Thanks for the explanation.
Glen
--- "Peter B. West" <[EMAIL PROTECTED]> wrote:
> Glen Mazza wrote:
> ...
> >
> > I think the next thing to consider is the storage
> of
> > specified vs. computed values. Let's say we store
> > pointers for many properties to the same
> > {"property-name", "property-value"} pair. A
> specified
> > property value of "10%" would not make this a very
> > helpful data structure if that percentage resolves
> to
> > different computed values for each property
> sharing
> > this pair. I believe the goal for us then would
> be
> > just store the computed value for each pair
> (meaning
> > many more pairs), as long as we take into account
> the
> >
> can't-resolve-everything-without-knowledge-of-layout
> > issue.
>
> alt.design makes no attempt to look for
> commonalities here. It resolves
> every possible property value, and keeps a
> partly-resolved value for
> percentages. Inheritance is (almost exclusively) of
> computed values.
> <quote>
> For a given inheritable property, if that property
> is present on a
> child, then that value of the property is used for
> that child (and its
> descendants until explicitly re-set in a lower
> descendant); otherwise,
> the specified value of that property on the child is
> the computed value
> of that property on the parent formatting object.
> </quote> 5.1.4 Inheritance
>
> There is an exception that comes to mind. For
> "line-height" a value may
> be specified which, although not specified as a
> percentage, is a factor
> by which the font-size (from memory) is multiplied.
> When such a value
> is inherited, it is the factor, not the computed
> value.
>
> In general, the computed value of a percentage is
> inherited. That still
> leaves a problem, because the computed value is
> unknown. In alt.design,
> what is effectively a link back to the unresolved
> property is specified
> as the value. When the parent property is resolved,
> that resolved value
> is then available to the inheriting descendants.
>
> Yet-to-be-implemented is the handling of expressions
> involving
> percentages, as mentioned in an earlier post.
>
> In essence, alt.design attempts to resolve every
> property to its
> computed value, and store the result only on nodes
> to which the property
> applies. There is no attempt to reduce storage by
> procedures like
> interning strings. Note, though, that the process
> of resolving
> properties does eliminate most strings. My
> objective was that when
> areas were being laid out, the relevant properties
> would all be directly
> available.
>
> Peter
> --
> Peter B. West
> <http://www.powerup.com.au/~pbwest/resume.html>
>
__________________________________
Do you Yahoo!?
Free Pop-Up Blocker - Get it now
http://companion.yahoo.com/
