Bug 78562 – New flexboxes don't split into columns

• Status: NEW
• Component: Layout and Rendering

[Ojan Vafai]

RenderBlock* RenderBlock::createAnonymousBlockWithSameTypeAs(RenderBlock* otherAnonymousBlock) const
{
    if (otherAnonymousBlock->isAnonymousColumnsBlock())
        return createAnonymousColumnsBlock();
    if (otherAnonymousBlock->isAnonymousColumnSpanBlock())
        return createAnonymousColumnSpanBlock();
    return createAnonymousBlock(otherAnonymousBlock->style()->display() == BOX);
}

[Ojan Vafai]

As well as:
RenderBlock* RenderBlock::createAnonymousBlock(bool isFlexibleBox) const
{
    RefPtr<RenderStyle> newStyle = RenderStyle::createAnonymousStyle(style());

    RenderBlock* newBox = 0;
    if (isFlexibleBox) {
        newStyle->setDisplay(BOX);
        newBox = new (renderArena()) RenderDeprecatedFlexibleBox(document() /* anonymous box */);
    } else {
        newStyle->setDisplay(BLOCK);
        newBox = new (renderArena()) RenderBlock(document() /* anonymous box */);
    }

    newBox->setStyle(newStyle.release());
    return newBox;
}

[Ojan Vafai]

And to round out the trio, RenderObject.h:
    bool isAnonymousBlock() const
    {
        // This function is kept in sync with anonymous block creation conditions in
        // RenderBlock::createAnonymousBlock(). This includes creating an anonymous
        // RenderBlock having a BLOCK or BOX display. Other classes such as RenderTextFragment
        // are not RenderBlocks and will return false. See https://bugs.webkit.org/show_bug.cgi?id=56709. 
        return isAnonymous() && (style()->display() == BLOCK || style()->display() == BOX) && style()->styleType() == NOPSEUDO && isRenderBlock() && !isListMarker()
#if ENABLE(FULLSCREEN_API)
            && !isRenderFullScreen()
            && !isRenderFullScreenPlaceholder()
#endif
            ;
    }

[Ojan Vafai]

We need createAnonymousBlock to create a RenderFlexibleBox when splitting flexboxes. This will get new flexboxes to match the old ones. Old flexboxes are all sorts of buggy in multi-column though.