Fix nullability for brushes and rich text rendering

Author: JimBobSquarePants

src/ImageSharp.Drawing/Processing/Extensions/DrawTextExtensions.cs

@@ -1,8 +1,6 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
-#nullable disable
-
 using SixLabors.Fonts;
 using SixLabors.ImageSharp.Drawing.Processing.Processors.Text;
 
@@ -163,8 +161,8 @@ public static IImageProcessingContext DrawText(
         this IImageProcessingContext source,
         RichTextOptions textOptions,
         string text,
-        Brush brush,
-        Pen pen) =>
+        Brush? brush,
+        Pen? pen) =>
         source.DrawText(source.GetDrawingOptions(), textOptions, text, brush, pen);
 
     /// <summary>
@@ -221,8 +219,8 @@ public static IImageProcessingContext DrawText(
         DrawingOptions drawingOptions,
         string text,
         Font font,
-        Brush brush,
-        Pen pen,
+        Brush? brush,
+        Pen? pen,
         PointF location)
     {
         RichTextOptions textOptions = new(font) { Origin = location };
@@ -244,7 +242,7 @@ public static IImageProcessingContext DrawText(
         DrawingOptions drawingOptions,
         RichTextOptions textOptions,
         string text,
-        Brush brush,
-        Pen pen)
+        Brush? brush,
+        Pen? pen)
         => source.ApplyProcessor(new DrawTextProcessor(drawingOptions, textOptions, text, brush, pen));
 }

src/ImageSharp.Drawing/Processing/GradientBrush.cs

@@ -32,7 +32,7 @@ protected GradientBrush(GradientRepetitionMode repetitionMode, params ColorStop[
     protected ColorStop[] ColorStops { get; }
 
     /// <inheritdoc />
-    public override bool Equals(Brush other)
+    public override bool Equals(Brush? other)
     {
         if (other is GradientBrush brush)
         {

src/ImageSharp.Drawing/Processing/LinearGradientBrush.cs

@@ -32,7 +32,7 @@ public LinearGradientBrush(
     }
 
     /// <inheritdoc/>
-    public override bool Equals(Brush other)
+    public override bool Equals(Brush? other)
     {
         if (other is LinearGradientBrush brush)
         {

src/ImageSharp.Drawing/Processing/PatternBrush.cs

@@ -84,7 +84,7 @@ internal PatternBrush(PatternBrush brush)
     }
 
     /// <inheritdoc />
-    public override bool Equals(Brush other)
+    public override bool Equals(Brush? other)
     {
         if (other is PatternBrush sb)
         {

src/ImageSharp.Drawing/Processing/PatternPen.cs

@@ -63,7 +63,7 @@ public PatternPen(PenOptions options)
     }
 
     /// <inheritdoc/>
-    public override bool Equals(Pen other)
+    public override bool Equals(Pen? other)
     {
         if (other is PatternPen)
         {

src/ImageSharp.Drawing/Processing/Pen.cs

@@ -21,7 +21,7 @@ namespace SixLabors.ImageSharp.Drawing.Processing;
 /// </remarks>
 public abstract class Pen : IEquatable<Pen>
 {
-    private readonly float[] pattern;
+    private readonly float[]? pattern;
 
     /// <summary>
     /// Initializes a new instance of the <see cref="Pen"/> class.

src/ImageSharp.Drawing/Processing/Processors/Text/DrawTextProcessor.cs

@@ -1,8 +1,6 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
-#nullable disable
-
 using SixLabors.ImageSharp.Processing.Processors;
 
 namespace SixLabors.ImageSharp.Drawing.Processing.Processors.Text;
@@ -20,7 +18,7 @@ public class DrawTextProcessor : IImageProcessor
     /// <param name="text">The text we want to render</param>
     /// <param name="brush">The brush to source pixel colors from.</param>
     /// <param name="pen">The pen to outline text with.</param>
-    public DrawTextProcessor(DrawingOptions drawingOptions, RichTextOptions textOptions, string text, Brush brush, Pen pen)
+    public DrawTextProcessor(DrawingOptions drawingOptions, RichTextOptions textOptions, string text, Brush? brush, Pen? pen)
     {
         Guard.NotNull(text, nameof(text));
         if (brush is null && pen is null)
@@ -38,7 +36,7 @@ public DrawTextProcessor(DrawingOptions drawingOptions, RichTextOptions textOpti
     /// <summary>
     /// Gets the brush used to fill the glyphs.
     /// </summary>
-    public Brush Brush { get; }
+    public Brush? Brush { get; }
 
     /// <summary>
     /// Gets the <see cref="Processing.DrawingOptions"/> defining blending modes and shape drawing settings.
@@ -58,7 +56,7 @@ public DrawTextProcessor(DrawingOptions drawingOptions, RichTextOptions textOpti
     /// <summary>
     /// Gets the pen used for outlining the text, if Null then we will not outline
     /// </summary>
-    public Pen Pen { get; }
+    public Pen? Pen { get; }
 
     /// <summary>
     /// Gets the location to draw the text at.

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

@@ -1,8 +1,6 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
-#nullable disable
-
 using System.Numerics;
 using SixLabors.Fonts;
 using SixLabors.ImageSharp.Memory;
@@ -17,7 +15,7 @@ namespace SixLabors.ImageSharp.Drawing.Processing.Processors.Text;
 internal class DrawTextProcessor<TPixel> : ImageProcessor<TPixel>
     where TPixel : unmanaged, IPixel<TPixel>
 {
-    private RichTextGlyphRenderer textRenderer;
+    private RichTextGlyphRenderer? textRenderer;
     private readonly DrawTextProcessor definition;
 
     public DrawTextProcessor(Configuration configuration, DrawTextProcessor definition, Image<TPixel> source, Rectangle sourceRectangle)
@@ -101,7 +99,7 @@ void Draw(IEnumerable<DrawingOperation> operations)
                 for (int row = firstRow; row < end; row++)
                 {
                     int y = startY + row;
-                    Span<float> span = buffer.DangerousGetRowSpan(row).Slice(offsetSpan);
+                    Span<float> span = buffer.DangerousGetRowSpan(row)[offsetSpan..];
                     app.Apply(span, startX, y);
                 }
             }

src/ImageSharp.Drawing/Processing/Processors/Text/RichTextGlyphRenderer.cs

@@ -1,8 +1,6 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
-#nullable disable
-
 using System.Numerics;
 using System.Runtime.CompilerServices;
 using SixLabors.Fonts;
@@ -24,15 +22,15 @@ internal sealed class RichTextGlyphRenderer : BaseGlyphBuilder, IColorGlyphRende
 
     private readonly DrawingOptions drawingOptions;
     private readonly MemoryAllocator memoryAllocator;
-    private readonly Pen defaultPen;
-    private readonly Brush defaultBrush;
-    private readonly IPathInternals path;
+    private readonly Pen? defaultPen;
+    private readonly Brush? defaultBrush;
+    private readonly IPathInternals? path;
     private bool isDisposed;
 
     private readonly Dictionary<Color, Brush> brushLookup = new();
-    private TextRun currentTextRun;
-    private Brush currentBrush;
-    private Pen currentPen;
+    private TextRun? currentTextRun;
+    private Brush? currentBrush;
+    private Pen? currentPen;
     private Color? currentColor;
     private TextDecorationDetails? currentUnderline;
     private TextDecorationDetails? currentStrikeout;
@@ -54,8 +52,8 @@ public RichTextGlyphRenderer(
         RichTextOptions textOptions,
         DrawingOptions drawingOptions,
         MemoryAllocator memoryAllocator,
-        Pen pen,
-        Brush brush)
+        Pen? pen,
+        Brush? brush)
         : base(drawingOptions.Transform)
     {
         this.drawingOptions = drawingOptions;
@@ -116,7 +114,7 @@ protected override void BeginGlyph(in FontRectangle bounds, in GlyphRendererPara
             // Create a cache entry for the glyph.
             // We need to apply the default transform to the bounds to get the correct size
             // for comparison with future glyphs. We can use this cached glyph anywhere in the text block.
-            var currentBounds = RectangleF.Transform(
+            RectangleF currentBounds = RectangleF.Transform(
                    new RectangleF(bounds.Location, new(bounds.Width, bounds.Height)),
                    this.drawingOptions.Transform);
 
@@ -150,8 +148,8 @@ public void SetColor(GlyphColor color)
 
     public override TextDecorations EnabledDecorations()
     {
-        TextRun run = this.currentTextRun;
-        TextDecorations decorations = run.TextDecorations;
+        TextRun? run = this.currentTextRun;
+        TextDecorations decorations = run?.TextDecorations ?? TextDecorations.None;
 
         if (this.currentTextRun is RichTextRun drawingRun)
         {
@@ -199,7 +197,7 @@ public override void SetDecoration(TextDecorations textDecorations, Vector2 star
             return;
         }
 
-        Pen pen = null;
+        Pen? pen = null;
         if (this.currentTextRun is RichTextRun drawingRun)
         {
             if (textDecorations == TextDecorations.Strikeout)
@@ -224,8 +222,9 @@ public override void SetDecoration(TextDecorations textDecorations, Vector2 star
         else
         {
             // Clamp the thickness to whole pixels.
+            // Brush cannot be null if pen is null.
             thickness = MathF.Max(1F, MathF.Round(thickness));
-            pen = new SolidPen(this.currentBrush ?? this.defaultBrush, thickness);
+            pen = new SolidPen((this.currentBrush ?? this.defaultBrush)!, thickness);
         }
 
         // Drawing is always centered around the point so we need to offset by half.
@@ -275,7 +274,7 @@ protected override void EndGlyph()
             renderFill = true;
             if (this.currentColor.HasValue)
             {
-                if (this.brushLookup.TryGetValue(this.currentColor.Value, out Brush brush))
+                if (this.brushLookup.TryGetValue(this.currentColor.Value, out Brush? brush))
                 {
                     this.currentBrush = brush;
                 }
@@ -309,7 +308,7 @@ protected override void EndGlyph()
 
             if (renderOutline)
             {
-                path = this.currentPen.GeneratePath(path);
+                path = this.currentPen!.GeneratePath(path);
                 renderData.OutlineMap = this.Render(path);
             }
 
@@ -361,7 +360,7 @@ protected override void EndGlyph()
             {
                 RenderLocation = renderLocation,
                 Map = renderData.FillMap,
-                Brush = this.currentBrush,
+                Brush = this.currentBrush!,
                 RenderPass = RenderOrderFill
             });
         }
@@ -372,7 +371,7 @@ protected override void EndGlyph()
             {
                 RenderLocation = renderLocation,
                 Map = renderData.OutlineMap,
-                Brush = this.currentPen?.StrokeFill ?? this.currentBrush,
+                Brush = this.currentPen?.StrokeFill ?? this.currentBrush!,
                 RenderPass = RenderOrderOutline
             });
         }
@@ -538,7 +537,7 @@ private Buffer2D<float> Render(IPath path)
         // Take the path inside the path builder, scan thing and generate a Buffer2D representing the glyph.
         Buffer2D<float> buffer = this.memoryAllocator.Allocate2D<float>(size.Width, size.Height, AllocationOptions.Clean);
 
-        var scanner = PolygonScanner.Create(
+        PolygonScanner scanner = PolygonScanner.Create(
             offsetPath,
             0,
             size.Height,

src/ImageSharp.Drawing/Processing/RadialGradientBrush.cs

@@ -28,7 +28,7 @@ public RadialGradientBrush(
     }
 
     /// <inheritdoc/>
-    public override bool Equals(Brush other)
+    public override bool Equals(Brush? other)
     {
         if (other is RadialGradientBrush brush)
         {