Add 2 new line styles for brushes Edge and EdgeWide

src/Consolonia.Core/Drawing/ConsoloniaRenderInterface.cs

@@ -6,6 +6,7 @@
 using Avalonia.Media.Imaging;
 using Avalonia.Media.TextFormatting;
 using Avalonia.Platform;
+using Consolonia.Core.InternalHelpers;
 using Consolonia.Core.Text;
 using SkiaSharp;
 
@@ -30,7 +31,7 @@ public IGeometryImpl CreateRectangleGeometry(Rect rect)
 
         public IStreamGeometryImpl CreateStreamGeometry()
         {
-            throw new NotImplementedException();
+            return new StreamGeometryImpl();
         }
 
         public IGeometryImpl CreateGeometryGroup(FillRule fillRule, IReadOnlyList<IGeometryImpl> children)
@@ -40,7 +41,56 @@ public IGeometryImpl CreateGeometryGroup(FillRule fillRule, IReadOnlyList<IGeome
 
         public IGeometryImpl CreateCombinedGeometry(GeometryCombineMode combineMode, IGeometryImpl g1, IGeometryImpl g2)
         {
-            throw new NotImplementedException();
+            // this is handcrafted to only combine single thickness line strokes for borders.
+            // This needs to be much more robust to handle general cases.
+
+            if (combineMode != GeometryCombineMode.Exclude)
+                throw new NotImplementedException("Only GeometryCombineMode.Exclude is supported");
+
+            if (g1 is not StreamGeometryImpl stream1 || g2 is not StreamGeometryImpl stream2)
+                throw new ArgumentException("Only StreamGeometryImpl is supported");
+
+            IStreamGeometryImpl newGeometry = CreateStreamGeometry();
+            using (IStreamGeometryContextImpl ctx = newGeometry.Open())
+            {
+                // Resharper disable UnusedVariable
+                bool hasLeftStroke = stream2.Bounds.X.IsNearlyEqual(1);
+                bool hasTopStroke = stream2.Bounds.Y.IsNearlyEqual(1);
+                bool hasRightStroke = (stream1.Bounds.Width - stream2.Bounds.Width).IsNearlyEqual(stream2.Bounds.X + 1);
+                bool hasBottomStroke =
+                    (stream1.Bounds.Height - stream2.Bounds.Height).IsNearlyEqual(stream2.Bounds.Y + 1);
+                Point topLeft = stream1.Bounds.TopLeft;
+                Point topRight = stream1.Bounds.TopRight;
+                Point bottomLeft = stream1.Bounds.BottomLeft;
+                Point bottomRight = stream1.Bounds.BottomRight;
+                Line topStroke = stream1.Strokes[0];
+                Line rightStroke = stream1.Strokes[1];
+                Line bottomStroke = stream1.Strokes[2];
+                Line leftStroke = stream1.Strokes[3];
+                // Resharper enable UnusedVariable
+
+                // add "null" strokes to establish boundries of box even when there is a single real stroke.
+                AddStroke(ctx, topLeft, topLeft);
+                AddStroke(ctx, bottomRight, bottomRight);
+
+                if (hasTopStroke)
+                    AddStroke(ctx, topStroke.PStart, topStroke.PEnd + new Vector(-1, 0));
+                if (hasRightStroke)
+                    AddStroke(ctx, rightStroke.PStart + new Vector(-1, 0), rightStroke.PEnd + new Vector(-1, -1));
+                if (hasBottomStroke)
+                    AddStroke(ctx, bottomStroke.PStart + new Vector(0, -1), bottomStroke.PEnd + new Vector(-1, -1));
+                if (hasLeftStroke)
+                    AddStroke(ctx, leftStroke.PStart, leftStroke.PEnd + new Vector(0, -1));
+            }
+
+            return newGeometry;
+        }
+
+        private static void AddStroke(IStreamGeometryContextImpl ctx, Point start, Point end)
+        {
+            ctx.BeginFigure(start, false);
+            ctx.LineTo(end);
+            ctx.EndFigure(true);
         }
 
         public IGeometryImpl BuildGlyphRunGeometry(GlyphRun glyphRun)

src/Consolonia.Core/Drawing/Line.cs

@@ -18,9 +18,22 @@ public Line(Point pStart, bool vertical, int length, IGeometryImpl sourceGeometr
             Transform = transform;
         }
 
+        public Line(Point pStart, Point pEnd, IGeometryImpl sourceGeometry = default, Matrix transform = default)
+        {
+            pStart = new Point(pStart.X, pStart.Y);
+            PStart = pStart;
+            pEnd = new Point(pEnd.X, pEnd.Y);
+            if (!(pStart.X.IsNearlyEqual(pEnd.X) || pStart.Y.IsNearlyEqual(pEnd.Y)))
+                throw new ArgumentException("Consolonia can only draw horizontal or vertical lines");
+            Vertical = pStart.X.IsNearlyEqual(pEnd.X);
+            Length = Vertical ? (int)Math.Abs(pStart.Y - pEnd.Y) : (int)Math.Abs(pStart.X - pEnd.X);
+            SourceGeometry = sourceGeometry!;
+            Transform = transform;
+        }
+
         public Point PStart { get; }
 
-        private Point PEnd => Vertical ? PStart.WithY(PStart.Y + Length) : PStart.WithX(PStart.X + Length);
+        public Point PEnd => Vertical ? PStart.WithY(PStart.Y + Length) : PStart.WithX(PStart.X + Length);
         public bool Vertical { get; }
         public int Length { get; }
 

src/Consolonia.Core/Drawing/LineBrush.cs

@@ -1,4 +1,4 @@
-using Avalonia;
+using Avalonia;
 using Avalonia.Animation;
 using Avalonia.Media;
 using Consolonia.Core.InternalHelpers;

src/Consolonia.Core/Drawing/LineStyle.cs

@@ -4,6 +4,8 @@ public enum LineStyle
     {
         SingleLine = 0,
         DoubleLine,
-        Bold
+        Bold,
+        Edge,
+        EdgeWide
     }
 }

src/Consolonia.Core/Drawing/RectangleLinePosition.cs

@@ -0,0 +1,11 @@
+namespace Consolonia.Core.Drawing
+{
+    internal enum RectangleLinePosition
+    {
+        Left,
+        Top,
+        Right,
+        Bottom,
+        Unknown
+    }
+}

src/Consolonia.Core/Drawing/StreamGeometryImpl.cs

@@ -0,0 +1,197 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using System.Linq;
+using Avalonia;
+using Avalonia.Media;
+using Avalonia.Platform;
+
+namespace Consolonia.Core.Drawing
+{
+    internal class StreamGeometryImpl : IStreamGeometryImpl
+    {
+        private readonly List<Rectangle> _fills;
+        private readonly List<Line> _strokes;
+        private Rect _bounds;
+
+        public StreamGeometryImpl()
+        {
+            _strokes = new List<Line>();
+            _fills = new List<Rectangle>();
+        }
+
+        public IReadOnlyList<Line> Strokes => _strokes;
+
+        public IReadOnlyList<Rectangle> Fills => _fills;
+        // private SKPath _path;
+
+        public Rect Bounds => _bounds;
+
+        public double ContourLength => _strokes.Sum(l => l.ContourLength);
+
+
+        public IStreamGeometryImpl Clone()
+        {
+            var clone = new StreamGeometryImpl();
+            foreach (Line line in _strokes) clone._strokes.Add(line);
+            foreach (Rectangle rect in _fills) clone._fills.Add(rect);
+            clone._bounds = _bounds;
+            return clone;
+        }
+
+        public bool FillContains(Point point)
+        {
+            return _bounds.Contains(point);
+        }
+
+        public Rect GetRenderBounds(IPen pen)
+        {
+            Rect strokeBounds = _strokes.Aggregate(new Rect(), (rect, line) => rect.Union(line.GetRenderBounds(pen)));
+            return _fills.Aggregate(strokeBounds, (rect, r) => rect.Union(r.GetRenderBounds(pen)));
+        }
+
+        public IGeometryImpl GetWidenedGeometry(IPen pen)
+        {
+            // TODO
+            throw new NotImplementedException();
+        }
+
+        public IGeometryImpl Intersect(IGeometryImpl geometry)
+        {
+            return geometry.Intersect(this);
+        }
+
+        public IStreamGeometryContextImpl Open()
+        {
+            return new StreamGeometryContextImpl(this);
+        }
+
+        public bool StrokeContains(IPen pen, Point point)
+        {
+            return _strokes.Any(line => line.StrokeContains(pen, point));
+        }
+
+        public bool TryGetPointAndTangentAtDistance(double distance, out Point point, out Point tangent)
+        {
+            throw new NotImplementedException();
+        }
+
+        public bool TryGetPointAtDistance(double distance, out Point point)
+        {
+            throw new NotImplementedException();
+        }
+
+        public bool TryGetSegment(double startDistance, double stopDistance, bool startOnBeginFigure,
+            [NotNullWhen(true)] out IGeometryImpl segmentGeometry)
+        {
+            throw new NotImplementedException();
+        }
+
+        public ITransformedGeometryImpl WithTransform(Matrix transform)
+        {
+            throw new NotImplementedException();
+        }
+
+        /// <summary>
+        ///     A Conolonia implementation of a <see cref="IStreamGeometryContextImpl" />.
+        /// </summary>
+        private class StreamGeometryContextImpl : IStreamGeometryContextImpl, IGeometryContext2
+        {
+            private readonly StreamGeometryImpl _geometryImpl;
+            private bool _isFilled;
+            private Point _lastPoint;
+
+            /// <summary>
+            ///     Initializes a new instance of the StreamGeometryContextImpl class.
+            ///     <param name="geometryImpl">Geometry to operate on.</param>
+            /// </summary>
+            public StreamGeometryContextImpl(StreamGeometryImpl geometryImpl)
+            {
+                _geometryImpl = geometryImpl;
+            }
+
+            /// <inheritdoc />
+            public void LineTo(Point point, bool isStroked)
+            {
+                LineTo(point);
+            }
+
+            /// <inheritdoc />
+            public void ArcTo(Point point, Size size, double rotationAngle, bool isLargeArc,
+                SweepDirection sweepDirection, bool isStroked)
+            {
+                _lastPoint = point;
+            }
+
+            /// <inheritdoc />
+            public void CubicBezierTo(Point point1, Point point2, Point point3, bool isStroked)
+            {
+                throw new NotSupportedException();
+            }
+
+            /// <inheritdoc />
+            public void QuadraticBezierTo(Point point1, Point point2, bool isStroked)
+            {
+                throw new NotSupportedException();
+            }
+
+            /// <inheritdoc />
+            public void ArcTo(Point point, Size size, double rotationAngle, bool isLargeArc,
+                SweepDirection sweepDirection)
+            {
+                // ignore arc instructions. It's attempt to draw rounded corners, we don't do that.
+                //_lastPoint = point;
+            }
+
+            /// <inheritdoc />
+            public void BeginFigure(Point startPoint, bool isFilled)
+            {
+                _isFilled = isFilled;
+                _lastPoint = startPoint;
+            }
+
+            /// <inheritdoc />
+            public void CubicBezierTo(Point point1, Point point2, Point point3)
+            {
+                throw new NotSupportedException();
+            }
+
+            /// <inheritdoc />
+            public void QuadraticBezierTo(Point point1, Point point2)
+            {
+                throw new NotSupportedException();
+            }
+
+            /// <inheritdoc />
+            public void LineTo(Point point)
+            {
+                // our strokes are oriented from UpperLeft corner to Right or Down
+                if (_lastPoint.X > point.X || _lastPoint.Y > point.Y)
+                    _geometryImpl._strokes.Add(new Line(point, _lastPoint));
+                else
+                    _geometryImpl._strokes.Add(new Line(_lastPoint, point));
+                _lastPoint = point;
+            }
+
+            /// <inheritdoc />
+            public void EndFigure(bool isClosed)
+            {
+                Rect bound = _geometryImpl._strokes.Aggregate(new Rect(), (rect, line) => rect.Union(line.Bounds));
+                _geometryImpl._bounds = bound;
+                if (_isFilled)
+                {
+                    // _geometryImpl._fills.Add(new Rectangle(bound));
+                }
+            }
+
+            /// <inheritdoc />
+            public void SetFillRule(FillRule fillRule)
+            {
+            }
+
+            public void Dispose()
+            {
+            }
+        }
+    }
+}