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

Re: Opacity 0-1: Bad Idea?

From: Andy <lordpixel@mac.com>
Date: Sun, 11 Nov 2001 19:38:32 -0500
Message-ID: <3BEF1A07.B63C2A43@mac.com>
To: www-style <www-style@w3.org>
Chris Lilley wrote:
> Andy wrote:
> >

> > No one says "that pane of glass in that window is semi-opaque". It would
> > always be "transparent" (or translucent!). Its just not English!
> In fact the term opacity has a long usage in the (English language)
> computer graphics literature at least back to 1963, and probably
> further.

Well, yes indeed. Of course its valid English, its just not the way
anyone would ever actually speak. Can you really see someone saying "I'm
going to make this box 25% opaque?" Somehow I suspect the range of
people wanting to use transparency effects in their pages is much
greater than computer programmers. 

As if to drive the point home, look at this link to the spec:


"3.2. Transparency: the 'opacity' property"

So its #transparency and the section heading is Transparency. I think my
point about how people think about this is adequately made by the spec itself!

I admit I would make my argument more convincing if I'd have omitted the
hyperbole implied by saying "Its just not English!". I probably deserved
to be jumped on for that.
> Secondly, the property is already in a W3C Recommendation (SVG 1.0), it
> is thus final; and being included into CSS3 to allow its use in areas
> other than purely graphical.
> http://www.w3.org/TR/SVG/masking.html#OpacityProperty

OK, I missed the SVG link (as J David Eisenberg pointed out, it makes
more sense with respect to image formats, where folks do "think
backwards" due to the way alpha channels are usually defined).

J David also proposes supporting both percentages and units, and both
opacity and transparency, thus covering both compatibility with SVG and
the way people think in real life. This would have been a much more
reasonable think for me to say. I apologise for going off half cocked -
it happens when I comment on something that has been irrating me for a
while sometimes.
> Thirdly, there are already a substantial number of implementations of
> this property, in both renderers and authoring tools.

-moz-opacity? That's deliberately in a private "namespace" particularly
so that it will be forwards compatible with CSS3. I don't doubt there
are other implementations other than that one, but how many of these
tools are widely used enough to influence the direction of the spec?

AndyT (lordpixel)
Received on Sunday, 11 November 2001 19:38:32 UTC

This archive was generated by hypermail 2.3.1 : Monday, 2 May 2016 14:26:59 UTC