[css3-images] object sizing edits

So, my goals for this section of the spec are:

   1. Minimize changes from LC so that we don't need another LC in order
      to get adequate review. Ideally each change should be justifiable
      as either a clarification or a straightforward error fix.

   2. Don't introduce any errors. See #1.

   3. Provide clear vocabulary and a simple reusable algorithm that future
      specs can use (and tweak as necessary) to define their object sizing
      rules with less repetition and therefore less errors.

   4. Don't attempt to normatively redefine sizing algorithms that are
      already normatively defined by existing specs. See #2. Also, that's
      not the job of this spec. See #3.

Non-goals:

   1. Defining an algorithm that handles all possible or used permutations of
      object sizing.

   2. Normatively redefining any other spec's sizing algorithms in order to
      update its algorithms to use CSS3 Images terminology.

To that end I've made the following changes against last week's Editor's Draft:

  5.1 Object-Sizing Terminology
   http://dev.w3.org/csswg/css3-images/#sizing-terms

   Reverted 'specified size' to its previous definition, which didn't try
   to be exhaustive about all the possible ways size constraints can be
   specified. (See goal #1 and non-goal #1.)

  5.2 CSS⇋Object Negotiation
   http://lists.w3.org/Archives/Public/www-archive/2012Mar/att-0025/Overview.html#object-negotiation

   No changes.

  5.3 Concrete Object Size Resolution
   http://dev.w3.org/csswg/css3-images/#concrete-size-resolution

   Rewrote the introduction to this section into several paragraphs that
   better explain what it's trying to do and how that relates to other
   parts of the CSS specs.

   Removed the concept of "rounding constraint" from the spec. It was not
   part of the LC, and isn't necessary. (See goal #1 and non-goal #1.)

   Addressed dbaron's comment about the "no specified size" case being
   confusing as described here:
     http://lists.w3.org/Archives/Public/www-style/2012Mar/0550.html

   Shifted the cover and contain constraints out into their own section,
   leaving the "default sizing algorithm" scoped to exactly what it was
   scoped to during LC. (See goals #1 and #2.)

   Made cover and contain use the exact wording from 'object-fit' instead
   of new wording. The old wording wasn't wrong, and I remember getting
   comments about it being unclear in previous renditions, so I don't want
   to change it now without a good reason. (See goal #2.)

   Removed "Default" from the section title and added subheads for both
   the default sizing algorithm and the constraint sizing section.

  5.4 Examples of CSS Object Sizing
   http://dev.w3.org/csswg/css3-images/#object-sizing-examples

   (This is the long list Tab added to redefined all the sizing algos in
   CSS2.1 and CSS3 Backgrounds and Borders in CSS3 Images terms.)

   I added direct links to the normative definitions of the sizing algos
   and reduced the text by summarizing what was going on instead of trying
   to be exhaustive about it.

   I folded the new sections on 'content' and the contents of replaced
   elements into just a 'replaced elements' section. I also corrected
   that definition and explained its relationship to 'object-fit'.

   I turned the whole list into an example so that it is non-normative.
   See goals #2 and #4 and non-goal #2.

  5.5. Sizing Objects: the ‘object-fit’ property
   http://dev.w3.org/csswg/css3-images/#object-fit

   Added some more human-readable text to the value definitions so that
   authors can get a better sense of what the values mean without having
   to understand the Concrete Object Size Resolution section.

   Updated references to the contain/cover constraint sizing rules.

This reduces the changes to these sections between LC and CR to
   - Rewrite of normative text to address dbaron's comment (described
     above)
   - An editorial rearrangement of the contain/cover definitions
   - An improved introduction to the default sizing algorithm
   - More detailed examples of the use of object sizing algorithms in
     CSS2.1 and CSS3 Backgrounds and Borders
   - Clarifications to the 'object-fit' value definitions that leave
     the normative definitions unchanged (though now indirect via
     reference rather than embedded inline) aside from Issue 24 [1]

[1] http://dev.w3.org/csswg/css3-images/issues-lc-2012#issue-24

~fantasai

Received on Tuesday, 27 March 2012 07:09:07 UTC