W3C home > Mailing lists > Public > www-svg@w3.org > October 2004

8 Progressive rendering

From: Doug Schepers <doug@schepers.cc>
Date: Thu, 28 Oct 2004 03:19:31 -0400
To: <www-svg@w3.org>
Message-Id: <20041028071934.9BCEB149690@pillage.dreamhost.com>

First, congratulations and thanks for getting the new version of the 1.2
Spec out. I like the styling of the document... I think it makes the spec
easier to read.

I like the nice concrete examples in section 8, Progressive rendering. A few
questions, just for clarification:

1) In the second example ("Forward reference of 'use' element"), the
'externalResourcesRequired' attribute is not used to indicate a true
external resource, but rather a resource later in the same document. The SVG
1.1 Spec, section 5.9 says that a value of true "[i]ndicates that resources
external to the current document are required." Either this wording should
be changed for 1.2, or the attribute should be renamed, or a discrete new
attribute should be created. Keeping the attribute name the same would be a
bit of a misnomer, but I think it's the best option.

2) "The user agent renders the conceptual document tree nodes in document
order up to, and not including the first node in the 'unresolved' state
which has externalResourcesRequired set to true."

Given the following:
   <rect ... />
   <image xlink:href="myImage.png" externalResourcesRequired="true" ... />
   <circle ... />
The 'rect' will always render. Will the 'circle'? I assume that it will, but
the wording of the Spec is ambiguous.

2a) What if the PNG image is never found? At what point is the UA supposed
to time out and give up? Or will the document keep trying to load? Is this
documented elsewhere in the Spec? If so, please link to that explanation in
this section.

3) Given an element with externalResourcesRequired="false", but which uses a
class defined in an external stylesheet, would that shape be rendered first
with the default style, then later have the new style info applied to it?

4) How does Progressive rendering interact with the 'loadprogress' event?
What if there are multiple external resources? In the ProgressEvent example,
it seems to be assumed that only one resource is being loaded. I'd like to
see a little more about the relationship of Progressive rendering,
'loadprogress', 'prefetch', and streaming touched on.

A few minor typos with this section:
* both eRR=true and eRR="true" are used; should they be the same?
* "use is resolved but eRR=true so rendering will no[t] proceed until that
reference enters the resolved state" : "no" should be "not"
* attribute names in the 1.1 Spec were tagged as attributes and colored
blue; I'd like to see that repeated consistently in this version
* the end of this section is cut off... Is it progressively rendering?

Received on Thursday, 28 October 2004 07:19:36 UTC

This archive was generated by hypermail 2.3.1 : Wednesday, 7 January 2015 15:29:24 UTC