fix(Geometries): Relative line drawing (#14013)

* test: Add invalid draw test

* fix: Geometry parsing

* test: Refactoring the test for address `h` and `v` command

* fix: Parser of `h` command

* fix: parser `v` command

* test: Add case `M50,50z l -5,-5`

* test: Add PathMarkupParserTests

* test: Removed render tests

Author: workgroupengineering

src/Avalonia.Base/Media/PathMarkupParser.cs

@@ -259,7 +259,7 @@ private void AddLine(ref ReadOnlySpan<char> span, bool relative)
         {
             ThrowIfDisposed();
 
-            _currentPoint = relative
+            var next = relative
                                 ? ReadRelativePoint(ref span, _currentPoint)
                                 : ReadPoint(ref span);
 
@@ -268,14 +268,15 @@ private void AddLine(ref ReadOnlySpan<char> span, bool relative)
                 CreateFigure();
             }
 
-            _geometryContext.LineTo(_currentPoint);
+            _geometryContext.LineTo(next);
+            _currentPoint = next;
         }
 
         private void AddHorizontalLine(ref ReadOnlySpan<char> span, bool relative)
         {
             ThrowIfDisposed();
 
-            _currentPoint = relative
+            var next = relative
                                 ? new Point(_currentPoint.X + ReadDouble(ref span), _currentPoint.Y)
                                 : _currentPoint.WithX(ReadDouble(ref span));
 
@@ -284,14 +285,15 @@ private void AddHorizontalLine(ref ReadOnlySpan<char> span, bool relative)
                 CreateFigure();
             }
 
-            _geometryContext.LineTo(_currentPoint);
+            _geometryContext.LineTo(next);
+            _currentPoint = next;
         }
 
         private void AddVerticalLine(ref ReadOnlySpan<char> span, bool relative)
         {
             ThrowIfDisposed();
 
-            _currentPoint = relative
+            var next = relative
                                 ? new Point(_currentPoint.X, _currentPoint.Y + ReadDouble(ref span))
                                 : _currentPoint.WithY(ReadDouble(ref span));
 
@@ -300,7 +302,8 @@ private void AddVerticalLine(ref ReadOnlySpan<char> span, bool relative)
                 CreateFigure();
             }
 
-            _geometryContext.LineTo(_currentPoint);
+            _geometryContext.LineTo(next);
+            _currentPoint = next;
         }
 
         private void AddCubicBezierCurve(ref ReadOnlySpan<char> span, bool relative)

tests/Avalonia.Base.UnitTests/Media/PathMarkupParserTests.cs

@@ -319,5 +319,24 @@ public void Should_Parse_Flags_Without_Separator()
                 Assert.IsType<ArcSegment>(arcSegment);
             }
         }
+
+        [Fact]
+        public void Should_Handle_StartPoint_After_Empty_Figure()
+        {
+            var pathGeometry = new PathGeometry();
+            using var context = new PathGeometryContext(pathGeometry);
+            using var parser = new PathMarkupParser(context);
+            parser.Parse("M50,50z l -5,-5");
+
+            Assert.Equal(2, pathGeometry.Figures.Count);
+
+            var firstFigure = pathGeometry.Figures[0];
+
+            Assert.Equal(new Point(50, 50), firstFigure.StartPoint);
+
+            var secondFigure = pathGeometry.Figures[1];
+
+            Assert.Equal(new Point(50, 50), secondFigure.StartPoint);
+        }
     }
 }