Extract and generalize rendering library with ELK-style API

.cspell.yaml

@@ -34,6 +34,42 @@ words:
   - weasyprint
   - netstandard
   - yamlfix
+  # Rendering library technical terms and referenced code identifiers
+  - Skia
+  - SkiaSharp
+  - Noto
+  - webp
+  - rasterizer
+  - rasterizes
+  - Sugiyama
+  - Brandes
+  - Kopf
+  - Hanan
+  - Precomputes
+  - subfolders
+  - Rects
+  - Premul
+  - dasharray
+  - RRGGBB
+  - RRGGBBAA
+  - vdir
+  - hdir
+  - posis
+  - longedge
+  - selfloop
+  - edgerouting
+  - hierarchyhandling
+  - facade
+  - browsable
+  # Non-ASCII terms retained verbatim in extracted source comments
+  - façade
+  - Köpf
+  # DEMA documentation spelling conventions (shared with sibling repositories)
+  - behaviour
+  - colour
+  - colours
+  - initialised
+  - optimised
 
 # Exclude common build artifacts, dependencies, and vendored third-party code
 ignorePaths:
@@ -44,6 +80,7 @@ ignorePaths:
   - "**/third-party/**"
   - "**/3rd-party/**"
   - "**/generated/**"
+  - "src/*/api/**"
   - "**/AGENT_REPORT_*.md"
   - "**/.agent-logs/**"
   - "**/bin/**"

.gitignore

@@ -90,6 +90,9 @@ __pycache__/
 # Generated documentation
 **/generated/
 
+# ApiMark-generated API reference (one api/ folder per library project)
+src/*/api/
+
 # Test results
 TestResults/
 *.trx

.markdownlint-cli2.yaml

@@ -51,5 +51,6 @@ ignores:
   - "**/third-party/**"
   - "**/3rd-party/**"
   - "**/generated/**"
+  - "src/*/api/**"
   - "**/AGENT_REPORT_*.md"
   - "**/.agent-logs/**"

README.md

@@ -9,52 +9,81 @@
 [![Security][badge-security]][link-security]
 [![NuGet][badge-nuget]][link-nuget]
 
-DEMA Consulting rendering library.
+General-purpose diagram layout and rendering for .NET. Describe a diagram as a graph, lay it out
+with a pluggable algorithm, and render it to SVG, PNG, JPEG, or WEBP. The design is inspired by the
+[Eclipse Layout Kernel (ELK)][link-elk]: layout and rendering are configured through an open,
+extensible property system, and new algorithms, renderers, and options are added additively.
 
-## Features
+## Packages
 
-This template demonstrates:
+The library is split into focused packages so consumers take only what they need:
 
-- **Simple Library Structure**: Demo class with example methods
-- **Multi-Platform Support**: Builds and runs on Windows, Linux, and macOS
-- **Multi-Runtime Support**: Targets .NET Standard 2.0, .NET 8, 9, and 10
-- **xUnit v3**: Modern unit testing with xUnit framework version 3
-- **Comprehensive CI/CD**: GitHub Actions workflows with quality checks and builds
-- **Linting Enforcement**: markdownlint, cspell, and yamllint enforced on every CI run
-- **Continuous Compliance**: Compliance evidence generated automatically on every CI run, following
-  the [Continuous Compliance][link-continuous-compliance] methodology
-- **SonarCloud Integration**: Quality gate and security analysis on every build
-- **Documentation Generation**: Automated build notes, user guide, code quality reports,
-  requirements, justifications, and trace matrix
-- **Requirements Traceability**: Requirements linked to passing tests with auto-generated trace matrix
+| Package | Purpose |
+| --- | --- |
+| `DemaConsulting.Rendering` | Layout model: the `LayoutTree` IR, the property system, and the input `LayoutGraph` |
+| `DemaConsulting.Rendering.Abstractions` | SPI: `ILayoutAlgorithm`/`IRenderer`, registries, `Theme`, notation metrics |
+| `DemaConsulting.Rendering.Layout` | Layout algorithms: the layered pipeline and `LayeredLayoutAlgorithm` |
+| `DemaConsulting.Rendering.Svg` | SVG renderer with zero external dependencies |
+| `DemaConsulting.Rendering.Skia` | SkiaSharp raster renderers (PNG, JPEG, WEBP) with an embedded Noto Sans font |
 
-## Installation
+Package dependencies form an acyclic graph: `Abstractions` and `Layout` depend on the model;
+`Svg` and `Skia` depend on the model and `Abstractions`; the model depends on nothing.
 
-Install the library using the .NET CLI:
+## Installation
 
 ```bash
-dotnet add package DemaConsulting.Rendering
+dotnet add package DemaConsulting.Rendering.Layout
+dotnet add package DemaConsulting.Rendering.Svg
 ```
 
 ## Usage
 
 ```csharp
+using System.IO;
 using DemaConsulting.Rendering;
-
-var demo = new Demo();
-var result = demo.DemoMethod("World"); // result = "Hello, World!"
+using DemaConsulting.Rendering.Abstractions;
+using DemaConsulting.Rendering.Layout;
+using DemaConsulting.Rendering.Svg;
+
+// Describe the diagram as a graph of sized boxes and directed edges.
+var graph = new LayoutGraph();
+var a = graph.AddNode("a", width: 80, height: 40);
+var b = graph.AddNode("b", width: 80, height: 40);
+graph.AddEdge("a-b", a, b);
+
+// Lay it out, then render the placed tree to SVG.
+var tree = new LayeredLayoutAlgorithm().Apply(graph, new LayoutOptions());
+using var output = File.Create("diagram.svg");
+new SvgRenderer().Render(tree, new RenderOptions(Themes.Light), output);
 ```
 
-## Documentation
+See the [user guide][link-user-guide] for configuration options and extension points.
+
+## API Reference
+
+Every package ships its full API reference as compact, AI-friendly Markdown in an `api/` folder
+inside the NuGet package, generated from the XML documentation comments by ApiMark. Start at
+`api/api.md` (the index) and drill into the per-namespace and per-type pages for signatures,
+remarks, and usage examples.
 
-Generated documentation includes:
+## Gallery
+
+A [rendering gallery][link-gallery] showcases what the library can produce — every bundled layout
+algorithm, orthogonal edge routing, all three themes, and both the SVG and PNG output paths. Each
+image is generated by the gallery test project directly from the public API, so the gallery doubles
+as an end-to-end rendering smoke test. Regenerate it with `./gallery.ps1`.
+
+## Extensibility
+
+- **New layout algorithms** implement `ILayoutAlgorithm` and register under a new id.
+- **New output formats** implement `IRenderer` with a distinct media type.
+- **New configuration options** are declared as typed `LayoutProperty<T>` keys carried in an open
+  property bag, so adding an option never changes an existing method signature.
+
+## Documentation
 
-- **Build Notes**: Release information and changes
-- **User Guide**: Comprehensive usage documentation
-- **Code Quality Report**: CodeQL and SonarCloud analysis results
-- **Requirements**: Functional and non-functional requirements
-- **Requirements Justifications**: Detailed requirement rationale
-- **Trace Matrix**: Requirements to test traceability
+Generated documentation includes build notes, a user guide, a code quality report, requirements,
+requirement justifications, and a requirements-to-test trace matrix.
 
 ## Contributing
 
@@ -86,5 +115,7 @@ By contributing to this project, you agree that your contributions will be licen
 [link-quality]: https://sonarcloud.io/dashboard?id=demaconsulting_Rendering
 [link-security]: https://sonarcloud.io/dashboard?id=demaconsulting_Rendering
 [link-nuget]: https://www.nuget.org/packages/DemaConsulting.Rendering
-[link-continuous-compliance]: https://github.com/demaconsulting/ContinuousCompliance
+[link-elk]: https://eclipse.dev/elk/
+[link-gallery]: https://github.com/demaconsulting/Rendering/blob/main/docs/gallery/gallery.md
+[link-user-guide]: https://github.com/demaconsulting/Rendering/blob/main/docs/user_guide/introduction.md
 [link-contributing]: https://github.com/demaconsulting/Rendering/blob/main/CONTRIBUTING.md

Rendering.slnx

@@ -1,8 +1,17 @@
 <Solution>
   <Folder Name="/src/">
     <Project Path="src/DemaConsulting.Rendering/DemaConsulting.Rendering.csproj" />
+    <Project Path="src/DemaConsulting.Rendering.Abstractions/DemaConsulting.Rendering.Abstractions.csproj" />
+    <Project Path="src/DemaConsulting.Rendering.Layout/DemaConsulting.Rendering.Layout.csproj" />
+    <Project Path="src/DemaConsulting.Rendering.Svg/DemaConsulting.Rendering.Svg.csproj" />
+    <Project Path="src/DemaConsulting.Rendering.Skia/DemaConsulting.Rendering.Skia.csproj" />
   </Folder>
   <Folder Name="/test/">
     <Project Path="test/DemaConsulting.Rendering.Tests/DemaConsulting.Rendering.Tests.csproj" />
+    <Project Path="test/DemaConsulting.Rendering.Abstractions.Tests/DemaConsulting.Rendering.Abstractions.Tests.csproj" />
+    <Project Path="test/DemaConsulting.Rendering.Layout.Tests/DemaConsulting.Rendering.Layout.Tests.csproj" />
+    <Project Path="test/DemaConsulting.Rendering.Svg.Tests/DemaConsulting.Rendering.Svg.Tests.csproj" />
+    <Project Path="test/DemaConsulting.Rendering.Skia.Tests/DemaConsulting.Rendering.Skia.Tests.csproj" />
+    <Project Path="test/DemaConsulting.Rendering.Gallery/DemaConsulting.Rendering.Gallery.csproj" />
   </Folder>
 </Solution>

docs/design/definition.yaml

@@ -6,7 +6,10 @@ input-files:
   - docs/design/title.txt
   - docs/design/introduction.md
   - docs/design/rendering/rendering.md
-  - docs/design/rendering/demo.md
+  - docs/design/rendering-abstractions/rendering-abstractions.md
+  - docs/design/rendering-layout/rendering-layout.md
+  - docs/design/rendering-svg/rendering-svg.md
+  - docs/design/rendering-skia/rendering-skia.md
 template: template.html
 table-of-contents: true
 number-sections: true