Hi David,
A browser will fetch a style sheet but only fetches an image background it
contains upon use in the XHTML.
Consequently overwriting background-image: url('http://example.com');
With background-image: url('data:...'); will not fetch the image but use the
data version.
So to the question "Do browsers which support the data scheme successfully
override the regular image before starting to download it?" the answer is yes.
Unfortunately the answer to the second question "Do browsers which don't
support it still use the earlier declaration? Or do they go "I accept url()
values, will override now"?" is no, they will display garbage if the data URI
is presented.
But please note all modern browsers support the data URI scheme.
IEv8 was the last to employ this standard.
There is a link at the page bottom which suggests a method of auto detecting
whether data URIs are supported.
I've not fully investigated the possibilities as I'm happy that support, except
IEv7 and below, is ubiquitous.
My whole site utilises CSS sprites and data URI's served via gzip.
The performance increase is phenomenal.
Regards
Mike Foskett
-----Original Message-----
From: li...@webstandardsgroup.org [mailto:li...@webstandardsgroup.org] On
Behalf Of David Dorward
Sent: 10 February 2010 11:59
To: wsg@webstandardsgroup.org
Subject: Re: [WSG] Data URI encoder
On 10 Feb 2010, at 11:48, Hugo Mendes wrote:
>> http://websemantics.co.uk/online_tools/image_to_data_uri_convertor/
> Unfortantly this technique doesn't work on IE6 and 7.
... as it says on the page? Which suggests work arounds?
On the subject of the suggested workaround (conditional comments) - what about
other browsers which don't support data URIs?
How do browsers behave, in practice, given:
background-image: url('http://example.com');
background-image: url('data:...');
Do browsers which support the data scheme successfully override the regular
image before starting to download it?
Do browsers which don't support it still use the earlier declaration? Or do
they go "I accept url() values, will override now"?
--
David Dorward
http://dorward.me.uk
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