Backport improvements from TechPizzaDev fork. by JimBobSquarePants · Pull Request #366 · SixLabors/ImageSharp.Drawing

JimBobSquarePants · 2025-10-30T11:35:56Z

Prerequisites

I have written a descriptive pull-request title
I have verified that there are no overlapping pull-requests open
I have verified that I am following matches the existing coding patterns and practice as demonstrated in the repository. These follow strict Stylecop rules 👮.
I have provided test coverage for my change (where applicable)

Description

Note: Most of the work here was done by @TechPizzaDev

This PR introduces several improvements and refactorings across the drawing and shapes components of the codebase. The most significant changes include refactoring the ComplexPolygon and EllipsePolygon classes for better performance and maintainability, updating the handling of Bezier and Arc line segments, and making various code quality and style improvements. Below are the most important changes grouped by theme:

Shapes and Geometry Refactoring

Refactored ComplexPolygon to lazily compute bounds and internal paths, reducing upfront computation and improving performance. Introduced helper methods for internal path initialization and bounds calculation.
Refactored EllipsePolygon to inherit from Polygon and removed redundant internal state. Updated transformation logic to work with the new structure, simplifying the class and aligning it with other shape types.
Added new PolygonStroker class designed to replace PolygonOffsetter

Line Segment Improvements

Updated CubicBezierLineSegment and ArcLineSegment to compute EndPoint and Flatten() lazily, improving efficiency and consistency. Added a convenience constructor and a method to retrieve control points for Bezier segments.

Code Quality and Style

Improved pattern and variable naming for clarity and consistency (e.g., opaque constant, use of slice syntax).
Removed unused usings and unnecessary project properties, and made minor code cleanups throughout the codebase.

Miscellaneous Fixes

Fixed a bug in RichTextGlyphRenderer by referencing the correct path list.
Updated the Visual Studio solution file for compatibility with Visual Studio 2022 (v18).

Copilot

Pull Request Overview

This PR includes a comprehensive set of code quality improvements, refactoring, and test infrastructure enhancements. The changes focus on modernizing C# code patterns, improving performance, and adding new drawing robustness test capabilities.

Modernization of C# syntax (range operators, simplified expressions, expression-bodied members)
Performance optimizations (lazy initialization, reduced allocations, better memory usage patterns)
Test infrastructure improvements (new test cases, Linux SkiaSharp support)

Reviewed Changes

Copilot reviewed 51 out of 51 changed files in this pull request and generated 12 comments.

Show a summary per file

File	Description
tests/.../DrawingRobustnessTests.cs	Adds new scaled GeoJSON test and enables previously skipped test
tests/.../TestImageProviderTests.cs	Moves variable declaration to inner scope
tests/.../Issue_28_108.cs	Replaces instance field with inline color conversion
tests/.../FillPatternBrushTests.cs	Removes unnecessary `this.` qualifiers
src/.../BaseGlyphBuilder.cs	Introduces duplicate `paths` and `PathList` fields causing confusion
src/.../ActiveEdgeList.cs	Removes exception throw and adds `readonly` modifier
src/.../ScanEdgeCollection.Build.cs	Extracts local method to private static method
src/.../InternalPath.cs	Fixes spelling typo and modernizes code patterns
src/.../PathCollection.cs	Implements lazy bounds calculation
src/.../ComplexPolygon.cs	Implements lazy initialization for bounds and internal paths
src/.../EllipsePolygon.cs	Refactors to inherit from Polygon, uses lazy flattening
src/.../CubicBezierLineSegment.cs	Implements lazy computation of line points
src/.../PolygonClipper/*	Adds new files and modernizes existing code
.github/workflows/build-and-test.yml	Adds release branch triggers and formatting fixes
Various project files	Adds Linux SkiaSharp native assets support

Comments suppressed due to low confidence (1)

src/ImageSharp.Drawing/Shapes/Text/BaseGlyphBuilder.cs:15

The existing paths field (line 15) is never used and creates confusion with the new PathList property (line 30). Both fields serve the same purpose. The old paths field should be removed, and all code should reference PathList instead.

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Copilot · 2025-10-30T12:24:55Z

src/ImageSharp.Drawing/Shapes/PolygonClipper/ClipperOffset.cs

        PathF points = new(pathPoints.Length);
-        for (int i = 0; i < pathPoints.Length; i++)
-        {
-            points.Add(pathPoints[i]);
-        }
+        points.AddRange(pathPoints);


Creating a new PathF with initial capacity and then calling AddRange is inefficient. Since PathF now inherits from List<PointF> (based on diff in PolygonOffsetter.cs), you can construct it directly: PathF points = new(pathPoints) which will be more efficient.

Copilot · 2025-10-30T12:24:55Z

src/ImageSharp.Drawing/Shapes/ComplexPolygon.cs

+        foreach (IPath p in this.paths)
+        {
+            RectangleF pBounds = p.Bounds;
+
+            minX = MathF.Min(minX, pBounds.Left);
+            maxX = MathF.Max(maxX, pBounds.Right);
+            minY = MathF.Min(minY, pBounds.Top);
+            maxY = MathF.Max(maxY, pBounds.Bottom);
+        }


This foreach loop immediately maps its iteration variable to another variable - consider mapping the sequence explicitly using '.Select(...)'.

Copilot · 2025-10-30T12:24:56Z

src/ImageSharp.Drawing/Shapes/PathCollection.cs

+        foreach (IPath path in this.paths)
+        {
+            RectangleF bounds = path.Bounds;
+            minX = Math.Min(bounds.Left, minX);
+            minY = Math.Min(bounds.Top, minY);
+            maxX = Math.Max(bounds.Right, maxX);
+            maxY = Math.Max(bounds.Bottom, maxY);
        }


This foreach loop immediately maps its iteration variable to another variable - consider mapping the sequence explicitly using '.Select(...)'.

Copilot · 2025-10-30T12:24:56Z

src/ImageSharp.Drawing/Common/Extensions/GraphicsOptionsExtensions.cs

+        const float opaque = 1f;

-        if (options.BlendPercentage != Opaque)
+        if (options.BlendPercentage != opaque)


Equality checks on floating point values can yield unexpected results.

Copilot · 2025-10-30T12:24:56Z

src/ImageSharp.Drawing/Common/Extensions/GraphicsOptionsExtensions.cs

        }

-        if (color.ToScaledVector4().W != Opaque)
+        if (color.ToScaledVector4().W != opaque)


Equality checks on floating point values can yield unexpected results.

Copilot · 2025-10-30T12:24:57Z

src/ImageSharp.Drawing/Shapes/PathCollection.cs

+            RectangleF bounds = path.Bounds;
+            minX = Math.Min(bounds.Left, minX);
+            minY = Math.Min(bounds.Top, minY);
+            maxX = Math.Max(bounds.Right, maxX);
+            maxY = Math.Max(bounds.Bottom, maxY);


Local scope variable 'bounds' shadows PathCollection.bounds.

Suggested change

RectangleF bounds = path.Bounds;

minX = Math.Min(bounds.Left, minX);

minY = Math.Min(bounds.Top, minY);

maxX = Math.Max(bounds.Right, maxX);

maxY = Math.Max(bounds.Bottom, maxY);

RectangleF pathBounds = path.Bounds;

minX = Math.Min(pathBounds.Left, minX);

minY = Math.Min(pathBounds.Top, minY);

maxX = Math.Max(pathBounds.Right, maxX);

maxY = Math.Max(pathBounds.Bottom, maxY);

Copilot · 2025-10-30T12:24:57Z

src/ImageSharp.Drawing/Shapes/PolygonClipper/PolygonStroker.cs

+        this.srcVertices.Add(new VertexDistance(x, y, distance));
+    }
+
+    private void CloseVertexPath(bool closed)


Local scope variable 'closed' shadows PolygonStroker.closed.

Copilot · 2025-10-30T12:24:57Z

src/ImageSharp.Drawing/Shapes/ComplexPolygon.cs

-        => this.internalPaths;
+    {
+        this.InitInternalPaths();
+        return this.internalPaths;


Variable this.internalPaths may be null at this access because it has a nullable type.

Suggested change

return this.internalPaths;

return this.internalPaths!;

Copilot · 2025-10-30T12:24:58Z

src/ImageSharp.Drawing/Shapes/PolygonClipper/VertexDistance.cs

+internal struct VertexDistance
+{
+    private const double Dd = 1.0 / Constants.Misc.VertexDistanceEpsilon;
+    public double X;


Field 'X' can be 'readonly'.

Copilot · 2025-10-30T12:24:58Z

src/ImageSharp.Drawing/Shapes/PolygonClipper/VertexDistance.cs

+{
+    private const double Dd = 1.0 / Constants.Misc.VertexDistanceEpsilon;
+    public double X;
+    public double Y;


Field 'Y' can be 'readonly'.

JimBobSquarePants and others added 30 commits January 27, 2024 21:18

Add hacked AGG stroker

4561a3c

Update PolygonStroker.cs

52c5312

Actually use the width

bed3722

Bad hack to attempt to close path

558de97

Close the polygons on stroking.

7527241

Clip dashed paths

3c8b5d3

Wire up options

319b80d

Cleanup

0a70463

Use latest ImageSharp build

2152cec

Added Blaze to some benchmarks

4fdddc4

Optimized ArrayBuilder

99a6283

Cleaned up PolygonStroker.Accumulate

4569fe7

Reduce allocs in InternalPath

0285e5d

Add methods on PolygonStroker for manually composing (line) paths

4bfa88b

Lazy-init bezier drawing points

0dbfc38

Access list of paths directly in RichTextGlyphRenderer

5703f58

Reduce ILineSegment[] copies for Path classes

0e0d9bf

Derive EllipsePolygon from Polygon

975c453

Lazy-init InternalPaths and Bounds in ComplexPolygon

5448713

Cleanup DrawPolygon

9b91ee4

Improve copying in ClipperOffset

d3ec07c

Merge main into blaze

d819f81

Merge branch 'main' into blaze

70da339

Update ImageSharp.Drawing.csproj

f8a963b

Fix merge conflicts and missing test output

c5c823c

Get solution building.

018962b

Fix benchmark csproj file.

9e8c991

Strip out blaze so we can port back improvements.

72bd892

Remove DebugFast

c40f450

Remove DebugFast

1e06414

JimBobSquarePants added 7 commits October 30, 2025 21:20

Remove bad target framework declaration

539e09d

Merge branch 'blaze' into js/updates-to-backport

f71184b

Remove more bad target framework declarations

4cf8fa3

Merge branch 'blaze' into js/updates-to-backport

b976617

Try matching build process with ImageSharp

ea766fd

Update build-and-test.yml

fdbb390

Try using the no-deps package

9c877af

JimBobSquarePants requested a review from Copilot October 30, 2025 12:20

Copilot AI reviewed Oct 30, 2025

View reviewed changes

JimBobSquarePants merged commit dd8f167 into SixLabors:main Oct 30, 2025
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Backport improvements from TechPizzaDev fork.#366

Backport improvements from TechPizzaDev fork.#366
JimBobSquarePants merged 37 commits intoSixLabors:mainfrom
TechPizzaDev:js/updates-to-backport

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JimBobSquarePants commented Oct 30, 2025

Prerequisites

Description

Shapes and Geometry Refactoring

Line Segment Improvements

Code Quality and Style

Miscellaneous Fixes

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Pull Request Overview

Reviewed Changes

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