375 lines
11 KiB
C
375 lines
11 KiB
C
/***************************************************************************/
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/* */
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/* afwarp.c */
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/* */
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/* Auto-fitter warping algorithm (body). */
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/* */
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/* Copyright 2006, 2007, 2011 by */
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/* David Turner, Robert Wilhelm, and Werner Lemberg. */
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/* */
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/* This file is part of the FreeType project, and may only be used, */
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/* modified, and distributed under the terms of the FreeType project */
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/* license, LICENSE.TXT. By continuing to use, modify, or distribute */
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/* this file you indicate that you have read the license and */
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/* understand and accept it fully. */
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/* */
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/***************************************************************************/
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/*
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* The idea of the warping code is to slightly scale and shift a glyph
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* within a single dimension so that as much of its segments are aligned
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* (more or less) on the grid. To find out the optimal scaling and
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* shifting value, various parameter combinations are tried and scored.
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*/
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#include "afwarp.h"
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#ifdef AF_CONFIG_OPTION_USE_WARPER
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/*************************************************************************/
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/* */
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/* The macro FT_COMPONENT is used in trace mode. It is an implicit */
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/* parameter of the FT_TRACE() and FT_ERROR() macros, used to print/log */
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/* messages during execution. */
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/* */
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#undef FT_COMPONENT
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#define FT_COMPONENT trace_afwarp
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/* The weights cover the range 0/64 - 63/64 of a pixel. Obviously, */
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/* values around a half pixel (which means exactly between two grid */
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/* lines) gets the worst weight. */
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#if 1
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static const AF_WarpScore
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af_warper_weights[64] =
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{
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35, 32, 30, 25, 20, 15, 12, 10, 5, 1, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, -1, -2, -5, -8,-10,-10,-20,-20,-30,-30,
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-30,-30,-20,-20,-10,-10, -8, -5, -2, -1, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 1, 5, 10, 12, 15, 20, 25, 30, 32,
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};
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#else
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static const AF_WarpScore
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af_warper_weights[64] =
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{
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30, 20, 10, 5, 4, 4, 3, 2, 1, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, -1, -2, -2, -5, -5,-10,-10,-15,-20,
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-20,-15,-15,-10,-10, -5, -5, -2, -2, -1, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 4, 5, 10, 20,
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};
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#endif
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/* Score segments for a given `scale' and `delta' in the range */
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/* `xx1' to `xx2', and store the best result in `warper'. If */
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/* the new best score is equal to the old one, prefer the */
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/* value with a smaller distortion (around `base_distort'). */
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static void
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af_warper_compute_line_best( AF_Warper warper,
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FT_Fixed scale,
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FT_Pos delta,
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FT_Pos xx1,
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FT_Pos xx2,
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AF_WarpScore base_distort,
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AF_Segment segments,
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FT_UInt num_segments )
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{
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FT_Int idx_min, idx_max, idx0;
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FT_UInt nn;
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AF_WarpScore scores[65];
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for ( nn = 0; nn < 65; nn++ )
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scores[nn] = 0;
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idx0 = xx1 - warper->t1;
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/* compute minimum and maximum indices */
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{
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FT_Pos xx1min = warper->x1min;
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FT_Pos xx1max = warper->x1max;
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FT_Pos w = xx2 - xx1;
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if ( xx1min + w < warper->x2min )
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xx1min = warper->x2min - w;
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xx1max = warper->x1max;
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if ( xx1max + w > warper->x2max )
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xx1max = warper->x2max - w;
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idx_min = xx1min - warper->t1;
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idx_max = xx1max - warper->t1;
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if ( idx_min < 0 || idx_min > idx_max || idx_max > 64 )
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{
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FT_TRACE5(( "invalid indices:\n"
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" min=%d max=%d, xx1=%ld xx2=%ld,\n"
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" x1min=%ld x1max=%ld, x2min=%ld x2max=%ld\n",
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idx_min, idx_max, xx1, xx2,
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warper->x1min, warper->x1max,
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warper->x2min, warper->x2max ));
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return;
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}
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}
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for ( nn = 0; nn < num_segments; nn++ )
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{
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FT_Pos len = segments[nn].max_coord - segments[nn].min_coord;
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FT_Pos y0 = FT_MulFix( segments[nn].pos, scale ) + delta;
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FT_Pos y = y0 + ( idx_min - idx0 );
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FT_Int idx;
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/* score the length of the segments for the given range */
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for ( idx = idx_min; idx <= idx_max; idx++, y++ )
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scores[idx] += af_warper_weights[y & 63] * len;
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}
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/* find best score */
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{
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FT_Int idx;
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for ( idx = idx_min; idx <= idx_max; idx++ )
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{
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AF_WarpScore score = scores[idx];
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AF_WarpScore distort = base_distort + ( idx - idx0 );
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if ( score > warper->best_score ||
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( score == warper->best_score &&
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distort < warper->best_distort ) )
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{
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warper->best_score = score;
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warper->best_distort = distort;
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warper->best_scale = scale;
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warper->best_delta = delta + ( idx - idx0 );
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}
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}
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}
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}
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/* Compute optimal scaling and delta values for a given glyph and */
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/* dimension. */
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FT_LOCAL_DEF( void )
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af_warper_compute( AF_Warper warper,
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AF_GlyphHints hints,
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AF_Dimension dim,
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FT_Fixed *a_scale,
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FT_Pos *a_delta )
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{
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AF_AxisHints axis;
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AF_Point points;
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FT_Fixed org_scale;
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FT_Pos org_delta;
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FT_UInt nn, num_points, num_segments;
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FT_Int X1, X2;
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FT_Int w;
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AF_WarpScore base_distort;
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AF_Segment segments;
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/* get original scaling transformation */
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if ( dim == AF_DIMENSION_VERT )
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{
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org_scale = hints->y_scale;
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org_delta = hints->y_delta;
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}
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else
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{
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org_scale = hints->x_scale;
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org_delta = hints->x_delta;
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}
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warper->best_scale = org_scale;
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warper->best_delta = org_delta;
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warper->best_score = INT_MIN;
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warper->best_distort = 0;
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axis = &hints->axis[dim];
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segments = axis->segments;
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num_segments = axis->num_segments;
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points = hints->points;
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num_points = hints->num_points;
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*a_scale = org_scale;
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*a_delta = org_delta;
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/* get X1 and X2, minimum and maximum in original coordinates */
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if ( num_segments < 1 )
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return;
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#if 1
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X1 = X2 = points[0].fx;
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for ( nn = 1; nn < num_points; nn++ )
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{
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FT_Int X = points[nn].fx;
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if ( X < X1 )
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X1 = X;
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if ( X > X2 )
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X2 = X;
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}
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#else
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X1 = X2 = segments[0].pos;
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for ( nn = 1; nn < num_segments; nn++ )
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{
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FT_Int X = segments[nn].pos;
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if ( X < X1 )
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X1 = X;
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if ( X > X2 )
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X2 = X;
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}
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#endif
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if ( X1 >= X2 )
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return;
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warper->x1 = FT_MulFix( X1, org_scale ) + org_delta;
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warper->x2 = FT_MulFix( X2, org_scale ) + org_delta;
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warper->t1 = AF_WARPER_FLOOR( warper->x1 );
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warper->t2 = AF_WARPER_CEIL( warper->x2 );
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/* examine a half pixel wide range around the maximum coordinates */
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warper->x1min = warper->x1 & ~31;
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warper->x1max = warper->x1min + 32;
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warper->x2min = warper->x2 & ~31;
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warper->x2max = warper->x2min + 32;
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if ( warper->x1max > warper->x2 )
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warper->x1max = warper->x2;
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if ( warper->x2min < warper->x1 )
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warper->x2min = warper->x1;
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warper->w0 = warper->x2 - warper->x1;
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if ( warper->w0 <= 64 )
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{
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warper->x1max = warper->x1;
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warper->x2min = warper->x2;
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}
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/* examine (at most) a pixel wide range around the natural width */
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warper->wmin = warper->x2min - warper->x1max;
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warper->wmax = warper->x2max - warper->x1min;
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#if 1
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/* some heuristics to reduce the number of widths to be examined */
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{
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int margin = 16;
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if ( warper->w0 <= 128 )
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{
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margin = 8;
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if ( warper->w0 <= 96 )
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margin = 4;
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}
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if ( warper->wmin < warper->w0 - margin )
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warper->wmin = warper->w0 - margin;
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if ( warper->wmax > warper->w0 + margin )
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warper->wmax = warper->w0 + margin;
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}
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if ( warper->wmin < warper->w0 * 3 / 4 )
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warper->wmin = warper->w0 * 3 / 4;
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if ( warper->wmax > warper->w0 * 5 / 4 )
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warper->wmax = warper->w0 * 5 / 4;
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#else
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/* no scaling, just translation */
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warper->wmin = warper->wmax = warper->w0;
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#endif
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for ( w = warper->wmin; w <= warper->wmax; w++ )
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{
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FT_Fixed new_scale;
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FT_Pos new_delta;
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FT_Pos xx1, xx2;
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/* compute min and max positions for given width, */
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/* assuring that they stay within the coordinate ranges */
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xx1 = warper->x1;
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xx2 = warper->x2;
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if ( w >= warper->w0 )
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{
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xx1 -= w - warper->w0;
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if ( xx1 < warper->x1min )
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{
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xx2 += warper->x1min - xx1;
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xx1 = warper->x1min;
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}
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}
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else
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{
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xx1 -= w - warper->w0;
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if ( xx1 > warper->x1max )
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{
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xx2 -= xx1 - warper->x1max;
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xx1 = warper->x1max;
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}
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}
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if ( xx1 < warper->x1 )
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base_distort = warper->x1 - xx1;
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else
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base_distort = xx1 - warper->x1;
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if ( xx2 < warper->x2 )
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base_distort += warper->x2 - xx2;
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else
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base_distort += xx2 - warper->x2;
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/* give base distortion a greater weight while scoring */
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base_distort *= 10;
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new_scale = org_scale + FT_DivFix( w - warper->w0, X2 - X1 );
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new_delta = xx1 - FT_MulFix( X1, new_scale );
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af_warper_compute_line_best( warper, new_scale, new_delta, xx1, xx2,
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base_distort,
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segments, num_segments );
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}
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{
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FT_Fixed best_scale = warper->best_scale;
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FT_Pos best_delta = warper->best_delta;
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hints->xmin_delta = FT_MulFix( X1, best_scale - org_scale )
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+ best_delta;
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hints->xmax_delta = FT_MulFix( X2, best_scale - org_scale )
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+ best_delta;
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*a_scale = best_scale;
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*a_delta = best_delta;
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}
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}
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#else /* !AF_CONFIG_OPTION_USE_WARPER */
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/* ANSI C doesn't like empty source files */
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typedef int _af_warp_dummy;
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#endif /* !AF_CONFIG_OPTION_USE_WARPER */
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/* END */
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