DOM-based SVG resource tracking

third_party/WebKit/Source/core/layout/svg/LayoutSVGResourceContainer.cpp

 /*
  * 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/LayoutSVGResourceContainer.h"
 
 #include "core/layout/svg/SVGResources.h"
 #include "core/layout/svg/SVGResourcesCache.h"
 #include "core/svg/SVGElementProxy.h"
 #include "core/svg/SVGTreeScopeResources.h"
 #include "platform/wtf/AutoReset.h"
 
 namespace blink {
 
-static inline SVGTreeScopeResources& SvgTreeScopeResourcesFromElement(
-    Element* element) {
-  DCHECK(element);
-  return element->GetTreeScope().EnsureSVGTreeScopedResources();
+namespace {
+
+SVGTreeScopeResources::Resource* ResourceForContainer(
+    const LayoutSVGResourceContainer& resource_container) {
+  const SVGElement& element = *resource_container.GetElement();
+  return element.GetTreeScope()
+      .EnsureSVGTreeScopedResources()
+      .ExistingResourceForId(element.GetIdAttribute());
 }
 
+}  // namespace
+
 LayoutSVGResourceContainer::LayoutSVGResourceContainer(SVGElement* node)
     : LayoutSVGHiddenContainer(node),
       is_in_layout_(false),
       invalidation_mask_(0),
-      registered_(false),
       is_invalidating_(false) {}
 
 LayoutSVGResourceContainer::~LayoutSVGResourceContainer() {}
 
 void LayoutSVGResourceContainer::UpdateLayout() {
   // FIXME: Investigate a way to detect and break resource layout dependency
   // cycles early. Then we can remove this method altogether, and fall back onto
   // LayoutSVGHiddenContainer::layout().
   DCHECK(NeedsLayout());
   if (is_in_layout_)
@@ skipping 10 matching lines @@
   return GetElement()->ElementProxySet();
 }
 
 void LayoutSVGResourceContainer::NotifyContentChanged() {
   if (SVGElementProxySet* proxy_set = ElementProxySet())
     proxy_set->NotifyContentChanged(GetElement()->GetTreeScope());
 }
 
 void LayoutSVGResourceContainer::WillBeDestroyed() {
   LayoutSVGHiddenContainer::WillBeDestroyed();
-  SvgTreeScopeResourcesFromElement(GetElement())
-      .RemoveResource(GetElement()->GetIdAttribute(), this);
-  DCHECK(clients_.IsEmpty());
+  // The resource is being torn down. If we have any clients, move those to be
+  // pending on the resource (if one exists.)
+  if (SVGTreeScopeResources::Resource* resource = ResourceForContainer(*this))
+    MakeClientsPending(*resource);
 }
 
 void LayoutSVGResourceContainer::StyleDidChange(
     StyleDifference diff,
     const ComputedStyle* old_style) {
   LayoutSVGHiddenContainer::StyleDidChange(diff, old_style);
-  SvgTreeScopeResourcesFromElement(GetElement())
-      .UpdateResource(GetElement()->GetIdAttribute(), this);
+  // The resource has (read: may have) been attached. Notify any pending
+  // clients that they can now try to add themselves as clients to the
+  // resource.
+  if (SVGTreeScopeResources::Resource* resource = ResourceForContainer(*this)) {
+    if (resource->Target() == GetElement())
+      resource->NotifyResourceClients();
+  }
 }
 
-void LayoutSVGResourceContainer::DetachAllClients(const AtomicString& to_id) {
+void LayoutSVGResourceContainer::MakeClientsPending(
+    SVGTreeScopeResources::Resource& resource) {
   RemoveAllClientsFromCache();
 
   for (auto* client : clients_) {
-    // Unlink the resource from the client's SVGResources. (The actual
-    // removal will be signaled after processing all the clients.)
+    // Unlink the resource from the client's SVGResources.
     SVGResources* resources =
         SVGResourcesCache::CachedResourcesForLayoutObject(client);
     // Or else the client wouldn't be in the list in the first place.
     DCHECK(resources);
     resources->ResourceDestroyed(this);
 
-    // Add a pending resolution based on the id of the old resource.
-    Element* client_element = ToElement(client->GetNode());
-    SvgTreeScopeResourcesFromElement(client_element)
-        .AddPendingResource(to_id, *client_element);
+    resource.AddWatch(ToSVGElement(*client->GetNode()));
   }
   clients_.clear();
 }
 
-void LayoutSVGResourceContainer::IdChanged(const AtomicString& old_id,
-                                           const AtomicString& new_id) {
-  SvgTreeScopeResourcesFromElement(GetElement())
-      .UpdateResource(old_id, new_id, this);
-}
-
 void LayoutSVGResourceContainer::MarkAllClientsForInvalidation(
     InvalidationMode mode) {
   if (is_invalidating_)
     return;
   SVGElementProxySet* proxy_set = ElementProxySet();
   if (clients_.IsEmpty() && (!proxy_set || proxy_set->IsEmpty()))
     return;
   if (invalidation_mask_ & mode)
     return;
 
@@ skipping 50 matching lines @@
       break;
   }
 }
 
 void LayoutSVGResourceContainer::AddClient(LayoutObject* client) {
   DCHECK(client);
   clients_.insert(client);
   ClearInvalidationMask();
 }
 
-void LayoutSVGResourceContainer::RemoveClient(LayoutObject* client) {
+bool LayoutSVGResourceContainer::RemoveClient(LayoutObject* client) {
   DCHECK(client);
   RemoveClientFromCache(client, false);
   clients_.erase(client);
+  return clients_.IsEmpty();
 }
 
 void LayoutSVGResourceContainer::InvalidateCacheAndMarkForLayout(
     SubtreeLayoutScope* layout_scope) {
   if (SelfNeedsLayout())
     return;
 
   SetNeedsLayoutAndFullPaintInvalidation(
       LayoutInvalidationReason::kSvgResourceInvalidated, kMarkContainerChain,
       layout_scope);
@@ skipping 62 matching lines @@
       // This will process the rest of the ancestors.
       ToLayoutSVGResourceContainer(current)->RemoveAllClientsFromCache();
       break;
     }
 
     current = current->Parent();
   }
 }
 
 }  // namespace blink