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Re: [css3-background] vastly different takes on "blur"

From: Brendan Kenny <bckenny@gmail.com>
Date: Wed, 23 Jun 2010 10:33:07 -0500
Message-ID: <AANLkTikq3JA2PD1DSg1qOo-h3sABynL_i03D3X65YcGh@mail.gmail.com>
To: "Tab Atkins Jr." <jackalmage@gmail.com>
Cc: robert@ocallahan.org, Simon Fraser <smfr@me.com>, Brad Kemper <brad.kemper@gmail.com>, fantasai <fantasai.lists@inkedblade.net>, Brian Manthos <brianman@microsoft.com>, "www-style@w3.org" <www-style@w3.org>
On Wed, Jun 23, 2010 at 10:17 AM, Tab Atkins Jr. <jackalmage@gmail.com> wrote:
> On Tue, Jun 22, 2010 at 9:28 PM, Robert O'Callahan <robert@ocallahan.org> wrote:
>> On Wed, Jun 23, 2010 at 3:08 PM, Tab Atkins Jr. <jackalmage@gmail.com>
>> wrote:
>>> Interesting.  I'm really not seeing that.  Check out this test case, frex:
>>> <!DOCTYPE html>
>>> <body style="font-size: 1000px; text-shadow: 0 0 100px black; color:
>>> white; font-family: Arial, sans-serif;">
>>> f
>>> <div style="background: red; width: 100px; height: 3px; position:
>>> absolute; top: 700px; left: 183px;"></div>
>>> (You may have to adjust the "left" on the <div>.)
>>> It seems very clear from a visual inspection that the blur only
>>> extends outward roughly 50px.  This effect occurs on both my Windows
>>> and Linux machines.
>> With that testcase, there's a 79 pixel-wide shadow of
>> not-completely-transparent pixels on both my Mac and Linux trunk builds.
>> Certainly some of those pixels are not apparent to the naked eye :-) ... a
>> screen magnifier that displays the actual color values of selected pixels is
>> useful.
> Oh, jeez.  I was looking at webkit's rendering twice, rather than
> looking at webkit and then firefox.  I feel silly.  You're correct -
> for a 100px blur, the shadow extends outward 79px.
> That still doesn't explain Simon's statement that the blur extends
> outward by the full blur length.  I continue to measure a nearly
> perfect half-blur-length of shadow extending from the main shadow body
> in Chrome, whether the blur is 8px or 100px.
> ~TJ


looks like Safari and Chrome handle the argument differently.
Received on Wednesday, 23 June 2010 15:33:40 UTC

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