Hi!
Tavmjonh Bah has suggested me to contact you and consult SPPaintServer class refactoring I would like to do.
Currently SPPaintServer contains pattern_new method. Since it directly handles rendering and uses cairo, I think it could be moved outside of SP tree.
My idea is to implement paint server drawing routines in a parallel hierarchy of classes belonging to New Renderer. Image [1] contains the class diagram. Common base for them would be NRPaintServer, containing pure virtual method pattern_new. Concrete NRPaintServer derivatives would contain a reference to corresponding SPTree items and use it while rendering.
To choose an appropriate NRPaintServer for given SPPaintServer I thought about a factory method in NRPaintServer class. Example interfaces and their usage are shown at [2]
The tricky part can be the implementation of NRPaintServer::create method. I have thought about two solutions: a) using a battery of dynamic_cast if statements like this: NRPaintServer* NRPaintServer::create(SPPaintServer* ps) { SPPattern* pattern = dynamic_cast<SPPattern*>ps; if (pattern != 0) { return new NRPattern(&pattern); } //and so on for gradients }
b) using double-dispatch strategy. There would be an .cpp file internal class NRPaintServerFactory. class NRPaintServerFactory { public: virtual NRPaintServer* create(SPPaintServer*); virtual NRPaintServer* create(SPLinearGradient*); virtual NRPaintServer* create(SPRadialGradient*); //and so on }
And NRPaintServer::create implementation would look like this: NRPaintServer* NRPaintServer::create(SPPaintServer* ps) { static NRPaintServerFactory *factory = new NRPaintServerFactory; return factory->create(ps); }
What are your thoughts about this solution?
[1]https://www.dropbox.com/s/bz83xd0ks378qys/NRPaintServer.svg [2]http://pastebin.com/h9AcrusW
Regards, Tomasz