2010/9/16 David Yip <yipdw1@...400...>:
My initial response recommended implementing Inkscape::UndoStackObserver, much as Inkboard did, as it's an easy way to obtain a stream of transactions on the document. However, questioner's concern with this approach was that listening for changes on the undo stack wouldn't capture intermediate states of actions, e.g. motion along a path. He brought up another possibility, which was to send changes in batches at short intervals (using, say, Inkscape::XML::NodeObserver).
You are not supposed to see the intermediate states, because they are not consistent. This is the whole point of the XML transaction stuff.
When the user moves something along a path, the XML is not updated until he finishes the drag. This is done for performance reasons. Right now there is no way to listen to SP layer events.
Regards, Krzysztof