Fixed recently introduced InflatePaths bug (#405)

Fixed Delphi 7 and FPC compatibility (#402)
AngusJohnson · Feb 10, 2023 · 9e8734a · 9e8734a
1 parent 7bad95c
commit 9e8734a
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Showing 4 changed files with 24 additions and 18 deletions.
diff --git a/CPP/Clipper2Lib/src/clipper.offset.cpp b/CPP/Clipper2Lib/src/clipper.offset.cpp
@@ -1,6 +1,6 @@
 /*******************************************************************************
 * Author    :  Angus Johnson                                                   *
-* Date      :  9 February 2023                                                 *
+* Date      :  10 February 2023                                                *
 * Website   :  http://www.angusj.com                                           *
 * Copyright :  Angus Johnson 2010-2023                                         *
 * Purpose   :  Path Offset (Inflate/Shrink)                                    *
@@ -288,7 +288,7 @@ void ClipperOffset::OffsetPoint(Group& group,
 		if (!almostNoAngle)
 		{
 			// create a simple self-intersection that will be cleaned up later
-			//group.path_.push_back(path[j]);
+			group.path_.push_back(path[j]); // definitely needed (#405)
 			group.path_.push_back(GetPerpendic(path[j], norms[j], group_delta_));
 		}
 	}

diff --git a/CPP/Tests/TestOffsets.cpp b/CPP/Tests/TestOffsets.cpp
@@ -22,10 +22,18 @@ TEST(Clipper2Tests, TestOffsets) {
         co.AddPaths(subject, Clipper2Lib::JoinType::Round, Clipper2Lib::EndType::Polygon);
         const auto outputs = co.Execute(1);
 
+        // is the sum total area of the solution is positive
+        const auto outer_is_positive = Clipper2Lib::Area(outputs) > 0;
+
         // there should be exactly one exterior path
-        const auto is_hole = Clipper2Lib::IsPositive<int64_t>;
-        const auto hole_count = std::count_if(outputs.begin(), outputs.end(), is_hole);
-        const auto exterior_count = outputs.size() - hole_count;
-        EXPECT_EQ(exterior_count, 1);
+        const auto is_positive_func = Clipper2Lib::IsPositive<int64_t>;
+        const auto is_positive_count = std::count_if(
+          outputs.begin(), outputs.end(), is_positive_func);
+        const auto is_negative_count = 
+          outputs.size() - is_positive_count;
+        if (outer_is_positive)
+          EXPECT_EQ(is_positive_count, 1);
+        else
+          EXPECT_EQ(is_negative_count, 1);
     }
 }
diff --git a/Delphi/Clipper2Lib/Clipper.Core.pas b/Delphi/Clipper2Lib/Clipper.Core.pas
@@ -2,7 +2,7 @@
 
 (*******************************************************************************
 * Author    :  Angus Johnson                                                   *
-* Date      :  9 February 2023                                                 *
+* Date      :  10 February 2023                                                *
 * Website   :  http://www.angusj.com                                           *
 * Copyright :  Angus Johnson 2010-2023                                         *
 * Purpose   :  Core Clipper Library module                                     *
@@ -102,6 +102,11 @@   TPointD   = record
     property MidPoint: TPointD read GetMidPoint;
   end;
 
+{$IF CompilerVersion <= 15}
+  TPointerList = array of Pointer;
+  TListSortCompareFunc = function (Item1, Item2: Pointer): Integer;
+{$IFEND}
+
   TListEx = class
   private
     fCount    : integer;
@@ -128,11 +133,6 @@   TListEx = class
 
   EClipper2LibException = class(Exception);
 
-{$IF CompilerVersion <= 15}
-  TPointerList = array of Pointer;
-  TListSortCompareFunc = function (Item1, Item2: Pointer): Integer;
-{$IFEND}
-
 function Area(const path: TPath64): Double; overload;
 function Area(const paths: TPaths64): Double; overload;
   {$IFDEF INLINING} inline; {$ENDIF}

diff --git a/Delphi/Clipper2Lib/Clipper.Offset.pas b/Delphi/Clipper2Lib/Clipper.Offset.pas
@@ -2,7 +2,7 @@
 
 (*******************************************************************************
 * Author    :  Angus Johnson                                                   *
-* Date      :  9 February 2023                                                 *
+* Date      :  10 February 2023                                                *
 * Website   :  http://www.angusj.com                                           *
 * Copyright :  Angus Johnson 2010-2023                                         *
 * Purpose   :  Path Offset (Inflate/Shrink)                                    *
@@ -299,14 +299,12 @@ procedure TClipperOffset.DoGroupOffset(group: TGroup);
       group.reversed := (area < 0);
     if group.reversed then fGroupDelta := -fDelta
     else fGroupDelta := fDelta;
-    fAbsGrpDelta := Abs(fGroupDelta);
   end else
   begin
     group.reversed := false;
     fGroupDelta := Abs(fDelta) * 0.5;
-    fAbsGrpDelta := fGroupDelta;
   end;
-
+  fAbsGrpDelta := Abs(fGroupDelta);
   fJoinType := group.joinType;
   if fArcTolerance > 0 then
     arcTol := Min(fAbsGrpDelta, fArcTolerance) else
@@ -697,8 +695,8 @@ procedure TClipperOffset.OffsetPoint(j: Integer;
     AddPoint(GetPerpendic(fInPath[j], fNorms[k], fGroupDelta));
     if not almostNoAngle then
     begin
-      // create a simple self-intersection that will be cleaned up later
-      //AddPoint(fInPath[j]); // todo: check, as may not be needed
+      // ensure a clean self-intersection ...
+      AddPoint(fInPath[j]); // definitely needed  (#405)
       AddPoint(GetPerpendic(fInPath[j], fNorms[j], fGroupDelta));
     end;
   end