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Re: [css21] images without intrinsic properties

From: fantasai <fantasai.lists@inkedblade.net>
Date: Tue, 22 Jan 2008 20:56:09 -0500
Message-ID: <47969EB9.1080604@inkedblade.net>
To: Anne van Kesteren <annevk@opera.com>
CC: www-style@w3.org

Anne van Kesteren wrote:
> 
> The CSS 2.1 specification has detailed rules for replaced elements 
> dealing with images that lack one or more of the following: intrinsic 
> height, intrinsic width and intrinsic aspect ratio.
> 
> The definition for 'background-image' doesn't seem to deal in with the 
> case where you have an intrinsic height and aspect ratio but do not have 
> an intrinsic width.

I think it's pretty obvious that the aspect ratio should be used to
resolve the width, but we could make that explicit.

   "If the image has one of either an intrinsic width or an intrinsic height
   and an intrinsic aspect ratio, then the missing dimension is calculated
   from the given dimension and the ratio."

We also need

   "If the image has one of either an intrinsic width or an intrinsic height
   and no intrinsic aspect ratio, then the missing dimension is matches the
   size of the rectangle that establishes the coordinate system for the
   'background-position' property."

> The definitions for 'content', 'list-style-image' and 'cursor' don't 
> deal with such images at all. (Although maybe for 'content' you'd use 
> the rules for replaced elements and if ::marker is ever implemented 
> 'list-style-image:foo' would be some type of short hand for ::marker { 
> content:foo }.)

I think the rules for 'cursor' should match the rules for background-image,
except that "rectangle that establishes the coordinate system for the
'background-position' property" is replaced by a UA-defined rectangle that
should match the size of a typical OS cursor.

For list-style-image, ideally I think we should set the image's height to
either 1em or the specified line-height, and if the aspect ratio is missing
assume 1:1.

~fantasai
Received on Wednesday, 23 January 2008 01:56:22 GMT

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