookback + 1, -1);
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for (int j = i - 2; j >= lookback_index; j--)
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{
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unsigned cost = j == -1 ? 1 : costs.arrayZ[j] + 1;
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/* num points between i and j */
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unsigned num_points = i - j - 1;
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unsigned p1 = (j == -1 ? n - 1 : j);
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if (cost < best_cost &&
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_can_iup_in_between (contour_points.as_array ().sub_array (j + 1, num_points),
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x_deltas.as_array ().sub_array (j + 1, num_points),
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y_deltas.as_array ().sub_array (j + 1, num_points),
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contour_points.arrayZ[p1], contour_points.arrayZ[i],
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x_deltas.arrayZ[p1], x_deltas.arrayZ[i],
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y_deltas.arrayZ[p1], y_deltas.arrayZ[i],
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tolerance))
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{
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best_cost = cost;
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costs.arrayZ[i] = best_cost;
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chain.arrayZ[i] = j;
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}
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if (j > 0 && forced_set.has (j))
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break;
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}
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}
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return true;
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}
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static bool _iup_contour_optimize (const hb_array_t<const contour_point_t> contour_points,
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const hb_array_t<const int> x_deltas,
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const hb_array_t<const int> y_deltas,
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hb_array_t<bool> opt_indices, /* OUT */
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double tolerance = 0.0)
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{
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unsigned n = contour_points.length;
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if (opt_indices.length != n ||
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x_deltas.length != n ||
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y_deltas.length != n)
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return false;
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bool all_within_tolerance = true;
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for (unsigned i = 0; i < n; i++)
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{
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int dx = x_deltas.arrayZ[i];
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int dy = y_deltas.arrayZ[i];
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if (sqrt ((double) dx * dx + (double) dy * dy) > tolerance)
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{
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all_within_tolerance = false;
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break;
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}
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}
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/* If all are within tolerance distance, do nothing, opt_indices is
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* initilized to false */
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if (all_within_tolerance)
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return true;
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/* If there's exactly one point, return it */
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if (n == 1)
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{
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opt_indices.arrayZ[0] = true;
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return true;
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}
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/* If all deltas are exactly the same, return just one (the first one) */
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bool all_deltas_are_equal = true;
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for (unsigned i = 1; i < n; i++)
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if (x_deltas.arrayZ[i] != x_deltas.arrayZ[0] ||
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y_deltas.arrayZ[i] != y_deltas.arrayZ[0])
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{
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all_deltas_are_equal = false;
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break;
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}
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if (all_deltas_are_equal)
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{
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opt_indices.arrayZ[0] = true;
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return true;
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}
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/* else, solve the general problem using Dynamic Programming */
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hb_set_t forced_set;
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_iup_contour_bound_forced_set (contour_points, x_deltas, y_deltas, forced_set, tolerance);
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if (!forced_set.is_empty ())
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{
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int k = n - 1 - forced_set.get_max ();
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if (k < 0)
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return false;
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hb_vector_t<int> rot_x_deltas, rot_y_deltas;
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contour_point_vector_t rot_points;
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hb_set_t rot_forced_set;
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if (!rotate_array (contour_points, k, rot_points) ||
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!rotate_array (x_deltas, k, rot_x_deltas) ||
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!rotate_array (y_deltas, k, rot_y_deltas) ||
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!rotate_set (forced_set, k, n, rot_forced_set))
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return false;
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hb_vector_t<unsigned> costs;
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hb_vector_t<int> chain;
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if (!_iup_contour_optimize_dp (rot_points, rot_x_deltas, rot_y_deltas,
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rot_forced_set, tolerance, n,
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costs, chain))
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return false;
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hb_set_t solution;
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int index = n - 1;
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while (index != -1)
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{
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solution.add (index);
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index = chain.arrayZ[index];
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}
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if (solution.is_empty () ||
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forced_set.get_population () > solution.get_population ())
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return false;
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for (unsigned i : solution)
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opt_indices.arrayZ[i] = true;
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hb_vector_t<bool> rot_indices;
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const hb_array_t<const bool> opt_indices_array (opt_indices.arrayZ, opt_indices.length);
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rotate_array (opt_indices_array, -k, rot_indices);
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for (unsigned i = 0; i < n; i++)
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opt_indices.arrayZ[i] = rot_indices.arrayZ[i];
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}
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else
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{
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hb_vector_t<int> repeat_x_deltas, repeat_y_deltas;
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contour_point_vector_t repeat_points;
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if (unlikely (!repeat_x_deltas.resize (n * 2, false) ||
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!repeat_y_deltas.resize (n * 2, false) ||
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!repeat_points.resize (n * 2, false)))
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return false;
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unsigned contour_point_size = hb_static_size (contour_point_t);
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for (unsigned i = 0; i < n; i++)
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{
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hb_memcpy ((void *) repeat_x_deltas.arrayZ, (const void *) x_deltas.arrayZ, n * sizeof (repeat_x_deltas[0]));
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hb_memcpy ((void *) (repeat_x_deltas.arrayZ + n), (const void *) x_deltas.arrayZ, n * sizeof (repeat_x_deltas[0]));
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hb_memcpy ((void *) repeat_y_deltas.arrayZ, (const void *) y_deltas.arrayZ, n * sizeof (repeat_x_deltas[0]));
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hb_memcpy ((void *) (repeat_y_deltas.arrayZ + n), (const void *) y_deltas.arrayZ, n * sizeof (repeat_x_deltas[0]));
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hb_memcpy ((void *) repeat_points.arrayZ, (const void *) contour_points.arrayZ, n * contour_point_size);
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hb_memcpy ((void *) (repeat_points.arrayZ + n), (const void *) contour_points.arrayZ, n * contour_point_size);
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}
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hb_vector_t<unsigned> costs;
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hb_vector_t<int> chain;
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if (!_iup_contour_optimize_dp (repeat_points, repeat_x_deltas, repeat_y_deltas,
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forced_set, tolerance, n,
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costs, chain))
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return false;
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unsigned best_cost = n + 1;
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int len = costs.length;
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hb_set_t best_sol;
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for (int start = n - 1; start < len; start++)
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{
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hb_set_t solution;
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int i = start;
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int lookback = start - (int) n;
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while (i > lookback)
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{
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solution.add (i % n);
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i = chain.arrayZ[i];
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}
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if (i == lookback)
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{
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unsigned cost_i = i < 0 ? 0 : costs.arrayZ[i];
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unsigned cost = costs.arrayZ[start] - cost_i;
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if (cost <= best_cost)
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{
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best_sol.set (solution);
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best_cost = cost;
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}
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}
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}
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for (unsigned i = 0; i < n; i++)
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|
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 */
|
|
double 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;
|
|
}
|