awaforge

pdfMarkedContent

AGPL-3.0-onlyRelease 2L4

Marked-content sequences — ISO 32000-2 §14.6 — bridge between content streams and the struct tree.

Module pdfMarkedContent | Source packages/front/office/pdf/src/tagged/markedContent.js | Deps pdfErrors, pdfParser, pdfParentTree | Worker-safe yes

The BMC / BDC / EMC operators (§14.6.1) delimit marked sequences in a content stream. BDC may carry an MCID in its properties dict, used as the key into the ParentTree (§14.7.5) to link content back to a StructElement. This module provides extractMcids (walks an ops list already typed by pdfContentStream) and resolveMcidToStruct (full resolution via pdfParentTree.lookupParent).

Resolve

const mc = runtime.resolve('pdfMarkedContent');
// Returns: { extractMcids, resolveMcidToStruct }

API

Method Signature Returns
extractMcids (opsList) => Array<{ tag, start, end, mcid, properties }> Linear walk, tracks the BMC/BDC/EMC stack; start/end are inclusive op-index positions, sorted by start.
resolveMcidToStruct (pageDict, mcid, parentTree, resolveRef) => PdfObject | null Lookup via pdfParentTree.lookupParent, indexed by the page's /StructParents then mcid.

Examples

Extraction from a content stream

const ops = runtime.resolve('pdfContentStream').parseContentStream(streamBytes);
const mc  = runtime.resolve('pdfMarkedContent');
const seqs = mc.extractMcids(ops);
// [{ tag: 'P', start: 3, end: 9, mcid: 0, properties: {…} }, …]

Resolution to the struct elem

const elemRef = mc.resolveMcidToStruct(pageDict, 0, parentTree, resolveRef);

Errors

Code Class When
pdf/tagged/marked-content/bad-ops ParseError Argument is not an array.
pdf/tagged/marked-content/unmatched-emc ParseError EMC without a matching BMC/BDC.
pdf/tagged/marked-content/unterminated ParseError Non-empty stack at end of stream.
pdf/tagged/marked-content/bad-tag ParseError BMC/BDC tag is not a name.
pdf/tagged/marked-content/bad-page ParseError Page argument is not a dict.
pdf/tagged/marked-content/bad-entry ParseError ParentTree entry for the page is not an array.

See also