fixes #175 - Text gets chopped when rotated >60 degrees.

The glyph size is not rendered with enough space when rotated, this fixes the issue at all rotation angles

Author: replaysMike

src/ImageSharp.Drawing/Processing/Processors/Text/DrawTextProcessor{TPixel}.cs

@@ -35,6 +35,7 @@ protected override void BeforeImageApply()
             this.textRenderer = new CachingGlyphRenderer(
                 this.Configuration.MemoryAllocator,
                 this.definition.Text.Length,
+                this.definition.TextOptions,
                 this.definition.Pen,
                 this.definition.Brush != null,
                 this.definition.DrawingOptions.Transform)
@@ -173,22 +174,21 @@ private class CachingGlyphRenderer : IColorGlyphRenderer, IDisposable
             private readonly bool renderFill;
             private bool rasterizationRequired;
 
-            public CachingGlyphRenderer(MemoryAllocator memoryAllocator, int size, IPen pen, bool renderFill, Matrix3x2 transform)
+            public CachingGlyphRenderer(MemoryAllocator memoryAllocator, int size, TextOptions textOptions, IPen pen, bool renderFill, Matrix3x2 transform)
             {
                 this.MemoryAllocator = memoryAllocator;
                 this.currentRenderPosition = default;
                 this.Pen = pen;
                 this.renderFill = renderFill;
                 this.renderOutline = pen != null;
-                this.offset = 2;
+                this.offset = (int)textOptions.Font.Size;
                 if (this.renderFill)
                 {
                     this.FillOperations = new List<DrawingOperation>(size);
                 }
 
                 if (this.renderOutline)
                 {
-                    this.offset = (int)MathF.Ceiling((pen.StrokeWidth * 2) + 2);
                     this.OutlineOperations = new List<DrawingOperation>(size);
                 }
 

tests/ImageSharp.Drawing.Tests/Issues/Issue_175.cs

@@ -0,0 +1,79 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+using System.Collections.Generic;
+using System.Linq;
+using SixLabors.ImageSharp.Drawing.Processing;
+using SixLabors.ImageSharp.Drawing.Tests.TestUtilities.ImageComparison;
+using SixLabors.ImageSharp.PixelFormats;
+using SixLabors.ImageSharp.Processing;
+using Xunit;
+
+namespace SixLabors.ImageSharp.Drawing.Tests.Issues
+{
+    public class Issue_175
+    {
+        [Fact]
+        public void CanRotateFilledFont()
+        {
+            if (!TestEnvironment.IsWindows)
+            {
+                return;
+            }
+
+            using (var image = new Image<Rgba32>(300, 200))
+            {
+                string text = "QuickTYZ";
+                int rotationAngle = 90;
+                Fonts.Font font = Fonts.SystemFonts.CreateFont("Arial", 40, Fonts.FontStyle.Regular);
+
+                AffineTransformBuilder builder = new AffineTransformBuilder()
+                        .AppendRotationDegrees(rotationAngle)
+                        .AppendTranslation(new PointF(0, 0));
+                var drawingOptions = new DrawingOptions
+                {
+                    Transform = builder.BuildMatrix(image.Bounds())
+                };
+
+                image.Mutate(c => c.DrawText(drawingOptions, text, font, Brushes.Solid(Color.Red), new PointF(0, 0)));
+
+                // ensure the font renders the same as the test image
+                IEnumerable<ImageSimilarityReport> reports = ExactImageComparer.Instance.CompareImages(Image.Load<Rgba32>(TestFile.GetInputFileFullPath(TestImages.Png.Issue175Filled)), image);
+                Assert.False(reports.Any());
+
+                // image.SaveAsPng(@"./issue175_filled.png");
+            }
+        }
+
+        [Fact]
+        public void CanRotateOutlineFont()
+        {
+            if (!TestEnvironment.IsWindows)
+            {
+                return;
+            }
+
+            using (var image = new Image<Rgba32>(300, 200))
+            {
+                string text = "QuickTYZ";
+                int rotationAngle = 90;
+                Fonts.Font font = Fonts.SystemFonts.CreateFont("Arial", 40, Fonts.FontStyle.Regular);
+
+                AffineTransformBuilder builder = new AffineTransformBuilder()
+                        .AppendRotationDegrees(rotationAngle)
+                        .AppendTranslation(new PointF(0, 0));
+                var drawingOptions = new DrawingOptions
+                {
+                    Transform = builder.BuildMatrix(image.Bounds())
+                };
+                image.Mutate(c => c.DrawText(drawingOptions, text, font, Pens.Solid(Color.Blue, 1), new PointF(0, 0)));
+
+                // ensure the font renders the same as the test image
+                IEnumerable<ImageSimilarityReport> reports = ExactImageComparer.Instance.CompareImages(Image.Load<Rgba32>(TestFile.GetInputFileFullPath(TestImages.Png.Issue175Outlined)), image);
+                Assert.False(reports.Any());
+
+                // image.SaveAsPng(@"./issue175_outlined.png");
+            }
+        }
+    }
+}

tests/ImageSharp.Drawing.Tests/TestImages.cs

@@ -90,6 +90,10 @@ public static class Png
             public const string Issue1014_5 = "Png/issues/Issue_1014_5.png";
             public const string Issue1014_6 = "Png/issues/Issue_1014_6.png";
 
+            // Issue 175: https://github.com/SixLabors/ImageSharp.Drawing/issues/175
+            public const string Issue175Filled = "Png/issues/issue175_filled.png";
+            public const string Issue175Outlined = "Png/issues/issue175_outlined.png";
+
             public static class Bad
             {
                 // Odd chunk lengths