Eric Wilhelm wrote:
# from Bob Jamison # on Friday 20 January 2006 07:45 pm:
I think that an Escher-like image of a man holding a picture of a man holding a picture of a man, etc... would be valid. Tough to render, but valid.
No, because there is no indication of where to stop (that fine line between circularity and recursion.) Unfortunately, this means that you cannot (in a recursive space-efficient way) include a finite number of successively smaller pictures of pictures. Rather, the best you could do would be to def the picture and then iteratively list N "use" copies of it on top of each other (explicitly scaling each one to the reduced size.) Without a finite limit, the render will never happen because it has to wait until the innermost element is rendered onto the next innermost element, and so on.
Yes, you are right about this. I should have made the distinction that a reference to itself would need to be made with a 'use'.
However, this would still allow recursion. You could make a viewport of any piece of the whole image, and put a viewbox of the piece anywhere on it.
Somewhere in the W3C docs, I think (Not the main one. I don't remember which) they have an example of a tree with self-referential pieces hanging from it.
bob
