1 Convertible: Data-Conversion Protocol

(require file/convertible)

The file/convertible library provides a protocol to mediate between providers of data in different possible formats and consumers of the formats. For example, a datatype that implements prop:convertible might be able to convert itself to a GIF or PDF stream, in which case it would produce data for 'gif-bytes or 'pdf-bytes requests.

Any symbol can be used for a conversion request, but the following should be considered standard:

• 'text — a string for human-readable text

• 'gif-bytes — a byte string containing a GIF image encoding

• 'png-bytes — a byte string containing a PNG image encoding

• 'ps-bytes — a byte string containing a PostScript document

• 'eps-bytes — a byte string containing an Encapsulated PostScript document

• 'pdf-bytes — a byte string containing a PDF document

• 'pdf-bytes+bounds — a list containing a byte string and four numbers; the byte string contains a PDF document and the four numbers are sizing information for the PDF document, namely the width, height, ascent and descent in that order