The Tor Browser: dom/smil/nsSMILCompositor.cpp@97036ab72558 (annotated)

dom/smil/nsSMILCompositor.cpp@97036ab72558 (annotated)

dom/smil/nsSMILCompositor.cpp

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 #include "nsSMILCompositor.h"
 #include "nsSMILCSSProperty.h"
 #include "nsCSSProps.h"
 #include "nsHashKeys.h"
 // PLDHashEntryHdr methods
 bool
 nsSMILCompositor::KeyEquals(KeyTypePointer aKey) const
 {
   return aKey && aKey->Equals(mKey);
 }
 /*static*/ PLDHashNumber
 nsSMILCompositor::HashKey(KeyTypePointer aKey)
 {
   // Combine the 3 values into one numeric value, which will be hashed.
   // NOTE: We right-shift one of the pointers by 2 to get some randomness in
   // its 2 lowest-order bits. (Those shifted-off bits will always be 0 since
   // our pointers will be word-aligned.)
   return (NS_PTR_TO_UINT32(aKey->mElement.get()) >> 2) +
     NS_PTR_TO_UINT32(aKey->mAttributeName.get()) +
     (aKey->mIsCSS ? 1 : 0);
 }
 // Cycle-collection support
 void
 nsSMILCompositor::Traverse(nsCycleCollectionTraversalCallback* aCallback)
 {
   if (!mKey.mElement)
     return;
   NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(*aCallback, "Compositor mKey.mElement");
   aCallback->NoteXPCOMChild(mKey.mElement);
 }
 // Other methods
 void
 nsSMILCompositor::AddAnimationFunction(nsSMILAnimationFunction* aFunc)
 {
   if (aFunc) {
     mAnimationFunctions.AppendElement(aFunc);
   }
 }
 void
 nsSMILCompositor::ComposeAttribute()
 {
   if (!mKey.mElement)
     return;
   // FIRST: Get the nsISMILAttr (to grab base value from, and to eventually
   // give animated value to)
   nsAutoPtr<nsISMILAttr> smilAttr(CreateSMILAttr());
   if (!smilAttr) {
     // Target attribute not found (or, out of memory)
     return;
   }
   if (mAnimationFunctions.IsEmpty()) {
     // No active animation functions. (We can still have a nsSMILCompositor in
     // that case if an animation function has *just* become inactive)
     smilAttr->ClearAnimValue();
     return;
   }
   // SECOND: Sort the animationFunctions, to prepare for compositing.
   nsSMILAnimationFunction::Comparator comparator;
   mAnimationFunctions.Sort(comparator);
   // THIRD: Step backwards through animation functions to find out
   // which ones we actually care about.
   uint32_t firstFuncToCompose = GetFirstFuncToAffectSandwich();
   // FOURTH: Get & cache base value
   nsSMILValue sandwichResultValue;
   if (!mAnimationFunctions[firstFuncToCompose]->WillReplace()) {
     sandwichResultValue = smilAttr->GetBaseValue();
   }
   UpdateCachedBaseValue(sandwichResultValue);
   if (!mForceCompositing) {
     return;
   }
   // FIFTH: Compose animation functions
   uint32_t length = mAnimationFunctions.Length();
   for (uint32_t i = firstFuncToCompose; i < length; ++i) {
     mAnimationFunctions[i]->ComposeResult(*smilAttr, sandwichResultValue);
   }
   if (sandwichResultValue.IsNull()) {
     smilAttr->ClearAnimValue();
     return;
   }
   // SIXTH: Set the animated value to the final composited result.
   nsresult rv = smilAttr->SetAnimValue(sandwichResultValue);
   if (NS_FAILED(rv)) {
     NS_WARNING("nsISMILAttr::SetAnimValue failed");
   }
 }
 void
 nsSMILCompositor::ClearAnimationEffects()
 {
   if (!mKey.mElement || !mKey.mAttributeName)
     return;
   nsAutoPtr<nsISMILAttr> smilAttr(CreateSMILAttr());
   if (!smilAttr) {
     // Target attribute not found (or, out of memory)
     return;
   }
   smilAttr->ClearAnimValue();
 }
 // Protected Helper Functions
 // --------------------------
 nsISMILAttr*
 nsSMILCompositor::CreateSMILAttr()
 {
   if (mKey.mIsCSS) {
     nsCSSProperty propId =
       nsCSSProps::LookupProperty(nsDependentAtomString(mKey.mAttributeName),
                                  nsCSSProps::eEnabledForAllContent);
     if (nsSMILCSSProperty::IsPropertyAnimatable(propId)) {
       return new nsSMILCSSProperty(propId, mKey.mElement.get());
     }
   } else {
     return mKey.mElement->GetAnimatedAttr(mKey.mAttributeNamespaceID,
                                           mKey.mAttributeName);
   }
   return nullptr;
 }
 uint32_t
 nsSMILCompositor::GetFirstFuncToAffectSandwich()
 {
   uint32_t i;
   for (i = mAnimationFunctions.Length(); i > 0; --i) {
     nsSMILAnimationFunction* curAnimFunc = mAnimationFunctions[i-1];
     // In the following, the lack of short-circuit behavior of |= means that we
     // will ALWAYS run UpdateCachedTarget (even if mForceCompositing is true)
     // but only call HasChanged and WasSkippedInPrevSample if necessary.  This
     // is important since we need UpdateCachedTarget to run in order to detect
     // changes to the target in subsequent samples.
     mForceCompositing |=
       curAnimFunc->UpdateCachedTarget(mKey) ||
       curAnimFunc->HasChanged() ||
       curAnimFunc->WasSkippedInPrevSample();
     if (curAnimFunc->WillReplace()) {
       --i;
       break;
     }
   }
   // Mark remaining animation functions as having been skipped so if we later
   // use them we'll know to force compositing.
   // Note that we only really need to do this if something has changed
   // (otherwise we would have set the flag on a previous sample) and if
   // something has changed mForceCompositing will be true.
   if (mForceCompositing) {
     for (uint32_t j = i; j > 0; --j) {
       mAnimationFunctions[j-1]->SetWasSkipped();
     }
   }
   return i;
 }
 void
 nsSMILCompositor::UpdateCachedBaseValue(const nsSMILValue& aBaseValue)
 {
   if (!mCachedBaseValue) {
     // We don't have last sample's base value cached. Assume it's changed.
     mCachedBaseValue = new nsSMILValue(aBaseValue);
     NS_WARN_IF_FALSE(mCachedBaseValue, "failed to cache base value (OOM?)");
     mForceCompositing = true;
   } else if (*mCachedBaseValue != aBaseValue) {
     // Base value has changed since last sample.
     *mCachedBaseValue = aBaseValue;
     mForceCompositing = true;
   }
 }

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dom/smil/nsSMILCompositor.cpp@97036ab72558 (annotated)

dom/smil/nsSMILCompositor.cpp