Description
bool 
cpdf_set_font ( int pdf_document, string font_name, float size, string encoding)
     The cpdf_set_font() function sets the
     current font face, font size and encoding. Currently only
     the standard postscript fonts are supported. 如果成功则返回 TRUE,失败则返回 FALSE。
    
     The last parameter encoding can take the
     following values: "MacRomanEncoding", "MacExpertEncoding",
     "WinAnsiEncoding", and "NULL". "NULL" stands for the font's
     built-in encoding.
    
     See the ClibPDF Manual for more information, especially how to support
     Asian fonts.