RESOLVED FIXED 97706
Scroll offset of flex items lost during relayout 
https://bugs.webkit.org/show_bug.cgi?id=97706
Summary Scroll offset of flex items lost during relayout
Tony Chang
Reported 2012-09-26 11:12:45 PDT
See the test case in the URL. It does the following: 1) A flexbox with a flexitem that has a scrollbar. 2) Set the scroll offset of the flexitem. 3) Change the flexbox (e.g., resize the window or insert a new flex item). 4) The scroll offset is lost. This is happening because flexbox does a 2 pass layout of the flex children. We layout the child without scrollbars (to get the size used for flexing), then we layout the child at it's final size. During the first layout, we remove the scrollbars, then during the second layout, we recreate the scrollbars (but without the scroll offset). There's some code in the old flexbox to handle this, we just need to add it to the new flexbox.
Attachments
Patch (6.63 KB, patch)
2012-09-27 16:05 PDT, Kenneth Rohde Christiansen 		no flags
DetailsFormatted DiffDiff
Patch (8.26 KB, patch)
2012-09-28 07:22 PDT, Kenneth Rohde Christiansen 		no flags
DetailsFormatted DiffDiff
Patch (8.20 KB, patch)
2012-09-29 02:45 PDT, Kenneth Rohde Christiansen 		no flags
DetailsFormatted DiffDiff
Show Obsolete (2) View All Add attachment proposed patch, testcase, etc.
Tony Chang
Comment 1 2012-09-26 11:13:07 PDT
Original bug reported here: http://code.google.com/p/chromium/issues/detail?id=113383
Tony Chang
Comment 2 2012-09-26 13:12:16 PDT
In RenderDeprecatedFlexibleBox.cpp, we use RenderBlock::startDelayUpdateScrollInfo() and RenderBlock::finishDelayUpdateScrollInfo() to keep our scroll info. We just need to call those in the right places in RenderFlexibleBox.cpp.
Kenneth Rohde Christiansen
Comment 3 2012-09-27 16:05:06 PDT
Created attachment 166085 [details] Patch
Ojan Vafai
Comment 4 2012-09-27 16:21:31 PDT
Comment on attachment 166085 [details] Patch View in context: https://bugs.webkit.org/attachment.cgi?id=166085&action=review Looks great. I have a bunch of nits about the test. It's not official style rules obviously, but keeping tests smaller is good practice IMO. Feel free to skip any bits you disagree with. > LayoutTests/fast/flexbox/overflow-keep-scrollpos.html:27 > + if (window.testRunner) > + testRunner.dumpAsText(); > + > + function log(message) > + { > + document.querySelector("#console").appendChild(document.createTextNode(message + "\n")); > + } How about importing js-test-pre.js? Then you wouldn't need to define any of this. > LayoutTests/fast/flexbox/overflow-keep-scrollpos.html:41 > + if (scrollPos === 50) > + log("SUCCESS") > + else > + log("FAIL: scrolltop should be 50, was: " + scrollPos) With js-test-pre.js these four lines would just be: shouldBe("document.querySelector('.overflow-auto').scrollTop", "50"); > LayoutTests/fast/flexbox/overflow-keep-scrollpos.html:46 > +<body onload="runTest()"> Can you move the script tag to the end of the body element? Then you don't need to run it onload and you don't need the runTest method at all. Not a big deal, but it makes the test a bit smaller. > LayoutTests/fast/flexbox/overflow-keep-scrollpos.html:57 > + <p>...</p> > + <p>...</p> > + <p>...</p> > + <p>...</p> > + <p>...</p> > + <p>...</p> > + <p>...</p> > + <p>...</p> How about just putting a single, 200px div in here? Makes for a more reduced test.
Build Bot
Comment 5 2012-09-27 16:36:22 PDT
Comment on attachment 166085 [details] Patch Attachment 166085 [details] did not pass mac-ews (mac): Output: http://queues.webkit.org/results/14038848 New failing tests: css3/flexbox/child-overflow.html
WebKit Review Bot
Comment 6 2012-09-27 18:04:08 PDT
Comment on attachment 166085 [details] Patch Attachment 166085 [details] did not pass chromium-ews (chromium-xvfb): Output: http://queues.webkit.org/results/14059094 New failing tests: css3/flexbox/child-overflow.html
Kenneth Rohde Christiansen
Comment 7 2012-09-28 01:01:37 PDT
(In reply to comment #5) > (From update of attachment 166085 [details]) > Attachment 166085 [details] did not pass mac-ews (mac): > Output: http://queues.webkit.org/results/14038848 > > New failing tests: > css3/flexbox/child-overflow.html I didn't notice the flexbox under css3. Anyway, this test is a bit weird as it works fine when running in the launcher, but not in the testing system. It seems like the result is dumped before the layout is complete. Maybe some of you have an idea
Kenneth Rohde Christiansen
Comment 8 2012-09-28 01:29:10 PDT
(In reply to comment #4) > (From update of attachment 166085 [details]) > View in context: https://bugs.webkit.org/attachment.cgi?id=166085&action=review > > Looks great. I have a bunch of nits about the test. It's not official style rules obviously, but keeping tests smaller is good practice IMO. Feel free to skip any bits you disagree with. I will fix this, no problem.
Kenneth Rohde Christiansen
Comment 9 2012-09-28 07:22:48 PDT
Created attachment 166249 [details] Patch
Tony Chang
Comment 10 2012-09-28 11:57:36 PDT
Comment on attachment 166249 [details] Patch View in context: https://bugs.webkit.org/attachment.cgi?id=166249&action=review > Source/WebCore/rendering/RenderBlock.cpp:1359 > + if (style()->isFlippedBlocksWritingMode()) { > + // FIXME: Workaround for now. We cannot delay the scroll info for overflow for We should file a bug about this (losing scroll position when using horizontal-bt or vertical-rl layout). It would probably be possible to move the code that scrolls a bt or rl layer or maybe make an exception for it. I'm not sure where that code is, but I bet we could make this work without too much effort. Seems fine to fix in a separate patch.
Tony Chang
Comment 11 2012-09-28 11:58:46 PDT
Comment on attachment 166249 [details] Patch View in context: https://bugs.webkit.org/attachment.cgi?id=166249&action=review > LayoutTests/fast/flexbox/overflow-keep-scrollpos.html:2 > +<!DOCTYPE html> > +<html> Oh, we should move this test to css3/flexbox. fast/flexbox are tests for the old flexbox (display: -webkit-box).
Kenneth Rohde Christiansen
Comment 12 2012-09-28 13:23:38 PDT
(In reply to comment #10) > (From update of attachment 166249 [details]) > View in context: https://bugs.webkit.org/attachment.cgi?id=166249&action=review > > > Source/WebCore/rendering/RenderBlock.cpp:1359 > > + if (style()->isFlippedBlocksWritingMode()) { > > + // FIXME: Workaround for now. We cannot delay the scroll info for overflow for > > We should file a bug about this (losing scroll position when using horizontal-bt or vertical-rl layout). It would probably be possible to move the code that scrolls a bt or rl layer or maybe make an exception for it. I'm not sure where that code is, but I bet we could make this work without too much effort. Seems fine to fix in a separate patch. Yes, I will file a bug after landing this. I will see if I can fix it later, but next week I am travelling. (In reply to comment #11) > (From update of attachment 166249 [details]) > View in context: https://bugs.webkit.org/attachment.cgi?id=166249&action=review > > > LayoutTests/fast/flexbox/overflow-keep-scrollpos.html:2 > > +<!DOCTYPE html> > > +<html> > > Oh, we should move this test to css3/flexbox. fast/flexbox are tests for the old flexbox (display: -webkit-box). Ah OK, I will move it before landing this sometime tomorrow. Thanks for the review.
Kenneth Rohde Christiansen
Comment 13 2012-09-28 13:41:03 PDT
Filed https://bugs.webkit.org/show_bug.cgi?id=97937 Will link to this in the patch.
Kenneth Rohde Christiansen
Comment 14 2012-09-29 02:45:49 PDT
Created attachment 166356 [details] Patch
WebKit Review Bot
Comment 15 2012-09-29 03:22:09 PDT
Comment on attachment 166356 [details] Patch Clearing flags on attachment: 166356 Committed r129975: <http://trac.webkit.org/changeset/129975>
WebKit Review Bot
Comment 16 2012-09-29 03:22:13 PDT
All reviewed patches have been landed. Closing bug.
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