Determines how the text is rendered.
pdf_document
The document handle, returned by cpdf_open().
rendermode
The possible values for rendermode
are 0=fill
text, 1=stroke text, 2=fill and stroke text, 3=invisible, 4=fill
text and add it to clipping path, 5=stroke text and add it to
clipping path, 6=fill and stroke text and add it to clipping
path, 7=add it to clipping path.