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/*
* Copyright (C) Research In Motion Limited 2010. All rights reserved.
*
* 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 "core/layout/svg/SVGResourcesCycleSolver.h"
// Set to a value > 0, to debug the resource cache.
#define DEBUG_CYCLE_DETECTION 0
#include "core/layout/svg/LayoutSVGResourceClipper.h"
#include "core/layout/svg/LayoutSVGResourceFilter.h"
#include "core/layout/svg/LayoutSVGResourceMarker.h"
#include "core/layout/svg/LayoutSVGResourceMasker.h"
#include "core/layout/svg/LayoutSVGResourcePaintServer.h"
#include "core/layout/svg/SVGResources.h"
#include "core/layout/svg/SVGResourcesCache.h"
namespace blink {
SVGResourcesCycleSolver::SVGResourcesCycleSolver(LayoutObject* layoutObject, SVGResources* resources)
: m_layoutObject(layoutObject)
, m_resources(resources)
{
ASSERT(m_layoutObject);
ASSERT(m_resources);
}
SVGResourcesCycleSolver::~SVGResourcesCycleSolver()
{
}
struct ActiveFrame {
typedef SVGResourcesCycleSolver::ResourceSet ResourceSet;
ActiveFrame(ResourceSet& activeSet, LayoutSVGResourceContainer* resource)
: m_activeSet(activeSet)
, m_resource(resource)
{
m_activeSet.add(m_resource);
}
~ActiveFrame()
{
m_activeSet.remove(m_resource);
}
ResourceSet& m_activeSet;
LayoutSVGResourceContainer* m_resource;
};
bool SVGResourcesCycleSolver::resourceContainsCycles(LayoutSVGResourceContainer* resource)
{
// If we've traversed this sub-graph before and no cycles were observed, then
// reuse that result.
if (m_dagCache.contains(resource))
return false;
ActiveFrame frame(m_activeResources, resource);
LayoutObject* node = resource;
while (node) {
// Skip subtrees which are themselves resources. (They will be
// processed - if needed - when they are actually referenced.)
if (node != resource && node->isSVGResourceContainer()) {
node = node->nextInPreOrderAfterChildren(resource);
continue;
}
if (SVGResources* nodeResources = SVGResourcesCache::cachedResourcesForLayoutObject(node)) {
// Fetch all the resources referenced by |node|.
ResourceSet nodeSet;
nodeResources->buildSetOfResources(nodeSet);
// Iterate resources referenced by |node|.
for (auto* node : nodeSet) {
if (m_activeResources.contains(node) || resourceContainsCycles(node))
return true;
}
}
node = node->nextInPreOrder(resource);
}
// No cycles found in (or from) this resource. Add it to the "DAG cache".
m_dagCache.add(resource);
return false;
}
void SVGResourcesCycleSolver::resolveCycles()
{
ASSERT(m_activeResources.isEmpty());
// If the starting LayoutObject is a resource container itself, then add it
// to the active set (to break direct self-references.)
if (m_layoutObject->isSVGResourceContainer())
m_activeResources.add(toLayoutSVGResourceContainer(m_layoutObject));
ResourceSet localResources;
m_resources->buildSetOfResources(localResources);
// This performs a depth-first search for a back-edge in all the
// (potentially disjoint) graphs formed by the resources referenced by
// |m_layoutObject|.
for (auto* localResource : localResources) {
if (m_activeResources.contains(localResource) || resourceContainsCycles(localResource))
breakCycle(localResource);
}
m_activeResources.clear();
}
void SVGResourcesCycleSolver::breakCycle(LayoutSVGResourceContainer* resourceLeadingToCycle)
{
ASSERT(resourceLeadingToCycle);
if (resourceLeadingToCycle == m_resources->linkedResource()) {
m_resources->resetLinkedResource();
return;
}
switch (resourceLeadingToCycle->resourceType()) {
case MaskerResourceType:
ASSERT(resourceLeadingToCycle == m_resources->masker());
m_resources->resetMasker();
break;
case MarkerResourceType:
ASSERT(resourceLeadingToCycle == m_resources->markerStart() || resourceLeadingToCycle == m_resources->markerMid() || resourceLeadingToCycle == m_resources->markerEnd());
if (m_resources->markerStart() == resourceLeadingToCycle)
m_resources->resetMarkerStart();
if (m_resources->markerMid() == resourceLeadingToCycle)
m_resources->resetMarkerMid();
if (m_resources->markerEnd() == resourceLeadingToCycle)
m_resources->resetMarkerEnd();
break;
case PatternResourceType:
case LinearGradientResourceType:
case RadialGradientResourceType:
ASSERT(resourceLeadingToCycle == m_resources->fill() || resourceLeadingToCycle == m_resources->stroke());
if (m_resources->fill() == resourceLeadingToCycle)
m_resources->resetFill();
if (m_resources->stroke() == resourceLeadingToCycle)
m_resources->resetStroke();
break;
case FilterResourceType:
ASSERT(resourceLeadingToCycle == m_resources->filter());
m_resources->resetFilter();
break;
case ClipperResourceType:
ASSERT(resourceLeadingToCycle == m_resources->clipper());
m_resources->resetClipper();
break;
default:
ASSERT_NOT_REACHED();
break;
}
}
} // namespace blink
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