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fix postscript hinter's handling of small and ghost stems

This commit is contained in:
David Turner 2007-02-21 16:47:49 +00:00
parent b68e025c1b
commit 601aefe4ec
2 changed files with 53 additions and 7 deletions
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5
ChangeLog
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@ -1,3 +1,8 @@
2007-02-21 David Turner <david@freetype.org>
* src/pshinter/pshalgo.c: fixed a bug in the hinting of small
and ghost stems in the Postscript interpreter
2007-02-20 suzuki toshiya <mpsuzuki@hiroshima-u.ac.jp>
* src/base/ftmac.c (FT_GetFileRef_From_Mac_ATS_Name): Fix memory

55
src/pshinter/pshalgo.c
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@ -543,13 +543,54 @@
/* the stem is less than one pixel; we will center it
* around the nearest pixel center
*/
#if 1
pos = FT_PIX_FLOOR( pos + ( len >> 1 ) );
#else
/* this seems to be a bug! */
pos = pos + FT_PIX_FLOOR( len >> 1 );
#endif
len = 64;
if (len >= 32)
{
/* this is a special case where we also widen the stem
* and align it to the pixel grid.
*
* stem_center = pos + (len/2)
* nearest_pixel_center = FT_ROUND(stem_center-32)+32
* new_pos = nearest_pixel_center-32
* = FT_ROUND(stem_center-32)
* = FT_FLOOR(stem_center-32+32)
* = FT_FLOOR(stem_center)
* new_len = 64
*/
pos = FT_PIX_FLOOR( pos + (len >> 1) );
len = 64;
}
else if (len > 0)
{
/* this is a very small stem, we simply align it to the
* pixel grid, trying to find the minimal displacement
*
* left = pos
* right = pos + len
* left_nearest_edge = ROUND(pos)
* right_nearest_edge = ROUND(right)
*
* if ( ABS(left_nearest_edge - left) <= ABS(right_nearest_edge - right)
* new_pos = left
* else
* new_pos = right
*/
FT_Pos left_nearest = FT_PIX_ROUND(pos);
FT_Pos right_nearest = FT_PIX_ROUND(pos+len);
FT_Pos left_disp = left_nearest - pos;
FT_Pos right_disp = right_nearest - (pos+len);
if (left_disp < 0) left_disp = -left_disp;
if (right_disp < 0) right_disp = -right_disp;
if (left_disp <= right_disp)
pos = left_nearest;
else
pos = right_nearest;
}
else
{
/* this is a ghost stem, we're going to simply round it */
pos = FT_PIX_ROUND( pos );
}
}
else
{