ASSERTION FAILED in WebCore::RenderFlowThread::getRegionRangeForBox
https://bugs.webkit.org/show_bug.cgi?id=135563
Reviewed by David Hyatt.
Source/WebCore:
The new multi-column code doesn't work correctly when the document contains nested fragmentation
contexts. The problem is the current flow thread concept that can store only one RenderFlowThread
at a time and use it during layout.
The stored flow thread is always correct for regions because named flow threads are absolutley positioned
so every child renderer is contained inside them (with the expcetion of fixed positioned elements which are
treated separately).
For multi-column elements this is no longer the case. An absolutely positioned element inside a static
multi-column element will be contained by a block outside the fragmentation context. It can even be
contained by a different multi-column element in the case of nested flow threads.
The patch below explores a solution that's not based on a current flow thread stored globally. The proposed
patch makes every block to store a pointer to its fragmentation context and a flag that states if this pointer
needs to be updated or not. If the renderer is not a block it will get its flow thread from the containing
block. Once the containing flow thread is requested for the block, the pointer is computed and cached until
invalidated:
- when a subtree is removed from a flow thread
- when the position property of an element inside a flow thread changes
The process is recursive and it doesn't affect elements that are not nested inside a flow thread. If a block
changes position from relative to static, any element that was contained by it can only be contained by an
ancestor of the block. This ancestor will still be outside of any flow thread. This ensures that non-fragmentation
code is not affected from a performance perspective.
The patch affects the results of the performance tests:
- the regions layout tests have a decreased performance raging from 2% to 5-6%
- the regions selection tests have an increased performance raging from 1-2% to 10%
- the multicolumn layout tests (now pending review in b137687) have an increased performance
raging from 1.8% to 5%
Tests: fast/multicol/multicol-all-positioned-crash.html
fast/multicol/multicol-transform-containing-block.html
* rendering/FlowThreadController.cpp:
(WebCore::FlowThreadController::FlowThreadController):
* rendering/FlowThreadController.h:
(WebCore::FlowThreadController::currentRenderFlowThread): Deleted.
(WebCore::FlowThreadController::setCurrentRenderFlowThread): Deleted.
* rendering/LayoutState.h:
(WebCore::LayoutState::currentRenderFlowThread):
(WebCore::LayoutState::setCurrentRenderFlowThread):
* rendering/RenderBlock.cpp:
(WebCore::RenderBlockRareData::RenderBlockRareData):
(WebCore::RenderBlock::styleWillChange):
(WebCore::RenderBlock::styleDidChange):
(WebCore::RenderBlock::collapseAnonymousBoxChild):
(WebCore::RenderBlock::cachedFlowThreadContainingBlock):
(WebCore::RenderBlock::cachedFlowThreadContainingBlockNeedsUpdate):
(WebCore::RenderBlock::setCachedFlowThreadContainingBlockNeedsUpdate):
(WebCore::RenderBlock::updateCachedFlowThreadContainingBlock):
(WebCore::RenderBlock::locateFlowThreadContainingBlock):
* rendering/RenderBlock.h:
* rendering/RenderBlockFlow.cpp:
(WebCore::RenderBlockFlow::styleWillChange):
* rendering/RenderBox.cpp:
(WebCore::RenderBox::borderBoxRectInRegion):
* rendering/RenderFlowThread.cpp:
(WebCore::RenderFlowThread::layout):
(WebCore::RenderFlowThread::updateAllLayerToRegionMappings):
(WebCore::RenderFlowThread::repaintRectangleInRegions):
(WebCore::CurrentRenderFlowThreadMaintainer::CurrentRenderFlowThreadMaintainer): Deleted.
(WebCore::CurrentRenderFlowThreadMaintainer::~CurrentRenderFlowThreadMaintainer): Deleted.
(WebCore::CurrentRenderFlowThreadDisabler::CurrentRenderFlowThreadDisabler): Deleted.
(WebCore::CurrentRenderFlowThreadDisabler::~CurrentRenderFlowThreadDisabler): Deleted.
* rendering/RenderFlowThread.h:
* rendering/RenderLayer.cpp:
(WebCore::RenderLayer::paintLayer):
(WebCore::RenderLayer::hitTestLayer):
(WebCore::RenderLayer::mapLayerClipRectsToFragmentationLayer):
(WebCore::RenderLayer::calculateClipRects):
* rendering/RenderObject.cpp:
(WebCore::RenderObject::showRegionsInformation):
(WebCore::RenderObject::insertedIntoTree):
(WebCore::RenderObject::removeFromRenderFlowThread):
(WebCore::RenderObject::removeFromRenderFlowThreadIncludingDescendants):
(WebCore::RenderObject::invalidateFlowThreadContainingBlockIncludingDescendants):
(WebCore::RenderObject::currentRenderNamedFlowFragment):
(WebCore::RenderObject::locateFlowThreadContainingBlock):
(WebCore::RenderObject::locateFlowThreadContainingBlockNoCache): Deleted.
(WebCore::RenderObject::removeFromRenderFlowThreadRecursive): Deleted.
* rendering/RenderObject.h:
(WebCore::RenderObject::flowThreadContainingBlock):
* rendering/RenderRegion.cpp:
(WebCore::RenderRegion::computeOverflowFromFlowThread):
* rendering/RenderView.cpp:
(WebCore::RenderView::pushLayoutStateForCurrentFlowThread):
(WebCore::RenderView::popLayoutStateForCurrentFlowThread):
* rendering/RenderView.h:
LayoutTests:
A test verifying that positioned elements inside multi-column containers don't
cause assertions or crashes.
* fast/multicol/multicol-all-positioned-crash-expected.txt: Added.
* fast/multicol/multicol-all-positioned-crash.html: Added.
* fast/multicol/multicol-transform-containing-block-expected.txt: Added.
* fast/multicol/multicol-transform-containing-block.html: Added.
git-svn-id: http://svn.webkit.org/repository/webkit/trunk@174761 268f45cc-cd09-0410-ab3c-d52691b4dbfc
21 files changed
