Merge pull request #964 from 101100/fix-indexoutofrangeexception-in-fillregionprocessor

Fix IndexOutOfRangeException in FillRegionProcessor

src/ImageSharp.Drawing/Processing/Processors/Drawing/FillRegionProcessor{TPixel}.cs

@@ -105,7 +105,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Drawing
 
                             QuickSort.Sort(buffer.Slice(0, pointsFound));
 
-                            for (int point = 0; point < pointsFound; point += 2)
+                            for (int point = 0; point < pointsFound && point < buffer.Length - 1; point += 2)
                             {
                                 // points will be paired up
                                 float scanStart = buffer[point] - minX;

tests/ImageSharp.Tests/Drawing/FillRegionProcessorTests.cs

@@ -12,6 +12,7 @@ using SixLabors.ImageSharp.Processing.Processors;
 using SixLabors.Primitives;
 using Xunit;
 using SixLabors.ImageSharp.Processing.Processors.Drawing;
+using SixLabors.Shapes;
 
 namespace SixLabors.ImageSharp.Tests.Drawing
 {
@@ -68,6 +69,50 @@ namespace SixLabors.ImageSharp.Tests.Drawing
             }
         }
 
+        [Fact]
+        public void DoesNotThrowForIssue928()
+        {
+            var rectText = new RectangleF(0, 0, 2000, 2000);
+            using (Image<Rgba32> img = new Image<Rgba32>((int)rectText.Width, (int)rectText.Height))
+            {
+                img.Mutate(x => x.Fill(Rgba32.Transparent));
+
+                img.Mutate(ctx => {
+                    ctx.DrawLines(
+                        Rgba32.Red,
+                        0.984252f,
+                        new PointF(104.762581f, 1074.99365f),
+                        new PointF(104.758667f, 1075.01721f),
+                        new PointF(104.757675f, 1075.04114f),
+                        new PointF(104.759628f, 1075.065f),
+                        new PointF(104.764488f, 1075.08838f),
+                        new PointF(104.772186f, 1075.111f),
+                        new PointF(104.782608f, 1075.13245f),
+                        new PointF(104.782608f, 1075.13245f)
+                        );
+                    }
+                );
+            }
+        }
+
+        [Fact]
+        public void DoesNotThrowFillingTriangle()
+        {
+            using(var image = new Image<Rgba32>(28, 28))
+            {
+                var path = new Polygon(
+                    new LinearLineSegment(new PointF(17.11f, 13.99659f), new PointF(14.01433f, 27.06201f)),
+                    new LinearLineSegment(new PointF(14.01433f, 27.06201f), new PointF(13.79267f, 14.00023f)),
+                    new LinearLineSegment(new PointF(13.79267f, 14.00023f), new PointF(17.11f, 13.99659f))
+                );
+
+                image.Mutate(ctx =>
+                {
+                    ctx.Fill(Rgba32.White, path);
+                });
+            }
+        }
+
         // Mocking the region throws an error in netcore2.0
         private class MockRegion1 : Region
         {