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Re: [css3-values] [css3-images] no units for default 'image-resolution'

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Tue, 26 Oct 2010 10:06:22 -0700
Message-ID: <AANLkTi=UtR9x5HYyfgR3Tg06E1UZesHU02wu=8-zcjre@mail.gmail.com>
To: shelby@coolpage.com
Cc: www-style@w3.org
On Tue, Oct 26, 2010 at 9:50 AM, Shelby Moore <shelby@coolpage.com> wrote:
> The 'px' is defined to respect relative ocular psychophysics:
> http://www.w3.org/TR/CSS21/syndata.html#numbers
> http://www.w3.org/TR/css3-values/#relative0
> The 'image-resolution' is by default 1 device pixel ('dppx'):
> http://dev.w3.org/csswg/css3-images/#image-resolution
> http://www.w3.org/TR/css3-images/#resolution-units
> But there exists no image pixel unit, i.e. 'px' is not equivalent to an
> image pixel.

Yes it is: "By default, CSS assumes a resolution of one image pixel
per CSS ‘px’ unit; however, the ‘image-resolution’ property allows
using some other resolution."

1dppx means "1 image pixel = 1 CSS px".

There isn't a unit that lets you, in some other property, reference
the pixel size of an image, but that hasn't had any decent use-cases
presented for it.

> This presents an irresolvable design error. For example, I want to put
> "Shift+Enter" in tiny text inside the button for "Send" on my chat
> application (because I want to support Enter normally in the <textarea>
> for the text being sent).
> The following works but the "Shift+Enter" overwhelms the "Send", since I
> have no way to make a portion of the text within the 'value' attribute
> smaller:
> <input type='button' value='Send&#10;Shift+Enter'/>
> The only way I found to accomplish this without making an image for the
> entire button (which I don't want to do for accessibility and other
> relativity breakage reasons), is as follows (and the background-image is a
> transparent background GIF so the button doesn't lose background
> capability).
> <input type='button' style='background:url(Shift+Enter.gif) no-repeat 50%
> 80%; padding-bottom:10px' value='Send'/>
> But the problem is that the above assumes that 'px' = '1dppx'.
> Do you know any solution in current CSS? If not, I hope we can fix this.

Using <input type=button> is only useful in very limited
circumstances; it's a pretty sucky design in general.  Use <button>

<button>Send <small>Shift+Enter</small></button>

Then a bit of CSS to style the <small> sufficiently small and in the
right position.

Received on Tuesday, 26 October 2010 17:07:17 UTC

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