Bug 120711 - [CSS Regions] Regions don't paint correctly in new-multicol elements
Summary: [CSS Regions] Regions don't paint correctly in new-multicol elements
Alias: None
Product: WebKit
Classification: Unclassified
Component: CSS (show other bugs)
Version: 528+ (Nightly build)
Hardware: Unspecified Unspecified
: P2 Normal
Assignee: Andrei Bucur
Keywords: AdobeTracked
Depends on:
Blocks: 53712
  Show dependency treegraph
Reported: 2013-09-04 17:32 PDT by Rebecca Hauck
Modified: 2014-02-21 03:21 PST (History)
7 users (show)

See Also:

test file for bug (2.44 KB, text/html)
2013-09-04 17:32 PDT, Rebecca Hauck
no flags Details
reference file for test (823 bytes, text/html)
2013-09-04 17:33 PDT, Rebecca Hauck
no flags Details
Patch (40.00 KB, patch)
2014-02-18 06:15 PST, Andrei Bucur
no flags Details | Formatted Diff | Diff
Patch for landing (39.64 KB, patch)
2014-02-21 02:17 PST, Andrei Bucur
no flags Details | Formatted Diff | Diff

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Description Rebecca Hauck 2013-09-04 17:32:00 PDT
This may be a variation of the numerous overflow/clipping issues we've seen. However, even if that is the case, that is blocking this test from verifying the overflow behaves correctly following the column layout

The attached test has named flow content that flows through three regions that are children of an element that has a three-column layout. The content overflows both the third region and the multicol container.

Result: The content flows correctly through the three region columns, but the overflow is clipped
Expected: The overflow should be visible and it should flow into a fourth column. If I remove the regions and only test content overflowing the multicol container, it overflows into a fourth column.
Comment 1 Rebecca Hauck 2013-09-04 17:32:49 PDT
Created attachment 210525 [details]
test file for bug
Comment 2 Rebecca Hauck 2013-09-04 17:33:03 PDT
Created attachment 210526 [details]
reference file for test
Comment 3 Mihai Balan 2013-11-11 02:10:35 PST
The problem here is that a multicolumn container with a definite size should produce overflow columns if there is more content inside it than would fit in the definite size.

However, when the contents of the multicolumn container are regions, no overflow columns are generated *for the overflow* of the last region. That means that if the content in the last region will not overflow the region, overflow columns will be properly generated.

In order to observe the latter behavior, just add to the `#region-3` element in the attached sample, the declaration: `height: 400px;` - this will lead to the expected result being produced.
Comment 4 Andrei Bucur 2014-02-13 07:13:22 PST
The test works with the old-multicol implementation. I'll investigate why it's not working with regions based multicol.
Comment 5 Andrei Bucur 2014-02-18 06:15:00 PST
Created attachment 224502 [details]
Comment 6 Dave Hyatt 2014-02-20 10:31:21 PST
Comment on attachment 224502 [details]

Comment 7 Andrei Bucur 2014-02-21 02:17:28 PST
Created attachment 224847 [details]
Patch for landing
Comment 8 WebKit Commit Bot 2014-02-21 03:21:25 PST
Comment on attachment 224847 [details]
Patch for landing

Clearing flags on attachment: 224847

Committed r164481: <http://trac.webkit.org/changeset/164481>
Comment 9 WebKit Commit Bot 2014-02-21 03:21:28 PST
All reviewed patches have been landed.  Closing bug.