Source/WebCore/rendering/svg/RenderSVGText.cpp

/*
 * Copyright (C) 2006 Apple Inc.
 * Copyright (C) 2006 Alexander Kellett <lypanov@kde.org>
 * Copyright (C) 2006 Oliver Hunt <ojh16@student.canterbury.ac.nz>
 * Copyright (C) 2007 Nikolas Zimmermann <zimmermann@kde.org>
 * Copyright (C) 2008 Rob Buis <buis@kde.org>
 * Copyright (C) 2009 Dirk Schulze <krit@webkit.org>
 * Copyright (C) Research In Motion Limited 2010-2012. All rights reserved.
 * Copyright (C) 2012 Google Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#include "config.h"
#include "RenderSVGText.h"

#include "FloatQuad.h"
#include "Font.h"
#include "GraphicsContext.h"
#include "HitTestRequest.h"
#include "HitTestResult.h"
#include "LayoutRepainter.h"
#include "PointerEventsHitRules.h"
#include "RenderIterator.h"
#include "RenderSVGInline.h"
#include "RenderSVGInlineText.h"
#include "RenderSVGResource.h"
#include "RenderSVGRoot.h"
#include "SVGLengthList.h"
#include "SVGResourcesCache.h"
#include "SVGRootInlineBox.h"
#include "SVGTextElement.h"
#include "SVGURIReference.h"
#include "TransformState.h"
#include "VisiblePosition.h"
#include <wtf/IsoMallocInlines.h>
#include <wtf/StackStats.h>

namespace WebCore {

WTF_MAKE_ISO_ALLOCATED_IMPL(RenderSVGText);

RenderSVGText::RenderSVGText(SVGTextElement& element, RenderStyle&& style)
    : RenderSVGBlock(element, WTFMove(style))
    , m_needsReordering(false)
    , m_needsPositioningValuesUpdate(false)
    , m_needsTransformUpdate(true)
    , m_needsTextMetricsUpdate(false)
{
}

RenderSVGText::~RenderSVGText()
{
    ASSERT(m_layoutAttributes.isEmpty());
}

SVGTextElement& RenderSVGText::textElement() const
{
    return downcast<SVGTextElement>(RenderSVGBlock::graphicsElement());
}

bool RenderSVGText::isChildAllowed(const RenderObject& child, const RenderStyle&) const
{
    return child.isInline();
}

RenderSVGText* RenderSVGText::locateRenderSVGTextAncestor(RenderObject& start)
{
    return lineageOfType<RenderSVGText>(start).first();
}

const RenderSVGText* RenderSVGText::locateRenderSVGTextAncestor(const RenderObject& start)
{
    return lineageOfType<RenderSVGText>(start).first();
}

LayoutRect RenderSVGText::clippedOverflowRectForRepaint(const RenderLayerModelObject* repaintContainer) const
{
    return SVGRenderSupport::clippedOverflowRectForRepaint(*this, repaintContainer);
}

Optional<LayoutRect> RenderSVGText::computeVisibleRectInContainer(const LayoutRect& rect, const RenderLayerModelObject* container, VisibleRectContext context) const
{
    Optional<FloatRect> adjustedRect = computeFloatVisibleRectInContainer(rect, container, context);
    if (adjustedRect)
        return enclosingLayoutRect(*adjustedRect);
    return WTF::nullopt;
}

Optional<FloatRect> RenderSVGText::computeFloatVisibleRectInContainer(const FloatRect& rect, const RenderLayerModelObject* container, VisibleRectContext context) const
{
    return SVGRenderSupport::computeFloatVisibleRectInContainer(*this, rect, container, context);
}

void RenderSVGText::mapLocalToContainer(const RenderLayerModelObject* repaintContainer, TransformState& transformState, MapCoordinatesFlags, bool* wasFixed) const
{
    SVGRenderSupport::mapLocalToContainer(*this, repaintContainer, transformState, wasFixed);
}

const RenderObject* RenderSVGText::pushMappingToContainer(const RenderLayerModelObject* ancestorToStopAt, RenderGeometryMap& geometryMap) const
{
    return SVGRenderSupport::pushMappingToContainer(*this, ancestorToStopAt, geometryMap);
}

static inline void collectLayoutAttributes(RenderObject* text, Vector<SVGTextLayoutAttributes*>& attributes)
{
    for (RenderObject* descendant = text; descendant; descendant = descendant->nextInPreOrder(text)) {
        if (is<RenderSVGInlineText>(*descendant))
            attributes.append(downcast<RenderSVGInlineText>(*descendant).layoutAttributes());
    }
}

static inline bool findPreviousAndNextAttributes(RenderElement& start, RenderSVGInlineText* locateElement, bool& stopAfterNext, SVGTextLayoutAttributes*& previous, SVGTextLayoutAttributes*& next)
{
    ASSERT(locateElement);
    // FIXME: Make this iterative.
    for (auto& child : childrenOfType<RenderObject>(start)) {
        if (is<RenderSVGInlineText>(child)) {
            auto& text = downcast<RenderSVGInlineText>(child);
            if (locateElement != &text) {
                if (stopAfterNext) {
                    next = text.layoutAttributes();
                    return true;
                }

                previous = text.layoutAttributes();
                continue;
            }

            stopAfterNext = true;
            continue;
        }

        if (!is<RenderSVGInline>(child))
            continue;

        if (findPreviousAndNextAttributes(downcast<RenderElement>(child), locateElement, stopAfterNext, previous, next))
            return true;
    }

    return false;
}

inline bool RenderSVGText::shouldHandleSubtreeMutations() const
{
    if (beingDestroyed() || !everHadLayout()) {
        ASSERT(m_layoutAttributes.isEmpty());
        ASSERT(!m_layoutAttributesBuilder.numberOfTextPositioningElements());
        return false;
    }
    return true;
}

void RenderSVGText::subtreeChildWasAdded(RenderObject* child)
{
    ASSERT(child);
    if (!shouldHandleSubtreeMutations() || renderTreeBeingDestroyed())
        return;

    // The positioning elements cache doesn't include the new 'child' yet. Clear the
    // cache, as the next buildLayoutAttributesForTextRenderer() call rebuilds it.
    m_layoutAttributesBuilder.clearTextPositioningElements();

    if (!child->isSVGInlineText() && !child->isSVGInline())
        return;

    // Detect changes in layout attributes and only measure those text parts that have changed!
    Vector<SVGTextLayoutAttributes*> newLayoutAttributes;
    collectLayoutAttributes(this, newLayoutAttributes);
    if (newLayoutAttributes.isEmpty()) {
        ASSERT(m_layoutAttributes.isEmpty());
        return;
    }

    // Compare m_layoutAttributes with newLayoutAttributes to figure out which attribute got added.
    size_t size = newLayoutAttributes.size();
    SVGTextLayoutAttributes* attributes = 0;
    for (size_t i = 0; i < size; ++i) {
        attributes = newLayoutAttributes[i];
        if (m_layoutAttributes.find(attributes) == notFound) {
            // Every time this is invoked, there's only a single new entry in the newLayoutAttributes list, compared to the old in m_layoutAttributes.
            bool stopAfterNext = false;
            SVGTextLayoutAttributes* previous = 0;
            SVGTextLayoutAttributes* next = 0;
            ASSERT_UNUSED(child, &attributes->context() == child);
            findPreviousAndNextAttributes(*this, &attributes->context(), stopAfterNext, previous, next);

            if (previous)
                m_layoutAttributesBuilder.buildLayoutAttributesForTextRenderer(previous->context());
            m_layoutAttributesBuilder.buildLayoutAttributesForTextRenderer(attributes->context());
            if (next)
                m_layoutAttributesBuilder.buildLayoutAttributesForTextRenderer(next->context());
            break;
        }
    }

#ifndef NDEBUG
    // Verify that m_layoutAttributes only differs by a maximum of one entry.
    for (size_t i = 0; i < size; ++i)
        ASSERT(m_layoutAttributes.find(newLayoutAttributes[i]) != notFound || newLayoutAttributes[i] == attributes);
#endif

    m_layoutAttributes = newLayoutAttributes;
}

static inline void checkLayoutAttributesConsistency(RenderSVGText* text, Vector<SVGTextLayoutAttributes*>& expectedLayoutAttributes)
{
#ifndef NDEBUG
    Vector<SVGTextLayoutAttributes*> newLayoutAttributes;
    collectLayoutAttributes(text, newLayoutAttributes);
    ASSERT(newLayoutAttributes == expectedLayoutAttributes);
#else
    UNUSED_PARAM(text);
    UNUSED_PARAM(expectedLayoutAttributes);
#endif
}

void RenderSVGText::willBeDestroyed()
{
    m_layoutAttributes.clear();
    m_layoutAttributesBuilder.clearTextPositioningElements();

    RenderSVGBlock::willBeDestroyed();
}

void RenderSVGText::subtreeChildWillBeRemoved(RenderObject* child, Vector<SVGTextLayoutAttributes*, 2>& affectedAttributes)
{
    ASSERT(child);
    if (!shouldHandleSubtreeMutations())
        return;

    checkLayoutAttributesConsistency(this, m_layoutAttributes);

    // The positioning elements cache depends on the size of each text renderer in the
    // subtree. If this changes, clear the cache. It's going to be rebuilt below.
    m_layoutAttributesBuilder.clearTextPositioningElements();
    if (m_layoutAttributes.isEmpty() || !child->isSVGInlineText())
        return;

    // This logic requires that the 'text' child is still inserted in the tree.
    auto& text = downcast<RenderSVGInlineText>(*child);
    bool stopAfterNext = false;
    SVGTextLayoutAttributes* previous = nullptr;
    SVGTextLayoutAttributes* next = nullptr;
    if (!renderTreeBeingDestroyed())
        findPreviousAndNextAttributes(*this, &text, stopAfterNext, previous, next);

    if (previous)
        affectedAttributes.append(previous);
    if (next)
        affectedAttributes.append(next);

    bool removed = m_layoutAttributes.removeFirst(text.layoutAttributes());
    ASSERT_UNUSED(removed, removed);
}

void RenderSVGText::subtreeChildWasRemoved(const Vector<SVGTextLayoutAttributes*, 2>& affectedAttributes)
{
    if (!shouldHandleSubtreeMutations() || renderTreeBeingDestroyed()) {
        ASSERT(affectedAttributes.isEmpty());
        return;
    }

    // This is called immediately after subtreeChildWillBeDestroyed, once the RenderSVGInlineText::willBeDestroyed() method
    // passes on to the base class, which removes us from the render tree. At this point we can update the layout attributes.
    unsigned size = affectedAttributes.size();
    for (unsigned i = 0; i < size; ++i)
        m_layoutAttributesBuilder.buildLayoutAttributesForTextRenderer(affectedAttributes[i]->context());
}

void RenderSVGText::subtreeStyleDidChange(RenderSVGInlineText* text)
{
    ASSERT(text);
    if (!shouldHandleSubtreeMutations() || renderTreeBeingDestroyed())
        return;

    checkLayoutAttributesConsistency(this, m_layoutAttributes);

    // Only update the metrics cache, but not the text positioning element cache
    // nor the layout attributes cached in the leaf #text renderers.
    for (RenderObject* descendant = text; descendant; descendant = descendant->nextInPreOrder(text)) {
        if (is<RenderSVGInlineText>(*descendant))
            m_layoutAttributesBuilder.rebuildMetricsForTextRenderer(downcast<RenderSVGInlineText>(*descendant));
    }
}

void RenderSVGText::subtreeTextDidChange(RenderSVGInlineText* text)
{
    ASSERT(text);
    ASSERT(!beingDestroyed());
    if (!everHadLayout()) {
        ASSERT(m_layoutAttributes.isEmpty());
        ASSERT(!m_layoutAttributesBuilder.numberOfTextPositioningElements());
        return;
    }
    // Text transforms can cause text change to be signaled during addChild before m_layoutAttributes has been updated.
    if (!m_layoutAttributes.contains(text->layoutAttributes())) {
        ASSERT(!text->everHadLayout());
        return;
    }

    // The positioning elements cache depends on the size of each text renderer in the
    // subtree. If this changes, clear the cache. It's going to be rebuilt below.
    m_layoutAttributesBuilder.clearTextPositioningElements();

    checkLayoutAttributesConsistency(this, m_layoutAttributes);
    for (RenderObject* descendant = text; descendant; descendant = descendant->nextInPreOrder(text)) {
        if (is<RenderSVGInlineText>(*descendant))
            m_layoutAttributesBuilder.buildLayoutAttributesForTextRenderer(downcast<RenderSVGInlineText>(*descendant));
    }
}

static inline void updateFontInAllDescendants(RenderObject* start, SVGTextLayoutAttributesBuilder* builder = nullptr)
{
    for (RenderObject* descendant = start; descendant; descendant = descendant->nextInPreOrder(start)) {
        if (!is<RenderSVGInlineText>(*descendant))
            continue;
        auto& text = downcast<RenderSVGInlineText>(*descendant);
        text.updateScaledFont();
        if (builder)
            builder->rebuildMetricsForTextRenderer(text);
    }
}

void RenderSVGText::layout()
{
    StackStats::LayoutCheckPoint layoutCheckPoint;
    ASSERT(needsLayout());
    LayoutRepainter repainter(*this, SVGRenderSupport::checkForSVGRepaintDuringLayout(*this));

    bool updateCachedBoundariesInParents = false;
    if (m_needsTransformUpdate) {
        m_localTransform = textElement().animatedLocalTransform();
        m_needsTransformUpdate = false;
        updateCachedBoundariesInParents = true;
    }

    if (!everHadLayout()) {
        // When laying out initially, collect all layout attributes, build the character data map,
        // and propogate resulting SVGLayoutAttributes to all RenderSVGInlineText children in the subtree.
        ASSERT(m_layoutAttributes.isEmpty());
        collectLayoutAttributes(this, m_layoutAttributes);
        updateFontInAllDescendants(this);
        m_layoutAttributesBuilder.buildLayoutAttributesForForSubtree(*this);

        m_needsReordering = true;
        m_needsTextMetricsUpdate = false;
        m_needsPositioningValuesUpdate = false;
        updateCachedBoundariesInParents = true;
    } else if (m_needsPositioningValuesUpdate) {
        // When the x/y/dx/dy/rotate lists change, recompute the layout attributes, and eventually
        // update the on-screen font objects as well in all descendants.
        if (m_needsTextMetricsUpdate) {
            updateFontInAllDescendants(this);
            m_needsTextMetricsUpdate = false;
        }

        m_layoutAttributesBuilder.buildLayoutAttributesForForSubtree(*this);
        m_needsReordering = true;
        m_needsPositioningValuesUpdate = false;
        updateCachedBoundariesInParents = true;
    } else if (m_needsTextMetricsUpdate || SVGRenderSupport::findTreeRootObject(*this)->isLayoutSizeChanged()) {
        // If the root layout size changed (eg. window size changes) or the transform to the root
        // context has changed then recompute the on-screen font size.
        updateFontInAllDescendants(this, &m_layoutAttributesBuilder);

        ASSERT(!m_needsReordering);
        ASSERT(!m_needsPositioningValuesUpdate);
        m_needsTextMetricsUpdate = false;
        updateCachedBoundariesInParents = true;
    }

    checkLayoutAttributesConsistency(this, m_layoutAttributes);

    // Reduced version of RenderBlock::layoutBlock(), which only takes care of SVG text.
    // All if branches that could cause early exit in RenderBlocks layoutBlock() method are turned into assertions.
    ASSERT(!isInline());
    ASSERT(!simplifiedLayout());
    ASSERT(!scrollsOverflow());
    ASSERT(!hasControlClip());
    ASSERT(!multiColumnFlow());
    ASSERT(!positionedObjects());
    ASSERT(!m_overflow);
    ASSERT(!isAnonymousBlock());

    if (!firstChild())
        setChildrenInline(true);

    // FIXME: We need to find a way to only layout the child boxes, if needed.
    FloatRect oldBoundaries = objectBoundingBox();
    ASSERT(childrenInline());
    LayoutUnit repaintLogicalTop;
    LayoutUnit repaintLogicalBottom;
    rebuildFloatingObjectSetFromIntrudingFloats();
    layoutInlineChildren(true, repaintLogicalTop, repaintLogicalBottom);

    if (m_needsReordering)
        m_needsReordering = false;

    if (!updateCachedBoundariesInParents)
        updateCachedBoundariesInParents = oldBoundaries != objectBoundingBox();

    // Invalidate all resources of this client if our layout changed.
    if (everHadLayout() && selfNeedsLayout())
        SVGResourcesCache::clientLayoutChanged(*this);

    // If our bounds changed, notify the parents.
    if (updateCachedBoundariesInParents)
        RenderSVGBlock::setNeedsBoundariesUpdate();

    repainter.repaintAfterLayout();
    clearNeedsLayout();
}

std::unique_ptr<RootInlineBox> RenderSVGText::createRootInlineBox()
{
    auto box = std::make_unique<SVGRootInlineBox>(*this);
    box->setHasVirtualLogicalHeight();
    return box;
}

bool RenderSVGText::nodeAtFloatPoint(const HitTestRequest& request, HitTestResult& result, const FloatPoint& pointInParent, HitTestAction hitTestAction)
{
    PointerEventsHitRules hitRules(PointerEventsHitRules::SVG_TEXT_HITTESTING, request, style().pointerEvents());
    bool isVisible = (style().visibility() == Visibility::Visible);
    if (isVisible || !hitRules.requireVisible) {
        if ((hitRules.canHitStroke && (style().svgStyle().hasStroke() || !hitRules.requireStroke))
            || (hitRules.canHitFill && (style().svgStyle().hasFill() || !hitRules.requireFill))) {
            FloatPoint localPoint = localToParentTransform().inverse().valueOr(AffineTransform()).mapPoint(pointInParent);

            if (!SVGRenderSupport::pointInClippingArea(*this, localPoint))
                return false;       

            HitTestLocation hitTestLocation(LayoutPoint(flooredIntPoint(localPoint)));
            return RenderBlock::nodeAtPoint(request, result, hitTestLocation, LayoutPoint(), hitTestAction);
        }
    }

    return false;
}

bool RenderSVGText::nodeAtPoint(const HitTestRequest&, HitTestResult&, const HitTestLocation&, const LayoutPoint&, HitTestAction)
{
    ASSERT_NOT_REACHED();
    return false;
}

VisiblePosition RenderSVGText::positionForPoint(const LayoutPoint& pointInContents, const RenderFragmentContainer* fragment)
{
    RootInlineBox* rootBox = firstRootBox();
    if (!rootBox)
        return createVisiblePosition(0, DOWNSTREAM);

    ASSERT(!rootBox->nextRootBox());
    ASSERT(childrenInline());

    InlineBox* closestBox = downcast<SVGRootInlineBox>(*rootBox).closestLeafChildForPosition(pointInContents);
    if (!closestBox)
        return createVisiblePosition(0, DOWNSTREAM);

    return closestBox->renderer().positionForPoint({ pointInContents.x(), LayoutUnit(closestBox->y()) }, fragment);
}

void RenderSVGText::absoluteQuads(Vector<FloatQuad>& quads, bool* wasFixed) const
{
    quads.append(localToAbsoluteQuad(strokeBoundingBox(), UseTransforms, wasFixed));
}

void RenderSVGText::paint(PaintInfo& paintInfo, const LayoutPoint&)
{
    if (paintInfo.context().paintingDisabled())
        return;

    if (paintInfo.phase != PaintPhase::Foreground && paintInfo.phase != PaintPhase::Selection)
         return;

    PaintInfo blockInfo(paintInfo);
    GraphicsContextStateSaver stateSaver(blockInfo.context());
    blockInfo.applyTransform(localToParentTransform());
    RenderBlock::paint(blockInfo, LayoutPoint());

    // Paint the outlines, if any
    if (paintInfo.phase == PaintPhase::Foreground) {
        blockInfo.phase = PaintPhase::SelfOutline;
        RenderBlock::paint(blockInfo, LayoutPoint());
    }
}

FloatRect RenderSVGText::strokeBoundingBox() const
{
    FloatRect strokeBoundaries = objectBoundingBox();
    const SVGRenderStyle& svgStyle = style().svgStyle();
    if (!svgStyle.hasStroke())
        return strokeBoundaries;

    SVGLengthContext lengthContext(&textElement());
    strokeBoundaries.inflate(lengthContext.valueForLength(style().strokeWidth()));
    return strokeBoundaries;
}

FloatRect RenderSVGText::repaintRectInLocalCoordinates() const
{
    FloatRect repaintRect = strokeBoundingBox();
    SVGRenderSupport::intersectRepaintRectWithResources(*this, repaintRect);

    if (const ShadowData* textShadow = style().textShadow())
        textShadow->adjustRectForShadow(repaintRect);

    return repaintRect;
}

// Fix for <rdar://problem/8048875>. We should not render :first-line CSS Style
// in a SVG text element context.
RenderBlock* RenderSVGText::firstLineBlock() const
{
    return 0;
}

}