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Re: [whatwg] Adding alpha channel to <input type=color>

From: Garrett Smith <dhtmlkitchen@gmail.com>
Date: Tue, 1 Sep 2009 17:52:14 -0700
Message-ID: <c9e12660909011752u2fe24bb0s9a68ab5ae4354d85@mail.gmail.com>
To: "Tab Atkins Jr." <jackalmage@gmail.com>
Cc: www-style <www-style@w3.org>
On Wed, Aug 26, 2009 at 6:15 AM, Tab Atkins Jr.<jackalmage@gmail.com> wrote:
> On Wed, Aug 26, 2009 at 2:35 AM, Max Romantschuk<max@romantschuk.fi> wrote:
>> Victor Vasiliev wrote:
>>>
>>> I suggest to add a boolean attribute "alpha" to <input type=color>
>>> (disabled by default). If this attribute is present, the color well
>>> allows to set opacity value, and instead of sRGB, sends RGBA.
>>>
>>> Another question is which format should be used to submit RGBA color. We
>>> have rgba(number, number, number, float) used in canvas, but I feel like
>>> it's not the best format to be used in submited data. Maybe #rrggbbaa or
>>> #aarrggbb?
>>
>> input type=color is specified to define a simple color:
>> http://dev.w3.org/html5/spec/Overview.html#simple-color
>>
>> While alpha information is useful, it's not really a color attribute is it?

Depends on which specification you consult. CSS 3 says it is.

Deferring to CSS 3 color module would help align the specs and ensure
consistency.

>> Using type=color paired with type=range for alpha would serve fairly well in
>> most cases, I believe.
>>
>> How do the people more into design feel about this? I'm mainly a coder
>> myself.
>
> Many, though certainly not all, applications that allow color-choosing
> make alpha a part of the color-chooser dialog.  (Some, like GIMP,
> offer it as a separate choice, similar to your <input type=slider>
> suggestion.)
>
> CSS has also trained many of us authors that alpha is a component of
> colors with its rgba() syntax.
>

"transparent" is now considerered a shorthand for "rgba(0, 0, 0, 0)".

This incompatibility is introduced with the new and impoverished "CSS
3 Color" module, which offers us a change from the CSS 2.1 "candidate
recommendation" (unfinished for over a decade now).

What is more important is being able to read an absolute style value.
Method - getComputedStyle - returns a CSS2 "computed style", but the
format of the computed value varies by design, where implemented.

Garrett
Received on Wednesday, 2 September 2009 00:52:54 GMT

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