Re: Options to cairo driver

[John Darrington]

On Sat, Dec 17, 2011 at 09:28:52AM -0800, Ben Pfaff wrote:
     John Darrington <address@hidden> writes:
     
     > In order to make the output window properly respond to changes
     > in style (eg. from gnome theme engines) we need to be able to
     > dynamically set options AFTER the driver has been created.
     >
     > I thought this would be straightforward, but it seems not to be
     > the case, because the parse_font, parse_dimension routeines etc.
     > demand a default value, which has means it's not possible to set
     > an indivual option, without also setting all the other options
     > back to their default values.
     
     I see two simple possibilities:
     
             * Keep the original options around at the driver level.
               Allow individual options to be set by modifying the
               original options.
     
             * Don't add any support for setting options at the driver
               level at all but instead just destroy the driver and
               create a new one with a new, complete set of options
               that has been adjusted as necessary.
     
To me, the first option sounds simpler, and more efficient, because
in most cases the options won't change and when they do, it's likely
to be just a single option.

But here lies the problem with the existing arrangement.  It doesn't
allow one to set a single option.  All the parse_option_* functions
take a default value, so if you don't pass it that option, it'll get
set back to the default.  We don't want that.  We want it left in its
current state.

J'

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