dom/smil/SMILCompositor.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "SMILCompositor.h"
   8
   9 #include "mozilla/dom/SVGSVGElement.h"
  10 #include "nsComputedDOMStyle.h"
  11 #include "nsCSSProps.h"
  12 #include "nsHashKeys.h"
  13 #include "SMILCSSProperty.h"
  14
  15 namespace mozilla {
  16
  17 // PLDHashEntryHdr methods
  18 bool SMILCompositor::KeyEquals(KeyTypePointer aKey) const {
  19   return aKey && aKey->Equals(mKey);
  20 }
  21
  22 /*static*/
  23 PLDHashNumber SMILCompositor::HashKey(KeyTypePointer aKey) {
  24   // Combine the 3 values into one numeric value, which will be hashed.
  25   // NOTE: We right-shift one of the pointers by 2 to get some randomness in
  26   // its 2 lowest-order bits. (Those shifted-off bits will always be 0 since
  27   // our pointers will be word-aligned.)
  28   return (NS_PTR_TO_UINT32(aKey->mElement.get()) >> 2) +
  29          NS_PTR_TO_UINT32(aKey->mAttributeName.get());
  30 }
  31
  32 // Cycle-collection support
  33 void SMILCompositor::Traverse(nsCycleCollectionTraversalCallback* aCallback) {
  34   if (!mKey.mElement) return;
  35
  36   NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(*aCallback, "Compositor mKey.mElement");
  37   aCallback->NoteXPCOMChild(mKey.mElement);
  38 }
  39
  40 // Other methods
  41 void SMILCompositor::AddAnimationFunction(SMILAnimationFunction* aFunc) {
  42   if (aFunc) {
  43     mAnimationFunctions.AppendElement(aFunc);
  44   }
  45 }
  46
  47 void SMILCompositor::ComposeAttribute(bool& aMightHavePendingStyleUpdates) {
  48   if (!mKey.mElement) return;
  49
  50   // If we might need to resolve base styles, grab a suitable ComputedStyle
  51   // for initializing our SMILAttr with.
  52   RefPtr<const ComputedStyle> baseComputedStyle;
  53   if (MightNeedBaseStyle()) {
  54     baseComputedStyle = nsComputedDOMStyle::GetUnanimatedComputedStyleNoFlush(
  55         mKey.mElement, PseudoStyleType::NotPseudo);
  56   }
  57
  58   // FIRST: Get the SMILAttr (to grab base value from, and to eventually
  59   // give animated value to)
  60   UniquePtr<SMILAttr> smilAttr = CreateSMILAttr(baseComputedStyle);
  61   if (!smilAttr) {
  62     // Target attribute not found (or, out of memory)
  63     return;
  64   }
  65   if (mAnimationFunctions.IsEmpty()) {
  66     // No active animation functions. (We can still have a SMILCompositor in
  67     // that case if an animation function has *just* become inactive)
  68     smilAttr->ClearAnimValue();
  69     // Removing the animation effect may require a style update.
  70     aMightHavePendingStyleUpdates = true;
  71     return;
  72   }
  73
  74   // SECOND: Sort the animationFunctions, to prepare for compositing.
  75   SMILAnimationFunction::Comparator comparator;
  76   mAnimationFunctions.Sort(comparator);
  77
  78   // THIRD: Step backwards through animation functions to find out
  79   // which ones we actually care about.
  80   uint32_t firstFuncToCompose = GetFirstFuncToAffectSandwich();
  81
  82   // FOURTH: Get & cache base value
  83   SMILValue sandwichResultValue;
  84   if (!mAnimationFunctions[firstFuncToCompose]->WillReplace()) {
  85     sandwichResultValue = smilAttr->GetBaseValue();
  86   }
  87   UpdateCachedBaseValue(sandwichResultValue);
  88
  89   if (!mForceCompositing) {
  90     return;
  91   }
  92
  93   // FIFTH: Compose animation functions
  94   aMightHavePendingStyleUpdates = true;
  95   uint32_t length = mAnimationFunctions.Length();
  96   for (uint32_t i = firstFuncToCompose; i < length; ++i) {
  97     mAnimationFunctions[i]->ComposeResult(*smilAttr, sandwichResultValue);
  98   }
  99   if (sandwichResultValue.IsNull()) {
 100     smilAttr->ClearAnimValue();
 101     return;
 102   }
 103
 104   // SIXTH: Set the animated value to the final composited result.
 105   nsresult rv = smilAttr->SetAnimValue(sandwichResultValue);
 106   if (NS_FAILED(rv)) {
 107     NS_WARNING("SMILAttr::SetAnimValue failed");
 108   }
 109 }
 110
 111 void SMILCompositor::ClearAnimationEffects() {
 112   if (!mKey.mElement || !mKey.mAttributeName) return;
 113
 114   UniquePtr<SMILAttr> smilAttr = CreateSMILAttr(nullptr);
 115   if (!smilAttr) {
 116     // Target attribute not found (or, out of memory)
 117     return;
 118   }
 119   smilAttr->ClearAnimValue();
 120 }
 121
 122 // Protected Helper Functions
 123 // --------------------------
 124 UniquePtr<SMILAttr> SMILCompositor::CreateSMILAttr(
 125     const ComputedStyle* aBaseComputedStyle) {
 126   nsCSSPropertyID propID = GetCSSPropertyToAnimate();
 127
 128   if (propID != eCSSProperty_UNKNOWN) {
 129     return MakeUnique<SMILCSSProperty>(propID, mKey.mElement.get(),
 130                                        aBaseComputedStyle);
 131   }
 132
 133   return mKey.mElement->GetAnimatedAttr(mKey.mAttributeNamespaceID,
 134                                         mKey.mAttributeName);
 135 }
 136
 137 nsCSSPropertyID SMILCompositor::GetCSSPropertyToAnimate() const {
 138   if (mKey.mAttributeNamespaceID != kNameSpaceID_None) {
 139     return eCSSProperty_UNKNOWN;
 140   }
 141
 142   nsCSSPropertyID propID =
 143       nsCSSProps::LookupProperty(nsAtomCString(mKey.mAttributeName));
 144
 145   if (!SMILCSSProperty::IsPropertyAnimatable(propID)) {
 146     return eCSSProperty_UNKNOWN;
 147   }
 148
 149   // If we are animating the 'width' or 'height' of an outer SVG
 150   // element we should animate it as a CSS property, but for other elements
 151   // in SVG namespace (e.g. <rect>) we should animate it as a length attribute.
 152   if ((mKey.mAttributeName == nsGkAtoms::width ||
 153        mKey.mAttributeName == nsGkAtoms::height) &&
 154       mKey.mElement->GetNameSpaceID() == kNameSpaceID_SVG) {
 155     // Not an <svg> element.
 156     if (!mKey.mElement->IsSVGElement(nsGkAtoms::svg)) {
 157       return eCSSProperty_UNKNOWN;
 158     }
 159
 160     // An inner <svg> element
 161     if (static_cast<dom::SVGSVGElement const&>(*mKey.mElement).IsInner()) {
 162       return eCSSProperty_UNKNOWN;
 163     }
 164
 165     // Indeed an outer <svg> element, fall through.
 166   }
 167
 168   return propID;
 169 }
 170
 171 bool SMILCompositor::MightNeedBaseStyle() const {
 172   if (GetCSSPropertyToAnimate() == eCSSProperty_UNKNOWN) {
 173     return false;
 174   }
 175
 176   // We should return true if at least one animation function might build on
 177   // the base value.
 178   for (const SMILAnimationFunction* func : mAnimationFunctions) {
 179     if (!func->WillReplace()) {
 180       return true;
 181     }
 182   }
 183
 184   return false;
 185 }
 186
 187 uint32_t SMILCompositor::GetFirstFuncToAffectSandwich() {
 188   // For performance reasons, we throttle most animations on elements in
 189   // display:none subtrees. (We can't throttle animations that target the
 190   // "display" property itself, though -- if we did, display:none elements
 191   // could never be dynamically displayed via animations.)
 192   // To determine whether we're in a display:none subtree, we will check the
 193   // element's primary frame since element in display:none subtree doesn't have
 194   // a primary frame. Before this process, we will construct frame when we
 195   // append an element to subtree. So we will not need to worry about pending
 196   // frame construction in this step.
 197   bool canThrottle = mKey.mAttributeName != nsGkAtoms::display &&
 198                      !mKey.mElement->GetPrimaryFrame();
 199
 200   uint32_t i;
 201   for (i = mAnimationFunctions.Length(); i > 0; --i) {
 202     SMILAnimationFunction* curAnimFunc = mAnimationFunctions[i - 1];
 203     // In the following, the lack of short-circuit behavior of |= means that we
 204     // will ALWAYS run UpdateCachedTarget (even if mForceCompositing is true)
 205     // but only call HasChanged and WasSkippedInPrevSample if necessary.  This
 206     // is important since we need UpdateCachedTarget to run in order to detect
 207     // changes to the target in subsequent samples.
 208     mForceCompositing |= curAnimFunc->UpdateCachedTarget(mKey) ||
 209                          (curAnimFunc->HasChanged() && !canThrottle) ||
 210                          curAnimFunc->WasSkippedInPrevSample();
 211
 212     if (curAnimFunc->WillReplace()) {
 213       --i;
 214       break;
 215     }
 216   }
 217
 218   // Mark remaining animation functions as having been skipped so if we later
 219   // use them we'll know to force compositing.
 220   // Note that we only really need to do this if something has changed
 221   // (otherwise we would have set the flag on a previous sample) and if
 222   // something has changed mForceCompositing will be true.
 223   if (mForceCompositing) {
 224     for (uint32_t j = i; j > 0; --j) {
 225       mAnimationFunctions[j - 1]->SetWasSkipped();
 226     }
 227   }
 228   return i;
 229 }
 230
 231 void SMILCompositor::UpdateCachedBaseValue(const SMILValue& aBaseValue) {
 232   if (mCachedBaseValue != aBaseValue) {
 233     // Base value has changed since last sample.
 234     mCachedBaseValue = aBaseValue;
 235     mForceCompositing = true;
 236   }
 237 }
 238
 239 }  // namespace mozilla