simonebortolin · Nov 9, 2026 · Nov 9, 2026 · Nov 9, 2026 · Nov 9, 2026 · Nov 9, 2026
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -21,8 +21,14 @@ env:
   DOTNET_SKIP_FIRST_TIME_EXPERIENCE: 'true'
   NUGET_PACKAGES: ${{ github.workspace }}/.nuget/packages
   SOLUTION: SharpEquations.slnx
-  LIBRARY_PROJECT: src/SharpEquations/SharpEquations.csproj
+  # the packages, all with the version of BuildVersion.props: the converter, and the equation editor on top of it
+  LIBRARY_PROJECTS: >-
+    src/SharpEquations/SharpEquations.csproj
+    src/SharpEquations.Editing/SharpEquations.Editing.csproj
+    src/SharpEquations.Rendering/SharpEquations.Rendering.csproj
+    src/SharpEquations.Avalonia/SharpEquations.Avalonia.csproj
   TEST_PROJECT: tests/SharpEquations.Tests/SharpEquations.Tests.csproj
+  EDITOR_TEST_PROJECT: tests/SharpEquations.Avalonia.Tests/SharpEquations.Avalonia.Tests.csproj
   FEED_URL: https://nuget.pkg.github.com/${{ github.repository_owner }}/index.json
 
 # Stages: Resolve Version -> Test (Linux, Windows, macOS) -> Pack NuGet
@@ -103,18 +109,21 @@ jobs:
             label: Linux x64
             os: ubuntu-latest
             tfms: net10.0 net8.0
+            editor_tfms: net10.0 net8.0
             dotnet: |
               8.0.x
               10.0.x
           - rid: win-x64
             label: Windows x64
             os: windows-latest
             tfms: net10.0 net481
+            editor_tfms: net10.0
             dotnet: 10.0.x
           - rid: osx-arm64
             label: macOS arm64
             os: macos-latest
             tfms: net10.0
+            editor_tfms: net10.0
             dotnet: 10.0.x
 
     steps:
@@ -150,6 +159,19 @@ jobs:
             echo "::endgroup::"
           done
 
+      # the equation editor (Avalonia 12 has no .NET Framework build: net10.0, and net8.0 where it is installed)
+      - name: Run editor tests
+        shell: bash
+        run: |
+          set -e
+          for TFM in ${{ matrix.editor_tfms }}; do
+            echo "::group::editor $TFM"
+            dotnet run --project "$EDITOR_TEST_PROJECT" -c Release -f "$TFM" --no-build -- \
+              --report-trx --report-trx-filename "${{ matrix.rid }}.editor.$TFM.trx" \
+              --results-directory "$GITHUB_WORKSPACE/TestResults"
+            echo "::endgroup::"
+          done
+
       - name: Upload test results
         if: always()
         uses: actions/upload-artifact@v7
@@ -199,11 +221,13 @@ jobs:
       # The .snupkg symbol package is written next to the .nupkg.
       - name: Pack
         run: |
-          dotnet pack "$LIBRARY_PROJECT" \
-            -c Release \
-            -o artifacts \
-            -p:VersionSuffix="$VERSION_SUFFIX" \
-            -p:ContinuousIntegrationBuild=true
+          for PROJECT in $LIBRARY_PROJECTS; do
+            dotnet pack "$PROJECT" \
+              -c Release \
+              -o artifacts \
+              -p:VersionSuffix="$VERSION_SUFFIX" \
+              -p:ContinuousIntegrationBuild=true
+          done
           ls -lh artifacts
 
       # nuget.org shows the README of the package: fail if it is missing or not declared.

diff --git a/.github/workflows/demo.yml b/.github/workflows/demo.yml
@@ -0,0 +1,69 @@
+name: Web demo
+
+# The equation editor on WebAssembly (samples/SharpEquations.Avalonia.Browser.Demo): built on every pull request,
+# published to GitHub Pages from main, or from any branch when the workflow is run by hand (Settings → Pages → Source:
+# GitHub Actions; a branch other than main must be allowed in Settings → Environments → github-pages).
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+concurrency:
+  group: demo-${{ github.ref }}
+  cancel-in-progress: true
+
+env:
+  DOTNET_NOLOGO: 'true'
+  DOTNET_CLI_TELEMETRY_OPTOUT: 'true'
+  DOTNET_SKIP_FIRST_TIME_EXPERIENCE: 'true'
+  PROJECT: samples/SharpEquations.Avalonia.Browser.Demo/SharpEquations.Avalonia.Browser.Demo.csproj
+
+jobs:
+  build:
+    name: Build the web demo
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v7
+        with:
+          persist-credentials: false
+
+      - name: Setup .NET
+        uses: actions/setup-dotnet@v6
+        with:
+          dotnet-version: '10.0.x'
+
+      - name: Install the WebAssembly workload
+        run: dotnet workload install wasm-tools
+
+      - name: Publish
+        run: dotnet publish "$PROJECT" -c Release -o publish
+
+      # GitHub Pages serves the site from a folder: no Jekyll, and the index for any path that is not a file
+      - name: Prepare the site
+        run: |
+          touch publish/wwwroot/.nojekyll
+          cp publish/wwwroot/index.html publish/wwwroot/404.html
+
+      - uses: actions/upload-pages-artifact@v4
+        with:
+          path: publish/wwwroot
+
+  deploy:
+    name: Deploy to GitHub Pages
+    if: github.event_name == 'workflow_dispatch' || github.event_name == 'push' && github.ref == 'refs/heads/main'
+    needs: build
+    runs-on: ubuntu-latest
+    permissions:
+      pages: write
+      id-token: write
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    steps:
+      - id: deployment
+        uses: actions/deploy-pages@v5
diff --git a/AGENTS.md b/AGENTS.md
@@ -14,8 +14,14 @@ generated parser, on netstandard2.0): keep it so, and keep containers and other
 | `src/SharpEquations/` | The library: `Public/` (the public API), `Internal/` (one folder per format), `Resources/` (XSLT stylesheets) |
 | `src/SharpEquations.RegexPolyfill/` | Build time only: the `[GeneratedRegex]` source generator of the netstandard2.0 build |
 | `src/SharpEquations.XsltGenerator/` | Build time only: the source generator that compiles the XSLT stylesheets of `Resources/` to C# |
+| `src/SharpEquations.Editing/` | The equation editor's model, no user interface: `MathNode` tree, caret, selection, undo, build up and build down |
+| `src/SharpEquations.Rendering/` | The layout of MathML Core over the OpenType MATH table, no user interface: `MathLayoutEngine`, `MathLayout` |
+| `src/SharpEquations.Avalonia/` | The controls for Avalonia: `MathEditBox` (the editor), `MathView`; embeds Libertinus Math |
+| `samples/SharpEquations.Avalonia.Demo/` | A window with the editor (`DemoView`, shared with the web demo) |
+| `samples/SharpEquations.Avalonia.Browser.Demo/` | The same demo on WebAssembly (needs the `wasm-tools` workload, so not in the solution; `.github/workflows/demo.yml` publishes it to GitHub Pages) |
 | `benchmarks/SharpEquations.Benchmarks/` | BenchmarkDotNet benchmarks of reading, writing and converting the corpora |
 | `tests/SharpEquations.Tests/` | TUnit tests, in folders by subject (PublicApi, MathML, Omml, Mtef, UnicodeMath, LaTeX, Property, Regression) |
+| `tests/SharpEquations.Avalonia.Tests/` | TUnit tests of the editor (Editing, Rendering, and the controls in a headless Avalonia session with Skia) |
 | `tests/data/` | Test data and its provenance (`tests/data/README.md`) |
 
 ## Code Style
@@ -82,6 +88,27 @@ init-only record: `Display`, `Strict`, `PreserveFormatting`, `LaTeXFlavor` stand
   UnicodeMath: a slash is a slash, not a fraction, and a bar without its pair is a bar, not an absolute value), and
   written as standard LaTeX or as the LaTeX Word writes (`LaTeXSerializer`).
 
+## The equation editor
+
+`docs/EDITOR.md` is its design. The core does not depend on it: the editor is built on the public API of the core only,
+and Avalonia is a dependency of `SharpEquations.Avalonia` alone (Editing and Rendering target netstandard2.0 and
+net10.0 with no package, as the core).
+
+- `Editing`: an equation being edited is a tree of `MathNode`s (the normalized MathML with a row, `mrow`, in every
+  slot) whose only text not built up is in runs. A run builds up with the nodes before it in its row: tokens are written
+  back as they were typed, structures as placeholders (Yi syllables, which the parsers read as identifiers) put back in
+  the result; this works because UnicodeMath round-trips exactly. Positions are paths of child indexes; offsets in runs
+  are code points.
+- `Rendering`: `Layout/Engine.cs` lays out after MathML Core with the constants of the MATH table; the ink boxes of the
+  glyphs come from the outlines of the font (`OpenType/GlyphOutlines.cs`: `glyf`, or the CFF charstrings), never from
+  the rasterizer, and the tables from a copy of the font file (`OpenType/FontFile.cs`).
+- `Avalonia`: `AvaloniaMathFont` reads the font file once with `TryGetStream` and asks Avalonia for its glyph typeface
+  only to draw, each time (`MathFonts.Register` registers the embedded font again with a new font manager: a headless
+  test session gives each test one, and a glyph typeface of the old one is released); the tests that use the headless
+  session are `[NotInParallel("headless")]`, since showing a window or typing runs the jobs of the dispatcher.
+- The core's `EquationCommands` (public) lists the control words of UnicodeMath and the commands of LaTeX with their
+  symbols, for the completion of the editor; `PublicApi/EquationCommandsTests` checks that the parsers read them.
+
 ## Building and Testing
 
 ```bash
@@ -94,12 +121,17 @@ net481 (Windows, where the test project targets net10.0 and net481). The 738 exa
 `tests/data/unicodemath/` test the UnicodeMath port, and `Property/RoundTripPropertyTests` checks, for all of them and
 for the equations of Word documents (`tests/data/omml/`), that an equation written in its own format (UnicodeMath,
 OMML) reads back to the same equation, and that one written in another format (standard LaTeX, Word's LaTeX, OMML)
-loses only the first time what that format cannot hold. Keep these at 100%.
+loses only the first time what that format cannot hold. Keep these at 100%. For the editor, an equation of the corpus
+loaded in the editor, or built down to linear text and up again, is the same equation (100%); typed one character at a
+time it is the equation of the whole text for 93% of the corpus (`Editing/CorpusTests`) and for 90% of the LaTeX of
+latex2mathml (`Editing/RepositoryCorporaTests`), which a change must not lower. The public API of the editor's
+packages is tracked in their `PublicAPI.*.txt`, as that of the core.
 
 ## Releases
 
 `.github/workflows/ci.yml`, the same pipeline as SharpMediaInfo and Letra200bSharp: it tests on Linux (net10.0, net8.0),
-Windows (net10.0, net481) and macOS (net10.0), packs, publishes a `pr-<N>-…` pre-release for each pull request (deleted on close by
+Windows (net10.0, net481) and macOS (net10.0), packs the four packages (`SharpEquations` and the editor's `SharpEquations.Editing`, `.Rendering`, `.Avalonia`, with
+one version), publishes a `pr-<N>-…` pre-release for each pull request (deleted on close by
 `prerelease-cleanup.yml`) and, on `main`, tags `v<VersionPrefix>` of `BuildVersion.props`, creates the GitHub release
 and pushes the package to GitHub Packages and nuget.org (Trusted Publishing, repository variable `NUGET_USER`). A change
 that should release bumps `VersionPrefix`; one that should not says `[no-new-version]` in its commit message.
diff --git a/Directory.Packages.props b/Directory.Packages.props
@@ -4,6 +4,13 @@
     <CentralPackageTransitivePinningEnabled>true</CentralPackageTransitivePinningEnabled>
   </PropertyGroup>
   <ItemGroup>
+    <PackageVersion Include="Avalonia" Version="12.1.4" />
+    <PackageVersion Include="Avalonia.Browser" Version="12.1.4" />
+    <PackageVersion Include="Avalonia.Desktop" Version="12.1.4" />
+    <PackageVersion Include="Avalonia.Fonts.Inter" Version="12.1.4" />
+    <PackageVersion Include="Avalonia.Headless" Version="12.1.4" />
+    <PackageVersion Include="Avalonia.Skia" Version="12.1.4" />
+    <PackageVersion Include="Avalonia.Themes.Fluent" Version="12.1.4" />
     <PackageVersion Include="BenchmarkDotNet" Version="0.15.8" />
     <PackageVersion Include="Microsoft.SourceLink.GitHub" Version="10.0.401" PrivateAssets="All" />
     <PackageVersion Include="Microsoft.CodeAnalysis.CSharp" Version="4.8.0" />

diff --git a/NOTICE b/NOTICE
@@ -300,3 +300,12 @@ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 
+----------------------------------------------------------------------------
+src/SharpEquations.Avalonia/Assets/Fonts/LibertinusMath-Regular.otf
+
+Libertinus Math 7.040, from the Libertinus fonts, https://github.com/alerque/libertinus,
+the math font that SharpEquations.Avalonia embeds for the systems without Cambria Math.
+Copyright © 2012-2021 The Libertinus Project Authors, with Reserved Font Name
+"Linux Libertine", "Biolinum", "STIX Fonts". Licensed under the SIL Open Font License,
+Version 1.1: src/SharpEquations.Avalonia/Assets/Fonts/OFL.txt (LibertinusMath-OFL.txt in
+the package).
diff --git a/README.md b/README.md
@@ -49,6 +49,46 @@ stream of its OLE object (`Equation.Parse(bytes, EquationFormat.Mtef)`); reading
 Equations compare by their normalized MathML: an equation written in its own format (UnicodeMath, OMML) reads back to
 the same equation, and one written in another format loses only what that format cannot hold.
 
+## Equation editor for Avalonia
+
+`SharpEquations.Avalonia` is a real-time equation editor in the manner of the `RichEditBox` of WinUI in math mode and of
+the equations of Word: UnicodeMath or LaTeX typed at the caret builds up into the equation when a space or an operator
+ends an argument (`a/b␣` becomes a fraction, `\alpha␣` α), the caret moves through the slots of the structures, and the
+equation is read and written as MathML or as an `Equation`.
+
+```xml
+<sharp:MathEditBox xmlns:sharp="using:SharpEquations.Avalonia" FontSize="28" InputFormat="UnicodeMath" Equation="{Binding Equation}" />
+```
+
+```csharp
+var editor = new MathEditBox { InputFormat = EquationFormat.LaTeX };
+editor.EquationChanged += (_, e) => Console.WriteLine(e.Equation?.ToString(EquationFormat.MathML));
+string mathML = editor.GetMath();        // as RichEditTextDocument.GetMath
+editor.SetMath(mathML);                  // as RichEditTextDocument.SetMath
+editor.ViewMode = MathViewMode.Linear;   // the equation as one line of UnicodeMath (Ctrl+Shift+L)
+editor.EquationNumber = "(1)";           // at the right of the line, as #(1) or \tag{1}
+string latex = editor.GetSelectedText(EquationFormat.LaTeX)!;
+editor.CopyTextFormat = EquationFormat.MathML;   // Ctrl+C pastes as an equation into Word
+editor.Editor.InsertLineBreak();         // Shift+Enter: lines aligned at &
+editor.Editor.InsertTableRow();          // and columns, in the matrix of the caret
+```
+
+Typing `\` and the start of a command opens a floating bar at the caret with its completions
+(`EquationCommands.Complete("al", EquationFormat.UnicodeMath)` gives them from the core); the bar also offers structures
+for the selection, the commands of a table and quick symbols.
+
+The packages are `SharpEquations.Avalonia` (the controls), `SharpEquations.Rendering` and `SharpEquations.Editing`, with
+the version of `SharpEquations`.
+
+`MathView` shows an equation without editing it. Both lay out MathML after MathML Core with the OpenType MATH table of
+a math font: Cambria Math on Windows, and Libertinus Math (SIL Open Font License), embedded, elsewhere. The editor is
+three projects, so that the core keeps no dependency: `SharpEquations.Editing` (the editing model, no user interface),
+`SharpEquations.Rendering` (the layout, no user interface) and `SharpEquations.Avalonia` (the controls). The design is in
+[docs/EDITOR.md](docs/EDITOR.md); `samples/SharpEquations.Avalonia.Demo` is a window with the editor and its MathML,
+UnicodeMath and LaTeX, and `samples/SharpEquations.Avalonia.Browser.Demo` the same demo in the browser, on WebAssembly
+(published to GitHub Pages from `main`; to run it locally: `dotnet workload install wasm-tools`, then
+`dotnet run --project samples/SharpEquations.Avalonia.Browser.Demo`).
+
 ## Architecture
 
 How the conversions work, format by format, and how round trips are kept exact: [docs/ARCHITECTURE.md](docs/ARCHITECTURE.md).
@@ -67,7 +107,7 @@ its README).
 ## Releases
 
 CI (`.github/workflows/ci.yml`) tests every push and pull request on Linux (.NET 10 and .NET 8), Windows (.NET 10 and
-.NET Framework 4.8.1) and macOS (.NET 10), and packs the NuGet package. The release version is `VersionPrefix` in `BuildVersion.props`: bump it, and merging to
+.NET Framework 4.8.1) and macOS (.NET 10), and packs the NuGet packages (the converter and the three of the editor, with one version). The release version is `VersionPrefix` in `BuildVersion.props`: bump it, and merging to
 `main` tags `vX.Y.Z`, creates the GitHub release with the package attached, and publishes it to GitHub Packages and to
 nuget.org (with [Trusted Publishing](https://learn.microsoft.com/nuget/nuget-org/trusted-publishing): the repository
 variable `NUGET_USER` names the nuget.org account; without it nuget.org is skipped). A push that keeps the version on

diff --git a/SharpEquations.slnx b/SharpEquations.slnx
@@ -1,4 +1,11 @@
 <Solution>
+  <Folder Name="/demo/" Id="5d20aa90-6969-d8bd-9dcd-8634f4692fda">
+    <!-- built by demo.yml only: it needs the wasm-tools workload -->
+    <Project Path="samples/SharpEquations.Avalonia.Browser.Demo/SharpEquations.Avalonia.Browser.Demo.csproj">
+      <Build Project="false" />
+    </Project>
+    <Project Path="samples/SharpEquations.Avalonia.Demo/SharpEquations.Avalonia.Demo.csproj" />
+  </Folder>
   <Folder Name="/Solution Items/">
     <File Path="AGENTS.md" />
     <File Path="BuildVersion.props" />
@@ -9,14 +16,18 @@
     <File Path="README.md" />
   </Folder>
   <Folder Name="/src/">
-    <Project Path="src/SharpEquations/SharpEquations.csproj" />
+    <Project Path="src/SharpEquations.Avalonia/SharpEquations.Avalonia.csproj" />
+    <Project Path="src/SharpEquations.Editing/SharpEquations.Editing.csproj" />
     <Project Path="src/SharpEquations.RegexPolyfill/SharpEquations.RegexPolyfill.csproj" />
+    <Project Path="src/SharpEquations.Rendering/SharpEquations.Rendering.csproj" />
     <Project Path="src/SharpEquations.XsltGenerator/SharpEquations.XsltGenerator.csproj" />
+    <Project Path="src/SharpEquations/SharpEquations.csproj" />
   </Folder>
   <Folder Name="/benchmarks/">
     <Project Path="benchmarks/SharpEquations.Benchmarks/SharpEquations.Benchmarks.csproj" />
   </Folder>
   <Folder Name="/tests/">
+    <Project Path="tests/SharpEquations.Avalonia.Tests/SharpEquations.Avalonia.Tests.csproj" />
     <Project Path="tests/SharpEquations.Tests/SharpEquations.Tests.csproj" />
   </Folder>
 </Solution>