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Re: DOM-2 CSSValue.CSS_INHERIT

From: Philippe Le Hegaret <plh@w3.org>
Date: Mon, 10 Apr 2000 14:31:42 -0400
Message-ID: <38F21E0E.F6086B5A@w3.org>
To: Glenn Adams <gadams@vgi.com>
CC: www-dom@w3.org
Glenn Adams wrote:
> 
> I believe I understand now: if valueType is CSS_INHERIT then no other
> information is available from that CSSValue instance (although, what would
> cssText be in this case? "inherit"?); in this case, one must use
> ViewCSS.getComputedStyle(...).getPropertyCSSValue(...) to obtain the actual
> (computed) value.
> 
> If this is correct, then some additional clarifying language would suffice.

I'm trying to clarify the difference between 'specified', 'computed' and
'actual'.

'specified':
- in the CSSOM, we use 'specified' to reference the values of the style
sheet. No computation at this level : 'what you get is what you write'.
  This is what you get in a CSSStyleDeclaration from a CSSRule.

- the CSS2 spec uses 'specified' for the first step of the style computation.
  These values are not exposed in the CSSOM.

'computed':
CSSOM and CSS2 are using the same definition for 'computed'.
  This is what you get in a CSSStyleDeclaration from a ViewCSS.

'actual':
  actual values are not exposed in the CSS OM.

According to these statements, I updated the description of the
CSSStyleDeclaration interface:

"The CSSStyleDeclaration interface represents a single CSS declaration
block. This interface may be used to determine the style properties currently
set in a block or to set style properties explicitly within the block.

While an implementation may not recognize all CSS properties within a CSS
declaration block, it is expected to provide access to all specified properties
in the style sheet through the CSSStyleDeclaration interface. Furthermore,
implementations that support a specific level of CSS should correctly handle
CSS shorthand properties for that level.  For a further discussion of shorthand
properties, see the CSS2Properties interface.

This interface is also used to provide a read-only access to the computed to
the computed values of an element. See also the ViewCSS interface.

Note: The CSS Object Model doesn't provide an access to the specified or actual
values of the CSS cascade."


Philippe.
Received on Monday, 10 April 2000 14:31:45 GMT

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