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Re: Views on some accessibility details

From: Al Gilman <asgilman@access.digex.net>
Date: Tue, 22 Jul 1997 08:42:36 -0400 (EDT)
Message-Id: <199707221242.IAA10223@access5.digex.net>
To: w3c-wai-ig@w3.org
I think that Hiram's explanation of point (1) is helpful.

The person viewing the page gets better incremental-loading
performance if the sizes are given.

-- Al Gilman

----- Forwarded message from Hiram Lester, Jr. -----

From hwlester@pobox.com  Tue Jul 22 02:19:38 1997
Date: Tue, 22 Jul 1997 01:21:31 -0500 (CDT)
From: "Hiram Lester, Jr." <hwlester@pobox.com>
Sender: cosc0065@frank.mtsu.edu
To: Al Gilman <asgilman@access.digex.net>
cc: webwatch-l@teleport.com, lynx-dev@sig.net
Subject: Re: Views on some accessibility details (questions)
In-Reply-To: <199707220221.WAA01488@access4.digex.net>
Message-ID: <Pine.HPP.3.96.970722010609.11672C-100000@frank.mtsu.edu>

On Mon, 21 Jul 1997, Al Gilman wrote:

> (4) Finally, does validation also serve the purpose of making a site
> accessible? 
> 
> Yes.  At least one non-trivial connection is this:
> 	Lynx serves the blind.
> 	Lynx does well with correct HTML; 
> 	not so well with not so correct HTML.
> 
> Most of the unusable sites that the Lynx developers hear about,
> at least, are unusable because the HTML is really bad.

Not directly related to accessibility, but it also goes a long way toward
assuring that the page looks correct regardless of the browser used.  It
ensures you aren't relying on error recovery which exists in your favorite
browser but may not exist in a newer version of that same browser or a
different browser.

I'm not sure if you were looking for comments on anything other than the
last two, but...

> (1) Do the Height and Width attributes in image tags alter page load time, 
> or do they simply load text first?

Yes, depending upon the browser, different results may be achieved without
these attributes.  In my experience, Netscape will not render text below
(or beside) images for which it has no size until it loads enough of the
image to get the size of the image itself.  It will then render down to
the next image.  Internet Explorer renders the entire text of the page
leaving small default sizes for the images.  When it begins loading the
image and figures out its size, it then RE-renders the text and other
images as necessary (possibly resulting in MANY redraws).  With both
browsers, if you specify proper HEIGHT and WIDTH attributes, the entire
text of the page will be rendered with the correct size for each image.
When those images are loaded, they will already have a space set aside for
them.

To get a perfect example, create a page with 20 or 30 small icons (all
different) on a single line (bigger file sizes for the icons will help).
If you don't put proper attributes on these, you probably won't see
ANYTHING until the last image or 2 has begun loading (depends on the
browser settings for the number of simultaneous connections).  If you put
the attributes in, the page will at least appear and show each icon as it
loads.

Your mileage may vary depending on the browser, but in all cases, the
attributes do speed up the time before the page is actually usable.

> (2) Is it the case that the vast majority of web clients wrap ALT text? 

I haven't given any thought to this, but I assume that this would be the
case unless nbsp's are included in the ALT text.

   +------------------------------------+-------------------------------+
   | Hiram W. Lester, Jr.               | E-Mail: hwlester@pobox.com    |
   | Computer Science                   | Home page:                    |
   | Middle Tennessee State University  |   http://pobox.com/~hwlester/ |
   +------------------------------------+-------------------------------+

----- End of forwarded message from Hiram Lester, Jr. -----
Received on Tuesday, 22 July 1997 08:42:38 GMT

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