AvaloniaControls.SpreadsheetEditor

An Excel-like spreadsheet editor control for Avalonia UI, published as the NuGet package Devolutions.AvaloniaControls.SpreadsheetEditor.

Important

This control requires a commercial Avalonia UI (Accelerate) license. It builds on the paid Avalonia.Controls.RichTextEditor and Avalonia.Controls.Charts packages, which need a valid license key at build time. The source is MIT-licensed, but you cannot build or run the control (or an app that consumes it) without your own Avalonia license. See Requirements.

It uses a custom rendering grid (not the Avalonia DataGrid) so cells can merge and host rich content:

• Custom grid with cell merging, frozen headers, drag-to-select, and infinite rows/columns.
• Rich in-cell editing (bold / italic / underline / strikethrough, fonts, colors, alignment).
• A hand-rolled = formula engine (arithmetic, ranges, SUM/AVERAGE/IF/…, named ranges, live recalc).
• Charts, multi-sheet tabs, undo/redo, clipboard, a symbol picker, and printing (cross-platform PDF export, a native Windows print dialog, and lpr/CUPS on Linux/macOS).
• An integration API modeled on Avalonia's RichTextEditor (IsReadOnly, Undo/Redo, CanUndo/CanRedo, SelectAll, SelectedRange, and ContentChanged / SelectionChanged / IsReadOnlyChanged events).

Repository layout

Path	Description
SpreadsheetEditor.Controls/	The reusable control library (the NuGet package).
SampleApp/	A sample desktop host app demonstrating the control (open/save .xlsx, print, …).
Common.props, Directory.Build.props	Shared build settings, dependency versions, and license handling.

Requirements

This control depends on the commercial Avalonia Accelerate packages (Avalonia.Controls.RichTextEditor, Avalonia.Controls.Charts). Building it — and any app that consumes it — requires a valid Avalonia UI license key. See https://avaloniaui.net/.

Building locally

Provide your Avalonia license key via a git-ignored .env file at the repository root:

AVALONIA_LICENSE_KEY=your-key-here

(Alternatively set an AVALONIA_LICENSE_KEY environment variable.) Then:

dotnet build SpreadSheetEditor.sln
dotnet run --project SampleApp        # launch the sample app
dotnet pack SpreadsheetEditor.Controls -c Release   # build the NuGet package

Localization

The editor uses .NET .resx resources, the same culture-based approach as RDM's UIResources/MsgResources. The English source text and keys are in SpreadsheetEditor.Controls/Localization/SpreadsheetStrings.resx; localized files use the same base name plus a culture suffix. The supported culture files match RDM: cs, de, es, fr, hu, it, ja, nb, nl, pl, pt, ru, sv, tr, uk, zh-Hans, and zh-Hant-TW.

RDM only needs to set the normal .NET CultureInfo.CurrentUICulture before creating the control; the editor has no dependency on RDM assemblies. XAML uses {loc:Loc Key} and C# uses EditorText.Get(EditorString.Key) or EditorText.Format(EditorString.Key, value). Missing locale entries fall back to the English resource. The XAML lookups are static, like RDM's UIRes, so recreate the editor after changing the UI language during a session.

For a quick demonstration, run the sample with dotnet run --project SampleApp -- --culture=fr. All 17 locale files have translations for every key. Existing RDM wording was reused where possible; editor-specific wording was machine-drafted and should be reviewed by native speakers before a production release. Add new UI strings to the neutral .resx and the matching EditorString enum, then translate them in each locale file. Formula identifiers, workbook content, file-format tokens, and user-entered data are intentionally not translated.

Installation

Install the NuGet package into your Avalonia project:

dotnet add package Devolutions.AvaloniaControls.SpreadsheetEditor

Or add a <PackageReference> to your .csproj:

<PackageReference Include="Devolutions.AvaloniaControls.SpreadsheetEditor" Version="2026.8.7" />

Note

A valid Avalonia UI (Accelerate) license is required to build and run — see Requirements.

Using the control

Add the required theme includes to your App.axaml (alongside FluentTheme):

<Application.Styles>
    <FluentTheme />
    <StyleInclude Source="avares://Avalonia.Controls.RichTextEditor/Themes/Default.axaml" />
    <StyleInclude Source="avares://Avalonia.Controls.Charts/Themes/Default.axaml" />
</Application.Styles>

Then place the control:

xmlns:se="clr-namespace:SpreadsheetEditor.Controls;assembly=SpreadsheetEditor.Controls"
...
<se:SpreadsheetEditor x:Name="Editor" />

License

MIT — see LICENSE.