/*
 * Copyright (C) 2017 Apple Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    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. ``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
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "config.h"
#include "LocalFrameViewLayoutContext.h"

#include "DebugPageOverlays.h"
#include "Document.h"
#include "InspectorInstrumentation.h"
#include "LayoutDisallowedScope.h"
#include "LocalFrameView.h"
#include "Logging.h"
#include "RenderElement.h"
#include "RenderLayoutState.h"
#include "RenderStyleInlines.h"
#include "RenderView.h"
#include "ScriptDisallowedScope.h"
#include "Settings.h"
#include "StyleScope.h"
#include "LayoutBoxGeometry.h"
#include "LayoutContext.h"
#include "LayoutIntegrationLineLayout.h"
#include "LayoutState.h"
#include "LayoutTreeBuilder.h"
#include "RenderDescendantIterator.h"
#include "RenderStyleInlines.h"
#include <wtf/SetForScope.h>
#include <wtf/SystemTracing.h>
#include <wtf/text/TextStream.h>

namespace WebCore {

UpdateScrollInfoAfterLayoutTransaction::UpdateScrollInfoAfterLayoutTransaction() = default;
UpdateScrollInfoAfterLayoutTransaction::~UpdateScrollInfoAfterLayoutTransaction() = default;

void LocalFrameViewLayoutContext::layoutUsingFormattingContext()
{
    if (!frame().settings().layoutFormattingContextEnabled())
        return;
    // LocalFrameView::setContentsSize temporary disables layout.
    if (m_disableSetNeedsLayoutCount)
        return;

    m_layoutState = nullptr;
    m_layoutTree = nullptr;

    auto& renderView = *this->renderView();
    m_layoutTree = Layout::TreeBuilder::buildLayoutTree(renderView);
    m_layoutState = makeUnique<Layout::LayoutState>(*document(), m_layoutTree->root());
    auto layoutContext = Layout::LayoutContext { *m_layoutState };
    layoutContext.layout(view().layoutSize());

    // Clean up the render tree state when we don't run RenderView::layout.
    if (renderView.needsLayout()) {
        auto contentSize = Layout::BoxGeometry::marginBoxRect(m_layoutState->geometryForBox(*m_layoutState->root().firstChild())).size();
        renderView.setSize(contentSize);
        renderView.repaintViewRectangle({ 0, 0, contentSize.width(), contentSize.height() });

        for (auto& descendant : descendantsOfType<RenderObject>(renderView))
            descendant.clearNeedsLayout();
        renderView.clearNeedsLayout();
    }
#if ASSERT_ENABLED
    Layout::LayoutContext::verifyAndOutputMismatchingLayoutTree(*m_layoutState, renderView);
#endif
}

static bool isObjectAncestorContainerOf(RenderElement& ancestor, RenderElement& descendant)
{
    for (auto* renderer = &descendant; renderer; renderer = renderer->container()) {
        if (renderer == &ancestor)
            return true;
    }
    return false;
}

#ifndef NDEBUG
class RenderTreeNeedsLayoutChecker {
public :
    RenderTreeNeedsLayoutChecker(const RenderView& renderView)
        : m_renderView(renderView)
    {
    }

    ~RenderTreeNeedsLayoutChecker()
    {
        auto checkAndReportNeedsLayoutError = [] (const RenderObject& renderer) {
            auto needsLayout = [&] {
                if (renderer.needsLayout())
                    return true;
                if (is<RenderBlockFlow>(renderer) && downcast<RenderBlockFlow>(renderer).modernLineLayout())
                    return downcast<RenderBlockFlow>(renderer).modernLineLayout()->hasDetachedContent();
                return false;
            };

            if (needsLayout()) {
                WTFReportError(__FILE__, __LINE__, WTF_PRETTY_FUNCTION, "post-layout: dirty renderer(s)");
                renderer.showRenderTreeForThis();
                ASSERT_NOT_REACHED();
            }
        };

        checkAndReportNeedsLayoutError(m_renderView);

        for (auto* descendant = m_renderView.firstChild(); descendant; descendant = descendant->nextInPreOrder(&m_renderView))
            checkAndReportNeedsLayoutError(*descendant);
    }

private:
    const RenderView& m_renderView;
};
#endif

class LayoutScope {
public:
    LayoutScope(LocalFrameViewLayoutContext& layoutContext)
        : m_view(layoutContext.view())
        , m_nestedState(layoutContext.m_layoutNestedState, layoutContext.m_layoutNestedState == LocalFrameViewLayoutContext::LayoutNestedState::NotInLayout ? LocalFrameViewLayoutContext::LayoutNestedState::NotNested : LocalFrameViewLayoutContext::LayoutNestedState::Nested)
        , m_schedulingIsEnabled(layoutContext.m_layoutSchedulingIsEnabled, false)
        , m_previousScrollType(layoutContext.view().currentScrollType())
    {
        m_view.setCurrentScrollType(ScrollType::Programmatic);
    }
        
    ~LayoutScope()
    {
        m_view.setCurrentScrollType(m_previousScrollType);
    }
        
private:
    LocalFrameView& m_view;
    SetForScope<LocalFrameViewLayoutContext::LayoutNestedState> m_nestedState;
    SetForScope<bool> m_schedulingIsEnabled;
    ScrollType m_previousScrollType;
};

LocalFrameViewLayoutContext::LocalFrameViewLayoutContext(LocalFrameView& frameView)
    : m_frameView(frameView)
    , m_layoutTimer(*this, &LocalFrameViewLayoutContext::layoutTimerFired)
    , m_postLayoutTaskTimer(*this, &LocalFrameViewLayoutContext::runPostLayoutTasks)
{
}

LocalFrameViewLayoutContext::~LocalFrameViewLayoutContext()
{
}

UpdateScrollInfoAfterLayoutTransaction& LocalFrameViewLayoutContext::updateScrollInfoAfterLayoutTransaction()
{
    if (!m_updateScrollInfoAfterLayoutTransaction)
        m_updateScrollInfoAfterLayoutTransaction = makeUnique<UpdateScrollInfoAfterLayoutTransaction>();
    return *m_updateScrollInfoAfterLayoutTransaction;
}

void LocalFrameViewLayoutContext::layout()
{
    LOG_WITH_STREAM(Layout, stream << "LocalFrameView " << &view() << " LocalFrameViewLayoutContext::layout() with size " << view().layoutSize());

    Ref<LocalFrameView> protectView(view());

    performLayout();

    if (view().hasOneRef())
        return;

    Style::Scope::QueryContainerUpdateContext queryContainerUpdateContext;
    while (document() && document()->styleScope().updateQueryContainerState(queryContainerUpdateContext)) {
        document()->updateStyleIfNeeded();

        if (!needsLayout())
            break;

        performLayout();

        if (view().hasOneRef())
            return;
    }
}

void LocalFrameViewLayoutContext::performLayout()
{
    RELEASE_ASSERT_WITH_SECURITY_IMPLICATION(!frame().document()->inRenderTreeUpdate());
    ASSERT(LayoutDisallowedScope::isLayoutAllowed());
    ASSERT(!view().isPainting());
    ASSERT(frame().view() == &view());
    ASSERT(frame().document());
    ASSERT(frame().document()->backForwardCacheState() == Document::NotInBackForwardCache
        || frame().document()->backForwardCacheState() == Document::AboutToEnterBackForwardCache);
    if (!canPerformLayout()) {
        LOG(Layout, "  is not allowed, bailing");
        return;
    }

    LayoutScope layoutScope(*this);
    TraceScope tracingScope(PerformLayoutStart, PerformLayoutEnd);
    ScriptDisallowedScope::InMainThread scriptDisallowedScope;
    InspectorInstrumentation::willLayout(downcast<LocalFrame>(view().frame()));
    WeakPtr<RenderElement> layoutRoot;
    
    m_layoutTimer.stop();
    m_setNeedsLayoutWasDeferred = false;

#if !LOG_DISABLED
    if (m_firstLayout && !frame().ownerElement())
        LOG_WITH_STREAM(Layout, stream << "LocalFrameView " << &view() << " elapsed time before first layout: " << document()->timeSinceDocumentCreation());
#endif
#if PLATFORM(IOS_FAMILY)
    if (view().updateFixedPositionLayoutRect() && subtreeLayoutRoot())
        convertSubtreeLayoutToFullLayout();
#endif
    {
        SetForScope layoutPhase(m_layoutPhase, LayoutPhase::InPreLayout);

        if (!frame().document()->isResolvingContainerQueriesForSelfOrAncestor()) {
            // If this is a new top-level layout and there are any remaining tasks from the previous layout, finish them now.
            if (!isLayoutNested() && m_postLayoutTaskTimer.isActive())
                runPostLayoutTasks();

            updateStyleForLayout();
        }

        if (view().hasOneRef())
            return;

        view().autoSizeIfEnabled();
        if (!renderView())
            return;

        layoutRoot = subtreeLayoutRoot() ? subtreeLayoutRoot() : renderView();
        m_needsFullRepaint = is<RenderView>(layoutRoot) && (m_firstLayout || renderView()->printing());

        LOG_WITH_STREAM(Layout, stream << "LocalFrameView " << &view() << " layout " << m_layoutCount << " - subtree root " << subtreeLayoutRoot() << ", needsFullRepaint " << m_needsFullRepaint);

        view().willDoLayout(layoutRoot);
        m_firstLayout = false;
    }
    {
        TraceScope tracingScope(RenderTreeLayoutStart, RenderTreeLayoutEnd);
        SetForScope layoutPhase(m_layoutPhase, LayoutPhase::InRenderTreeLayout);
        ScriptDisallowedScope::InMainThread scriptDisallowedScope;
        SubtreeLayoutStateMaintainer subtreeLayoutStateMaintainer(subtreeLayoutRoot());
        RenderView::RepaintRegionAccumulator repaintRegionAccumulator(renderView());
#ifndef NDEBUG
        RenderTreeNeedsLayoutChecker checker(*renderView());
#endif
        layoutRoot->layout();
        layoutUsingFormattingContext();
        ++m_layoutCount;
#if ENABLE(TEXT_AUTOSIZING)
        applyTextSizingIfNeeded(*layoutRoot.get());
#endif
        clearSubtreeLayoutRoot();

#if !LOG_DISABLED
        auto layoutLogEnabled = [] {
            return LogLayout.state == WTFLogChannelState::On;
        };
        if (layoutLogEnabled())
            showRenderTree(renderView());
#endif
    }
    {
        SetForScope layoutPhase(m_layoutPhase, LayoutPhase::InViewSizeAdjust);
        ScriptDisallowedScope::InMainThread scriptDisallowedScope;
        if (is<RenderView>(layoutRoot) && !renderView()->printing()) {
            // This is to protect m_needsFullRepaint's value when layout() is getting re-entered through adjustViewSize().
            SetForScope needsFullRepaint(m_needsFullRepaint);
            view().adjustViewSize();
            // FIXME: Firing media query callbacks synchronously on nested frames could produced a detached FrameView here by
            // navigating away from the current document (see webkit.org/b/173329).
            if (view().hasOneRef())
                return;
        }
    }
    {
        SetForScope layoutPhase(m_layoutPhase, LayoutPhase::InPostLayout);
        if (m_needsFullRepaint)
            renderView()->repaintRootContents();
        ASSERT(!layoutRoot->needsLayout());
        view().didLayout(layoutRoot);
        runOrScheduleAsynchronousTasks();
    }
    InspectorInstrumentation::didLayout(downcast<LocalFrame>(view().frame()), *layoutRoot);
    DebugPageOverlays::didLayout(downcast<LocalFrame>(view().frame()));
}

void LocalFrameViewLayoutContext::runOrScheduleAsynchronousTasks()
{
    if (m_postLayoutTaskTimer.isActive())
        return;

    if (frame().document()->isResolvingContainerQueries()) {
        // We are doing layout from style resolution to resolve container queries.
        m_postLayoutTaskTimer.startOneShot(0_s);
        return;
    }

    // If we are already in performPostLayoutTasks(), defer post layout tasks until after we return
    // to avoid re-entrancy.
    if (m_inAsynchronousTasks) {
        m_postLayoutTaskTimer.startOneShot(0_s);
        return;
    }

    runPostLayoutTasks();
    if (needsLayout()) {
        // If runPostLayoutTasks() made us layout again, let's defer the tasks until after we return.
        m_postLayoutTaskTimer.startOneShot(0_s);
        layout();
    }
}

void LocalFrameViewLayoutContext::runPostLayoutTasks()
{
    m_postLayoutTaskTimer.stop();
    if (m_inAsynchronousTasks)
        return;
    SetForScope inAsynchronousTasks(m_inAsynchronousTasks, true);
    view().performPostLayoutTasks();
}

void LocalFrameViewLayoutContext::flushPostLayoutTasks()
{
    if (!m_postLayoutTaskTimer.isActive())
        return;
    runPostLayoutTasks();
}

void LocalFrameViewLayoutContext::reset()
{
    m_layoutPhase = LayoutPhase::OutsideLayout;
    clearSubtreeLayoutRoot();
    m_layoutCount = 0;
    m_layoutSchedulingIsEnabled = true;
    m_layoutTimer.stop();
    m_firstLayout = true;
    m_postLayoutTaskTimer.stop();
    m_needsFullRepaint = true;
}

bool LocalFrameViewLayoutContext::needsLayout() const
{
    // This can return true in cases where the document does not have a body yet.
    // Document::shouldScheduleLayout takes care of preventing us from scheduling
    // layout in that case.
    auto* renderView = this->renderView();
    return isLayoutPending()
        || (renderView && renderView->needsLayout())
        || subtreeLayoutRoot()
        || (m_disableSetNeedsLayoutCount && m_setNeedsLayoutWasDeferred);
}

void LocalFrameViewLayoutContext::setNeedsLayoutAfterViewConfigurationChange()
{
    if (m_disableSetNeedsLayoutCount) {
        m_setNeedsLayoutWasDeferred = true;
        return;
    }

    if (auto* renderView = this->renderView()) {
        ASSERT(!frame().document()->inHitTesting());
        renderView->setNeedsLayout();
        scheduleLayout();
    }
}

void LocalFrameViewLayoutContext::enableSetNeedsLayout()
{
    ASSERT(m_disableSetNeedsLayoutCount);
    if (!--m_disableSetNeedsLayoutCount)
        m_setNeedsLayoutWasDeferred = false; // FIXME: Find a way to make the deferred layout actually happen.
}

void LocalFrameViewLayoutContext::disableSetNeedsLayout()
{
    ++m_disableSetNeedsLayoutCount;
}

void LocalFrameViewLayoutContext::scheduleLayout()
{
    // FIXME: We should assert the page is not in the back/forward cache, but that is causing
    // too many false assertions. See <rdar://problem/7218118>.
    ASSERT(frame().view() == &view());

    if (subtreeLayoutRoot())
        convertSubtreeLayoutToFullLayout();
    if (!isLayoutSchedulingEnabled())
        return;
    if (!needsLayout())
        return;
    if (!frame().document()->shouldScheduleLayout())
        return;

    InspectorInstrumentation::didInvalidateLayout(frame());
    if (m_layoutTimer.isActive())
        return;

#if !LOG_DISABLED
    if (!frame().document()->ownerElement())
        LOG(Layout, "LocalFrameView %p layout timer scheduled at %.3fs", this, frame().document()->timeSinceDocumentCreation().value());
#endif

    m_layoutTimer.startOneShot(0_s);
}

void LocalFrameViewLayoutContext::unscheduleLayout()
{
    if (m_postLayoutTaskTimer.isActive())
        m_postLayoutTaskTimer.stop();

    if (!m_layoutTimer.isActive())
        return;

#if !LOG_DISABLED
    if (!frame().document()->ownerElement())
        LOG_WITH_STREAM(Layout, stream << "LocalFrameViewLayoutContext for LocalFrameView " << frame().view() << " layout timer unscheduled at " << frame().document()->timeSinceDocumentCreation().value());
#endif

    m_layoutTimer.stop();
}

void LocalFrameViewLayoutContext::scheduleSubtreeLayout(RenderElement& layoutRoot)
{
    ASSERT(renderView());
    auto& renderView = *this->renderView();

    // Try to catch unnecessary work during render tree teardown.
    ASSERT(!renderView.renderTreeBeingDestroyed());
    ASSERT(frame().view() == &view());

    if (renderView.needsLayout() && !subtreeLayoutRoot()) {
        layoutRoot.markContainingBlocksForLayout(ScheduleRelayout::No);
        return;
    }

    if (!isLayoutPending() && isLayoutSchedulingEnabled()) {
        ASSERT(!layoutRoot.container() || is<RenderView>(layoutRoot.container()) || !layoutRoot.container()->needsLayout());
        setSubtreeLayoutRoot(layoutRoot);
        InspectorInstrumentation::didInvalidateLayout(frame());
        m_layoutTimer.startOneShot(0_s);
        return;
    }

    auto* subtreeLayoutRoot = this->subtreeLayoutRoot();
    if (subtreeLayoutRoot == &layoutRoot)
        return;

    if (!subtreeLayoutRoot) {
        // We already have a pending (full) layout. Just mark the subtree for layout.
        layoutRoot.markContainingBlocksForLayout(ScheduleRelayout::No);
        InspectorInstrumentation::didInvalidateLayout(frame());
        return;
    }

    if (isObjectAncestorContainerOf(*subtreeLayoutRoot, layoutRoot)) {
        // Keep the current root.
        layoutRoot.markContainingBlocksForLayout(ScheduleRelayout::No, subtreeLayoutRoot);
        ASSERT(!subtreeLayoutRoot->container() || is<RenderView>(subtreeLayoutRoot->container()) || !subtreeLayoutRoot->container()->needsLayout());
        return;
    }

    if (isObjectAncestorContainerOf(layoutRoot, *subtreeLayoutRoot)) {
        // Re-root at newRelayoutRoot.
        subtreeLayoutRoot->markContainingBlocksForLayout(ScheduleRelayout::No, &layoutRoot);
        setSubtreeLayoutRoot(layoutRoot);
        ASSERT(!layoutRoot.container() || is<RenderView>(layoutRoot.container()) || !layoutRoot.container()->needsLayout());
        InspectorInstrumentation::didInvalidateLayout(frame());
        return;
    }
    // Two disjoint subtrees need layout. Mark both of them and issue a full layout instead.
    convertSubtreeLayoutToFullLayout();
    layoutRoot.markContainingBlocksForLayout(ScheduleRelayout::No);
    InspectorInstrumentation::didInvalidateLayout(frame());
}

void LocalFrameViewLayoutContext::layoutTimerFired()
{
#if !LOG_DISABLED
    if (!frame().document()->ownerElement())
        LOG_WITH_STREAM(Layout, stream << "LocalFrameViewLayoutContext for LocalFrameView " << frame().view() << " layout timer fired at " << frame().document()->timeSinceDocumentCreation().value());
#endif
    layout();
}

RenderElement* LocalFrameViewLayoutContext::subtreeLayoutRoot() const
{
    return m_subtreeLayoutRoot.get();
}

void LocalFrameViewLayoutContext::convertSubtreeLayoutToFullLayout()
{
    ASSERT(subtreeLayoutRoot());
    subtreeLayoutRoot()->markContainingBlocksForLayout(ScheduleRelayout::No);
    clearSubtreeLayoutRoot();
}

void LocalFrameViewLayoutContext::setSubtreeLayoutRoot(RenderElement& layoutRoot)
{
    m_subtreeLayoutRoot = layoutRoot;
}

bool LocalFrameViewLayoutContext::canPerformLayout() const
{
    if (isInRenderTreeLayout())
        return false;

    if (view().isPainting())
        return false;

    if (!subtreeLayoutRoot() && !frame().document()->renderView())
        return false;

    return true;
}

#if ENABLE(TEXT_AUTOSIZING)
void LocalFrameViewLayoutContext::applyTextSizingIfNeeded(RenderElement& layoutRoot)
{
    auto& settings = layoutRoot.settings();
    bool idempotentMode = settings.textAutosizingUsesIdempotentMode();
    if (!settings.textAutosizingEnabled() || idempotentMode || renderView()->printing())
        return;
    auto minimumZoomFontSize = settings.minimumZoomFontSize();
    if (!idempotentMode && !minimumZoomFontSize)
        return;
    auto textAutosizingWidth = layoutRoot.page().textAutosizingWidth();
    if (auto overrideWidth = settings.textAutosizingWindowSizeOverrideWidth())
        textAutosizingWidth = overrideWidth;
    if (!idempotentMode && !textAutosizingWidth)
        return;
    layoutRoot.adjustComputedFontSizesOnBlocks(minimumZoomFontSize, textAutosizingWidth);
    if (!layoutRoot.needsLayout())
        return;
    LOG(TextAutosizing, "Text Autosizing: minimumZoomFontSize=%.2f textAutosizingWidth=%.2f", minimumZoomFontSize, textAutosizingWidth);
    layoutRoot.layout();
}
#endif

void LocalFrameViewLayoutContext::updateStyleForLayout()
{
    ScriptDisallowedScope::InMainThread scriptDisallowedScope;
    Document& document = *frame().document();

    // FIXME: This shouldn't be necessary, but see rdar://problem/36670246.
    if (!document.styleScope().resolverIfExists())
        document.styleScope().didChangeStyleSheetEnvironment();

    // Viewport-dependent media queries may cause us to need completely different style information.
    document.styleScope().evaluateMediaQueriesForViewportChange();

    document.updateElementsAffectedByMediaQueries();
    // If there is any pagination to apply, it will affect the RenderView's style, so we should
    // take care of that now.
    view().applyPaginationToViewport();
    // Always ensure our style info is up-to-date. This can happen in situations where
    // the layout beats any sort of style recalc update that needs to occur.
    document.updateStyleIfNeeded();
}

LayoutSize LocalFrameViewLayoutContext::layoutDelta() const
{
    if (auto* layoutState = this->layoutState())
        return layoutState->layoutDelta();
    return { };
}
    
void LocalFrameViewLayoutContext::addLayoutDelta(const LayoutSize& delta)
{
    if (auto* layoutState = this->layoutState())
        layoutState->addLayoutDelta(delta);
}
    
#if ASSERT_ENABLED
bool LocalFrameViewLayoutContext::layoutDeltaMatches(const LayoutSize& delta)
{
    if (auto* layoutState = this->layoutState())
        return layoutState->layoutDeltaMatches(delta);
    return false;
}
#endif

RenderLayoutState* LocalFrameViewLayoutContext::layoutState() const
{
    if (m_layoutStateStack.isEmpty())
        return nullptr;
    return m_layoutStateStack.last().get();
}

void LocalFrameViewLayoutContext::pushLayoutState(RenderElement& root)
{
    ASSERT(!m_paintOffsetCacheDisableCount);
    ASSERT(!layoutState());

    m_layoutStateStack.append(makeUnique<RenderLayoutState>(root));
}

bool LocalFrameViewLayoutContext::pushLayoutStateForPaginationIfNeeded(RenderBlockFlow& layoutRoot)
{
    if (layoutState())
        return false;
    m_layoutStateStack.append(makeUnique<RenderLayoutState>(layoutRoot, RenderLayoutState::IsPaginated::Yes));
    return true;
}
    
bool LocalFrameViewLayoutContext::pushLayoutState(RenderBox& renderer, const LayoutSize& offset, LayoutUnit pageHeight, bool pageHeightChanged)
{
    // We push LayoutState even if layoutState is disabled because it stores layoutDelta too.
    auto* layoutState = this->layoutState();
    if (!layoutState || !needsFullRepaint() || layoutState->isPaginated() || renderer.enclosingFragmentedFlow()
        || layoutState->lineGrid() || (renderer.style().lineGrid() != RenderStyle::initialLineGrid() && renderer.isRenderBlockFlow())) {
        m_layoutStateStack.append(makeUnique<RenderLayoutState>(m_layoutStateStack
            , renderer
            , offset
            , pageHeight
            , pageHeightChanged
            , layoutState ? layoutState->lineClamp() : std::nullopt
            , layoutState ? layoutState->textBoxTrim() : RenderLayoutState::TextBoxTrim()));
        return true;
    }
    return false;
}
    
void LocalFrameViewLayoutContext::popLayoutState()
{
    if (!layoutState())
        return;

    auto currentLineClamp = layoutState()->lineClamp();

    m_layoutStateStack.removeLast();

    if (currentLineClamp) {
        // Propagates the current line clamp state to the parent.
        if (auto* layoutState = this->layoutState(); layoutState && layoutState->lineClamp()) {
            ASSERT(layoutState->lineClamp()->maximumLineCount == currentLineClamp->maximumLineCount);
            layoutState->setLineClamp(currentLineClamp);
        }
    }
}

#ifndef NDEBUG
void LocalFrameViewLayoutContext::checkLayoutState()
{
    ASSERT(layoutDeltaMatches(LayoutSize()));
    ASSERT(!m_paintOffsetCacheDisableCount);
}
#endif

LocalFrame& LocalFrameViewLayoutContext::frame() const
{
    return downcast<LocalFrame>(view().frame());
}

LocalFrameView& LocalFrameViewLayoutContext::view() const
{
    return m_frameView;
}

RenderView* LocalFrameViewLayoutContext::renderView() const
{
    return view().renderView();
}

Document* LocalFrameViewLayoutContext::document() const
{
    return frame().document();
}

} // namespace WebCore