W3C home > Mailing lists > Public > www-style@w3.org > September 2003

Re: background-image-opacity suggestion

From: Sigurd Lerstad <sigler@bredband.no>
Date: Mon, 22 Sep 2003 20:09:35 +0200
Message-ID: <06ee01c38134$ae377b60$6e1273d5@mmstudio>
To: "Ian Hickson" <ian@hixie.ch>
Cc: <www-style@w3.org>


>
> On Sun, 21 Sep 2003, Sigurd Lerstad wrote:
> >>
> >> Just use a PNG.
> >
> > I'm aware of png, but that property seems very useful to me. It's a non
> > destructive way to turn any image in any format into a watermark
background.
>
> The working group did consider having a -opacity property for everything
> that could have opacity:
>
>    color-opacity
>    border-top-opacity
>    background-image-opacity
>    background-color-opacity
>    text-decoration-opacity
>
> ...etc, but decided instead to add rgba() support to colors, rely on the
> alpha channel for images, and introduce a global 'opacity' property that
> would start a new stacking context with atomic opacity.
>

I wasn't going to say anything, as css color is a candiate recommendation,
but the more I'm thinking about it, the choice of having rgba/hsla instead
of separate opacity properties isn' the best choice. Separating color and
opacity is the better choice, this will make things more consistent,
especially considering svg fill-opacity and stroke-opacity.

The ONLY downside is it will introduce a lot of new properties, but there
are more upsides than downsides.

I can't really explain all the upsides, it's just a strong feeling I have.
Things will be more consistent and more logical. I'm making an editor (both
for XML+CSS and SVG) and how the user sets color and opacity gets really
unintuitive, it's really inconsistent that some properties have embedded
opacity, while others do not (like the SVG ones) opacity can set be set only
on rgba/hsla, but not with the hex notation.
Animating css properties: In SVG animateColor is used for animating the
color, and animate is used for animating opacity. In CSS box model, you can
only animate color and opacity at the same time. It's just inconsistent. I
realize that you have spent a lot of time and you probably have your
reasons, but please change it :)

I'm not 100% sure about this, but I am 90% sure. I've used the word
inconsistency a lot, that's the keyword.

--
Sigurd Lerstad
Received on Monday, 22 September 2003 14:05:47 GMT

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