image/VectorImage.cpp
author Timothy Nikkel <tnikkel@gmail.com>
Thu, 16 Mar 2017 03:06:06 -0500
changeset 347865 d4cafcc44babd82e009801f6d453b6002fb280d7
parent 347677 0394f4a6e9e9436e70409bc9f0eff8378f945f27
child 348798 0b797601dc36ce8b3758aa9b39eaa2f20356d239
permissions -rw-r--r--
Bug 1343341. Only set the animation state as discarded if we discarded the animated frames (and not a static frame from a first-frame-only decode). r=aosmond The SurfaceCache can hold the first frame of a "static" decode as well as the animated frames in two seperate entries. We only care about what happens to the animated frames, so ignore OnSurfaceDiscarded for anything else. To accomplish this we must pass the SurfaceKey to OnSurfaceDiscarded.

/* -*- 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 "VectorImage.h"

#include "gfx2DGlue.h"
#include "gfxContext.h"
#include "gfxDrawable.h"
#include "gfxPlatform.h"
#include "gfxUtils.h"
#include "imgFrame.h"
#include "mozilla/AutoRestore.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/dom/SVGSVGElement.h"
#include "mozilla/gfx/2D.h"
#include "mozilla/RefPtr.h"
#include "nsIDOMEvent.h"
#include "nsIPresShell.h"
#include "nsIStreamListener.h"
#include "nsMimeTypes.h"
#include "nsPresContext.h"
#include "nsRect.h"
#include "nsString.h"
#include "nsStubDocumentObserver.h"
#include "nsSVGEffects.h" // for nsSVGRenderingObserver
#include "nsWindowMemoryReporter.h"
#include "ImageRegion.h"
#include "ISurfaceProvider.h"
#include "LookupResult.h"
#include "Orientation.h"
#include "SVGDocumentWrapper.h"
#include "nsIDOMEventListener.h"
#include "SurfaceCache.h"
#include "nsDocument.h"

// undef the GetCurrentTime macro defined in WinBase.h from the MS Platform SDK
#undef GetCurrentTime

namespace mozilla {

using namespace dom;
using namespace gfx;
using namespace layers;

namespace image {

// Helper-class: SVGRootRenderingObserver
class SVGRootRenderingObserver final : public nsSVGRenderingObserver {
public:
  NS_DECL_ISUPPORTS

  SVGRootRenderingObserver(SVGDocumentWrapper* aDocWrapper,
                           VectorImage*        aVectorImage)
    : nsSVGRenderingObserver()
    , mDocWrapper(aDocWrapper)
    , mVectorImage(aVectorImage)
    , mHonoringInvalidations(true)
  {
    MOZ_ASSERT(mDocWrapper, "Need a non-null SVG document wrapper");
    MOZ_ASSERT(mVectorImage, "Need a non-null VectorImage");

    StartListening();
    Element* elem = GetTarget();
    MOZ_ASSERT(elem, "no root SVG node for us to observe");

    nsSVGEffects::AddRenderingObserver(elem, this);
    mInObserverList = true;
  }


  void ResumeHonoringInvalidations()
  {
    mHonoringInvalidations = true;
  }

protected:
  virtual ~SVGRootRenderingObserver()
  {
    StopListening();
  }

  virtual Element* GetTarget() override
  {
    return mDocWrapper->GetRootSVGElem();
  }

  virtual void DoUpdate() override
  {
    Element* elem = GetTarget();
    MOZ_ASSERT(elem, "missing root SVG node");

    if (mHonoringInvalidations && !mDocWrapper->ShouldIgnoreInvalidation()) {
      nsIFrame* frame = elem->GetPrimaryFrame();
      if (!frame || frame->PresContext()->PresShell()->IsDestroying()) {
        // We're being destroyed. Bail out.
        return;
      }

      // Ignore further invalidations until we draw.
      mHonoringInvalidations = false;

      mVectorImage->InvalidateObserversOnNextRefreshDriverTick();
    }

    // Our caller might've removed us from rendering-observer list.
    // Add ourselves back!
    if (!mInObserverList) {
      nsSVGEffects::AddRenderingObserver(elem, this);
      mInObserverList = true;
    }
  }

  // Private data
  const RefPtr<SVGDocumentWrapper> mDocWrapper;
  VectorImage* const mVectorImage;   // Raw pointer because it owns me.
  bool mHonoringInvalidations;
};

NS_IMPL_ISUPPORTS(SVGRootRenderingObserver, nsIMutationObserver)

class SVGParseCompleteListener final : public nsStubDocumentObserver {
public:
  NS_DECL_ISUPPORTS

  SVGParseCompleteListener(nsIDocument* aDocument,
                           VectorImage* aImage)
    : mDocument(aDocument)
    , mImage(aImage)
  {
    MOZ_ASSERT(mDocument, "Need an SVG document");
    MOZ_ASSERT(mImage, "Need an image");

    mDocument->AddObserver(this);
  }

private:
  ~SVGParseCompleteListener()
  {
    if (mDocument) {
      // The document must have been destroyed before we got our event.
      // Otherwise this can't happen, since documents hold strong references to
      // their observers.
      Cancel();
    }
  }

public:
  void EndLoad(nsIDocument* aDocument) override
  {
    MOZ_ASSERT(aDocument == mDocument, "Got EndLoad for wrong document?");

    // OnSVGDocumentParsed will release our owner's reference to us, so ensure
    // we stick around long enough to complete our work.
    RefPtr<SVGParseCompleteListener> kungFuDeathGrip(this);

    mImage->OnSVGDocumentParsed();
  }

  void Cancel()
  {
    MOZ_ASSERT(mDocument, "Duplicate call to Cancel");
    if (mDocument) {
      mDocument->RemoveObserver(this);
      mDocument = nullptr;
    }
  }

private:
  nsCOMPtr<nsIDocument> mDocument;
  VectorImage* const mImage; // Raw pointer to owner.
};

NS_IMPL_ISUPPORTS(SVGParseCompleteListener, nsIDocumentObserver)

class SVGLoadEventListener final : public nsIDOMEventListener {
public:
  NS_DECL_ISUPPORTS

  SVGLoadEventListener(nsIDocument* aDocument,
                       VectorImage* aImage)
    : mDocument(aDocument)
    , mImage(aImage)
  {
    MOZ_ASSERT(mDocument, "Need an SVG document");
    MOZ_ASSERT(mImage, "Need an image");

    mDocument->AddEventListener(NS_LITERAL_STRING("MozSVGAsImageDocumentLoad"),
                                this, true, false);
    mDocument->AddEventListener(NS_LITERAL_STRING("SVGAbort"), this, true,
                                false);
    mDocument->AddEventListener(NS_LITERAL_STRING("SVGError"), this, true,
                                false);
  }

private:
  ~SVGLoadEventListener()
  {
    if (mDocument) {
      // The document must have been destroyed before we got our event.
      // Otherwise this can't happen, since documents hold strong references to
      // their observers.
      Cancel();
    }
  }

public:
  NS_IMETHOD HandleEvent(nsIDOMEvent* aEvent) override
  {
    MOZ_ASSERT(mDocument, "Need an SVG document. Received multiple events?");

    // OnSVGDocumentLoaded/OnSVGDocumentError will release our owner's reference
    // to us, so ensure we stick around long enough to complete our work.
    RefPtr<SVGLoadEventListener> kungFuDeathGrip(this);

    nsAutoString eventType;
    aEvent->GetType(eventType);
    MOZ_ASSERT(eventType.EqualsLiteral("MozSVGAsImageDocumentLoad")  ||
               eventType.EqualsLiteral("SVGAbort")                   ||
               eventType.EqualsLiteral("SVGError"),
               "Received unexpected event");

    if (eventType.EqualsLiteral("MozSVGAsImageDocumentLoad")) {
      mImage->OnSVGDocumentLoaded();
    } else {
      mImage->OnSVGDocumentError();
    }

    return NS_OK;
  }

  void Cancel()
  {
    MOZ_ASSERT(mDocument, "Duplicate call to Cancel");
    if (mDocument) {
      mDocument
        ->RemoveEventListener(NS_LITERAL_STRING("MozSVGAsImageDocumentLoad"),
                              this, true);
      mDocument->RemoveEventListener(NS_LITERAL_STRING("SVGAbort"), this, true);
      mDocument->RemoveEventListener(NS_LITERAL_STRING("SVGError"), this, true);
      mDocument = nullptr;
    }
  }

private:
  nsCOMPtr<nsIDocument> mDocument;
  VectorImage* const mImage; // Raw pointer to owner.
};

NS_IMPL_ISUPPORTS(SVGLoadEventListener, nsIDOMEventListener)

// Helper-class: SVGDrawingCallback
class SVGDrawingCallback : public gfxDrawingCallback {
public:
  SVGDrawingCallback(SVGDocumentWrapper* aSVGDocumentWrapper,
                     const IntSize& aViewportSize,
                     const IntSize& aSize,
                     uint32_t aImageFlags)
    : mSVGDocumentWrapper(aSVGDocumentWrapper)
    , mViewportSize(aViewportSize)
    , mSize(aSize)
    , mImageFlags(aImageFlags)
  { }
  virtual bool operator()(gfxContext* aContext,
                          const gfxRect& aFillRect,
                          const SamplingFilter aSamplingFilter,
                          const gfxMatrix& aTransform);
private:
  RefPtr<SVGDocumentWrapper> mSVGDocumentWrapper;
  const IntSize                mViewportSize;
  const IntSize                mSize;
  uint32_t                     mImageFlags;
};

// Based loosely on nsSVGIntegrationUtils' PaintFrameCallback::operator()
bool
SVGDrawingCallback::operator()(gfxContext* aContext,
                               const gfxRect& aFillRect,
                               const SamplingFilter aSamplingFilter,
                               const gfxMatrix& aTransform)
{
  MOZ_ASSERT(mSVGDocumentWrapper, "need an SVGDocumentWrapper");

  // Get (& sanity-check) the helper-doc's presShell
  nsCOMPtr<nsIPresShell> presShell;
  if (NS_FAILED(mSVGDocumentWrapper->GetPresShell(getter_AddRefs(presShell)))) {
    NS_WARNING("Unable to draw -- presShell lookup failed");
    return false;
  }
  MOZ_ASSERT(presShell, "GetPresShell succeeded but returned null");

  gfxContextAutoSaveRestore contextRestorer(aContext);

  // Clip to aFillRect so that we don't paint outside.
  aContext->NewPath();
  aContext->Rectangle(aFillRect);
  aContext->Clip();

  gfxMatrix matrix = aTransform;
  if (!matrix.Invert()) {
    return false;
  }
  aContext->SetMatrix(
    aContext->CurrentMatrix().PreMultiply(matrix).
                              Scale(double(mSize.width) / mViewportSize.width,
                                    double(mSize.height) / mViewportSize.height));

  nsPresContext* presContext = presShell->GetPresContext();
  MOZ_ASSERT(presContext, "pres shell w/out pres context");

  nsRect svgRect(0, 0,
                 presContext->DevPixelsToAppUnits(mViewportSize.width),
                 presContext->DevPixelsToAppUnits(mViewportSize.height));

  uint32_t renderDocFlags = nsIPresShell::RENDER_IGNORE_VIEWPORT_SCROLLING;
  if (!(mImageFlags & imgIContainer::FLAG_SYNC_DECODE)) {
    renderDocFlags |= nsIPresShell::RENDER_ASYNC_DECODE_IMAGES;
  }

  presShell->RenderDocument(svgRect, renderDocFlags,
                            NS_RGBA(0, 0, 0, 0), // transparent
                            aContext);

  return true;
}

// Implement VectorImage's nsISupports-inherited methods
NS_IMPL_ISUPPORTS(VectorImage,
                  imgIContainer,
                  nsIStreamListener,
                  nsIRequestObserver)

//------------------------------------------------------------------------------
// Constructor / Destructor

VectorImage::VectorImage(ImageURL* aURI /* = nullptr */) :
  ImageResource(aURI), // invoke superclass's constructor
  mLockCount(0),
  mIsInitialized(false),
  mIsFullyLoaded(false),
  mIsDrawing(false),
  mHaveAnimations(false),
  mHasPendingInvalidation(false)
{ }

VectorImage::~VectorImage()
{
  CancelAllListeners();
  SurfaceCache::RemoveImage(ImageKey(this));
}

//------------------------------------------------------------------------------
// Methods inherited from Image.h

nsresult
VectorImage::Init(const char* aMimeType,
                  uint32_t aFlags)
{
  // We don't support re-initialization
  if (mIsInitialized) {
    return NS_ERROR_ILLEGAL_VALUE;
  }

  MOZ_ASSERT(!mIsFullyLoaded && !mHaveAnimations && !mError,
             "Flags unexpectedly set before initialization");
  MOZ_ASSERT(!strcmp(aMimeType, IMAGE_SVG_XML), "Unexpected mimetype");

  mDiscardable = !!(aFlags & INIT_FLAG_DISCARDABLE);

  // Lock this image's surfaces in the SurfaceCache if we're not discardable.
  if (!mDiscardable) {
    mLockCount++;
    SurfaceCache::LockImage(ImageKey(this));
  }

  mIsInitialized = true;
  return NS_OK;
}

size_t
VectorImage::SizeOfSourceWithComputedFallback(MallocSizeOf aMallocSizeOf) const
{
  if (!mSVGDocumentWrapper) {
    return 0; // No document, so no memory used for the document.
  }

  nsIDocument* doc = mSVGDocumentWrapper->GetDocument();
  if (!doc) {
    return 0; // No document, so no memory used for the document.
  }

  nsWindowSizes windowSizes(aMallocSizeOf);
  doc->DocAddSizeOfIncludingThis(&windowSizes);

  if (windowSizes.getTotalSize() == 0) {
    // MallocSizeOf fails on this platform. Because we also use this method for
    // determining the size of cache entries, we need to return something
    // reasonable here. Unfortunately, there's no way to estimate the document's
    // size accurately, so we just use a constant value of 100KB, which will
    // generally underestimate the true size.
    return 100 * 1024;
  }

  return windowSizes.getTotalSize();
}

void
VectorImage::CollectSizeOfSurfaces(nsTArray<SurfaceMemoryCounter>& aCounters,
                                   MallocSizeOf aMallocSizeOf) const
{
  SurfaceCache::CollectSizeOfSurfaces(ImageKey(this), aCounters, aMallocSizeOf);
}

nsresult
VectorImage::OnImageDataComplete(nsIRequest* aRequest,
                                 nsISupports* aContext,
                                 nsresult aStatus,
                                 bool aLastPart)
{
  // Call our internal OnStopRequest method, which only talks to our embedded
  // SVG document. This won't have any effect on our ProgressTracker.
  nsresult finalStatus = OnStopRequest(aRequest, aContext, aStatus);

  // Give precedence to Necko failure codes.
  if (NS_FAILED(aStatus)) {
    finalStatus = aStatus;
  }
  
  Progress loadProgress = LoadCompleteProgress(aLastPart, mError, finalStatus);

  if (mIsFullyLoaded || mError) {
    // Our document is loaded, so we're ready to notify now.
    mProgressTracker->SyncNotifyProgress(loadProgress);
  } else {
    // Record our progress so far; we'll actually send the notifications in
    // OnSVGDocumentLoaded or OnSVGDocumentError.
    mLoadProgress = Some(loadProgress);
  }

  return finalStatus;
}

nsresult
VectorImage::OnImageDataAvailable(nsIRequest* aRequest,
                                  nsISupports* aContext,
                                  nsIInputStream* aInStr,
                                  uint64_t aSourceOffset,
                                  uint32_t aCount)
{
  return OnDataAvailable(aRequest, aContext, aInStr, aSourceOffset, aCount);
}

nsresult
VectorImage::StartAnimation()
{
  if (mError) {
    return NS_ERROR_FAILURE;
  }

  MOZ_ASSERT(ShouldAnimate(), "Should not animate!");

  mSVGDocumentWrapper->StartAnimation();
  return NS_OK;
}

nsresult
VectorImage::StopAnimation()
{
  nsresult rv = NS_OK;
  if (mError) {
    rv = NS_ERROR_FAILURE;
  } else {
    MOZ_ASSERT(mIsFullyLoaded && mHaveAnimations,
               "Should not have been animating!");

    mSVGDocumentWrapper->StopAnimation();
  }

  mAnimating = false;
  return rv;
}

bool
VectorImage::ShouldAnimate()
{
  return ImageResource::ShouldAnimate() && mIsFullyLoaded && mHaveAnimations;
}

NS_IMETHODIMP_(void)
VectorImage::SetAnimationStartTime(const TimeStamp& aTime)
{
  // We don't care about animation start time.
}

//------------------------------------------------------------------------------
// imgIContainer methods

//******************************************************************************
NS_IMETHODIMP
VectorImage::GetWidth(int32_t* aWidth)
{
  if (mError || !mIsFullyLoaded) {
    // XXXdholbert Technically we should leave outparam untouched when we
    // fail. But since many callers don't check for failure, we set it to 0 on
    // failure, for sane/predictable results.
    *aWidth = 0;
    return NS_ERROR_FAILURE;
  }

  SVGSVGElement* rootElem = mSVGDocumentWrapper->GetRootSVGElem();
  MOZ_ASSERT(rootElem, "Should have a root SVG elem, since we finished "
             "loading without errors");
  int32_t rootElemWidth = rootElem->GetIntrinsicWidth();
  if (rootElemWidth < 0) {
    *aWidth = 0;
    return NS_ERROR_FAILURE;
  }
  *aWidth = rootElemWidth;
  return NS_OK;
}

//******************************************************************************
NS_IMETHODIMP_(void)
VectorImage::RequestRefresh(const TimeStamp& aTime)
{
  if (HadRecentRefresh(aTime)) {
    return;
  }

  PendingAnimationTracker* tracker =
    mSVGDocumentWrapper->GetDocument()->GetPendingAnimationTracker();
  if (tracker && ShouldAnimate()) {
    tracker->TriggerPendingAnimationsOnNextTick(aTime);
  }

  EvaluateAnimation();

  mSVGDocumentWrapper->TickRefreshDriver();

  if (mHasPendingInvalidation) {
    mHasPendingInvalidation = false;
    SendInvalidationNotifications();
  }
}

void
VectorImage::SendInvalidationNotifications()
{
  // Animated images don't send out invalidation notifications as soon as
  // they're generated. Instead, InvalidateObserversOnNextRefreshDriverTick
  // records that there are pending invalidations and then returns immediately.
  // The notifications are actually sent from RequestRefresh(). We send these
  // notifications there to ensure that there is actually a document observing
  // us. Otherwise, the notifications are just wasted effort.
  //
  // Non-animated images call this method directly from
  // InvalidateObserversOnNextRefreshDriverTick, because RequestRefresh is never
  // called for them. Ordinarily this isn't needed, since we send out
  // invalidation notifications in OnSVGDocumentLoaded, but in rare cases the
  // SVG document may not be 100% ready to render at that time. In those cases
  // we would miss the subsequent invalidations if we didn't send out the
  // notifications directly in |InvalidateObservers...|.

  if (mProgressTracker) {
    SurfaceCache::RemoveImage(ImageKey(this));
    mProgressTracker->SyncNotifyProgress(FLAG_FRAME_COMPLETE,
                                         GetMaxSizedIntRect());
  }
}

NS_IMETHODIMP_(IntRect)
VectorImage::GetImageSpaceInvalidationRect(const IntRect& aRect)
{
  return aRect;
}

//******************************************************************************
NS_IMETHODIMP
VectorImage::GetHeight(int32_t* aHeight)
{
  if (mError || !mIsFullyLoaded) {
    // XXXdholbert Technically we should leave outparam untouched when we
    // fail. But since many callers don't check for failure, we set it to 0 on
    // failure, for sane/predictable results.
    *aHeight = 0;
    return NS_ERROR_FAILURE;
  }

  SVGSVGElement* rootElem = mSVGDocumentWrapper->GetRootSVGElem();
  MOZ_ASSERT(rootElem, "Should have a root SVG elem, since we finished "
             "loading without errors");
  int32_t rootElemHeight = rootElem->GetIntrinsicHeight();
  if (rootElemHeight < 0) {
    *aHeight = 0;
    return NS_ERROR_FAILURE;
  }
  *aHeight = rootElemHeight;
  return NS_OK;
}

//******************************************************************************
NS_IMETHODIMP
VectorImage::GetIntrinsicSize(nsSize* aSize)
{
  if (mError || !mIsFullyLoaded) {
    return NS_ERROR_FAILURE;
  }

  nsIFrame* rootFrame = mSVGDocumentWrapper->GetRootLayoutFrame();
  if (!rootFrame) {
    return NS_ERROR_FAILURE;
  }

  *aSize = nsSize(-1, -1);
  IntrinsicSize rfSize = rootFrame->GetIntrinsicSize();
  if (rfSize.width.GetUnit() == eStyleUnit_Coord) {
    aSize->width = rfSize.width.GetCoordValue();
  }
  if (rfSize.height.GetUnit() == eStyleUnit_Coord) {
    aSize->height = rfSize.height.GetCoordValue();
  }

  return NS_OK;
}

//******************************************************************************
NS_IMETHODIMP
VectorImage::GetIntrinsicRatio(nsSize* aRatio)
{
  if (mError || !mIsFullyLoaded) {
    return NS_ERROR_FAILURE;
  }

  nsIFrame* rootFrame = mSVGDocumentWrapper->GetRootLayoutFrame();
  if (!rootFrame) {
    return NS_ERROR_FAILURE;
  }

  *aRatio = rootFrame->GetIntrinsicRatio();
  return NS_OK;
}

NS_IMETHODIMP_(Orientation)
VectorImage::GetOrientation()
{
  return Orientation();
}

//******************************************************************************
NS_IMETHODIMP
VectorImage::GetType(uint16_t* aType)
{
  NS_ENSURE_ARG_POINTER(aType);

  *aType = imgIContainer::TYPE_VECTOR;
  return NS_OK;
}

//******************************************************************************
NS_IMETHODIMP
VectorImage::GetAnimated(bool* aAnimated)
{
  if (mError || !mIsFullyLoaded) {
    return NS_ERROR_FAILURE;
  }

  *aAnimated = mSVGDocumentWrapper->IsAnimated();
  return NS_OK;
}

//******************************************************************************
int32_t
VectorImage::GetFirstFrameDelay()
{
  if (mError) {
    return -1;
  }

  if (!mSVGDocumentWrapper->IsAnimated()) {
    return -1;
  }

  // We don't really have a frame delay, so just pretend that we constantly
  // need updates.
  return 0;
}

NS_IMETHODIMP_(bool)
VectorImage::WillDrawOpaqueNow()
{
  return false; // In general, SVG content is not opaque.
}

//******************************************************************************
NS_IMETHODIMP_(already_AddRefed<SourceSurface>)
VectorImage::GetFrame(uint32_t aWhichFrame, uint32_t aFlags)
{
  if (mError) {
    return nullptr;
  }

  // Look up height & width
  // ----------------------
  SVGSVGElement* svgElem = mSVGDocumentWrapper->GetRootSVGElem();
  MOZ_ASSERT(svgElem, "Should have a root SVG elem, since we finished "
                      "loading without errors");
  nsIntSize imageIntSize(svgElem->GetIntrinsicWidth(),
                         svgElem->GetIntrinsicHeight());

  if (imageIntSize.IsEmpty()) {
    // We'll get here if our SVG doc has a percent-valued or negative width or
    // height.
    return nullptr;
  }

  return GetFrameAtSize(imageIntSize, aWhichFrame, aFlags);
}

NS_IMETHODIMP_(already_AddRefed<SourceSurface>)
VectorImage::GetFrameAtSize(const IntSize& aSize,
                            uint32_t aWhichFrame,
                            uint32_t aFlags)
{
  MOZ_ASSERT(aWhichFrame <= FRAME_MAX_VALUE);

  if (aSize.IsEmpty()) {
    return nullptr;
  }

  if (aWhichFrame > FRAME_MAX_VALUE) {
    return nullptr;
  }

  if (mError || !mIsFullyLoaded) {
    return nullptr;
  }

  // Make our surface the size of what will ultimately be drawn to it.
  // (either the full image size, or the restricted region)
  RefPtr<DrawTarget> dt = gfxPlatform::GetPlatform()->
    CreateOffscreenContentDrawTarget(aSize, SurfaceFormat::B8G8R8A8);
  if (!dt || !dt->IsValid()) {
    NS_ERROR("Could not create a DrawTarget");
    return nullptr;
  }

  RefPtr<gfxContext> context = gfxContext::CreateOrNull(dt);
  MOZ_ASSERT(context); // already checked the draw target above

  auto result = Draw(context, aSize, ImageRegion::Create(aSize),
                     aWhichFrame, SamplingFilter::POINT, Nothing(), aFlags,
                     1.0);

  return result == DrawResult::SUCCESS ? dt->Snapshot() : nullptr;
}

NS_IMETHODIMP_(bool)
VectorImage::IsImageContainerAvailable(LayerManager* aManager, uint32_t aFlags)
{
  return false;
}

//******************************************************************************
NS_IMETHODIMP_(already_AddRefed<ImageContainer>)
VectorImage::GetImageContainer(LayerManager* aManager, uint32_t aFlags)
{
  return nullptr;
}

struct SVGDrawingParameters
{
  SVGDrawingParameters(gfxContext* aContext,
                       const nsIntSize& aSize,
                       const ImageRegion& aRegion,
                       SamplingFilter aSamplingFilter,
                       const Maybe<SVGImageContext>& aSVGContext,
                       float aAnimationTime,
                       uint32_t aFlags,
                       float aOpacity)
    : context(aContext)
    , size(aSize.width, aSize.height)
    , region(aRegion)
    , samplingFilter(aSamplingFilter)
    , svgContext(aSVGContext)
    , viewportSize(aSize)
    , animationTime(aAnimationTime)
    , flags(aFlags)
    , opacity(aSVGContext ? aSVGContext->GetGlobalOpacity() : aOpacity)
  {
    if (aSVGContext) {
      auto sz = aSVGContext->GetViewportSize();
      if (sz) {
        viewportSize = nsIntSize(sz->width, sz->height); // XXX losing unit
      }
    }
  }

  gfxContext*                   context;
  IntSize                       size;
  ImageRegion                   region;
  SamplingFilter                samplingFilter;
  const Maybe<SVGImageContext>& svgContext;
  nsIntSize                     viewportSize;
  float                         animationTime;
  uint32_t                      flags;
  gfxFloat                      opacity;
};

//******************************************************************************
NS_IMETHODIMP_(DrawResult)
VectorImage::Draw(gfxContext* aContext,
                  const nsIntSize& aSize,
                  const ImageRegion& aRegion,
                  uint32_t aWhichFrame,
                  SamplingFilter aSamplingFilter,
                  const Maybe<SVGImageContext>& aSVGContext,
                  uint32_t aFlags,
                  float aOpacity)
{
  if (aWhichFrame > FRAME_MAX_VALUE) {
    return DrawResult::BAD_ARGS;
  }

  if (!aContext) {
    return DrawResult::BAD_ARGS;
  }

  if (mError) {
    return DrawResult::BAD_IMAGE;
  }

  if (!mIsFullyLoaded) {
    return DrawResult::NOT_READY;
  }

  if (mIsDrawing) {
    NS_WARNING("Refusing to make re-entrant call to VectorImage::Draw");
    return DrawResult::TEMPORARY_ERROR;
  }

  if (mAnimationConsumers == 0) {
    SendOnUnlockedDraw(aFlags);
  }

  AutoRestore<bool> autoRestoreIsDrawing(mIsDrawing);
  mIsDrawing = true;

  // If FLAG_FORCE_PRESERVEASPECTRATIO_NONE bit is set, that means we should
  // overwrite SVG preserveAspectRatio attibute of this image with none, and
  // always stretch this image to viewport non-uniformly.
  // And we can do this only if the caller pass in the the SVG viewport, via
  // aSVGContext.
  Maybe<SVGImageContext> newSVGContext;
  if ((aFlags & FLAG_FORCE_PRESERVEASPECTRATIO_NONE) && aSVGContext) {
    Maybe<SVGPreserveAspectRatio> aspectRatio =
      Some(SVGPreserveAspectRatio(SVG_PRESERVEASPECTRATIO_NONE,
                                  SVG_MEETORSLICE_UNKNOWN));
    newSVGContext = aSVGContext; // copy
    newSVGContext->SetPreserveAspectRatio(aspectRatio);
  }

  float animTime =
    (aWhichFrame == FRAME_FIRST) ? 0.0f
                                 : mSVGDocumentWrapper->GetCurrentTime();
  AutoSVGRenderingState autoSVGState(newSVGContext ? newSVGContext : aSVGContext,
                                     animTime,
                                     mSVGDocumentWrapper->GetRootSVGElem());


  SVGDrawingParameters params(aContext, aSize, aRegion, aSamplingFilter,
                              newSVGContext ? newSVGContext : aSVGContext,
                              animTime, aFlags, aOpacity);

  // If we have an prerasterized version of this image that matches the
  // drawing parameters, use that.
  RefPtr<gfxDrawable> svgDrawable = LookupCachedSurface(params);
  if (svgDrawable) {
    Show(svgDrawable, params);
    return DrawResult::SUCCESS;
  }

  Maybe<AutoSetRestoreSVGContextPaint> autoContextPaint;
  if (aSVGContext &&
      aSVGContext->GetContextPaint()) {
    autoContextPaint.emplace(aSVGContext->GetContextPaint(),
                             mSVGDocumentWrapper->GetDocument());
  }

  // We didn't get a hit in the surface cache, so we'll need to rerasterize.
  CreateSurfaceAndShow(params, aContext->GetDrawTarget()->GetBackendType());
  return DrawResult::SUCCESS;
}

already_AddRefed<gfxDrawable>
VectorImage::LookupCachedSurface(const SVGDrawingParameters& aParams)
{
  // If we're not allowed to use a cached surface, don't attempt a lookup.
  if (aParams.flags & FLAG_BYPASS_SURFACE_CACHE) {
    return nullptr;
  }

  // We don't do any caching if we have animation, so don't bother with a lookup
  // in this case either.
  if (mHaveAnimations) {
    return nullptr;
  }

  LookupResult result =
    SurfaceCache::Lookup(ImageKey(this),
                         VectorSurfaceKey(aParams.size, aParams.svgContext));
  if (!result) {
    return nullptr;  // No matching surface, or the OS freed the volatile buffer.
  }

  RefPtr<SourceSurface> sourceSurface = result.Surface()->GetSourceSurface();
  if (!sourceSurface) {
    // Something went wrong. (Probably a GPU driver crash or device reset.)
    // Attempt to recover.
    RecoverFromLossOfSurfaces();
    return nullptr;
  }

  RefPtr<gfxDrawable> svgDrawable =
    new gfxSurfaceDrawable(sourceSurface, result.Surface()->GetSize());
  return svgDrawable.forget();
}

void
VectorImage::CreateSurfaceAndShow(const SVGDrawingParameters& aParams, BackendType aBackend)
{
  mSVGDocumentWrapper->UpdateViewportBounds(aParams.viewportSize);
  mSVGDocumentWrapper->FlushImageTransformInvalidation();

  RefPtr<gfxDrawingCallback> cb =
    new SVGDrawingCallback(mSVGDocumentWrapper,
                           aParams.viewportSize,
                           aParams.size,
                           aParams.flags);

  RefPtr<gfxDrawable> svgDrawable =
    new gfxCallbackDrawable(cb, aParams.size);

  bool bypassCache = bool(aParams.flags & FLAG_BYPASS_SURFACE_CACHE) ||
                     // Refuse to cache animated images:
                     // XXX(seth): We may remove this restriction in bug 922893.
                     mHaveAnimations ||
                     // The image is too big to fit in the cache:
                     !SurfaceCache::CanHold(aParams.size);
  if (bypassCache) {
    return Show(svgDrawable, aParams);
  }

  // We're about to rerasterize, which may mean that some of the previous
  // surfaces we've rasterized aren't useful anymore. We can allow them to
  // expire from the cache by unlocking them here, and then sending out an
  // invalidation. If this image is locked, any surfaces that are still useful
  // will become locked again when Draw touches them, and the remainder will
  // eventually expire.
  SurfaceCache::UnlockEntries(ImageKey(this));

  // Try to create an imgFrame, initializing the surface it contains by drawing
  // our gfxDrawable into it. (We use FILTER_NEAREST since we never scale here.)
  NotNull<RefPtr<imgFrame>> frame = WrapNotNull(new imgFrame);
  nsresult rv =
    frame->InitWithDrawable(svgDrawable, aParams.size,
                            SurfaceFormat::B8G8R8A8,
                            SamplingFilter::POINT, aParams.flags,
                            aBackend);

  // If we couldn't create the frame, it was probably because it would end
  // up way too big. Generally it also wouldn't fit in the cache, but the prefs
  // could be set such that the cache isn't the limiting factor.
  if (NS_FAILED(rv)) {
    return Show(svgDrawable, aParams);
  }

  // Take a strong reference to the frame's surface and make sure it hasn't
  // already been purged by the operating system.
  RefPtr<SourceSurface> surface = frame->GetSourceSurface();
  if (!surface) {
    return Show(svgDrawable, aParams);
  }

  // Attempt to cache the frame.
  SurfaceKey surfaceKey = VectorSurfaceKey(aParams.size, aParams.svgContext);
  NotNull<RefPtr<ISurfaceProvider>> provider =
    WrapNotNull(new SimpleSurfaceProvider(ImageKey(this), surfaceKey, frame));
  SurfaceCache::Insert(provider);

  // Draw.
  RefPtr<gfxDrawable> drawable =
    new gfxSurfaceDrawable(surface, aParams.size);
  Show(drawable, aParams);

  // Send out an invalidation so that surfaces that are still in use get
  // re-locked. See the discussion of the UnlockSurfaces call above.
  if (!(aParams.flags & FLAG_ASYNC_NOTIFY)) {
    mProgressTracker->SyncNotifyProgress(FLAG_FRAME_COMPLETE,
                                         GetMaxSizedIntRect());
  } else {
    NotNull<RefPtr<VectorImage>> image = WrapNotNull(this);
    NS_DispatchToMainThread(NS_NewRunnableFunction(
                              "ProgressTracker::SyncNotifyProgress",
                              [=]() -> void {
      RefPtr<ProgressTracker> tracker = image->GetProgressTracker();
      if (tracker) {
        tracker->SyncNotifyProgress(FLAG_FRAME_COMPLETE,
                                    GetMaxSizedIntRect());
      }
    }));
  }
}


void
VectorImage::Show(gfxDrawable* aDrawable, const SVGDrawingParameters& aParams)
{
  MOZ_ASSERT(aDrawable, "Should have a gfxDrawable by now");
  gfxUtils::DrawPixelSnapped(aParams.context, aDrawable,
                             aParams.size,
                             aParams.region,
                             SurfaceFormat::B8G8R8A8,
                             aParams.samplingFilter,
                             aParams.flags, aParams.opacity);

  MOZ_ASSERT(mRenderingObserver, "Should have a rendering observer by now");
  mRenderingObserver->ResumeHonoringInvalidations();
}

void
VectorImage::RecoverFromLossOfSurfaces()
{
  NS_WARNING("An imgFrame became invalid. Attempting to recover...");

  // Discard all existing frames, since they're probably all now invalid.
  SurfaceCache::RemoveImage(ImageKey(this));
}

NS_IMETHODIMP
VectorImage::StartDecoding(uint32_t aFlags)
{
  // Nothing to do for SVG images
  return NS_OK;
}

bool
VectorImage::StartDecodingWithResult(uint32_t aFlags)
{
  // SVG images are ready to draw when they are loaded
  return mIsFullyLoaded;
}

NS_IMETHODIMP
VectorImage::RequestDecodeForSize(const nsIntSize& aSize, uint32_t aFlags)
{
  // Nothing to do for SVG images, though in theory we could rasterize to the
  // provided size ahead of time if we supported off-main-thread SVG
  // rasterization...
  return NS_OK;
}

//******************************************************************************

NS_IMETHODIMP
VectorImage::LockImage()
{
  MOZ_ASSERT(NS_IsMainThread());

  if (mError) {
    return NS_ERROR_FAILURE;
  }

  mLockCount++;

  if (mLockCount == 1) {
    // Lock this image's surfaces in the SurfaceCache.
    SurfaceCache::LockImage(ImageKey(this));
  }

  return NS_OK;
}

//******************************************************************************

NS_IMETHODIMP
VectorImage::UnlockImage()
{
  MOZ_ASSERT(NS_IsMainThread());

  if (mError) {
    return NS_ERROR_FAILURE;
  }

  if (mLockCount == 0) {
    MOZ_ASSERT_UNREACHABLE("Calling UnlockImage with a zero lock count");
    return NS_ERROR_ABORT;
  }

  mLockCount--;

  if (mLockCount == 0) {
    // Unlock this image's surfaces in the SurfaceCache.
    SurfaceCache::UnlockImage(ImageKey(this));
  }

  return NS_OK;
}

//******************************************************************************

NS_IMETHODIMP
VectorImage::RequestDiscard()
{
  MOZ_ASSERT(NS_IsMainThread());

  if (mDiscardable && mLockCount == 0) {
    SurfaceCache::RemoveImage(ImageKey(this));
    mProgressTracker->OnDiscard();
  }

  return NS_OK;
}

void
VectorImage::OnSurfaceDiscarded(const SurfaceKey& aSurfaceKey)
{
  MOZ_ASSERT(mProgressTracker);

  NS_DispatchToMainThread(NewRunnableMethod(mProgressTracker, &ProgressTracker::OnDiscard));
}

//******************************************************************************
NS_IMETHODIMP
VectorImage::ResetAnimation()
{
  if (mError) {
    return NS_ERROR_FAILURE;
  }

  if (!mIsFullyLoaded || !mHaveAnimations) {
    return NS_OK; // There are no animations to be reset.
  }

  mSVGDocumentWrapper->ResetAnimation();

  return NS_OK;
}

NS_IMETHODIMP_(float)
VectorImage::GetFrameIndex(uint32_t aWhichFrame)
{
  MOZ_ASSERT(aWhichFrame <= FRAME_MAX_VALUE, "Invalid argument");
  return aWhichFrame == FRAME_FIRST
         ? 0.0f
         : mSVGDocumentWrapper->GetCurrentTime();
}

//------------------------------------------------------------------------------
// nsIRequestObserver methods

//******************************************************************************
NS_IMETHODIMP
VectorImage::OnStartRequest(nsIRequest* aRequest, nsISupports* aCtxt)
{
  MOZ_ASSERT(!mSVGDocumentWrapper,
             "Repeated call to OnStartRequest -- can this happen?");

  mSVGDocumentWrapper = new SVGDocumentWrapper();
  nsresult rv = mSVGDocumentWrapper->OnStartRequest(aRequest, aCtxt);
  if (NS_FAILED(rv)) {
    mSVGDocumentWrapper = nullptr;
    mError = true;
    return rv;
  }

  // ProgressTracker::SyncNotifyProgress may release us, so ensure we
  // stick around long enough to complete our work.
  RefPtr<VectorImage> kungFuDeathGrip(this);

  // Block page load until the document's ready.  (We unblock it in
  // OnSVGDocumentLoaded or OnSVGDocumentError.)
  if (mProgressTracker) {
    mProgressTracker->SyncNotifyProgress(FLAG_ONLOAD_BLOCKED);
  }

  // Create a listener to wait until the SVG document is fully loaded, which
  // will signal that this image is ready to render. Certain error conditions
  // will prevent us from ever getting this notification, so we also create a
  // listener that waits for parsing to complete and cancels the
  // SVGLoadEventListener if needed. The listeners are automatically attached
  // to the document by their constructors.
  nsIDocument* document = mSVGDocumentWrapper->GetDocument();
  mLoadEventListener = new SVGLoadEventListener(document, this);
  mParseCompleteListener = new SVGParseCompleteListener(document, this);

  return NS_OK;
}

//******************************************************************************
NS_IMETHODIMP
VectorImage::OnStopRequest(nsIRequest* aRequest, nsISupports* aCtxt,
                           nsresult aStatus)
{
  if (mError) {
    return NS_ERROR_FAILURE;
  }

  return mSVGDocumentWrapper->OnStopRequest(aRequest, aCtxt, aStatus);
}

void
VectorImage::OnSVGDocumentParsed()
{
  MOZ_ASSERT(mParseCompleteListener, "Should have the parse complete listener");
  MOZ_ASSERT(mLoadEventListener, "Should have the load event listener");

  if (!mSVGDocumentWrapper->GetRootSVGElem()) {
    // This is an invalid SVG document. It may have failed to parse, or it may
    // be missing the <svg> root element, or the <svg> root element may not
    // declare the correct namespace. In any of these cases, we'll never be
    // notified that the SVG finished loading, so we need to treat this as an
    // error.
    OnSVGDocumentError();
  }
}

void
VectorImage::CancelAllListeners()
{
  if (mParseCompleteListener) {
    mParseCompleteListener->Cancel();
    mParseCompleteListener = nullptr;
  }
  if (mLoadEventListener) {
    mLoadEventListener->Cancel();
    mLoadEventListener = nullptr;
  }
}

void
VectorImage::OnSVGDocumentLoaded()
{
  MOZ_ASSERT(mSVGDocumentWrapper->GetRootSVGElem(),
             "Should have parsed successfully");
  MOZ_ASSERT(!mIsFullyLoaded && !mHaveAnimations,
             "These flags shouldn't get set until OnSVGDocumentLoaded. "
             "Duplicate calls to OnSVGDocumentLoaded?");

  CancelAllListeners();

  // XXX Flushing is wasteful if embedding frame hasn't had initial reflow.
  mSVGDocumentWrapper->FlushLayout();

  mIsFullyLoaded = true;
  mHaveAnimations = mSVGDocumentWrapper->IsAnimated();

  // Start listening to our image for rendering updates.
  mRenderingObserver = new SVGRootRenderingObserver(mSVGDocumentWrapper, this);

  // ProgressTracker::SyncNotifyProgress may release us, so ensure we
  // stick around long enough to complete our work.
  RefPtr<VectorImage> kungFuDeathGrip(this);

  // Tell *our* observers that we're done loading.
  if (mProgressTracker) {
    Progress progress = FLAG_SIZE_AVAILABLE |
                        FLAG_HAS_TRANSPARENCY |
                        FLAG_FRAME_COMPLETE |
                        FLAG_DECODE_COMPLETE |
                        FLAG_ONLOAD_UNBLOCKED;

    if (mHaveAnimations) {
      progress |= FLAG_IS_ANIMATED;
    }

    // Merge in any saved progress from OnImageDataComplete.
    if (mLoadProgress) {
      progress |= *mLoadProgress;
      mLoadProgress = Nothing();
    }

    mProgressTracker->SyncNotifyProgress(progress, GetMaxSizedIntRect());
  }

  EvaluateAnimation();
}

void
VectorImage::OnSVGDocumentError()
{
  CancelAllListeners();

  mError = true;

  if (mProgressTracker) {
    // Notify observers about the error and unblock page load.
    Progress progress = FLAG_ONLOAD_UNBLOCKED | FLAG_HAS_ERROR;

    // Merge in any saved progress from OnImageDataComplete.
    if (mLoadProgress) {
      progress |= *mLoadProgress;
      mLoadProgress = Nothing();
    }

    mProgressTracker->SyncNotifyProgress(progress);
  }
}

//------------------------------------------------------------------------------
// nsIStreamListener method

//******************************************************************************
NS_IMETHODIMP
VectorImage::OnDataAvailable(nsIRequest* aRequest, nsISupports* aCtxt,
                             nsIInputStream* aInStr, uint64_t aSourceOffset,
                             uint32_t aCount)
{
  if (mError) {
    return NS_ERROR_FAILURE;
  }

  return mSVGDocumentWrapper->OnDataAvailable(aRequest, aCtxt, aInStr,
                                              aSourceOffset, aCount);
}

// --------------------------
// Invalidation helper method

void
VectorImage::InvalidateObserversOnNextRefreshDriverTick()
{
  if (mHaveAnimations) {
    mHasPendingInvalidation = true;
  } else {
    SendInvalidationNotifications();
  }
}

void
VectorImage::PropagateUseCounters(nsIDocument* aParentDocument)
{
  nsIDocument* doc = mSVGDocumentWrapper->GetDocument();
  if (doc) {
    doc->PropagateUseCounters(aParentDocument);
  }
}

void
VectorImage::ReportUseCounters()
{
  nsIDocument* doc = mSVGDocumentWrapper->GetDocument();
  if (doc) {
    static_cast<nsDocument*>(doc)->ReportUseCounters();
  }
}

nsIntSize
VectorImage::OptimalImageSizeForDest(const gfxSize& aDest,
                                     uint32_t aWhichFrame,
                                     SamplingFilter aSamplingFilter,
                                     uint32_t aFlags)
{
  MOZ_ASSERT(aDest.width >= 0 || ceil(aDest.width) <= INT32_MAX ||
             aDest.height >= 0 || ceil(aDest.height) <= INT32_MAX,
             "Unexpected destination size");

  // We can rescale SVGs freely, so just return the provided destination size.
  return nsIntSize::Ceil(aDest.width, aDest.height);
}

already_AddRefed<imgIContainer>
VectorImage::Unwrap()
{
  nsCOMPtr<imgIContainer> self(this);
  return self.forget();
}

} // namespace image
} // namespace mozilla