ref: 601aefe4eccd84c8fbca4d43bd8fa68fe6a342d9
parent: b68e025c1b888a1d06e3617d768d616d5469f754
author: David Turner <[email protected]>
date: Wed Feb 21 11:47:49 EST 2007
fix postscript hinter's handling of small and ghost stems
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2007-02-21 David Turner <[email protected]>
+
+ * src/pshinter/pshalgo.c: fixed a bug in the hinting of small
+ and ghost stems in the Postscript interpreter
+
2007-02-20 suzuki toshiya <[email protected]>
* src/base/ftmac.c (FT_GetFileRef_From_Mac_ATS_Name): Fix memory
--- a/src/pshinter/pshalgo.c
+++ b/src/pshinter/pshalgo.c
@@ -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
{