Add drawing centric path building api.

-migrate GlyphRenderer to use new helper class directly

Author: tocsoft

src/ImageSharp.Drawing/Shapes/PathDrawer.cs

@@ -0,0 +1,106 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+using System.Numerics;
+
+namespace SixLabors.ImageSharp.Drawing
+{
+    /// <summary>
+    /// Allow you to derivatively draw shapes and paths.
+    /// </summary>
+    public class PathDrawer
+    {
+        private readonly PathBuilder builder;
+        private Vector2 currentPoint = default;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="PathDrawer"/> class.
+        /// </summary>
+        /// <param name="pathBuilder">The path build to draw to.</param>
+        public PathDrawer(PathBuilder pathBuilder) => this.builder = pathBuilder;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="PathDrawer"/> class.
+        /// </summary>
+        public PathDrawer()
+            : this(new PathBuilder())
+        {
+        }
+
+        /// <summary>
+        /// Clears all drawn paths, Leaving any applied transforms.
+        /// </summary>
+        public void Clear() => this.builder.Clear();
+
+        /// <summary>
+        /// Begins the figure.
+        /// </summary>
+        public void StartFigure() => this.builder.StartFigure();
+
+        /// <summary>
+        /// Draws a cubic bezier from the current point  to the <paramref name="point"/>
+        /// </summary>
+        /// <param name="secondControlPoint">The second control point.</param>
+        /// <param name="thirdControlPoint">The third control point.</param>
+        /// <param name="point">The point.</param>
+        public void CubicBezierTo(Vector2 secondControlPoint, Vector2 thirdControlPoint, Vector2 point)
+        {
+            this.builder.AddBezier(this.currentPoint, secondControlPoint, thirdControlPoint, point);
+            this.currentPoint = point;
+        }
+
+        /// <summary>
+        /// Ends the glyph.
+        /// </summary>
+        /// <returns>The built path</returns>
+        public IPath Build() => this.builder.Build();
+
+        /// <summary>
+        /// Ends the figure.
+        /// </summary>
+        public void CloseFigure() => this.builder.CloseFigure();
+
+        /// <summary>
+        /// Draws a line from the current point  to the <paramref name="point"/>.
+        /// </summary>
+        /// <param name="point">The point.</param>
+        public void LineTo(Vector2 point)
+        {
+            this.builder.AddLine(this.currentPoint, point);
+            this.currentPoint = point;
+        }
+
+        /// <summary>
+        /// Moves to current point to the supplied vector.
+        /// </summary>
+        /// <param name="point">The point.</param>
+        public void MoveTo(Vector2 point)
+        {
+            this.builder.StartFigure();
+            this.currentPoint = point;
+        }
+
+        /// <summary>
+        /// Draws a quadratics bezier from the current point  to the <paramref name="point"/>
+        /// </summary>
+        /// <param name="secondControlPoint">The second control point.</param>
+        /// <param name="point">The point.</param>
+        public void QuadraticBezierTo(Vector2 secondControlPoint, Vector2 point)
+        {
+            this.builder.AddBezier(this.currentPoint, secondControlPoint, point);
+            this.currentPoint = point;
+        }
+
+        /// <summary>
+        /// Sets the translation to be applied to all items to follow being applied to the <see cref="PathDrawer"/>.
+        /// </summary>
+        /// <param name="translation">The translation.</param>
+        public void SetTransform(Matrix3x2 translation) => this.builder.SetTransform(translation);
+
+        /// <summary>
+        /// Sets the origin all subsequent point should be relative to.
+        /// </summary>
+        /// <param name="origin">The origin.</param>
+        public void SetOrigin(Vector2 origin) => this.builder.SetOrigin(origin);
+    }
+}

src/ImageSharp.Drawing/Shapes/Text/BaseGlyphBuilder.cs

@@ -17,19 +17,14 @@ internal class BaseGlyphBuilder : IGlyphRenderer
         /// The builder. TODO: Should this be a property?
         /// </summary>
         // ReSharper disable once InconsistentNaming
-        protected readonly PathBuilder builder;
+        protected readonly PathDrawer drawer;
 #pragma warning restore SA1401 // Fields should be private
-        private readonly List<IPath> paths = new List<IPath>();
-        private Vector2 currentPoint = default;
+        private readonly List<IPath> paths = new();
 
         /// <summary>
         /// Initializes a new instance of the <see cref="BaseGlyphBuilder"/> class.
         /// </summary>
-        public BaseGlyphBuilder()
-        {
-            // glyphs are renderd realative to bottom left so invert the Y axis to allow it to render on top left origin surface
-            this.builder = new PathBuilder();
-        }
+        public BaseGlyphBuilder() => this.drawer = new PathDrawer();
 
         /// <summary>
         /// Gets the paths that have been rendered by this.
@@ -43,14 +38,12 @@ void IGlyphRenderer.EndText()
 
         /// <inheritdoc/>
         void IGlyphRenderer.BeginText(FontRectangle bounds)
-        {
-            this.BeginText(bounds);
-        }
+            => this.BeginText(bounds);
 
         /// <inheritdoc/>
         bool IGlyphRenderer.BeginGlyph(FontRectangle bounds, GlyphRendererParameters paramaters)
         {
-            this.builder.Clear();
+            this.drawer.Clear();
             this.BeginGlyph(bounds);
             return true;
         }
@@ -59,9 +52,7 @@ bool IGlyphRenderer.BeginGlyph(FontRectangle bounds, GlyphRendererParameters par
         /// Begins the figure.
         /// </summary>
         void IGlyphRenderer.BeginFigure()
-        {
-            this.builder.StartFigure();
-        }
+            => this.drawer.StartFigure();
 
         /// <summary>
         /// Draws a cubic bezier from the current point  to the <paramref name="point"/>
@@ -70,57 +61,41 @@ void IGlyphRenderer.BeginFigure()
         /// <param name="thirdControlPoint">The third control point.</param>
         /// <param name="point">The point.</param>
         void IGlyphRenderer.CubicBezierTo(Vector2 secondControlPoint, Vector2 thirdControlPoint, Vector2 point)
-        {
-            this.builder.AddBezier(this.currentPoint, secondControlPoint, thirdControlPoint, point);
-            this.currentPoint = point;
-        }
+            => this.drawer.CubicBezierTo(secondControlPoint, thirdControlPoint, point);
 
         /// <summary>
         /// Ends the glyph.
         /// </summary>
         void IGlyphRenderer.EndGlyph()
-        {
-            this.paths.Add(this.builder.Build());
-        }
+            => this.paths.Add(this.drawer.Build());
 
         /// <summary>
         /// Ends the figure.
         /// </summary>
         void IGlyphRenderer.EndFigure()
-        {
-            this.builder.CloseFigure();
-        }
+            => this.drawer.CloseFigure();
 
         /// <summary>
         /// Draws a line from the current point  to the <paramref name="point"/>.
         /// </summary>
         /// <param name="point">The point.</param>
         void IGlyphRenderer.LineTo(Vector2 point)
-        {
-            this.builder.AddLine(this.currentPoint, point);
-            this.currentPoint = point;
-        }
+            => this.drawer.LineTo(point);
 
         /// <summary>
         /// Moves to current point to the supplied vector.
         /// </summary>
         /// <param name="point">The point.</param>
         void IGlyphRenderer.MoveTo(Vector2 point)
-        {
-            this.builder.StartFigure();
-            this.currentPoint = point;
-        }
+            => this.drawer.MoveTo(point);
 
         /// <summary>
         /// Draws a quadratics bezier from the current point  to the <paramref name="point"/>
         /// </summary>
         /// <param name="secondControlPoint">The second control point.</param>
         /// <param name="point">The point.</param>
         void IGlyphRenderer.QuadraticBezierTo(Vector2 secondControlPoint, Vector2 point)
-        {
-            this.builder.AddBezier(this.currentPoint, secondControlPoint, point);
-            this.currentPoint = point;
-        }
+            => this.drawer.QuadraticBezierTo(secondControlPoint, point);
 
         /// <summary>Called before any glyphs have been rendered.</summary>
         /// <param name="rect">The bounds the text will be rendered at and at whats size.</param>

src/ImageSharp.Drawing/Shapes/Text/GlyphBuilder.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Six Labors.
+// Copyright (c) Six Labors.
 // Licensed under the Apache License, Version 2.0.
 
 using System.Numerics;
@@ -25,7 +25,7 @@ public GlyphBuilder()
         public GlyphBuilder(Vector2 origin)
             : base()
         {
-            this.builder.SetOrigin(origin);
+            this.drawer.SetOrigin(origin);
         }
     }
 }

src/ImageSharp.Drawing/Shapes/Text/PathGlyphBuilder.cs

@@ -45,7 +45,7 @@ protected override void BeginGlyph(FontRectangle rect)
             // Due to how matrix combining works you have to combine this in the reverse order of operation
             // this one rotates the glype then moves it.
             Matrix3x2 matrix = Matrix3x2.CreateTranslation(targetPoint - rect.Location) * Matrix3x2.CreateRotation(point.Angle - Pi, point.Point);
-            this.builder.SetTransform(matrix);
+            this.drawer.SetTransform(matrix);
         }
     }
 }