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kc3-lang/freetype/src/autofit/afwarp.c
Werner Lemberg
- src/autofit/afwarp.c
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/**************************************************************************** * * afwarp.c * * Auto-fitter warping algorithm (body). * * Copyright (C) 2006-2020 by * David Turner, Robert Wilhelm, and Werner Lemberg. * * This file is part of the FreeType project, and may only be used, * modified, and distributed under the terms of the FreeType project * license, LICENSE.TXT. By continuing to use, modify, or distribute * this file you indicate that you have read the license and * understand and accept it fully. * */ /* * The idea of the warping code is to slightly scale and shift a glyph * within a single dimension so that as much of its segments are aligned * (more or less) on the grid. To find out the optimal scaling and * shifting value, various parameter combinations are tried and scored. */ #include "afwarp.h" #ifdef AF_CONFIG_OPTION_USE_WARPER /************************************************************************** * * The macro FT_COMPONENT is used in trace mode. It is an implicit * parameter of the FT_TRACE() and FT_ERROR() macros, used to print/log * messages during execution. */ #undef FT_COMPONENT #define FT_COMPONENT afwarp /* The weights cover the range 0/64 - 63/64 of a pixel. Obviously, */ /* values around a half pixel (which means exactly between two grid */ /* lines) gets the worst weight. */ #if 1 static const AF_WarpScore af_warper_weights[64] = { 35, 32, 30, 25, 20, 15, 12, 10, 5, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, -2, -5, -8,-10,-10,-20,-20,-30,-30, -30,-30,-20,-20,-10,-10, -8, -5, -2, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 5, 10, 12, 15, 20, 25, 30, 32, }; #else static const AF_WarpScore af_warper_weights[64] = { 30, 20, 10, 5, 4, 4, 3, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, -2, -2, -5, -5,-10,-10,-15,-20, -20,-15,-15,-10,-10, -5, -5, -2, -2, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 4, 5, 10, 20, }; #endif /* Score segments for a given `scale' and `delta' in the range */ /* `xx1' to `xx2', and store the best result in `warper'. If */ /* the new best score is equal to the old one, prefer the */ /* value with a smaller distortion (around `base_distort'). */ static void af_warper_compute_line_best( AF_Warper warper, FT_Fixed scale, FT_Pos delta, FT_Pos xx1, FT_Pos xx2, AF_WarpScore base_distort, AF_Segment segments, FT_Int num_segments ) { FT_Int idx_min, idx_max, idx0; FT_Int nn; AF_WarpScore scores[65]; for ( nn = 0; nn < 65; nn++ ) scores[nn] = 0; idx0 = xx1 - warper->t1; /* compute minimum and maximum indices */ { FT_Pos xx1min = warper->x1min; FT_Pos xx1max = warper->x1max; FT_Pos w = xx2 - xx1; if ( xx1min + w < warper->x2min ) xx1min = warper->x2min - w; if ( xx1max + w > warper->x2max ) xx1max = warper->x2max - w; idx_min = xx1min - warper->t1; idx_max = xx1max - warper->t1; if ( idx_min < 0 || idx_min > idx_max || idx_max > 64 ) { FT_TRACE5(( "invalid indices:\n" " min=%d max=%d, xx1=%ld xx2=%ld,\n" " x1min=%ld x1max=%ld, x2min=%ld x2max=%ld\n", idx_min, idx_max, xx1, xx2, warper->x1min, warper->x1max, warper->x2min, warper->x2max )); return; } } for ( nn = 0; nn < num_segments; nn++ ) { FT_Pos len = segments[nn].max_coord - segments[nn].min_coord; FT_Pos y0 = FT_MulFix( segments[nn].pos, scale ) + delta; FT_Pos y = y0 + ( idx_min - idx0 ); FT_Int idx; /* score the length of the segments for the given range */ for ( idx = idx_min; idx <= idx_max; idx++, y++ ) scores[idx] += af_warper_weights[y & 63] * len; } /* find best score */ { FT_Int idx; for ( idx = idx_min; idx <= idx_max; idx++ ) { AF_WarpScore score = scores[idx]; AF_WarpScore distort = base_distort + ( idx - idx0 ); if ( score > warper->best_score || ( score == warper->best_score && distort < warper->best_distort ) ) { warper->best_score = score; warper->best_distort = distort; warper->best_scale = scale; warper->best_delta = delta + ( idx - idx0 ); } } } } /* Compute optimal scaling and delta values for a given glyph and */ /* dimension. */ FT_LOCAL_DEF( void ) af_warper_compute( AF_Warper warper, AF_GlyphHints hints, AF_Dimension dim, FT_Fixed *a_scale, FT_Pos *a_delta ) { AF_AxisHints axis; AF_Point points; FT_Fixed org_scale; FT_Pos org_delta; FT_Int nn, num_points, num_segments; FT_Int X1, X2; FT_Int w; AF_WarpScore base_distort; AF_Segment segments; /* get original scaling transformation */ if ( dim == AF_DIMENSION_VERT ) { org_scale = hints->y_scale; org_delta = hints->y_delta; } else { org_scale = hints->x_scale; org_delta = hints->x_delta; } warper->best_scale = org_scale; warper->best_delta = org_delta; warper->best_score = FT_INT_MIN; warper->best_distort = 0; axis = &hints->axis[dim]; segments = axis->segments; num_segments = axis->num_segments; points = hints->points; num_points = hints->num_points; *a_scale = org_scale; *a_delta = org_delta; /* get X1 and X2, minimum and maximum in original coordinates */ if ( num_segments < 1 ) return; #if 1 X1 = X2 = points[0].fx; for ( nn = 1; nn < num_points; nn++ ) { FT_Int X = points[nn].fx; if ( X < X1 ) X1 = X; if ( X > X2 ) X2 = X; } #else X1 = X2 = segments[0].pos; for ( nn = 1; nn < num_segments; nn++ ) { FT_Int X = segments[nn].pos; if ( X < X1 ) X1 = X; if ( X > X2 ) X2 = X; } #endif if ( X1 >= X2 ) return; warper->x1 = FT_MulFix( X1, org_scale ) + org_delta; warper->x2 = FT_MulFix( X2, org_scale ) + org_delta; warper->t1 = AF_WARPER_FLOOR( warper->x1 ); warper->t2 = AF_WARPER_CEIL( warper->x2 ); /* examine a half pixel wide range around the maximum coordinates */ warper->x1min = warper->x1 & ~31; warper->x1max = warper->x1min + 32; warper->x2min = warper->x2 & ~31; warper->x2max = warper->x2min + 32; if ( warper->x1max > warper->x2 ) warper->x1max = warper->x2; if ( warper->x2min < warper->x1 ) warper->x2min = warper->x1; warper->w0 = warper->x2 - warper->x1; if ( warper->w0 <= 64 ) { warper->x1max = warper->x1; warper->x2min = warper->x2; } /* examine (at most) a pixel wide range around the natural width */ warper->wmin = warper->x2min - warper->x1max; warper->wmax = warper->x2max - warper->x1min; #if 1 /* some heuristics to reduce the number of widths to be examined */ { int margin = 16; if ( warper->w0 <= 128 ) { margin = 8; if ( warper->w0 <= 96 ) margin = 4; } if ( warper->wmin < warper->w0 - margin ) warper->wmin = warper->w0 - margin; if ( warper->wmax > warper->w0 + margin ) warper->wmax = warper->w0 + margin; } if ( warper->wmin < warper->w0 * 3 / 4 ) warper->wmin = warper->w0 * 3 / 4; if ( warper->wmax > warper->w0 * 5 / 4 ) warper->wmax = warper->w0 * 5 / 4; #else /* no scaling, just translation */ warper->wmin = warper->wmax = warper->w0; #endif for ( w = warper->wmin; w <= warper->wmax; w++ ) { FT_Fixed new_scale; FT_Pos new_delta; FT_Pos xx1, xx2; /* compute min and max positions for given width, */ /* assuring that they stay within the coordinate ranges */ xx1 = warper->x1; xx2 = warper->x2; if ( w >= warper->w0 ) { xx1 -= w - warper->w0; if ( xx1 < warper->x1min ) { xx2 += warper->x1min - xx1; xx1 = warper->x1min; } } else { xx1 -= w - warper->w0; if ( xx1 > warper->x1max ) { xx2 -= xx1 - warper->x1max; xx1 = warper->x1max; } } if ( xx1 < warper->x1 ) base_distort = warper->x1 - xx1; else base_distort = xx1 - warper->x1; if ( xx2 < warper->x2 ) base_distort += warper->x2 - xx2; else base_distort += xx2 - warper->x2; /* give base distortion a greater weight while scoring */ base_distort *= 10; new_scale = org_scale + FT_DivFix( w - warper->w0, X2 - X1 ); new_delta = xx1 - FT_MulFix( X1, new_scale ); af_warper_compute_line_best( warper, new_scale, new_delta, xx1, xx2, base_distort, segments, num_segments ); } { FT_Fixed best_scale = warper->best_scale; FT_Pos best_delta = warper->best_delta; hints->xmin_delta = FT_MulFix( X1, best_scale - org_scale ) + best_delta; hints->xmax_delta = FT_MulFix( X2, best_scale - org_scale ) + best_delta; *a_scale = best_scale; *a_delta = best_delta; } } #else /* !AF_CONFIG_OPTION_USE_WARPER */ /* ANSI C doesn't like empty source files */ typedef int _af_warp_dummy; #endif /* !AF_CONFIG_OPTION_USE_WARPER */ /* END */