[freetype2] master ebfd7ce 1/2: [autofit] Improve BOUND action.

[Werner LEMBERG]

branch: master
commit ebfd7ce52f6b3c81d522b03f8faf029b7ffb7cbc
Author: Werner Lemberg <address@hidden>
Commit: Werner Lemberg <address@hidden>

    [autofit] Improve BOUND action.
    
    In complex glyph shapes, the original logic was too simple to cater
    for situations that would actually need something similar to PS Hint
    masks.  This fix should alleviate the worst cases.
    
    * src/autofit/aflatin.c (af_latin_hint_edges): Don't allow
    complete disappearance of stems.
---
 ChangeLog             |   11 +++++++++++
 src/autofit/aflatin.c |   45 +++++++++++++++++++++++++++++++++------------
 2 files changed, 44 insertions(+), 12 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index c58dc16..a8d1c64 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2016-02-26  Werner Lemberg  <address@hidden>
+
+       [autofit] Improve BOUND action.
+
+       In complex glyph shapes, the original logic was too simple to cater
+       for situations that would actually need something similar to PS Hint
+       masks.  This fix should alleviate the worst cases.
+
+       * src/autofit/aflatin.c (af_latin_hint_edges): Don't allow
+       complete disappearance of stems.
+
 2016-02-25  Werner Lemberg  <address@hidden>
 
        [autofit] Add blue-zone support for Tamil script.
diff --git a/src/autofit/aflatin.c b/src/autofit/aflatin.c
index 8a45116..8da6ce1 100644
--- a/src/autofit/aflatin.c
+++ b/src/autofit/aflatin.c
@@ -2885,14 +2885,21 @@
              ( top_to_bottom_hinting ? ( edge->pos > edge[-1].pos )
                                      : ( edge->pos < edge[-1].pos ) ) )
         {
+          /* don't move if stem would (almost) disappear otherwise; */
+          /* the ad-hoc value 16 corresponds to 1/4px               */
+          if ( edge->link && FT_ABS( edge->link->pos - edge[-1].pos ) > 16 )
+          {
 #ifdef FT_DEBUG_LEVEL_TRACE
-          FT_TRACE5(( "  BOUND: edge %d (pos=%.2f) moved to %.2f\n",
-                      edge - edges, edge->pos / 64.0, edge[-1].pos / 64.0 ));
+            FT_TRACE5(( "  BOUND: edge %d (pos=%.2f) moved to %.2f\n",
+                        edge - edges,
+                        edge->pos / 64.0,
+                        edge[-1].pos / 64.0 ));
 
-          num_actions++;
+            num_actions++;
 #endif
 
-          edge->pos = edge[-1].pos;
+            edge->pos = edge[-1].pos;
+          }
         }
       }
     }
@@ -3048,13 +3055,20 @@
              ( top_to_bottom_hinting ? ( edge->pos > edge[-1].pos )
                                      : ( edge->pos < edge[-1].pos ) ) )
         {
+          /* don't move if stem would (almost) disappear otherwise; */
+          /* the ad-hoc value 16 corresponds to 1/4px               */
+          if ( edge->link && FT_ABS( edge->link->pos - edge[-1].pos ) > 16 )
+          {
 #ifdef FT_DEBUG_LEVEL_TRACE
-          FT_TRACE5(( "  BOUND: edge %d (pos=%.2f) moved to %.2f\n",
-                      edge - edges, edge->pos / 64.0, edge[-1].pos / 64.0 ));
+            FT_TRACE5(( "  BOUND: edge %d (pos=%.2f) moved to %.2f\n",
+                        edge - edges,
+                        edge->pos / 64.0,
+                        edge[-1].pos / 64.0 ));
 
-          num_actions++;
+            num_actions++;
 #endif
-          edge->pos = edge[-1].pos;
+            edge->pos = edge[-1].pos;
+          }
         }
 
         if ( edge + 1 < edge_limit                                   &&
@@ -3062,14 +3076,21 @@
              ( top_to_bottom_hinting ? ( edge->pos < edge[1].pos )
                                      : ( edge->pos > edge[1].pos ) ) )
         {
+          /* don't move if stem would (almost) disappear otherwise; */
+          /* the ad-hoc value 16 corresponds to 1/4px               */
+          if ( edge->link && FT_ABS( edge->link->pos - edge[-1].pos ) > 16 )
+          {
 #ifdef FT_DEBUG_LEVEL_TRACE
-          FT_TRACE5(( "  BOUND: edge %d (pos=%.2f) moved to %.2f\n",
-                      edge - edges, edge->pos / 64.0, edge[1].pos / 64.0 ));
+            FT_TRACE5(( "  BOUND: edge %d (pos=%.2f) moved to %.2f\n",
+                        edge - edges,
+                        edge->pos / 64.0,
+                        edge[1].pos / 64.0 ));
 
-          num_actions++;
+            num_actions++;
 #endif
 
-          edge->pos = edge[1].pos;
+            edge->pos = edge[1].pos;
+          }
         }
       }
     }