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

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Mon, 21 Jun 2010 14:31:40 -0700
Message-ID: <AANLkTimH9RUiWtljkNljhSl4G0WkCUIwU-dadqvATeGb@mail.gmail.com>
To: Brad Kemper <brad.kemper@gmail.com>
Cc: Simon Fraser <smfr@me.com>, "robert@ocallahan.org" <robert@ocallahan.org>, Brendan Kenny <bckenny@gmail.com>, fantasai <fantasai.lists@inkedblade.net>, "L. David Baron" <dbaron@dbaron.org>, Brian Manthos <brianman@microsoft.com>, "www-style@w3.org" <www-style@w3.org>
On Mon, Jun 21, 2010 at 2:05 PM, Brad Kemper <brad.kemper@gmail.com> wrote:
> On Jun 21, 2010, at 11:02 AM, "Tab Atkins Jr." <jackalmage@gmail.com> wrote:
>> On Sat, Jun 19, 2010 at 9:45 AM, Brad Kemper <brad.kemper@gmail.com>
>> wrote:
>>> But when an
>>> author provides a measure for blur, it is because he wants a certain
>>> amount
>>> of blurriness.  It does not make sense to me that the number he picks
>>> should
>>> only measure the part of the blur that extends outside the original box,
>>> and
>>> not the whole blur.
>>
>> It's fine that you think that makes the most sense.  I think the
>> opposite.  ^_^  To me, the fact that the blur extends inward is
>> sensical but irrelevant here.
>
> The size of the blur when you provide a distance measurement for blur can
> not be irrelevant. It is the primary reason and use case for having blur on
> a shadow!

What I mean is that the amount which the blur extends inward really
doesn't matter to me.  What's most important when I'm blurring a
shadow is how big the shadow becomes.


>> I care about how large the shadow
>> becomes post-blur, and so to me having the length indicate the
>> distance the blur extends outward from the shadow is most sensical.
>
> If you care about how far it extends, you can still figure that out easily
> (divide by two), if you are worried about it overlapping something, for
> instance. But for simplicity it should still be a total blur amount
> specified when specifying blur.

That's not a strong argument.  I could make an identical "simplicity"
argument for having the length be the amount it extends outwards and
inwards, because then the meaning of the length is similar to the
meaning of the spread length.  After all, if you care about the total
size of the blurring effect, you can just multiply by two.


>> Having the blur length match the spread length thematically is an
>> added bonus - both lengths act similarly and thus are easier to use.
>
> Far from it. It just adds confusion to what is being measured, when it can
> be pretty obvious, based on the extent of the visual effect.

I've explained why I feel the opposite.  To me, the relevant length to
measure is the amount the blur extends out from the original shadow,
same as spread.  The fact that the blur also affects the inside of the
shadow is just a detail - I could care less how far it does so, so
long as it looks pretty.

It certainly doesn't *add* any confusion, though.  In both cases, the
length will be measuring how much the effect makes the shadow grow
from the base.  (I'm not saying that your idea isn't coherent in this
respect either, just defending my own claim.)

~TJ
Received on Monday, 21 June 2010 21:32:41 GMT

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