Font ascent and descent for a text page-object's font

Returns the font's vertical metrics — ascent (the maximum height above the baseline) and descent (the maximum depth below the baseline, conventionally a negative number) — at the requested font_size. Useful for laying out text with consistent line heights and for converting between PDF text coordinates (baseline-relative) and bounding-box coordinates.

Usage

pdf_text_font_metrics(obj, font_size = 1)

Arguments

obj

A pdfium_obj of type "text".

font_size

Numeric font size in PDF points (default 1, so the result is in "em" units — multiply by the actual font size you care about).

Value

A named list with two numeric scalars: ascent and descent. Either is NA when PDFium can't resolve it.

Details

Wraps FPDFFont_GetAscent and FPDFFont_GetDescent.

See also

pdf_text_font() for the font's name + weight + italic-angle metadata; pdf_glyph_path() for per-glyph outlines.