SFDT to PDF

This page documents the pure-Dart path used when docx_editor or a backend service converts Syncfusion Document Text (SFDT) JSON into a PDF.

High-Level Flow

SFDT JSON string or map
  -> SfdtReader.read / readMap
  -> DocxBuiltDocument
  -> PdfExporter.exportToBytes
  -> PdfLayoutEngine
  -> PdfLayoutDocument / paginated pages
  -> PdfDocumentWriter
  -> PDF bytes

No Syncfusion DocumentEditor web service and no .NET process are required for this path.

Minimal Example

final document = const SfdtReader().read(sfdtJson);
final pdfBytes = PdfExporter(
  creationDate: DateTime.utc(2026, 6, 20),
  strictFonts: true,
).exportToBytes(document);

What SfdtReader Preserves

SfdtReader converts Syncfusion JSON into DocxBuiltDocument.

SFDT area	Model result
sections and blocks	DocxSectionDef, DocxSectionBreakBlock, body nodes
paragraphs and runs	DocxParagraph, DocxText, tabs, breaks, fields
tables	DocxTable, rows, cells, borders, margins, spans, widths
lists	DocxList and numbering data
headers and footers	section furniture
images	inline or block image nodes with relationship-backed bytes where present
comments	DocxComment and comment anchors where modeled
revisions	DocxRunRevision and revision metadata
protection	protection type, hash, salt, spin count, enforcement
custom XML	DocxCustomXml parts
document defaults	default run style through DocxTheme

What PdfExporter Does

PdfExporter.exportToBytes:

1. creates a PdfDocumentWriter;
2. reads w:defaultTabStop from settings XML, falling back to the OOXML default;
3. splits the document into sections;
4. appends authored footnotes to the final section using the current simplified end-of-document behavior;
5. builds a PdfLayoutEngine for each section using page geometry, margins, headers, footers, columns, document grid, and font configuration;
6. paginates content into pages or builds a PdfLayoutDocument for multi-column layout;
7. renders page content, furniture, watermarks, images, and text streams;
8. writes the PDF object graph and returns bytes.

Export Configuration

Option	Purpose
pageWidth, pageHeight	Default page size when the document does not override it.
marginTop, marginBottom, marginLeft, marginRight	Default margins.
fontSize	Default body font size. The default is 11pt to match Word defaults.
compressContent	Compress PDF content streams.
watermark	Optional diagonal watermark on every page.
watermarkColorHex	Watermark fill color.
watermarkOpacity	Watermark alpha in the PDF graphics state.
creationDate	Fixed PDF creation timestamp for deterministic output.
strictFonts	Throw when a glyph cannot be represented by registered fonts.
registerFont	Add custom font bytes for rendering.

Deterministic Rendering

For controlled workflows, pass a trusted UTC creationDate and enable strictFonts. This avoids client-clock leaks and prevents silent glyph loss in issued PDFs.

final exporter = PdfExporter(
  creationDate: trustedIssuedAt,
  strictFonts: true,
  watermark: 'CONTROLLED',
);

exporter.registerFont('Arial', arialBytes);
final bytes = exporter.exportToBytes(document);

Known Simplification

Footnotes are currently appended to the end of the document with matching markers. They are not yet laid out at the bottom of each page because that would require reserving variable page-bottom space during pagination.