Feature Request: Access to Font Size of Text Elements

[minsung-ee]

Is your feature request related to a problem? Please describe.
I am using pypdfium2 to extract and analyze text from PDF documents. However, I need to access the font size of each text element for layout analysis and semantic structure detection (e.g., to differentiate headings from body text). Currently, the library does not seem to expose font size information.

Describe the solution you'd like
It would be very helpful if pypdfium2 could expose the font size of each text element in the output of get_textpage_text_range() or any other relevant API.
Additionally, having a utility function to compute the dominant font size per page (e.g., most common font size) would also be useful for quick analysis.

Describe alternatives you've considered

I’ve considered post-processing the bounding boxes and estimating the font size heuristically based on height, but this is unreliable.

Other libraries like pdfminer.six provide font size information, but they are heavier and less performant compared to pypdfium2.

Additional context
Example use case:

import pypdfium2

pdf = pypdfium2.PdfDocument("sample.pdf")
page = pdf[0]
textpage = page.get_textpage()
text_elements = textpage.get_text_range()

# Ideally, each element could have something like:
# {'text': 'Heading 1', 'font_size': 18.0, 'bbox': ...}

[mara004]

I believe this is possible with the raw API (namespace pypdfium2.raw), and some downstreams are already doing it (e.g. VikParuchuri's pdftext).

At a quick glance, I can find e.g. FPDFText_GetFontSize(), FPDFText_GetFontWeight(), FPDFText_GetFontInfo().
Check out pdfium's headers for more info, particularly fpdf_text.h.

The readme has instructions how to work with the raw APIs.