RTF Documents

OfficeIMO.Rtf provides both an editable semantic document and a source-preserving syntax tree. Use the semantic model for normalized authoring and the lossless editor when untouched control words, destinations, binary data, or trailing bytes must survive exactly.

Install and create

dotnet add package OfficeIMO.Rtf

using OfficeIMO.Rtf;

RtfDocument document = RtfDocument.Create();
document.AddParagraph().AddText("Quarterly report").SetBold();
document.AddParagraph("Prepared by OfficeIMO");
File.WriteAllText("report.rtf", document.ToRtf());

Edit semantically

RtfDocument document = RtfDocument.Load("input.rtf").Document;

document.InsertParagraph(0, "Confidential");
document.ReplaceText("Contoso Ltd.", "Contoso Europe");
document.ReplaceBookmarkText("CustomerName", "Contoso Europe");
File.WriteAllText("updated.rtf", document.ToRtf());

Semantic saves normalize the document. For surgical edits that retain untouched syntax, use EditLossless():

RtfLosslessEditor editor = RtfDocument.Load("input.rtf").EditLossless();
editor.ReplaceText("Old text", "New text");
editor.SetInfo(RtfDocumentInfoField.Title, "Updated title");
editor.SaveLossless("updated-lossless.rtf");

Process uploaded RTF safely

RtfReadOptions options = RtfReadOptions.CreateUntrustedProfile();
using FileStream input = File.OpenRead("upload.rtf");

RtfReadResult read = await RtfDocument.LoadAsync(
    input,
    options,
    cancellationToken: cancellationToken);

The untrusted profile limits input, group depth/count, tokens, text, binary payloads, images, objects, and semantic blocks. It disables embedded-object and file-reference materialization and restricts semantic hyperlinks to web and mail schemes. The engine does not fetch external resources.

Convert with an explicit fidelity policy

Focused adapters connect RTF to Word, Markdown, HTML, PDF, and Reader. Each adapter reports preserved, flattened, omitted, blocked, and failed content through RtfConversionReport.

Install the adapter for the destination you need. This example uses OfficeIMO.Rtf.Markdown:

dotnet add package OfficeIMO.Rtf.Markdown

using OfficeIMO.Rtf;
using OfficeIMO.Rtf.Markdown;

RtfReadResult read = RtfDocument.Load("input.rtf");
RtfConversionResult<string> conversion =
    read.Document.ToMarkdownResult();

var report = new RtfConversionReport();
report.AddReadDiagnostics(read.Diagnostics, "input.rtf");
report.Merge(conversion.Report);
report.RequireNoLoss();

File.WriteAllText("output.md", conversion.Value);

Use RequireNoLoss() for strict archival or compliance workflows. In permissive workflows, inspect each diagnostic and accept only the tradeoffs appropriate for the destination.

See the RTF support matrix and the content publishing patterns.