Map between PDFium's "all characters" and "extractable text" indices

PDFium's text page surfaces two parallel views of the page's text: the full character list (positioned glyphs including PDFium-synthesised whitespace between them), and the extractable text string (only characters that appear in pdf_doc_text()'s output). These helpers translate between the two indexing systems.

Usage

pdf_text_index_from_char(page, char_index, page_num = 1L)

pdf_text_char_from_text_index(page, text_index, page_num = 1L)

Arguments

page

A pdfium_page from pdf_page_load(), or a pdfium_doc.

char_index

One-based character index (matches pdf_text_chars()$char_index).

page_num

One-based page index. Only used when page is a pdfium_doc. Ignored otherwise.

text_index

Zero-based offset into the extractable text string.

Value

An integer scalar — the converted index, or NA when the character has no counterpart in the other indexing system.

Details

pdf_text_index_from_char() converts a 1-based char_index (matches pdf_text_chars()'s char_index column) into the 0-based position in the extractable text string, or NA if the character has no extractable-text counterpart.

pdf_text_char_from_text_index() does the reverse: given a 0-based text-string index, returns the 1-based char_index.

Wraps FPDFText_GetTextIndexFromCharIndex / FPDFText_GetCharIndexFromTextIndex.

See also

pdf_text_chars(), pdf_doc_text(), pdf_text_search().