diff options
Diffstat (limited to 'src/autofit/afwarp.c')
| -rw-r--r-- | src/autofit/afwarp.c | 62 |
1 files changed, 49 insertions, 13 deletions
diff --git a/src/autofit/afwarp.c b/src/autofit/afwarp.c index f5bb9b1..d0d4850 100644 --- a/src/autofit/afwarp.c +++ b/src/autofit/afwarp.c @@ -4,7 +4,7 @@ /* */ /* Auto-fitter warping algorithm (body). */ /* */ -/* Copyright 2006, 2007 by */ +/* 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, */ @@ -16,10 +16,30 @@ /***************************************************************************/ + /* + * 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_USE_WARPER +#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 trace_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] = @@ -43,6 +63,11 @@ #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, @@ -82,12 +107,12 @@ if ( idx_min < 0 || idx_min > idx_max || idx_max > 64 ) { - AF_LOG(( "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 )); + 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; } } @@ -100,6 +125,7 @@ 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; } @@ -115,9 +141,9 @@ AF_WarpScore distort = base_distort + ( idx - idx0 ); - if ( score > warper->best_score || + if ( score > warper->best_score || ( score == warper->best_score && - distort < warper->best_distort ) ) + distort < warper->best_distort ) ) { warper->best_score = score; warper->best_distort = distort; @@ -129,6 +155,9 @@ } + /* 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, @@ -215,6 +244,7 @@ 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; @@ -234,10 +264,12 @@ 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; @@ -273,6 +305,8 @@ 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 ) @@ -304,6 +338,7 @@ 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 ); @@ -329,10 +364,11 @@ } } -#else /* !AF_USE_WARPER */ +#else /* !AF_CONFIG_OPTION_USE_WARPER */ -char af_warper_dummy = 0; /* make compiler happy */ + /* ANSI C doesn't like empty source files */ + typedef int _af_warp_dummy; -#endif /* !AF_USE_WARPER */ +#endif /* !AF_CONFIG_OPTION_USE_WARPER */ /* END */ |