Devolutions.AvaloniaControls.SpreadsheetEditor 2026.8.14

Devolutions.AvaloniaControls.SpreadsheetEditor

An Excel-like spreadsheet editor control for Avalonia UI. It uses a custom grid (not the Avalonia DataGrid) so cells can merge and host rich content, and it ships with:

• A custom rendering grid with cell merging, frozen headers, and drag-to-select.
• 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, infinite rows/columns, undo/redo, clipboard, and printing (cross-platform PDF export + HTML preview).

Requirements

This control depends on the commercial Avalonia Accelerate packages (Avalonia.Controls.RichTextEditor, Avalonia.Controls.Charts). You must supply your own Avalonia UI license key (via the <AvaloniaUILicenseKey> MSBuild item or the standard licensing mechanism) in the application that consumes this control. See https://avaloniaui.net/.

Setup

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>

Usage

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

The control exposes an integration API similar to Avalonia's RichTextEditor: IsReadOnly, Undo()/Redo() + CanUndo/CanRedo, SelectAll(), SelectedRange, and the ContentChanged, SelectionChanged, and IsReadOnlyChanged events. Load data via LoadSheet, LoadWorkbook, LoadCellData, or LoadRows; read it back with GetCellData/GetRows.

Excel (.xlsx) files — included

Excel read/write is built in (backed by ClosedXML plus OOXML chart parsing), so no extra package is needed:

using System.IO;

// Load an .xlsx (every worksheet → one tab) into the control:
await using (FileStream fs = File.OpenRead("book.xlsx"))
    editor.OpenXlsx(fs);

// Save the active sheet back to .xlsx:
await using (FileStream fs = File.Create("out.xlsx"))
    editor.SaveXlsx(fs);

For headless / non-UI use, the readers/writers are also available directly via SpreadsheetEditor.Controls.Xlsx.XlsxFile (ReadWorkbook/Read/Write) returning the library's SheetData model.

Printing (cross-platform)

Avalonia has no built-in print API, so the control offers two portable routes — both work on Windows, macOS, and Linux:

using System.IO;

// 1. PDF export (recommended). Self-contained, rendered with SkiaSharp — no browser needed.
//    Cell fills, borders, alignment, and rich run formatting are preserved; the sheet is scaled
//    to fit the page width and rows flow across pages.
await using (FileStream fs = File.Create("sheet.pdf"))
    editor.ExportPdf(fs);

editor.SavePdf("sheet.pdf");   // convenience overload for a file path
editor.PrintPdf();             // writes a temp PDF and sends it to the printer (see below)

// 2. HTML preview. Opens the sheet in the default browser, where the user prints (or saves a PDF)
//    via the browser's own print dialog.
string html = editor.ExportHtml();
editor.Print();

PrintPdf() sends the PDF straight to the printer: on Windows via the shell "print" verb (the registered PDF handler prints to the default printer), and on Linux/macOS via lpr (the default CUPS printer). Print() instead opens the HTML in the default browser (ShellExecute/open/xdg-open) for browser-driven printing. Images are not drawn into the PDF/HTML (data only); charts are included in the PDF.