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