OfficeIMO.Word.Html 1.0.35

OfficeIMO.Word.Html

Bidirectional HTML conversion for OfficeIMO.Word.

What It Does Today

• Converts HTML into WordDocument with headings, paragraphs, inline formatting, links, images, SVG, lists, tables, captions, form controls, notes, headers, footers, and sections.
• Converts WordDocument back to HTML with document metadata, optional custom property metadata, optional headers and footers, optional comments, paragraph/run styles, optional list definition CSS, lists, tables, images, SVG, footnotes, endnotes, disabled form controls, and optional default CSS.
• Preserves document-level language metadata between HTML lang attributes and WordDocument.Settings.Language.
• Supports inline CSS, embedded stylesheet content, external stylesheet paths, remote stylesheet loading through a caller-provided HttpClient, stylesheet URI scheme/host policy controls, stylesheet content-type validation, aggregate CSS byte limits, and common CSS page-break declarations.
• Reuses parsed stylesheet rules by CSS content hash, while changed local or remote stylesheet content is parsed as fresh input.
• Supports image embedding, external image links, data URI images, resource timeouts, optional per-image and total image byte limits, declared image content-type validation, and image URI scheme/host policy controls.
• Supports optional HTML node, HTML depth, per-stylesheet CSS byte, aggregate CSS byte, and table-cell limits for safer conversion of large or hostile inputs.
• Provides named import profiles through HtmlToWordOptions.CreateOfficeIMOProfile(), CreateUntrustedHtmlProfile(), and CreateTrustedDocumentProfile(), plus Clone() for reusable option templates.
• Reports HTML import diagnostics through HtmlToWordOptions.Diagnostics and DiagnosticHandler when content is skipped, degraded, or not mapped, such as image load failures, raw HTML comments, disabled or invalid stylesheet links, stylesheet policy/HTTP/transport/timeout failures, and unsupported CSS declarations or values.
• Can opt in to import non-empty raw HTML comments as native Word comments with configurable author and initials metadata.
• Skips unsupported embedded media/widget elements such as iframe, object, embed, video, audio, and canvas with diagnostics instead of importing fallback text as document content.
• Can emit opt-in accessibility diagnostics for missing image alternate text, weak or empty link text, skipped heading levels, and data tables without header cells.
• Lets callers choose unsupported CSS behavior with HtmlToWordOptions.UnsupportedCssHandling: ignore, warn by default, or stop conversion with HtmlUnsupportedCssException.
• Maps common document-table styling, including table/cell widths, borders, padding, horizontal and vertical alignment, captions, column groups, header/footer row groups, HTML cellspacing, and CSS border-spacing.
• Imports text and visible value-bearing inputs, dates, text areas, meter/progress values, single-select dropdowns, named radio groups, multi-select values, datalist-backed combo boxes, and checkbox markers into Word content controls where Word has a practical equivalent.
• Targets netstandard2.0, net8.0, net10.0, and net472 on Windows.

The current supported feature set is tracked in Docs/officeimo.word-html-support-matrix.md.

Entry Points

using OfficeIMO.Word.Html;

WordDocument document = html.LoadFromHtml(new HtmlToWordOptions());
string roundTrip = document.ToHtml(new WordToHtmlOptions {
    IncludeDefaultCss = true,
    IncludeRunColorStyles = true,
    IncludeRunHighlightStyles = true,
    ExportEndnotes = true,
    ExportComments = true,
    ExportHeadersAndFooters = true,
    IncludeTableColumnGroups = true
});

HTML can also be appended to an existing body, header, or footer with the AddHtmlToBody, AddHtmlToHeader, and AddHtmlToFooter extension methods.

Import Profiles

var safeOptions = HtmlToWordOptions.CreateUntrustedHtmlProfile();
safeOptions.MaxHtmlNodes = 5000;
safeOptions.DiagnosticHandler = diagnostic => Console.WriteLine($"{diagnostic.Code}: {diagnostic.Source}");

WordDocument safeDocument = html.LoadFromHtml(safeOptions);

var trustedOptions = HtmlToWordOptions.CreateTrustedDocumentProfile();
trustedOptions.AllowedStylesheetHosts.Add("cdn.example.com");

WordDocument trustedDocument = trustedHtml.LoadFromHtml(trustedOptions);

• CreateOfficeIMOProfile() preserves the default compatibility-oriented behavior.
• CreateUntrustedHtmlProfile() keeps external document resources offline by default, enables accessibility diagnostics, and applies bounded HTML, CSS, image, and table limits.
• CreateTrustedDocumentProfile() enables document-provided stylesheet links for known-good HTML while retaining the current resource validation defaults.
• Clone() copies configuration values, allow-lists, configured stylesheets, and callbacks while starting with an empty diagnostics collection.

Roadmap

The current plan for making this the market-leading HTML and Word conversion surface is tracked in Docs/officeimo.word-html-roadmap.md.