Re: [css-regions] The region-overflow property

From: David Hyatt <hyatt@apple.com<mailto:hyatt@apple.com>>
Date: Wed, 5 Oct 2011 13:12:39 -0700
To: Alan Stearns <stearns@adobe.com<mailto:stearns@adobe.com>>
Cc: Adobe Systems <vhardy@adobe.com<mailto:vhardy@adobe.com>>, "www-style@w3.org<mailto:www-style@w3.org> list" <www-style@w3.org<mailto:www-style@w3.org>>
Subject: Re: [css-regions] The region-overflow property

On Oct 5, 2011, at 2:47 PM, Alan Stearns wrote:

On 10/5/11 12:35 PM, "Vincent Hardy" <vhardy@adobe.com<mailto:vhardy@adobe.com>> wrote:
On Oct 4, 2011, at 2:30 PM, David Hyatt wrote:
On Oct 4, 2011, at 1:23 PM, David Hyatt wrote:
http://dev.w3.org/csswg/css3-regions/#region-overflow
It is ambiguous (to me at least) in section 4.4 whether
region-overflow:break causes clipping to occur when content spills out of
the last region. I am assuming the only thing it affects is pagination at
the last region edge, and that clipping is always controlled by overflow.
Actually upon re-reading this, it sounds like you do expect the content that
paginates as a result of region-overflow:break to be into some unrendered
space when region-overflow:break is specified. That seems like fine behavior
to me, but it should probably be specified a bit more clearly in the text.
Hi Dave,
After reading the all thread where you said you are fine with the current
spec. and this initial email, I will add an action for met to be a bit more
specific about the expected behavior.
Thanks,
Vincent
There's a green section at the end of 4.4 that says "The 'overflow' property
is honored on a region..." Given the recent discussion I do not think this
is correct. When you add more detail to region-overflow:break you'll
probably need to remove the green section.

Note that in the WebKit implementation at least, I made region-overflow:break only clip in the pagination direction. overflow:visible is still honored for content that spills out of the sides of the region.

Actually, the green section reflects what I meant. I did not mean for the region-overflow to clip at all. Instead, it determines whether or not the flow content is broken at the end of the last region. The clipping introduced by the overflow property is orthogonal. So if, for example, we had a relatively positioned element on the last line of the flow content that fits in the last region and:

- overflow was set to visisble,
- region-overflow was set to break,
- with the relative positioning, the element overflows to the right and bottom

the element should be fully visible, despite its overflowing the region box.

The region break just gives the last region the same behavior as other (not last) regions. Another way to think about it: with region-overflow: break, the last region's rendering should be exactly the same as if there was an other pseudo-not-rendered-region to take some or all of the content that does not fit in the region.

Cheers,
Vincent

dave
(hyatt@apple.com<mailto:hyatt@apple.com>)