On Fri, Oct 27, 2006 at 11:17:22AM -0400, Matthew Krauss wrote: > Stefan Monnier wrote: > > someone wrote: > >><theory> > >>AFAIK: PDF is not strictly speaking a vector-graphics format. It is > >>a subset of Postscript, which is actually a programming language for > >>drawing > >>documents. It is designed for output, not input or editing. Therefor, it > >>is *very* hard to convert from PDF to a structured document format. > >></theory> > >> > > > >Actually, PDF is not a programming language, contrary to Postscript. > >So it's much easier to deal with (and more difficult to introduce viruses > >into it, among other things). > > > Really? Can you explain more about this? I thought PDF was a subset of > Postscript with some kind of compression and/or encryption applied. Was > I mislead? If so, what is it really? Is there no relationship between > the two?
>From http://en.wikipedia.org/wiki/Pdf, PDF is primarily the combination of three technologies: * a sub-set of the PostScript page description programming language, for generating the layout and graphics, * a font-embedding/replacement system to allow fonts to travel with the documents, and * a structured storage system to bundle these elements and any associated content into a single file, with data compression where appropriate. PostScript is a computer language -- more precisely, a page description language -- that is run in an interpreter to generate an image. This process requires a fair amount of resources. PDF is a file format instead of a programming language and for that reason it doesn't need to be interpreted. For instance, flow control commands like if and loop are removed, while graphics commands such as lineto remain. I don't know if there's anything in the wikipedia article to address the subject question. -- Ken Irving, [EMAIL PROTECTED] -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
