Commit a345c0e1d5fd368a0d2a53c2283b3ccd5262ee8f
2011-04-21T10:58:33
[autofit] Blur CJK stems if too many to preserve their gaps
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diff --git a/ChangeLog b/ChangeLog
index 6adc549..24d0e5f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,18 @@
+2011-04-21 rainy6144 <rainy6144@gmail.com>
+
+ [autofit] Blur CJK stems if too many to preserve their gaps.
+ When there are too many stems to preserve their gaps in the
+ rasterization of CJK Ideographs at a low resolution, blur the
+ stems instead of showing clumped stems. See
+ http://lists.gnu.org/archive/html/freetype-devel/2011-02/msg00011.html
+ http://lists.gnu.org/archive/html/freetype-devel/2011-04/msg00046.html
+ for detail.
+
+ * src/autofit/afcjk.c (af_cjk_hint_edges): Store the position of
+ the previous stem by `has_last_stem' and `last_stem_pos', and skip
+ a stem if the current and previous stem are too near to preserve
+ the gap.
+
2011-04-18 Werner Lemberg <wl@gnu.org>
Integrate autofitter debugging stuff.
diff --git a/src/autofit/afcjk.c b/src/autofit/afcjk.c
index af4597c..c15d343 100644
--- a/src/autofit/afcjk.c
+++ b/src/autofit/afcjk.c
@@ -1025,6 +1025,8 @@
AF_Edge anchor = 0;
FT_Pos delta = 0;
FT_Int skipped = 0;
+ FT_Bool has_last_stem = FALSE;
+ FT_Pos last_stem_pos = 0;
/* now we align all stem edges. */
@@ -1044,12 +1046,34 @@
continue;
}
+ /* Some CJK characters have so many stems that
+ * the hinter is likely to merge two adjacent ones.
+ * To solve this problem, if either edge of a stem
+ * is too close to the previous one, we avoid
+ * aligning the two edges, but rather interpolate
+ * their locations at the end of this function in
+ * order to preserve the space between the stems.
+ */
+ if ( has_last_stem &&
+ ( edge->pos < last_stem_pos + 64 ||
+ edge2->pos < last_stem_pos + 64 ) )
+ {
+ skipped++;
+ continue;
+ }
+
/* now align the stem */
if ( edge2 < edge )
{
af_cjk_align_linked_edge( hints, dim, edge2, edge );
edge->flags |= AF_EDGE_DONE;
+ /* We rarely reaches here it seems;
+ * usually the two edges belonging
+ * to one stem are marked as DONE together
+ */
+ has_last_stem = TRUE;
+ last_stem_pos = edge->pos;
continue;
}
@@ -1142,6 +1166,8 @@
anchor = edge;
edge->flags |= AF_EDGE_DONE;
edge2->flags |= AF_EDGE_DONE;
+ has_last_stem = TRUE;
+ last_stem_pos = edge2->pos;
}
/* make sure that lowercase m's maintain their symmetry */