[CREATE] OpenRaster clarifications

[Calle Laakkonen]

>> 3. Are the x & y coordinates needed? Are there any cases where it would
>> be needed to set these to something else than what can be computed
>> from the layer positions?
>
> No, they are useless. I was thinking first you would just take (x, y, w, h)
> and crop the contents of <image> to that.  But "x" and "y" specify by
> convention the position where the current element should be placed.  Adding
> "w" and "h" to that concept will always crop the content at (0, 0).
>
> The consistent solution would be to disallow all of x, y, w, h in the
> <image> tag and require an explicit crop filter instead, but I think this
> can stay a special case because most applications have the concept of a
> canvas size.
>
> Let's remove "x" and "y" from the toplevel <image> tag, and add only "w" and
> "h" instead.  I will change this in the wiki if nobody objects, and describe
> its meaning as above.

This makes sense. The effect is still the same, but with less  
ambiguity on where
the origin should lay.

> And should this canvas width and height be mandatory? This would allow
> preview widgets to display the size easily.
>

It should also simplify any implementation of an ORA loader. At least in
DrawPile's case, it would remove the need to traverse the layer stack to
calculate the real size before actually loading the images.

	-Calle