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

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Tue, 22 Jun 2010 18:11:59 -0700
Message-ID: <AANLkTikAFh3Ji5MMnOt44YIjSnV64OymahpoxEGJg31A@mail.gmail.com>
To: Simon Fraser <smfr@me.com>
Cc: Brad Kemper <brad.kemper@gmail.com>, fantasai <fantasai.lists@inkedblade.net>, "robert@ocallahan.org" <robert@ocallahan.org>, Brian Manthos <brianman@microsoft.com>, "www-style@w3.org" <www-style@w3.org>
On Tue, Jun 22, 2010 at 3:39 PM, Simon Fraser <smfr@me.com> wrote:
> On Jun 22, 2010, at 3:20 PM, Tab Atkins Jr. wrote:
>> If we don't want to change text-shadow (we don't), then we should go
>> ahead and make the blur length specify the full size of the blur
>> region, like Brad suggests.  While I do prefer the other way, I value
>> consistency between nearly-identical properties more.
>
> That's not what I see. Don't forget that shadows larger than 8px are
> buggy in WebKit. Here's a test with an 8px shadow:
> <http://smfr.org/misc/shadow.html>
>
> and here's what it looks like in WebKit:
> <http://smfr.org/misc/shadow-webkit.png>
>
> The box and text shadows are identical, and Pixie shows that the shadow extends out by 8px (for a total shadow transition of 16px).

Hmm, my own somewhat unscientific test of taking a screenshot and
checking pixel colors in GIMP doesn't agree.  I get 4px of blur
extending out from the character.  (On one side there's a 5th layer of
pixels that are #fefefe, but I think we can chalk that up to vagaries
of gaussian blurs.)  Similarly, I have 4px of gradually solidifying
color extending inwards (again, with one extra layer of #010101 on
some sides, but again, that's okay).

Perhaps platform differences are causing this?  I'm using Chrome5 and
FF3.6 on Linux.

Roc, does Firefox have similarly buggy behavior with shadows > 8px?
Like I said, I looked in both Firefox and Chrome with a 100px blur
shadow, and they both agreed that the shadow extended outwards by
approximately 50px.  (By the way, FF's text-shadows are absolutely
beautiful at large sizes - good job.)


>>> 2. In the public-fx group, we will be discussion the addition of filters to CSS, with convenience properties for common filters. Blur will be one of these, and it will have a radius, as input, which should give behavior comparable to box/text-shadow's blur radius. This filter will be based on SVG's gaussian blur, and so the behavior of the radius parameter should match SVG.
>>
>> If we want the blur filter to work similarly to text-shadow, then it
>> needs to work as Brad wants.
>
> I think we agree that the following should all match:
>
> * text-shadow
> * box-shadow
> * SVG gaussian blur
> * hypothetical future blur filter in CSS
> * PhotoShop, probably
>
> and bonus points if we choose something that matches what browsers do today (modulo bugs).

Agreed that we should match as much as possible.  That's why the
text-shadow is kicking me over to Brad's camp.  ^_^

~TJ
Received on Wednesday, 23 June 2010 01:12:52 GMT

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