Safer safety_offset() for ExPolygons

lib/Slic3r/ExPolygon.pm

@@ -85,15 +85,7 @@ sub offset_ex {
 
 sub safety_offset {
     my $self = shift;
-    
-    # we're offsetting contour and holes separately
-    # because Clipper doesn't return polygons in the same order as 
-    # we feed them to it
-    
-    return (ref $self)->new(
-        $self->contour->safety_offset,
-        @{ Slic3r::Geometry::Clipper::safety_offset([$self->holes]) },
-    );
+    return Slic3r::Geometry::Clipper::safety_offset_ex($self, @_);
 }
 
 sub noncollapsing_offset_ex {

lib/Slic3r/Geometry/Clipper.pm

@@ -4,7 +4,7 @@ use warnings;
 
 require Exporter;
 our @ISA = qw(Exporter);
-our @EXPORT_OK = qw(safety_offset offset offset_ex collapse_ex
+our @EXPORT_OK = qw(safety_offset safety_offset_ex offset offset_ex collapse_ex
     diff_ex diff union_ex intersection_ex xor_ex PFT_EVENODD JT_MITER JT_ROUND
     JT_SQUARE is_counter_clockwise);
 
@@ -17,6 +17,11 @@ sub safety_offset {
     return Math::Clipper::offset($polygons, $factor // (scale 1e-05), 100000, JT_MITER, 2);
 }
 
+sub safety_offset_ex {
+    # offset polygons and then apply holes to the right contours
+    return @{ union_ex([ safety_offset(@_) ]) };
+}
+
 sub offset {
     my ($polygons, $distance, $scale, $joinType, $miterLimit) = @_;
     $scale      ||= 100000;

lib/Slic3r/Polygon.pm

@@ -95,11 +95,6 @@ sub area {
     return Slic3r::Geometry::Clipper::area($self);
 }
 
-sub safety_offset {
-    my $self = shift;
-    return (ref $self)->new(Slic3r::Geometry::Clipper::safety_offset([$self])->[0]);
-}
-
 sub offset {
     my $self = shift;
     return map Slic3r::Polygon->new($_), Slic3r::Geometry::Clipper::offset([$self], @_);