[Webkit-unassigned] [Bug 99002] New: floating box is higher than previous floating box

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=99002

           Summary: floating box is higher than previous floating box
           Product: WebKit
           Version: 528+ (Nightly build)
          Platform: PC
        OS/Version: Windows 7
            Status: UNCONFIRMED
          Severity: Normal
          Priority: P2
         Component: Layout and Rendering
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: wxz0114 at gmail.com


In "http://www.w3.org/TR/CSS2/visuren.html", 9.5.1 Positioning the float, item 5 said that "The outer top of a floating box may not be higher than the outer top of any block or floated box generated by an element earlier in the source document.". But    if i create a page like

<div style="float:left; border:red 1px solid; width:350px; ">
        <div class="float1" style="float:left; border:red 1px solid; width:100px; height:100px">float1</div>
    aaaaaaaaaaaa
    <div class="float2" style="float:left; border:red 1px solid; width:300px; height:100px">float2</div>
    <div class="float3" style="float:left; border:red 1px solid; width:100px; height:100px">float3</div>
</div>

then open it with webkit, the last floating box(float3) is higher than it's previous floating box. By the way, IE and firefox works well.

This bug is caused that when the agent layout more than one floating boxes(in such case) in RenderBlock::positionNewFloats, it don't update its logicalTop. So if we add such process(logicalTop = max(logicalTopForFloat(floatingObject), logicalTop);) in RenderBlock::positionNewFloats, then webkit works well too.

====================================== code in RenderBlock::positionNewFloats ===================================
    for (; it != end; ++it) {
        FloatingObject* floatingObject = *it;
        // The containing block is responsible for positioning floats, so if we have floats in our
        // list that come from somewhere else, do not attempt to position them.
        if (floatingObject->renderer()->containingBlock() != this)
            continue;

        RenderBox* childBox = floatingObject->renderer();
        LayoutUnit childLogicalLeftMargin = style()->isLeftToRightDirection() ? marginStartForChild(childBox) : marginEndForChild(childBox);

        LayoutRect oldRect = childBox->frameRect();

        if (childBox->style()->clear() & CLEFT)
            logicalTop = max(lowestFloatLogicalBottom(FloatingObject::FloatLeft), logicalTop);
        if (childBox->style()->clear() & CRIGHT)
            logicalTop = max(lowestFloatLogicalBottom(FloatingObject::FloatRight), logicalTop);

        LayoutPoint floatLogicalLocation = computeLogicalLocationForFloat(floatingObject, logicalTop);

        setLogicalLeftForFloat(floatingObject, floatLogicalLocation.x());
        setLogicalLeftForChild(childBox, floatLogicalLocation.x() + childLogicalLeftMargin);
        setLogicalTopForChild(childBox, floatLogicalLocation.y() + marginBeforeForChild(childBox));

        LayoutState* layoutState = view()->layoutState();
        bool isPaginated = layoutState->isPaginated();
        if (isPaginated && !childBox->needsLayout())
            childBox->markForPaginationRelayoutIfNeeded();

        childBox->layoutIfNeeded();

        if (isPaginated) {
            // If we are unsplittable and don't fit, then we need to move down.
            // We include our margins as part of the unsplittable area.
            LayoutUnit newLogicalTop = adjustForUnsplittableChild(childBox, floatLogicalLocation.y(), true);

            // See if we have a pagination strut that is making us move down further.
            // Note that an unsplittable child can't also have a pagination strut, so this is
            // exclusive with the case above.
            RenderBlock* childBlock = childBox->isRenderBlock() ? toRenderBlock(childBox) : 0;
            if (childBlock && childBlock->paginationStrut()) {
                newLogicalTop += childBlock->paginationStrut();
                childBlock->setPaginationStrut(0);
            }

            if (newLogicalTop != floatLogicalLocation.y()) {
                floatingObject->m_paginationStrut = newLogicalTop - floatLogicalLocation.y();

                floatLogicalLocation = computeLogicalLocationForFloat(floatingObject, newLogicalTop);
                setLogicalLeftForFloat(floatingObject, floatLogicalLocation.x());
                setLogicalLeftForChild(childBox, floatLogicalLocation.x() + childLogicalLeftMargin);
                setLogicalTopForChild(childBox, floatLogicalLocation.y() + marginBeforeForChild(childBox));

                if (childBlock)
                    childBlock->setChildNeedsLayout(true, MarkOnlyThis);
                childBox->layoutIfNeeded();
            }
        }

        setLogicalTopForFloat(floatingObject, floatLogicalLocation.y());
        setLogicalHeightForFloat(floatingObject, logicalHeightForChild(childBox) + marginBeforeForChild(childBox) + marginAfterForChild(childBox));

        m_floatingObjects->addPlacedObject(floatingObject);

        // If the child moved, we have to repaint it.
        if (childBox->checkForRepaintDuringLayout())
            childBox->repaintDuringLayoutIfMoved(oldRect);

        logicalTop = max(logicalTopForFloat(floatingObject), logicalTop);  // add this 
    }
==========================================================================================

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