[Drawkit] SVG / other file format support

[Brad Larson]

After a significant delay, I'm starting to work on porting our drawing  
software across to DrawKit.  One thing that we will need is native  
load/save support for our custom XML file format, and we're looking at  
moving to SVG.  I am willing to add this functionality to DrawKit, but  
I noticed that you have SVG import and export on the roadmap and I  
thought I'd get your thoughts first before I started.

How, architecturally, would you like this to be added?  Personally, I  
would like to see SVG as a native file format for DrawKit, rather than  
something you have to do a File | Import and Export for.  It is a  
highly extensible standard that a lot of people are getting behind  
(including Apple with WebKit).  Inkscape uses SVG as its native file  
format and it seems to keep up well with all of its capabilities.  If  
you'd prefer to have different file formats be handled via import and  
export instead of the standard load / save functions, I could do that,  
too.

Right now, all loading from disk is handled with a simple unarchiver  
in DKDrawing's drawingWithData: method that takes only an NSData  
object.  If you were able to pass in the filename or extension, you  
might be able to have different parsers for different file extensions  
(svg, svgz, dxf, ai, etc.) within this method.  The same could be done  
in reverse for the writeToFile:atomically: method.   This would make  
it possible to do different file formats during the load / save  
operation.  If so, would you want separate helper classes for each  
different file type, load / save methods under DKDrawing, or DKDrawing  
categories for each file type?

I figure saving would be accomplished by iterating through the  
internal store of objects and calling an svgRepresentation method, or  
something corresponding to the file format, on them.  This might be  
where separate categories for the file formats would be useful, so  
that the drawing objects could each have their own input / output  
methods.

I wanted to check first so that anything I did would not conflict with  
anything you had in mind or had already started.

______________________
Brad Larson
SonoPlot, Inc.
3030 Laura Lane, Suite 120
Middleton, WI 53562