Rendering a Cairo drawing to a printer.

[PaulJohnson]

Raised following this question on StackExchange.

The PrintOperation module has a printOptDrawPage signal which provides its callback with a printContext value. This has a function printContextGetCairoContext which returns a Cairo Context. However the library documentation doesn't have an entry for this Context type. See also Issue #215.

Daniel Wagner responded with the following options for fixing this:

I think one of two patches would be sensible here:

1. Expose a renderWith-alike that consumes a Cairo. Let the user connect up printContextGetCairoContext with the new renderWith-alike.

2. Don't expose printContextGetCairoContext at all; replace it with

    printContextRender :: PrintContextClass self => self -> Render a -> IO a
   

   and have printContextRender merge the call to printContextGetCairoContext with the renderWith-style cleanup.

I like option (1) for its clean backwards-compatibility story; but I like (2) a lot better from the API-design side of things. Since this module probably hasn't seen much use for the reasons you're describing, I'd lean towards patch (2).