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Extract all path geometry on a page into a single tibble

Source: R/extract.R
pdf_extract_paths.Rd

One-call helper that opens a document (or accepts an already-open one), enumerates every path object on the requested page, and returns a tibble with one row per path segment carrying both the geometry and the containing path's stroke / fill style and bounding box. This is the function kmextract consumes via the pdfium_native backend.

Usage

pdf_extract_paths(doc, page_num = 1L, password = NULL)

Arguments

doc

Either a character scalar path to a PDF file, or an already-open pdfium_doc returned by pdf_doc_open(). When doc is a character path the document is opened and closed internally.

page_num

One-based page index (default 1).

password

Optional password for encrypted PDFs when doc is a path. Ignored when doc is already an open pdfium_doc.

Value

A tibble with the schema described above.

Details

Returned tibble

Each row describes one path-segment operator (a moveto, lineto, or bezierto), in the order PDFium emits them:

Path identity & segment geometry:

  • path_index - 1-based index of the parent path object on the page

  • segment_index - 1-based segment index within the path

  • segment_type - "moveto", "lineto", "bezierto", or "unknown"

  • x, y - the segment's anchor / endpoint in PDF points

  • close_figure - logical, segment closes the current subpath

Style (constant across all rows of one path):

  • stroke_red, stroke_green, stroke_blue, stroke_alpha - 0-255 channels; NA if no stroke

  • stroke_width - PDF points; NA if no stroke

  • fill_red, fill_green, fill_blue, fill_alpha - 0-255 channels; NA if no fill

Path bounding box (constant across rows of one path):

  • bounds_left, bounds_bottom, bounds_right, bounds_top - PDF points

Attributes

  • page_size - named numeric c(width, height) of the page in PDF points, from pdf_page_size()

  • page_rotation - integer in {0, 90, 180, 270}, from pdf_page_rotation()

  • text_runs - tibble with one row per text object on the page, the output of pdf_text_runs().

Known limitations

  • Bezier control points are not exposed - only segment endpoints. PDFium does not expose them through its public C API; see dev/decisions/ADR-009-defer-bezier-controls.md.

See also

pdf_path_segments(), pdf_path_stroke(), pdf_path_fill(), pdf_obj_bounds()

Examples

fixture <- system.file("extdata", "fixtures", "shapes.pdf",
  package = "pdfium"
)
if (nzchar(fixture)) {
  paths <- pdf_extract_paths(fixture, page_num = 1)
  head(paths)
  attr(paths, "page_size")
  attr(paths, "text_runs")
}
#> # A tibble: 1 × 13
#>   obj_index bounds_left bounds_bottom bounds_right bounds_top font_size text 
#>       <int>       <dbl>         <dbl>        <dbl>      <dbl>     <dbl> <chr>
#> 1         5        129.          103.         159.       114.         1 Hello
#> # ℹ 6 more variables: font_base_name <chr>, font_family <chr>,
#> #   font_weight <int>, font_italic_angle <int>, font_is_embedded <lgl>,
#> #   font_flags <int>