Merge pull request #69 from SixLabors/js/issue-54

Prevent issue with zero width pens

Author: tocsoft

src/ImageSharp.Drawing/Processing/Pen.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Six Labors.
+// Copyright (c) Six Labors.
 // Licensed under the Apache License, Version 2.0.
 
 using System;
@@ -39,6 +39,8 @@ public Pen(Color color, float width, float[] pattern)
         /// <param name="pattern">The pattern.</param>
         public Pen(IBrush brush, float width, float[] pattern)
         {
+            Guard.MustBeGreaterThan(width, 0, nameof(width));
+
             this.StrokeFill = brush;
             this.StrokeWidth = width;
             this.pattern = pattern;

src/ImageSharp.Drawing/Shapes/ComplexPolygon.cs

@@ -36,42 +36,52 @@ public ComplexPolygon(params IPath[] paths)
         {
             this.paths = paths ?? throw new ArgumentNullException(nameof(paths));
 
-            float minX = float.MaxValue;
-            float maxX = float.MinValue;
-            float minY = float.MaxValue;
-            float maxY = float.MinValue;
-            float length = 0;
-            int intersections = 0;
-
-            foreach (IPath s in this.paths)
+            if (paths.Length > 0)
             {
-                length += s.Length;
-                if (s.Bounds.Left < minX)
+                float minX = float.MaxValue;
+                float maxX = float.MinValue;
+                float minY = float.MaxValue;
+                float maxY = float.MinValue;
+                float length = 0;
+                int intersections = 0;
+
+                foreach (IPath s in this.paths)
                 {
-                    minX = s.Bounds.Left;
-                }
+                    length += s.Length;
+                    if (s.Bounds.Left < minX)
+                    {
+                        minX = s.Bounds.Left;
+                    }
 
-                if (s.Bounds.Right > maxX)
-                {
-                    maxX = s.Bounds.Right;
-                }
+                    if (s.Bounds.Right > maxX)
+                    {
+                        maxX = s.Bounds.Right;
+                    }
 
-                if (s.Bounds.Top < minY)
-                {
-                    minY = s.Bounds.Top;
-                }
+                    if (s.Bounds.Top < minY)
+                    {
+                        minY = s.Bounds.Top;
+                    }
 
-                if (s.Bounds.Bottom > maxY)
-                {
-                    maxY = s.Bounds.Bottom;
+                    if (s.Bounds.Bottom > maxY)
+                    {
+                        maxY = s.Bounds.Bottom;
+                    }
+
+                    intersections += s.MaxIntersections;
                 }
 
-                intersections += s.MaxIntersections;
+                this.MaxIntersections = intersections;
+                this.Length = length;
+                this.Bounds = new RectangleF(minX, minY, maxX - minX, maxY - minY);
+            }
+            else
+            {
+                this.MaxIntersections = 0;
+                this.Length = 0;
+                this.Bounds = RectangleF.Empty;
             }
 
-            this.MaxIntersections = intersections;
-            this.Length = length;
-            this.Bounds = new RectangleF(minX, minY, maxX - minX, maxY - minY);
             this.PathType = PathTypes.Mixed;
         }
 

tests/ImageSharp.Drawing.Tests/Issues/Issue-54.cs

@@ -0,0 +1,69 @@
+using System;
+using System.Runtime.InteropServices;
+using SixLabors.Fonts;
+using SixLabors.ImageSharp.Drawing.Processing;
+using SixLabors.ImageSharp.Drawing.Tests.TestUtilities.Attributes;
+using SixLabors.ImageSharp.PixelFormats;
+using SixLabors.ImageSharp.Processing;
+using Xunit;
+
+namespace SixLabors.ImageSharp.Drawing.Tests.Issues
+{
+    public class Issue_54
+    {
+        [WindowsFact]
+        public void CanDrawWithoutMemoryException()
+        {
+            int width = 768;
+            int height = 438;
+
+            // Creates a new image with empty pixel data. 
+            using (var image = new Image<Rgba32>(width, height))
+            {
+                FontFamily family = SystemFonts.Find("verdana");
+                Font font = family.CreateFont(48, FontStyle.Bold);
+
+                // The options are optional
+                TextGraphicsOptions options = new TextGraphicsOptions()
+                {
+                    TextOptions = new TextOptions()
+                    {
+                        ApplyKerning = true,
+                        TabWidth = 8, // a tab renders as 8 spaces wide
+                        WrapTextWidth = width, // greater than zero so we will word wrap at 100 pixels wide
+                        HorizontalAlignment = HorizontalAlignment.Center // right align
+                    }
+                };
+
+                IBrush brush = Brushes.Solid(Color.White);
+                IPen pen = Pens.Solid(Color.White, 1);
+                string text = "sample text";
+
+                // Draw the text
+                image.Mutate(x => x.DrawText(options, text, font, brush, pen, new PointF(0, 100)));
+            }
+        }
+
+        [Fact]
+        public void PenMustHaveAWidthGraterThanZero()
+        {
+            ArgumentOutOfRangeException ex = Assert.Throws<ArgumentOutOfRangeException>(() =>
+            {
+                IPen pen = new Pen(Color.White, 0);
+            });
+
+            Assert.StartsWith("Parameter \"width\" (System.Single) must be greater than 0, was 0", ex.Message);
+        }
+
+
+        [Fact]
+        public void ComplexPolygoWithZeroPathsCausesBoundsToBeNonSensicalValue()
+        {
+            var polygon = new ComplexPolygon(Array.Empty<IPath>());
+
+            Assert.NotEqual(float.NegativeInfinity, polygon.Bounds.Width);
+            Assert.NotEqual(float.PositiveInfinity, polygon.Bounds.Width);
+            Assert.NotEqual(float.NaN, polygon.Bounds.Width);
+        }
+    }
+}

tests/ImageSharp.Drawing.Tests/TestUtilities/Attributes/PlatformFactAttribute.cs

@@ -0,0 +1,26 @@
+using System;
+using System.Collections.Generic;
+using System.Runtime.InteropServices;
+using System.Text;
+using Xunit;
+
+namespace SixLabors.ImageSharp.Drawing.Tests.TestUtilities.Attributes
+{
+    public class PlatformFactAttribute : FactAttribute
+    {
+        public PlatformFactAttribute(OSPlatform platform)
+        {
+            if (!RuntimeInformation.IsOSPlatform(platform))
+            {
+                this.Skip = $"Platform specific test, runs only on '{platform}'";
+            }
+        }
+    }
+
+    public class WindowsFactAttribute : PlatformFactAttribute
+    {
+        public WindowsFactAttribute() : base(OSPlatform.Windows)
+        {
+        }
+    }
+}