Improved testing for excessive offset shrinking //#651

Author: AngusJohnson

Delphi/Clipper2Lib/Clipper.Offset.pas

@@ -2,7 +2,7 @@
 
 (*******************************************************************************
 * Author    :  Angus Johnson                                                   *
-* Date      :  16 September 2023                                               *
+* Date      :  19 September 2023                                               *
 * Website   :  http://www.angusj.com                                           *
 * Copyright :  Angus Johnson 2010-2023                                         *
 * Purpose   :  Path Offset (Inflate/Shrink)                                    *
@@ -430,7 +430,7 @@ procedure TClipperOffset.BuildNormals;
 procedure TClipperOffset.OffsetPolygon;
 var
   i,j: integer;
-  a: double;
+  a, offsetMinDim: double;
   rec: TRect64;
 begin
   //when the path is contracting, make sure
@@ -440,7 +440,8 @@ procedure TClipperOffset.OffsetPolygon;
   if (a < 0) <> (fGroupDelta < 0) then
   begin
     rec := GetBounds(fInPath);
-    if Abs(fGroupDelta) * 2 >= rec.Width then Exit;
+    offsetMinDim := Abs(fGroupDelta) * 2;
+    if (offsetMinDim >= rec.Width) or (offsetMinDim >= rec.Height) then Exit;
   end;
 
   j := high(fInPath);