FPDFText_GetFontSize

FPDFText_GetFontSize :Get the font size of a particular character
Protetype: double FPDFText_GetFontSize(FPDF_TEXTPAGE text_page,int index);
text_page -：Handle to a text page information structure
Returned by FPDFText_LoadPage function
index: Zero-based index of the character
the font-size of the particular character measured in points about 1/72 inch
this is tht typographic size of the font so called em size