LayoutState.cpp   [plain text]

/*
 * Copyright (C) 2007, 2013 Apple Inc.  All rights reserved.
 *
 * 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.
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 *
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 * 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
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#include "config.h"
#include "LayoutState.h"

#include "RenderFlowThread.h"
#include "RenderInline.h"
#include "RenderLayer.h"
#include "RenderMultiColumnFlowThread.h"
#include "RenderView.h"

namespace WebCore {

LayoutState::LayoutState(std::unique_ptr<LayoutState> next, RenderBox* renderer, const LayoutSize& offset, LayoutUnit pageLogicalHeight, bool pageLogicalHeightChanged)
    : m_next(WTFMove(next))
#ifndef NDEBUG
    , m_renderer(renderer)
#endif
{
    ASSERT(m_next);

    bool fixed = renderer->isOutOfFlowPositioned() && renderer->style().position() == FixedPosition;
    if (fixed) {
        // FIXME: This doesn't work correctly with transforms.
        FloatPoint fixedOffset = renderer->view().localToAbsolute(FloatPoint(), IsFixed);
        m_paintOffset = LayoutSize(fixedOffset.x(), fixedOffset.y()) + offset;
    } else
        m_paintOffset = m_next->m_paintOffset + offset;

    if (renderer->isOutOfFlowPositioned() && !fixed) {
        if (RenderElement* container = renderer->container()) {
            if (container->isInFlowPositioned() && is<RenderInline>(*container))
                m_paintOffset += downcast<RenderInline>(*container).offsetForInFlowPositionedInline(renderer);
        }
    }

    m_layoutOffset = m_paintOffset;

    if (renderer->isInFlowPositioned() && renderer->hasLayer())
        m_paintOffset += renderer->layer()->offsetForInFlowPosition();

    m_clipped = !fixed && m_next->m_clipped;
    if (m_clipped)
        m_clipRect = m_next->m_clipRect;

    if (renderer->hasOverflowClip()) {
        LayoutRect clipRect(toLayoutPoint(m_paintOffset) + renderer->view().layoutDelta(), renderer->cachedSizeForOverflowClip());
        if (m_clipped)
            m_clipRect.intersect(clipRect);
        else {
            m_clipRect = clipRect;
            m_clipped = true;
        }

        m_paintOffset -= toLayoutSize(renderer->scrollPosition());
    }

    // If we establish a new page height, then cache the offset to the top of the first page.
    // We can compare this later on to figure out what part of the page we're actually on,
    if (pageLogicalHeight || renderer->isRenderFlowThread()) {
        m_pageLogicalHeight = pageLogicalHeight;
        bool isFlipped = renderer->style().isFlippedBlocksWritingMode();
        m_pageOffset = LayoutSize(m_layoutOffset.width() + (!isFlipped ? renderer->borderLeft() + renderer->paddingLeft() : renderer->borderRight() + renderer->paddingRight()),
                               m_layoutOffset.height() + (!isFlipped ? renderer->borderTop() + renderer->paddingTop() : renderer->borderBottom() + renderer->paddingBottom()));
        m_pageLogicalHeightChanged = pageLogicalHeightChanged;
        m_isPaginated = true;
    } else {
        // If we don't establish a new page height, then propagate the old page height and offset down.
        m_pageLogicalHeight = m_next->m_pageLogicalHeight;
        m_pageLogicalHeightChanged = m_next->m_pageLogicalHeightChanged;
        m_pageOffset = m_next->m_pageOffset;
        
        // Disable pagination for objects we don't support. For now this includes overflow:scroll/auto, inline blocks and
        // writing mode roots.
        if (renderer->isUnsplittableForPagination()) {
            m_pageLogicalHeight = 0;
            m_isPaginated = false;
        } else
            m_isPaginated = m_pageLogicalHeight || renderer->flowThreadContainingBlock();
    }
    
    // Propagate line grid information.
    propagateLineGridInfo(renderer);

    m_layoutDelta = m_next->m_layoutDelta;
#if !ASSERT_DISABLED
    m_layoutDeltaXSaturated = m_next->m_layoutDeltaXSaturated;
    m_layoutDeltaYSaturated = m_next->m_layoutDeltaYSaturated;
#endif

    if (lineGrid() && (lineGrid()->style().writingMode() == renderer->style().writingMode()) && is<RenderMultiColumnFlowThread>(*renderer))
        downcast<RenderMultiColumnFlowThread>(*renderer).computeLineGridPaginationOrigin(*this);

    // If we have a new grid to track, then add it to our set.
    if (renderer->style().lineGrid() != RenderStyle::initialLineGrid() && is<RenderBlockFlow>(*renderer))
        establishLineGrid(downcast<RenderBlockFlow>(renderer));

    // FIXME: <http://bugs.webkit.org/show_bug.cgi?id=13443> Apply control clip if present.
}

LayoutState::LayoutState(RenderObject& root)
    : m_clipped(false)
    , m_isPaginated(false)
    , m_pageLogicalHeightChanged(false)
#if !ASSERT_DISABLED
    , m_layoutDeltaXSaturated(false)
    , m_layoutDeltaYSaturated(false)
#endif    
#ifndef NDEBUG
    , m_renderer(&root)
#endif
{
    if (RenderElement* container = root.container()) {
        FloatPoint absContentPoint = container->localToAbsolute(FloatPoint(), UseTransforms);
        m_paintOffset = LayoutSize(absContentPoint.x(), absContentPoint.y());

        if (container->hasOverflowClip()) {
            m_clipped = true;
            auto& containerBox = downcast<RenderBox>(*container);
            m_clipRect = LayoutRect(toLayoutPoint(m_paintOffset), containerBox.cachedSizeForOverflowClip());
            m_paintOffset -= toLayoutSize(containerBox.scrollPosition());
        }
    }
}

void LayoutState::clearPaginationInformation()
{
    m_pageLogicalHeight = m_next->m_pageLogicalHeight;
    m_pageOffset = m_next->m_pageOffset;
}

LayoutUnit LayoutState::pageLogicalOffset(RenderBox* child, LayoutUnit childLogicalOffset) const
{
    if (child->isHorizontalWritingMode())
        return m_layoutOffset.height() + childLogicalOffset - m_pageOffset.height();
    return m_layoutOffset.width() + childLogicalOffset - m_pageOffset.width();
}

void LayoutState::propagateLineGridInfo(RenderBox* renderer)
{
    // Disable line grids for objects we don't support. For now this includes overflow:scroll/auto, inline blocks and
    // writing mode roots.
    if (!m_next || renderer->isUnsplittableForPagination())
        return;

    m_lineGrid = m_next->m_lineGrid;
    m_lineGridOffset = m_next->m_lineGridOffset;
    m_lineGridPaginationOrigin = m_next->m_lineGridPaginationOrigin;
}

void LayoutState::establishLineGrid(RenderBlockFlow* block)
{
    // First check to see if this grid has been established already.
    if (m_lineGrid) {
        if (m_lineGrid->style().lineGrid() == block->style().lineGrid())
            return;
        RenderBlockFlow* currentGrid = m_lineGrid;
        for (LayoutState* currentState = m_next.get(); currentState; currentState = currentState->m_next.get()) {
            if (currentState->m_lineGrid == currentGrid)
                continue;
            currentGrid = currentState->m_lineGrid;
            if (!currentGrid)
                break;
            if (currentGrid->style().lineGrid() == block->style().lineGrid()) {
                m_lineGrid = currentGrid;
                m_lineGridOffset = currentState->m_lineGridOffset;
                return;
            }
        }
    }
    
    // We didn't find an already-established grid with this identifier. Our render object establishes the grid.
    m_lineGrid = block;
    m_lineGridOffset = m_layoutOffset; 
}

} // namespace WebCore