W3C home > Mailing lists > Public > www-style@w3.org > November 2001

Re: Opacity 0-1: Bad Idea?

From: Jan Roland Eriksson <jrexon@newsguy.com>
Date: Sun, 11 Nov 2001 11:55:49 +0100
To: www-style@w3.org
Message-ID: <n7lsut4tucebt34p19av5mgb9f2rf6olq0@4ax.com>
On Sat, 10 Nov 2001 20:29:29 -0500, you wrote:

>In the world of computer graphics, there are generally two ways to do opacity.
>They either range from 0 to 100 (aka 0$ to 100%).
>or they range from 0 to 256 (thus mor in line with the 256 used to mix colors).
>The first is perhaps easier to understand.
>The second can be useful if you are doing something that needs to be exact.

What on earth would need to be "exact" in a www context?

You just can not know your arbitrary clients display settings.

>However, I am fully convinced of W3's method of using a value from 0 to 1.
>It seems neither easy (intuitive as in 0 to 100%) or exacting (as in the
>standard 256).
>Also, if you can only use 0 .1 .2 .3 .4 .... to- 1   and not things
>like .13  for 13% then I believe this method is gonna be rather limiting
>in the future.

You can "use" any floating point number with as many decimal places as
you like. From there you also need to tell browser programmers to make
use of a real floating point code library instead of the fixed point
code that seems to be most popular today.

Round off errors, thanks to fixed point math, is plentiful in today's
"cutting edge" browsers.

From there it's all up to your arbitrary client and his display device
to handle what you send him. Control? you have none on the www.
Learn to live with that and life gets so much easier.

Received on Sunday, 11 November 2001 05:56:29 UTC

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