| /**************************************************************************** |
| * |
| * afwarp.c |
| * |
| * Auto-fitter warping algorithm (body). |
| * |
| * Copyright (C) 2006-2021 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" )); |
| FT_TRACE5(( " min=%d max=%d, xx1=%ld xx2=%ld,\n", |
| idx_min, idx_max, xx1, xx2 )); |
| FT_TRACE5(( " x1min=%ld x1max=%ld, x2min=%ld x2max=%ld\n", |
| 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 */ |
