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/***************************************************************************/ |
/* */ |
/* afwarp.c */ |
/* */ |
/* Auto-fitter warping algorithm (body). */ |
/* */ |
/* Copyright 2006, 2007, 2011 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. */ |
/* */ |
/***************************************************************************/ |
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/* |
* 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. |
*/ |
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#include "afwarp.h" |
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#ifdef AF_CONFIG_OPTION_USE_WARPER |
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/*************************************************************************/ |
/* */ |
/* 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 trace_afwarp |
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/* 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, |
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-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, |
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-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 |
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/* 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'). */ |
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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_UInt num_segments ) |
{ |
FT_Int idx_min, idx_max, idx0; |
FT_UInt nn; |
AF_WarpScore scores[65]; |
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for ( nn = 0; nn < 65; nn++ ) |
scores[nn] = 0; |
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idx0 = xx1 - warper->t1; |
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/* compute minimum and maximum indices */ |
{ |
FT_Pos xx1min = warper->x1min; |
FT_Pos xx1max = warper->x1max; |
FT_Pos w = xx2 - xx1; |
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if ( xx1min + w < warper->x2min ) |
xx1min = warper->x2min - w; |
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xx1max = warper->x1max; |
if ( xx1max + w > warper->x2max ) |
xx1max = warper->x2max - w; |
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idx_min = xx1min - warper->t1; |
idx_max = xx1max - warper->t1; |
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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; |
} |
} |
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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; |
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/* 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; |
} |
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/* find best score */ |
{ |
FT_Int idx; |
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for ( idx = idx_min; idx <= idx_max; idx++ ) |
{ |
AF_WarpScore score = scores[idx]; |
AF_WarpScore distort = base_distort + ( idx - idx0 ); |
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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 ); |
} |
} |
} |
} |
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/* Compute optimal scaling and delta values for a given glyph and */ |
/* dimension. */ |
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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; |
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FT_Fixed org_scale; |
FT_Pos org_delta; |
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FT_UInt nn, num_points, num_segments; |
FT_Int X1, X2; |
FT_Int w; |
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AF_WarpScore base_distort; |
AF_Segment segments; |
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/* 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; |
} |
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warper->best_scale = org_scale; |
warper->best_delta = org_delta; |
warper->best_score = INT_MIN; |
warper->best_distort = 0; |
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axis = &hints->axis[dim]; |
segments = axis->segments; |
num_segments = axis->num_segments; |
points = hints->points; |
num_points = hints->num_points; |
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*a_scale = org_scale; |
*a_delta = org_delta; |
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/* get X1 and X2, minimum and maximum in original coordinates */ |
if ( num_segments < 1 ) |
return; |
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#if 1 |
X1 = X2 = points[0].fx; |
for ( nn = 1; nn < num_points; nn++ ) |
{ |
FT_Int X = points[nn].fx; |
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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; |
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if ( X < X1 ) |
X1 = X; |
if ( X > X2 ) |
X2 = X; |
} |
#endif |
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if ( X1 >= X2 ) |
return; |
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warper->x1 = FT_MulFix( X1, org_scale ) + org_delta; |
warper->x2 = FT_MulFix( X2, org_scale ) + org_delta; |
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warper->t1 = AF_WARPER_FLOOR( warper->x1 ); |
warper->t2 = AF_WARPER_CEIL( warper->x2 ); |
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/* 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; |
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if ( warper->x1max > warper->x2 ) |
warper->x1max = warper->x2; |
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if ( warper->x2min < warper->x1 ) |
warper->x2min = warper->x1; |
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warper->w0 = warper->x2 - warper->x1; |
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if ( warper->w0 <= 64 ) |
{ |
warper->x1max = warper->x1; |
warper->x2min = warper->x2; |
} |
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/* examine (at most) a pixel wide range around the natural width */ |
warper->wmin = warper->x2min - warper->x1max; |
warper->wmax = warper->x2max - warper->x1min; |
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#if 1 |
/* some heuristics to reduce the number of widths to be examined */ |
{ |
int margin = 16; |
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if ( warper->w0 <= 128 ) |
{ |
margin = 8; |
if ( warper->w0 <= 96 ) |
margin = 4; |
} |
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if ( warper->wmin < warper->w0 - margin ) |
warper->wmin = warper->w0 - margin; |
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if ( warper->wmax > warper->w0 + margin ) |
warper->wmax = warper->w0 + margin; |
} |
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if ( warper->wmin < warper->w0 * 3 / 4 ) |
warper->wmin = warper->w0 * 3 / 4; |
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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 |
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for ( w = warper->wmin; w <= warper->wmax; w++ ) |
{ |
FT_Fixed new_scale; |
FT_Pos new_delta; |
FT_Pos xx1, xx2; |
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/* 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; |
} |
} |
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if ( xx1 < warper->x1 ) |
base_distort = warper->x1 - xx1; |
else |
base_distort = xx1 - warper->x1; |
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if ( xx2 < warper->x2 ) |
base_distort += warper->x2 - xx2; |
else |
base_distort += xx2 - warper->x2; |
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/* give base distortion a greater weight while scoring */ |
base_distort *= 10; |
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new_scale = org_scale + FT_DivFix( w - warper->w0, X2 - X1 ); |
new_delta = xx1 - FT_MulFix( X1, new_scale ); |
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af_warper_compute_line_best( warper, new_scale, new_delta, xx1, xx2, |
base_distort, |
segments, num_segments ); |
} |
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{ |
FT_Fixed best_scale = warper->best_scale; |
FT_Pos best_delta = warper->best_delta; |
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hints->xmin_delta = FT_MulFix( X1, best_scale - org_scale ) |
+ best_delta; |
hints->xmax_delta = FT_MulFix( X2, best_scale - org_scale ) |
+ best_delta; |
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*a_scale = best_scale; |
*a_delta = best_delta; |
} |
} |
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#else /* !AF_CONFIG_OPTION_USE_WARPER */ |
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/* ANSI C doesn't like empty source files */ |
typedef int _af_warp_dummy; |
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#endif /* !AF_CONFIG_OPTION_USE_WARPER */ |
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/* END */ |