Commit 05c1421f8d1d0db83819be975c5a149ae41885da
2013-07-19T23:11:23
[autofit] Fix segment classification for blue zones. The old code (essentially unchanged since the very beginning) incorrectly handled this configuration x -o- x / \ / \ / \ o o as flat and this o o / / x| x| | | o---------------o as round. (`o' and `x' are on and off points, respectively). This is a major change which should improve the rendering results enormously for many TrueType fonts, especially in the range approx. 20-40ppem, fixing the appearance of many overshoots. * src/autofit/aflatin.c (af_latin_metrics_init_blues): Look at the first and last points of the segment, not the points right before and after.
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diff --git a/ChangeLog b/ChangeLog
index f525b2d..592ffca 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,4 +1,35 @@
-2013-07-18 Behdad Esfahbod <behdad@google.com>
+2013-07-19 Werner Lemberg <wl@gnu.org>
+
+ [autofit] Fix segment classification for blue zones.
+
+ The old code (essentially unchanged since the very beginning)
+ incorrectly handled this configuration
+
+ x -o- x
+ / \
+ / \
+ / \
+ o o
+
+ as flat and this
+
+ o o
+ / /
+ x| x|
+ | |
+ o---------------o
+
+ as round. (`o' and `x' are on and off points, respectively).
+
+ This is a major change which should improve the rendering results
+ enormously for many TrueType fonts, especially in the range approx.
+ 20-40ppem, fixing the appearance of many overshoots.
+
+ * src/autofit/aflatin.c (af_latin_metrics_init_blues): Look at the
+ first and last points of the segment, not the points right before
+ and after.
+
+2013-07-19 Behdad Esfahbod <behdad@google.com>
[sfnt] `sbix' fix-ups.
diff --git a/src/autofit/aflatin.c b/src/autofit/aflatin.c
index a5d80c1..ec54b70 100644
--- a/src/autofit/aflatin.c
+++ b/src/autofit/aflatin.c
@@ -328,10 +328,14 @@
{
FT_Pos best_x = points[best_point].x;
FT_Int prev, next;
+ FT_Int best_segment_first, best_segment_last;
FT_Int best_on_point_first, best_on_point_last;
FT_Pos dist;
+ best_segment_first = best_point;
+ best_segment_last = best_point;
+
if ( FT_CURVE_TAG( outline.tags[best_point] ) == FT_CURVE_TAG_ON )
{
best_on_point_first = best_point;
@@ -343,8 +347,9 @@
best_on_point_last = -1;
}
- /* look for the previous and next points that are not on the */
- /* same Y coordinate, then threshold the `closeness'... */
+ /* look for the previous and next points on the contour */
+ /* that are not on the same Y coordinate, then threshold */
+ /* the `closeness'... */
prev = best_point;
next = prev;
@@ -362,6 +367,8 @@
if ( FT_ABS( points[prev].x - best_x ) <= 20 * dist )
break;
+ best_segment_first = prev;
+
if ( FT_CURVE_TAG( outline.tags[prev] ) == FT_CURVE_TAG_ON )
{
best_on_point_first = prev;
@@ -383,6 +390,8 @@
if ( FT_ABS( points[next].x - best_x ) <= 20 * dist )
break;
+ best_segment_last = next;
+
if ( FT_CURVE_TAG( outline.tags[next] ) == FT_CURVE_TAG_ON )
{
best_on_point_last = next;
@@ -392,8 +401,14 @@
} while ( next != best_point );
- /* now set the `round' flag depending on the segment's kind */
- /* (value 8 is heuristic) */
+ /* now set the `round' flag depending on the segment's kind: */
+ /* */
+ /* - if the horizontal distance between the first and last */
+ /* `on' point is larger than upem/8 (value 8 is heuristic) */
+ /* we have a flat segment */
+ /* - if either the first or the last point of the segment is */
+ /* an `off' point, the segment is round, otherwise it is */
+ /* flat */
if ( best_on_point_first >= 0 &&
best_on_point_last >= 0 &&
(FT_UInt)( FT_ABS( points[best_on_point_last].x -
@@ -402,8 +417,10 @@
round = 0;
else
round = FT_BOOL(
- FT_CURVE_TAG( outline.tags[prev] ) != FT_CURVE_TAG_ON ||
- FT_CURVE_TAG( outline.tags[next] ) != FT_CURVE_TAG_ON );
+ FT_CURVE_TAG( outline.tags[best_segment_first] ) !=
+ FT_CURVE_TAG_ON ||
+ FT_CURVE_TAG( outline.tags[best_segment_last] ) !=
+ FT_CURVE_TAG_ON );
FT_TRACE5(( " (%s)\n", round ? "round" : "flat" ));
}