RE: [css3-page] Page area changes within a document

From: www-style-request@w3.org [mailto:www-style-request@w3.org] On Behalf Of Grant, Melinda
Sent: Tuesday, October 21, 2008 4:30 AM
To: www-style@w3.org
Subject: [css3-page] Page area changes within a document

Neither 2.1 nor http://www.w3.org/TR/css3-page is clear about how print layout should be done when the page area changes within a document.

The page area can change when a different 'page' property is applied or when :right, :left, or :first page contexts are used.  Some possibilities:
    o the size of the medium being printed on changes (this is very rare in my experience)
    o the page orientation changes
    o the page margins/borders/padding changes

To address this deficiency, I propose to add the following (probably in a new sub-section 4.4):
        "Each page in turn is laid out as if the initial containing block were the same size as its page area."

Clarification sounds reasonable.

CSS 2.1 has this text in 13.2.2:
“Margin declarations on left, right, and first pages may result in different page area<http://www.w3.org/TR/CSS21/page.html#page-area> widths. To simplify implementations, user agents may use a single page area width on left, right, and first pages. In this case, the page area width of the first page should be used. “

That leaves layout across different page sizes intentionally undefined. We’ll not change that for 2.1, right?

And provide a couple examples, showing:
    o right-aligned content stays right-aligned;
    o content positioned relative to bottom right retains its relationship to bottom right;
    o percentages scale appropriately;
    o when an element is broken across pages and its width is 'auto', its width adapts to the page area width across pages.

I have concerns with each bullet in this list. Although it is possible to show an example where it works, but also there are cases where it creates a problem.E.g.


-          Changing an element’s width on different pages may work for text flow, but it definitely doesn’t work for a table.

-          An image with width:50% split across pages really shouldn’t have different scale on different pages

-          Even for plain text flow, a change of width can be complicated, e.g. when there are floats or positioned content involved.

I think it is still fine to have examples of content that adapts to variable page width but it should remain optional.

Regards
Alex