LayoutIntegrationBoxTree.cpp   [plain text]

/*
 * Copyright (C) 2020 Apple Inc. All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
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#include "config.h"
#include "LayoutIntegrationBoxTree.h"

#if ENABLE(LAYOUT_FORMATTING_CONTEXT)

#include "InlineIterator.h"
#include "LayoutContainerBox.h"
#include "LayoutInlineTextBox.h"
#include "LayoutLineBreakBox.h"
#include "LayoutReplacedBox.h"
#include "RenderBlockFlow.h"
#include "RenderChildIterator.h"
#include "RenderImage.h"
#include "RenderLineBreak.h"

namespace WebCore {
namespace LayoutIntegration {

static constexpr size_t smallTreeThreshold = 8;

static RenderStyle rootBoxStyle(const RenderStyle& style)
{
    auto clonedStyle = RenderStyle::clone(style);
    clonedStyle.setDisplay(DisplayType::Block);
    return clonedStyle;
}

BoxTree::BoxTree(RenderBlockFlow& flow)
    : m_flow(flow)
    , m_root(rootBoxStyle(flow.style()))
{
    if (flow.isAnonymous())
        m_root.setIsAnonymous();

    buildTree();
}

void BoxTree::buildTree()
{
    auto createChildBox = [&](RenderObject& childRenderer) -> std::unique_ptr<Layout::Box> {
        if (is<RenderText>(childRenderer)) {
            auto& textRenderer = downcast<RenderText>(childRenderer);
            auto style = RenderStyle::createAnonymousStyleWithDisplay(textRenderer.style(), DisplayType::Inline);
            return makeUnique<Layout::InlineTextBox>(textRenderer.text(), textRenderer.canUseSimplifiedTextMeasuring(), WTFMove(style));
        }

        auto style = RenderStyle::clone(childRenderer.style());
        if (childRenderer.isLineBreak()) {
            style.setDisplay(DisplayType::Inline);
            style.setFloating(Float::No);
            style.setPosition(PositionType::Static);
            return makeUnique<Layout::LineBreakBox>(downcast<RenderLineBreak>(childRenderer).isWBR(), WTFMove(style));
        }

        if (is<RenderReplaced>(childRenderer))
            return makeUnique<Layout::ReplacedBox>(Layout::Box::ElementAttributes { is<RenderImage>(childRenderer) ? Layout::Box::ElementType::Image : Layout::Box::ElementType::GenericElement }, WTFMove(style));

        if (is<RenderBlock>(childRenderer))
            return makeUnique<Layout::ReplacedBox>(Layout::Box::ElementAttributes { Layout::Box::ElementType::GenericElement }, WTFMove(style));

        if (is<RenderInline>(childRenderer))
            return makeUnique<Layout::ContainerBox>(Layout::Box::ElementAttributes { Layout::Box::ElementType::GenericElement }, WTFMove(style));

        ASSERT_NOT_REACHED();
        return nullptr;
    };

    for (auto walker = InlineWalker(m_flow); !walker.atEnd(); walker.advance()) {
        if (walker.atEndOfInline())
            continue;
        auto& childRenderer = *walker.current();
        auto childBox = createChildBox(childRenderer);
        appendChild(WTFMove(childBox), childRenderer);
    }
}

void BoxTree::appendChild(std::unique_ptr<Layout::Box> childBox, RenderObject& childRenderer)
{
    auto& parentBox = downcast<Layout::ContainerBox>(layoutBoxForRenderer(*childRenderer.parent()));
    parentBox.appendChild(*childBox);

    m_boxes.append({ WTFMove(childBox), &childRenderer });

    if (m_boxes.size() > smallTreeThreshold) {
        if (m_rendererToBoxMap.isEmpty()) {
            for (auto& entry : m_boxes)
                m_rendererToBoxMap.add(entry.renderer, entry.box.get());
        } else
            m_rendererToBoxMap.add(&childRenderer, m_boxes.last().box.get());
    }
}

void BoxTree::updateStyle(const RenderBoxModelObject& renderer)
{
    auto& layoutBox = layoutBoxForRenderer(renderer);
    auto& style = renderer.style();

    layoutBox.updateStyle(style);

    if (is<Layout::ContainerBox>(layoutBox)) {
        for (auto* child = downcast<Layout::ContainerBox>(layoutBox).firstChild(); child; child = child->nextSibling()) {
            if (child->isInlineTextBox())
                child->updateStyle(RenderStyle::createAnonymousStyleWithDisplay(style, DisplayType::Inline));
        }
    }
}

Layout::Box& BoxTree::layoutBoxForRenderer(const RenderObject& renderer)
{
    if (&renderer == &m_flow)
        return m_root;

    if (m_boxes.size() <= smallTreeThreshold) {
        auto index = m_boxes.findMatching([&](auto& entry) {
            return entry.renderer == &renderer;
        });
        RELEASE_ASSERT(index != notFound);
        return *m_boxes[index].box;
    }

    return *m_rendererToBoxMap.get(&renderer);
}

const Layout::Box& BoxTree::layoutBoxForRenderer(const RenderObject& renderer) const
{
    return const_cast<BoxTree&>(*this).layoutBoxForRenderer(renderer);
}

RenderObject& BoxTree::rendererForLayoutBox(const Layout::Box& box)
{
    if (&box == &m_root)
        return m_flow;

    if (m_boxes.size() <= smallTreeThreshold) {
        auto index = m_boxes.findMatching([&](auto& entry) {
            return entry.box.get() == &box;
        });
        RELEASE_ASSERT(index != notFound);
        return *m_boxes[index].renderer;
    }

    if (m_boxToRendererMap.isEmpty()) {
        for (auto& entry : m_boxes)
            m_boxToRendererMap.add(entry.box.get(), entry.renderer);
    }
    return *m_boxToRendererMap.get(&box);
}

const RenderObject& BoxTree::rendererForLayoutBox(const Layout::Box& box) const
{
    return const_cast<BoxTree&>(*this).rendererForLayoutBox(box);
}

}
}

#endif