@ -171,7 +171,15 @@
if ( error )
goto Exit ;
/*
* We assume that the glyphs selected for the stem width
* computation are ` featureless ' enough so that the linking
* algorithm works fine without adjustments of its scoring
* function .
*/
af_latin_hints_link_segments ( hints ,
0 ,
NULL ,
( AF_Dimension ) dim ) ;
seg = axhints - > segments ;
@ -1338,19 +1346,28 @@
}
/* Link segments to form stems and serifs. */
/* Link segments to form stems and serifs. If `width_count' and */
/* `widths' are non-zero, use them to fine-tune the scoring function. */
FT_LOCAL_DEF ( void )
af_latin_hints_link_segments ( AF_GlyphHints hints ,
FT_UInt width_count ,
AF_WidthRec * widths ,
AF_Dimension dim )
{
AF_AxisHints axis = & hints - > axis [ dim ] ;
AF_Segment segments = axis - > segments ;
AF_Segment segment_limit = segments + axis - > num_segments ;
FT_Pos len_threshold , len_score ;
FT_Pos len_threshold , len_score , dist_score , max_width ;
AF_Segment seg1 , seg2 ;
if ( width_count )
max_width = widths [ width_count - 1 ] . org ;
else
max_width = 0 ;
/* a heuristic value to set up a minimum value for overlapping */
len_threshold = AF_LATIN_CONSTANT ( hints - > metrics , 8 ) ;
if ( len_threshold = = 0 )
len_threshold = 1 ;
@ -1358,6 +1375,11 @@
/* a heuristic value to weight lengths */
len_score = AF_LATIN_CONSTANT ( hints - > metrics , 6000 ) ;
/* a heuristic value to weight distances (no call to */
/* AF_LATIN_CONSTANT needed, since we work on multiples */
/* of the stem width) */
dist_score = 3000 ;
/* now compare each segment to the others */
for ( seg1 = segments ; seg1 < segment_limit ; seg1 + + )
{
@ -1377,10 +1399,9 @@
if ( seg1 - > dir + seg2 - > dir = = 0 & & pos2 > pos1 )
{
/* compute distance between the two segments */
FT_Pos dist = pos2 - pos1 ;
FT_Pos min = seg1 - > min_coord ;
FT_Pos max = seg1 - > max_coord ;
FT_Pos len , score ;
FT_Pos min = seg1 - > min_coord ;
FT_Pos max = seg1 - > max_coord ;
FT_Pos len ;
if ( min < seg2 - > min_coord )
@ -1394,12 +1415,43 @@
len = max - min ;
if ( len > = len_threshold )
{
/* the score is the sum of two values indicating the */
/* `quality' of a fit, measured along the segments' main */
/* axis (`len_score / len') and orthogonal to it (`dist'): */
/* smaller overlappings cause a higher score, and segments */
/* with a greater distance cause a higher score also */
score = dist + len_score / len ;
/*
* The score is the sum of two demerits indicating the
* ` badness ' of a fit , measured along the segments ' main axis
* and orthogonal to it , respectively .
*
* o The less overlapping along the main axis , the worse it
* is , causing a larger demerit .
*
* o The nearer the orthogonal distance to a stem width , the
* better it is , causing a smaller demerit . For simplicity ,
* however , we only increase the demerit for values that
* exceed the largest stem width .
*/
FT_Pos dist = pos2 - pos1 ;
FT_Pos dist_demerit , score ;
if ( max_width )
{
/* distance demerits are based on multiples of `max_width'; */
/* we scale by 1024 for getting more precision */
FT_Pos delta = ( dist < < 10 ) / max_width - ( 1 < < 10 ) ;
if ( delta > 10000 )
dist_demerit = 32000 ;
else if ( delta > 0 )
dist_demerit = delta * delta / dist_score ;
else
dist_demerit = 0 ;
}
else
dist_demerit = dist ; /* default if no widths available */
score = dist_demerit + len_score / len ;
/* and we search for the smallest score */
if ( score < seg1 - > score )
@ -1733,6 +1785,8 @@
FT_LOCAL_DEF ( FT_Error )
af_latin_hints_detect_features ( AF_GlyphHints hints ,
FT_UInt width_count ,
AF_WidthRec * widths ,
AF_Dimension dim )
{
FT_Error error ;
@ -1741,7 +1795,7 @@
error = af_latin_hints_compute_segments ( hints , dim ) ;
if ( ! error )
{
af_latin_hints_link_segments ( hints , dim ) ;
af_latin_hints_link_segments ( hints , width_count , widths , dim ) ;
error = af_latin_hints_compute_edges ( hints , dim ) ;
}
@ -2694,6 +2748,8 @@
FT_Error error ;
int dim ;
AF_LatinAxis axis ;
error = af_glyph_hints_reload ( hints , outline ) ;
if ( error )
@ -2707,14 +2763,22 @@
if ( AF_HINTS_DO_HORIZONTAL ( hints ) )
# endif
{
error = af_latin_hints_detect_features ( hints , AF_DIMENSION_HORZ ) ;
axis = & metrics - > axis [ AF_DIMENSION_HORZ ] ;
error = af_latin_hints_detect_features ( hints ,
axis - > width_count ,
axis - > widths ,
AF_DIMENSION_HORZ ) ;
if ( error )
goto Exit ;
}
if ( AF_HINTS_DO_VERTICAL ( hints ) )
{
error = af_latin_hints_detect_features ( hints , AF_DIMENSION_VERT ) ;
axis = & metrics - > axis [ AF_DIMENSION_VERT ] ;
error = af_latin_hints_detect_features ( hints ,
axis - > width_count ,
axis - > widths ,
AF_DIMENSION_VERT ) ;
if ( error )
goto Exit ;
Werner Lemberg
11 years ago