DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Line Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 "nsSMILAnimationController.h"
#include "nsSMILCompositor.h"
#include "nsSMILCSSProperty.h"
#include "nsCSSProps.h"
#include "nsITimer.h"
#include "mozilla/dom/Element.h"
#include "nsIDocument.h"
#include "mozilla/dom/SVGAnimationElement.h"
#include "nsSMILTimedElement.h"
#include <algorithm>
#include "mozilla/AutoRestore.h"
#include "RestyleTracker.h"

using namespace mozilla;
using namespace mozilla::dom;

//----------------------------------------------------------------------
// nsSMILAnimationController implementation

//----------------------------------------------------------------------
// ctors, dtors, factory methods

nsSMILAnimationController::nsSMILAnimationController(nsIDocument* aDoc)
  : mAvgTimeBetweenSamples(0),
    mResampleNeeded(false),
    mDeferredStartSampling(false),
    mRunningSample(false),
    mRegisteredWithRefreshDriver(false),
    mMightHavePendingStyleUpdates(false),
    mDocument(aDoc)
{
  MOZ_ASSERT(aDoc, "need a non-null document");

  nsRefreshDriver* refreshDriver = GetRefreshDriver();
  if (refreshDriver) {
    mStartTime = refreshDriver->MostRecentRefresh();
  } else {
    mStartTime = mozilla::TimeStamp::Now();
  }
  mCurrentSampleTime = mStartTime;

  Begin();
}

nsSMILAnimationController::~nsSMILAnimationController()
{
  NS_ASSERTION(mAnimationElementTable.Count() == 0,
               "Animation controller shouldn't be tracking any animation"
               " elements when it dies");
  NS_ASSERTION(!mRegisteredWithRefreshDriver,
               "Leaving stale entry in refresh driver's observer list");
}

void
nsSMILAnimationController::Disconnect()
{
  MOZ_ASSERT(mDocument, "disconnecting when we weren't connected...?");
  MOZ_ASSERT(mRefCnt.get() == 1,
             "Expecting to disconnect when doc is sole remaining owner");
  NS_ASSERTION(mPauseState & nsSMILTimeContainer::PAUSE_PAGEHIDE,
               "Expecting to be paused for pagehide before disconnect");

  StopSampling(GetRefreshDriver());

  mDocument = nullptr; // (raw pointer)
}

//----------------------------------------------------------------------
// nsSMILTimeContainer methods:

void
nsSMILAnimationController::Pause(uint32_t aType)
{
  nsSMILTimeContainer::Pause(aType);

  if (mPauseState) {
    mDeferredStartSampling = false;
    StopSampling(GetRefreshDriver());
  }
}

void
nsSMILAnimationController::Resume(uint32_t aType)
{
  bool wasPaused = (mPauseState != 0);
  // Update mCurrentSampleTime so that calls to GetParentTime--used for
  // calculating parent offsets--are accurate
  mCurrentSampleTime = mozilla::TimeStamp::Now();

  nsSMILTimeContainer::Resume(aType);

  if (wasPaused && !mPauseState && mChildContainerTable.Count()) {
    MaybeStartSampling(GetRefreshDriver());
    Sample(); // Run the first sample manually
  }
}

nsSMILTime
nsSMILAnimationController::GetParentTime() const
{
  return (nsSMILTime)(mCurrentSampleTime - mStartTime).ToMilliseconds();
}

//----------------------------------------------------------------------
// nsARefreshObserver methods:
NS_IMPL_ADDREF(nsSMILAnimationController)
NS_IMPL_RELEASE(nsSMILAnimationController)

// nsRefreshDriver Callback function
void
nsSMILAnimationController::WillRefresh(mozilla::TimeStamp aTime)
{
  // Although we never expect aTime to go backwards, when we initialise the
  // animation controller, if we can't get hold of a refresh driver we
  // initialise mCurrentSampleTime to Now(). It may be possible that after
  // doing so we get sampled by a refresh driver whose most recent refresh time
  // predates when we were initialised, so to be safe we make sure to take the
  // most recent time here.
  aTime = std::max(mCurrentSampleTime, aTime);

  // Sleep detection: If the time between samples is a whole lot greater than we
  // were expecting then we assume the computer went to sleep or someone's
  // messing with the clock. In that case, fiddle our parent offset and use our
  // average time between samples to calculate the new sample time. This
  // prevents us from hanging while trying to catch up on all the missed time.

  // Smoothing of coefficient for the average function. 0.2 should let us track
  // the sample rate reasonably tightly without being overly affected by
  // occasional delays.
  static const double SAMPLE_DUR_WEIGHTING = 0.2;
  // If the elapsed time exceeds our expectation by this number of times we'll
  // initiate special behaviour to basically ignore the intervening time.
  static const double SAMPLE_DEV_THRESHOLD = 200.0;

  nsSMILTime elapsedTime =
    (nsSMILTime)(aTime - mCurrentSampleTime).ToMilliseconds();
  if (mAvgTimeBetweenSamples == 0) {
    // First sample.
    mAvgTimeBetweenSamples = elapsedTime;
  } else {
    if (elapsedTime > SAMPLE_DEV_THRESHOLD * mAvgTimeBetweenSamples) {
      // Unexpectedly long delay between samples.
      NS_WARNING("Detected really long delay between samples, continuing from "
                 "previous sample");
      mParentOffset += elapsedTime - mAvgTimeBetweenSamples;
    }
    // Update the moving average. Due to truncation here the average will
    // normally be a little less than it should be but that's probably ok.
    mAvgTimeBetweenSamples =
      (nsSMILTime)(elapsedTime * SAMPLE_DUR_WEIGHTING +
      mAvgTimeBetweenSamples * (1.0 - SAMPLE_DUR_WEIGHTING));
  }
  mCurrentSampleTime = aTime;

  Sample();
}

//----------------------------------------------------------------------
// Animation element registration methods:

void
nsSMILAnimationController::RegisterAnimationElement(
                                  SVGAnimationElement* aAnimationElement)
{
  mAnimationElementTable.PutEntry(aAnimationElement);
  if (mDeferredStartSampling) {
    mDeferredStartSampling = false;
    if (mChildContainerTable.Count()) {
      // mAnimationElementTable was empty, but now we've added its 1st element
      MOZ_ASSERT(mAnimationElementTable.Count() == 1,
                 "we shouldn't have deferred sampling if we already had "
                 "animations registered");
      StartSampling(GetRefreshDriver());
      Sample(); // Run the first sample manually
    } // else, don't sample until a time container is registered (via AddChild)
  }
}

void
nsSMILAnimationController::UnregisterAnimationElement(
                                  SVGAnimationElement* aAnimationElement)
{
  mAnimationElementTable.RemoveEntry(aAnimationElement);
}

//----------------------------------------------------------------------
// Page show/hide

void
nsSMILAnimationController::OnPageShow()
{
  Resume(nsSMILTimeContainer::PAUSE_PAGEHIDE);
}

void
nsSMILAnimationController::OnPageHide()
{
  Pause(nsSMILTimeContainer::PAUSE_PAGEHIDE);
}

//----------------------------------------------------------------------
// Cycle-collection support

void
nsSMILAnimationController::Traverse(
    nsCycleCollectionTraversalCallback* aCallback)
{
  // Traverse last compositor table
  if (mLastCompositorTable) {
    for (auto iter = mLastCompositorTable->Iter(); !iter.Done(); iter.Next()) {
      nsSMILCompositor* compositor = iter.Get();
      compositor->Traverse(aCallback);
    }
  }
}

void
nsSMILAnimationController::Unlink()
{
  mLastCompositorTable = nullptr;
}

//----------------------------------------------------------------------
// Refresh driver lifecycle related methods

void
nsSMILAnimationController::NotifyRefreshDriverCreated(
    nsRefreshDriver* aRefreshDriver)
{
  if (!mPauseState) {
    MaybeStartSampling(aRefreshDriver);
  }
}

void
nsSMILAnimationController::NotifyRefreshDriverDestroying(
    nsRefreshDriver* aRefreshDriver)
{
  if (!mPauseState && !mDeferredStartSampling) {
    StopSampling(aRefreshDriver);
  }
}

//----------------------------------------------------------------------
// Timer-related implementation helpers

void
nsSMILAnimationController::StartSampling(nsRefreshDriver* aRefreshDriver)
{
  NS_ASSERTION(mPauseState == 0, "Starting sampling but controller is paused");
  NS_ASSERTION(!mDeferredStartSampling,
               "Started sampling but the deferred start flag is still set");
  if (aRefreshDriver) {
    MOZ_ASSERT(!mRegisteredWithRefreshDriver,
               "Redundantly registering with refresh driver");
    MOZ_ASSERT(!GetRefreshDriver() || aRefreshDriver == GetRefreshDriver(),
               "Starting sampling with wrong refresh driver");
    // We're effectively resuming from a pause so update our current sample time
    // or else it will confuse our "average time between samples" calculations.
    mCurrentSampleTime = mozilla::TimeStamp::Now();
    aRefreshDriver->AddRefreshObserver(this, Flush_Style);
    mRegisteredWithRefreshDriver = true;
  }
}

void
nsSMILAnimationController::StopSampling(nsRefreshDriver* aRefreshDriver)
{
  if (aRefreshDriver && mRegisteredWithRefreshDriver) {
    // NOTE: The document might already have been detached from its PresContext
    // (and RefreshDriver), which would make GetRefreshDriver() return null.
    MOZ_ASSERT(!GetRefreshDriver() || aRefreshDriver == GetRefreshDriver(),
               "Stopping sampling with wrong refresh driver");
    aRefreshDriver->RemoveRefreshObserver(this, Flush_Style);
    mRegisteredWithRefreshDriver = false;
  }
}

void
nsSMILAnimationController::MaybeStartSampling(nsRefreshDriver* aRefreshDriver)
{
  if (mDeferredStartSampling) {
    // We've received earlier 'MaybeStartSampling' calls, and we're
    // deferring until we get a registered animation.
    return;
  }

  if (mAnimationElementTable.Count()) {
    StartSampling(aRefreshDriver);
  } else {
    mDeferredStartSampling = true;
  }
}

//----------------------------------------------------------------------
// Sample-related methods and callbacks

void
nsSMILAnimationController::DoSample()
{
  DoSample(true); // Skip unchanged time containers
}

void
nsSMILAnimationController::DoSample(bool aSkipUnchangedContainers)
{
  if (!mDocument) {
    NS_ERROR("Shouldn't be sampling after document has disconnected");
    return;
  }
  if (mRunningSample) {
    NS_ERROR("Shouldn't be recursively sampling");
    return;
  }

  bool isStyleFlushNeeded = mResampleNeeded;
  mResampleNeeded = false;

  if (mDocument->IsStyledByServo()) {
    NS_ERROR("stylo: SMIL animations not supported yet");
    return;
  }

  // Set running sample flag -- do this before flushing styles so that when we
  // flush styles we don't end up requesting extra samples
  AutoRestore<bool> autoRestoreRunningSample(mRunningSample);
  mRunningSample = true;

  // STEP 1: Bring model up to date
  // (i)  Rewind elements where necessary
  // (ii) Run milestone samples
  RewindElements();
  DoMilestoneSamples();

  // STEP 2: Sample the child time containers
  //
  // When we sample the child time containers they will simply record the sample
  // time in document time.
  TimeContainerHashtable activeContainers(mChildContainerTable.Count());
  for (auto iter = mChildContainerTable.Iter(); !iter.Done(); iter.Next()) {
    nsSMILTimeContainer* container = iter.Get()->GetKey();
    if (!container) {
      continue;
    }

    if (!container->IsPausedByType(nsSMILTimeContainer::PAUSE_BEGIN) &&
        (container->NeedsSample() || !aSkipUnchangedContainers)) {
      container->ClearMilestones();
      container->Sample();
      container->MarkSeekFinished();
      activeContainers.PutEntry(container);
    }
  }

  // STEP 3: (i)  Sample the timed elements AND
  //         (ii) Create a table of compositors
  //
  // (i) Here we sample the timed elements (fetched from the
  // SVGAnimationElements) which determine from the active time if the
  // element is active and what its simple time etc. is. This information is
  // then passed to its time client (nsSMILAnimationFunction).
  //
  // (ii) During the same loop we also build up a table that contains one
  // compositor for each animated attribute and which maps animated elements to
  // the corresponding compositor for their target attribute.
  //
  // Note that this compositor table needs to be allocated on the heap so we can
  // store it until the next sample. This lets us find out which elements were
  // animated in sample 'n-1' but not in sample 'n' (and hence need to have
  // their animation effects removed in sample 'n').
  //
  // Parts (i) and (ii) are not functionally related but we combine them here to
  // save iterating over the animation elements twice.

  // Create the compositor table
  nsAutoPtr<nsSMILCompositorTable>
    currentCompositorTable(new nsSMILCompositorTable(0));

  for (auto iter = mAnimationElementTable.Iter(); !iter.Done(); iter.Next()) {
    SVGAnimationElement* animElem = iter.Get()->GetKey();
    SampleTimedElement(animElem, &activeContainers);
    AddAnimationToCompositorTable(animElem,
                                  currentCompositorTable,
                                  isStyleFlushNeeded);
  }
  activeContainers.Clear();

  // STEP 4: Compare previous sample's compositors against this sample's.
  // (Transfer cached base values across, & remove animation effects from
  // no-longer-animated targets.)
  if (mLastCompositorTable) {
    // * Transfer over cached base values, from last sample's compositors
    for (auto iter = currentCompositorTable->Iter();
         !iter.Done();
         iter.Next()) {
      nsSMILCompositor* compositor = iter.Get();
      nsSMILCompositor* lastCompositor =
        mLastCompositorTable->GetEntry(compositor->GetKey());

      if (lastCompositor) {
        compositor->StealCachedBaseValue(lastCompositor);
      }
    }

    // * For each compositor in current sample's hash table, remove entry from
    // prev sample's hash table -- we don't need to clear animation
    // effects of those compositors, since they're still being animated.
    for (auto iter = currentCompositorTable->Iter();
         !iter.Done();
         iter.Next()) {
      mLastCompositorTable->RemoveEntry(iter.Get()->GetKey());
    }

    // * For each entry that remains in prev sample's hash table (i.e. for
    // every target that's no longer animated), clear animation effects.
    for (auto iter = mLastCompositorTable->Iter(); !iter.Done(); iter.Next()) {
      iter.Get()->ClearAnimationEffects();
    }
  }

  // return early if there are no active animations to avoid a style flush
  if (currentCompositorTable->Count() == 0) {
    mLastCompositorTable = nullptr;
    return;
  }

  nsCOMPtr<nsIDocument> document(mDocument);  // keeps 'this' alive too
  if (isStyleFlushNeeded) {
    document->FlushPendingNotifications(Flush_Style);
  }

  // WARNING:
  // WARNING: the above flush may have destroyed the pres shell and/or
  // WARNING: frames and other layout related objects.
  // WARNING:

  // STEP 5: Compose currently-animated attributes.
  // XXXdholbert: This step traverses our animation targets in an effectively
  // random order. For animation from/to 'inherit' values to work correctly
  // when the inherited value is *also* being animated, we really should be
  // traversing our animated nodes in an ancestors-first order (bug 501183)
  bool mightHavePendingStyleUpdates = false;
  for (auto iter = currentCompositorTable->Iter(); !iter.Done(); iter.Next()) {
    iter.Get()->ComposeAttribute(mightHavePendingStyleUpdates);
  }

  // Update last compositor table
  mLastCompositorTable = currentCompositorTable.forget();
  mMightHavePendingStyleUpdates = mightHavePendingStyleUpdates;

  NS_ASSERTION(!mResampleNeeded, "Resample dirty flag set during sample!");
}

void
nsSMILAnimationController::RewindElements()
{
  bool rewindNeeded = false;
  for (auto iter = mChildContainerTable.Iter(); !iter.Done(); iter.Next()) {
    nsSMILTimeContainer* container = iter.Get()->GetKey();
    if (container->NeedsRewind()) {
      rewindNeeded = true;
      break;
    }
  }

  if (!rewindNeeded)
    return;

  for (auto iter = mAnimationElementTable.Iter(); !iter.Done(); iter.Next()) {
    SVGAnimationElement* animElem = iter.Get()->GetKey();
    nsSMILTimeContainer* timeContainer = animElem->GetTimeContainer();
    if (timeContainer && timeContainer->NeedsRewind()) {
      animElem->TimedElement().Rewind();
    }
  }

  for (auto iter = mChildContainerTable.Iter(); !iter.Done(); iter.Next()) {
    iter.Get()->GetKey()->ClearNeedsRewind();
  }
}

void
nsSMILAnimationController::DoMilestoneSamples()
{
  // We need to sample the timing model but because SMIL operates independently
  // of the frame-rate, we can get one sample at t=0s and the next at t=10min.
  //
  // In between those two sample times a whole string of significant events
  // might be expected to take place: events firing, new interdependencies
  // between animations resolved and dissolved, etc.
  //
  // Furthermore, at any given time, we want to sample all the intervals that
  // end at that time BEFORE any that begin. This behaviour is implied by SMIL's
  // endpoint-exclusive timing model.
  //
  // So we have the animations (specifically the timed elements) register the
  // next significant moment (called a milestone) in their lifetime and then we
  // step through the model at each of these moments and sample those animations
  // registered for those times. This way events can fire in the correct order,
  // dependencies can be resolved etc.

  nsSMILTime sampleTime = INT64_MIN;

  while (true) {
    // We want to find any milestones AT OR BEFORE the current sample time so we
    // initialise the next milestone to the moment after (1ms after, to be
    // precise) the current sample time and see if there are any milestones
    // before that. Any other milestones will be dealt with in a subsequent
    // sample.
    nsSMILMilestone nextMilestone(GetCurrentTime() + 1, true);
    for (auto iter = mChildContainerTable.Iter(); !iter.Done(); iter.Next()) {
      nsSMILTimeContainer* container = iter.Get()->GetKey();
      if (container->IsPausedByType(nsSMILTimeContainer::PAUSE_BEGIN)) {
        continue;
      }
      nsSMILMilestone thisMilestone;
      bool didGetMilestone =
        container->GetNextMilestoneInParentTime(thisMilestone);
      if (didGetMilestone && thisMilestone < nextMilestone) {
        nextMilestone = thisMilestone;
      }
    }

    if (nextMilestone.mTime > GetCurrentTime()) {
      break;
    }

    nsTArray<RefPtr<mozilla::dom::SVGAnimationElement>> elements;
    for (auto iter = mChildContainerTable.Iter(); !iter.Done(); iter.Next()) {
      nsSMILTimeContainer* container = iter.Get()->GetKey();
      if (container->IsPausedByType(nsSMILTimeContainer::PAUSE_BEGIN)) {
        continue;
      }
      container->PopMilestoneElementsAtMilestone(nextMilestone, elements);
    }

    uint32_t length = elements.Length();

    // During the course of a sampling we don't want to actually go backwards.
    // Due to negative offsets, early ends and the like, a timed element might
    // register a milestone that is actually in the past. That's fine, but it's
    // still only going to get *sampled* with whatever time we're up to and no
    // earlier.
    //
    // Because we're only performing this clamping at the last moment, the
    // animations will still all get sampled in the correct order and
    // dependencies will be appropriately resolved.
    sampleTime = std::max(nextMilestone.mTime, sampleTime);

    for (uint32_t i = 0; i < length; ++i) {
      SVGAnimationElement* elem = elements[i].get();
      MOZ_ASSERT(elem, "nullptr animation element in list");
      nsSMILTimeContainer* container = elem->GetTimeContainer();
      if (!container)
        // The container may be nullptr if the element has been detached from its
        // parent since registering a milestone.
        continue;

      nsSMILTimeValue containerTimeValue =
        container->ParentToContainerTime(sampleTime);
      if (!containerTimeValue.IsDefinite())
        continue;

      // Clamp the converted container time to non-negative values.
      nsSMILTime containerTime = std::max<nsSMILTime>(0, containerTimeValue.GetMillis());

      if (nextMilestone.mIsEnd) {
        elem->TimedElement().SampleEndAt(containerTime);
      } else {
        elem->TimedElement().SampleAt(containerTime);
      }
    }
  }
}

/*static*/ void
nsSMILAnimationController::SampleTimedElement(
  SVGAnimationElement* aElement, TimeContainerHashtable* aActiveContainers)
{
  nsSMILTimeContainer* timeContainer = aElement->GetTimeContainer();
  if (!timeContainer)
    return;

  // We'd like to call timeContainer->NeedsSample() here and skip all timed
  // elements that belong to paused time containers that don't need a sample,
  // but that doesn't work because we've already called Sample() on all the time
  // containers so the paused ones don't need a sample any more and they'll
  // return false.
  //
  // Instead we build up a hashmap of active time containers during the previous
  // step (SampleTimeContainer) and then test here if the container for this
  // timed element is in the list.
  if (!aActiveContainers->GetEntry(timeContainer))
    return;

  nsSMILTime containerTime = timeContainer->GetCurrentTime();

  MOZ_ASSERT(!timeContainer->IsSeeking(),
             "Doing a regular sample but the time container is still seeking");
  aElement->TimedElement().SampleAt(containerTime);
}

/*static*/ void
nsSMILAnimationController::AddAnimationToCompositorTable(
  SVGAnimationElement* aElement,
  nsSMILCompositorTable* aCompositorTable,
  bool& aStyleFlushNeeded)
{
  // Add a compositor to the hash table if there's not already one there
  nsSMILTargetIdentifier key;
  if (!GetTargetIdentifierForAnimation(aElement, key))
    // Something's wrong/missing about animation's target; skip this animation
    return;

  nsSMILAnimationFunction& func = aElement->AnimationFunction();

  // Only add active animation functions. If there are no active animations
  // targeting an attribute, no compositor will be created and any previously
  // applied animations will be cleared.
  if (func.IsActiveOrFrozen()) {
    // Look up the compositor for our target, & add our animation function
    // to its list of animation functions.
    nsSMILCompositor* result = aCompositorTable->PutEntry(key);
    result->AddAnimationFunction(&func);

  } else if (func.HasChanged()) {
    // Look up the compositor for our target, and force it to skip the
    // "nothing's changed so don't bother compositing" optimization for this
    // sample. |func| is inactive, but it's probably *newly* inactive (since
    // it's got HasChanged() == true), so we need to make sure to recompose
    // its target.
    nsSMILCompositor* result = aCompositorTable->PutEntry(key);
    result->ToggleForceCompositing();

    // We've now made sure that |func|'s inactivity will be reflected as of
    // this sample. We need to clear its HasChanged() flag so that it won't
    // trigger this same clause in future samples (until it changes again).
    func.ClearHasChanged();
  }
  aStyleFlushNeeded |= func.ValueNeedsReparsingEverySample();
}

static inline bool
IsTransformAttribute(int32_t aNamespaceID, nsIAtom *aAttributeName)
{
  return aNamespaceID == kNameSpaceID_None &&
         (aAttributeName == nsGkAtoms::transform ||
          aAttributeName == nsGkAtoms::patternTransform ||
          aAttributeName == nsGkAtoms::gradientTransform);
}

// Helper function that, given a SVGAnimationElement, looks up its target
// element & target attribute and populates a nsSMILTargetIdentifier
// for this target.
/*static*/ bool
nsSMILAnimationController::GetTargetIdentifierForAnimation(
    SVGAnimationElement* aAnimElem, nsSMILTargetIdentifier& aResult)
{
  // Look up target (animated) element
  Element* targetElem = aAnimElem->GetTargetElementContent();
  if (!targetElem)
    // Animation has no target elem -- skip it.
    return false;

  // Look up target (animated) attribute
  // SMILANIM section 3.1, attributeName may
  // have an XMLNS prefix to indicate the XML namespace.
  nsCOMPtr<nsIAtom> attributeName;
  int32_t attributeNamespaceID;
  if (!aAnimElem->GetTargetAttributeName(&attributeNamespaceID,
                                         getter_AddRefs(attributeName)))
    // Animation has no target attr -- skip it.
    return false;

  // animateTransform can only animate transforms, conversely transforms
  // can only be animated by animateTransform
  if (IsTransformAttribute(attributeNamespaceID, attributeName) !=
      (aAnimElem->IsSVGElement(nsGkAtoms::animateTransform)))
    return false;

  // Look up target (animated) attribute-type
  nsSMILTargetAttrType attributeType = aAnimElem->GetTargetAttributeType();

  // Check if an 'auto' attributeType refers to a CSS property or XML attribute.
  // Note that SMIL requires we search for CSS properties first. So if they
  // overlap, 'auto' = 'CSS'. (SMILANIM 3.1)
  bool isCSS = false;
  if (attributeType == eSMILTargetAttrType_auto) {
    if (attributeNamespaceID == kNameSpaceID_None) {
      // width/height are special as they may be attributes or for
      // outer-<svg> elements, mapped into style.
      if (attributeName == nsGkAtoms::width ||
          attributeName == nsGkAtoms::height) {
        isCSS = targetElem->GetNameSpaceID() != kNameSpaceID_SVG;
      } else {
        nsCSSPropertyID prop =
          nsCSSProps::LookupProperty(nsDependentAtomString(attributeName),
                                     CSSEnabledState::eForAllContent);
        isCSS = nsSMILCSSProperty::IsPropertyAnimatable(prop);
      }
    }
  } else {
    isCSS = (attributeType == eSMILTargetAttrType_CSS);
  }

  // Construct the key
  aResult.mElement = targetElem;
  aResult.mAttributeName = attributeName;
  aResult.mAttributeNamespaceID = attributeNamespaceID;
  aResult.mIsCSS = isCSS;

  return true;
}

void
nsSMILAnimationController::AddStyleUpdatesTo(RestyleTracker& aTracker)
{
  MOZ_ASSERT(mMightHavePendingStyleUpdates,
             "Should only add style updates when we think we might have some");

  for (auto iter = mAnimationElementTable.Iter(); !iter.Done(); iter.Next()) {
    SVGAnimationElement* animElement = iter.Get()->GetKey();

    nsSMILTargetIdentifier key;
    if (!GetTargetIdentifierForAnimation(animElement, key)) {
      // Something's wrong/missing about animation's target; skip this animation
      continue;
    }

    // mIsCSS true means that the rules are the ones returned from
    // Element::GetSMILOverrideStyleDeclaration (via nsSMILCSSProperty objects),
    // and mIsCSS false means the rules are nsSMILMappedAttribute objects
    // returned from nsSVGElement::GetAnimatedContentStyleRule.
    nsRestyleHint rshint = key.mIsCSS ? eRestyle_StyleAttribute_Animations
                                      : eRestyle_SVGAttrAnimations;
    aTracker.AddPendingRestyle(key.mElement, rshint, nsChangeHint(0));
  }

  mMightHavePendingStyleUpdates = false;
}

//----------------------------------------------------------------------
// Add/remove child time containers

nsresult
nsSMILAnimationController::AddChild(nsSMILTimeContainer& aChild)
{
  TimeContainerPtrKey* key = mChildContainerTable.PutEntry(&aChild);
  NS_ENSURE_TRUE(key, NS_ERROR_OUT_OF_MEMORY);

  if (!mPauseState && mChildContainerTable.Count() == 1) {
    MaybeStartSampling(GetRefreshDriver());
    Sample(); // Run the first sample manually
  }

  return NS_OK;
}

void
nsSMILAnimationController::RemoveChild(nsSMILTimeContainer& aChild)
{
  mChildContainerTable.RemoveEntry(&aChild);

  if (!mPauseState && mChildContainerTable.Count() == 0) {
    StopSampling(GetRefreshDriver());
  }
}

// Helper method
nsRefreshDriver*
nsSMILAnimationController::GetRefreshDriver()
{
  if (!mDocument) {
    NS_ERROR("Requesting refresh driver after document has disconnected!");
    return nullptr;
  }

  nsIPresShell* shell = mDocument->GetShell();
  if (!shell) {
    return nullptr;
  }

  nsPresContext* context = shell->GetPresContext();
  return context ? context->RefreshDriver() : nullptr;
}

void
nsSMILAnimationController::FlagDocumentNeedsFlush()
{
  mDocument->SetNeedStyleFlush();
}