author Andrew Osmond <>
Wed, 13 Mar 2019 12:43:52 -0400
changeset 521902 8647c1f78210adcb01511ea27eecfb53bc5c1a5d
parent 519777 e0fb4657355d4d8052bff3f1e8baac265b5efef7
child 522601 5f22cf5bfe6f0281522103ecf8d23c88dc37b5e6
permissions -rw-r--r--
Bug 1534188 - Use high quality downscaling for raster images embedded in SVGs. r=tnikkel Differential Revision:

/* -*- 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 */

// Main header first:
#include "nsSVGOuterSVGFrame.h"

// Keep others in (case-insensitive) order:
#include "gfxContext.h"
#include "nsDisplayList.h"
#include "mozilla/dom/Document.h"
#include "nsIInterfaceRequestorUtils.h"
#include "nsIObjectLoadingContent.h"
#include "nsSVGIntegrationUtils.h"
#include "nsSVGForeignObjectFrame.h"
#include "mozilla/dom/Element.h"
#include "mozilla/dom/SVGSVGElement.h"
#include "mozilla/dom/SVGViewElement.h"
#include "nsSubDocumentFrame.h"

using namespace mozilla;
using namespace mozilla::dom;
using namespace mozilla::gfx;
using namespace mozilla::image;

// Implementation helpers

void nsSVGOuterSVGFrame::RegisterForeignObject(
    nsSVGForeignObjectFrame* aFrame) {
  NS_ASSERTION(aFrame, "Who on earth is calling us?!");

  if (!mForeignObjectHash) {
    mForeignObjectHash =
        new nsTHashtable<nsPtrHashKey<nsSVGForeignObjectFrame> >();

               "nsSVGForeignObjectFrame already registered!");


               "Failed to register nsSVGForeignObjectFrame!");

void nsSVGOuterSVGFrame::UnregisterForeignObject(
    nsSVGForeignObjectFrame* aFrame) {
  NS_ASSERTION(aFrame, "Who on earth is calling us?!");
  NS_ASSERTION(mForeignObjectHash && mForeignObjectHash->GetEntry(aFrame),
               "nsSVGForeignObjectFrame not in registry!");
  return mForeignObjectHash->RemoveEntry(aFrame);

// Implementation

nsContainerFrame* NS_NewSVGOuterSVGFrame(nsIPresShell* aPresShell,
                                         ComputedStyle* aStyle) {
  return new (aPresShell)
      nsSVGOuterSVGFrame(aStyle, aPresShell->GetPresContext());


nsSVGOuterSVGFrame::nsSVGOuterSVGFrame(ComputedStyle* aStyle,
                                       nsPresContext* aPresContext)
    : nsSVGDisplayContainerFrame(aStyle, aPresContext, kClassID),
      mIsRootContent(false) {
  // Outer-<svg> has CSS layout, so remove this bit:

// helper
static inline bool DependsOnIntrinsicSize(const nsIFrame* aEmbeddingFrame) {
  const nsStylePosition* pos = aEmbeddingFrame->StylePosition();
  const auto& width = pos->mWidth;
  const auto& height = pos->mHeight;

  // XXX it would be nice to know if the size of aEmbeddingFrame's containing
  // block depends on aEmbeddingFrame, then we'd know if we can return false
  // for eStyleUnit_Percent too.
  return !width.ConvertsToLength() || !height.ConvertsToLength();

void nsSVGOuterSVGFrame::Init(nsIContent* aContent, nsContainerFrame* aParent,
                              nsIFrame* aPrevInFlow) {
               "Content is not an SVG 'svg' element!");


  // Check for conditional processing attributes here rather than in
  // nsCSSFrameConstructor::FindSVGData because we want to avoid
  // simply giving failing outer <svg> elements an nsSVGContainerFrame.
  // We don't create other SVG frames if PassesConditionalProcessingTests
  // returns false, but since we do create nsSVGOuterSVGFrame frames we
  // prevent them from painting by [ab]use NS_FRAME_IS_NONDISPLAY. The
  // frame will be recreated via an nsChangeHint_ReconstructFrame restyle if
  // the value returned by PassesConditionalProcessingTests changes.
  SVGSVGElement* svg = static_cast<SVGSVGElement*>(aContent);
  if (!svg->PassesConditionalProcessingTests()) {

  nsSVGDisplayContainerFrame::Init(aContent, aParent, aPrevInFlow);

  Document* doc = mContent->GetUncomposedDoc();
  if (doc) {
    // we only care about our content's zoom and pan values if it's the root
    // element
    if (doc->GetRootElement() == mContent) {
      mIsRootContent = true;

      nsIFrame* embeddingFrame;
      if (IsRootOfReplacedElementSubDoc(&embeddingFrame) && embeddingFrame) {
        if (MOZ_UNLIKELY(!embeddingFrame->HasAllStateBits(NS_FRAME_IS_DIRTY)) &&
            DependsOnIntrinsicSize(embeddingFrame)) {
          // Looks like this document is loading after the embedding element
          // has had its first reflow, and that its size depends on our
          // intrinsic size.  We need it to resize itself to use our (now
          // available) intrinsic size:
              embeddingFrame, nsIPresShell::eStyleChange, NS_FRAME_IS_DIRTY);

// nsQueryFrame methods


// nsIFrame methods
// reflowing

/* virtual */
nscoord nsSVGOuterSVGFrame::GetMinISize(gfxContext* aRenderingContext) {
  nscoord result;
  DISPLAY_MIN_INLINE_SIZE(this, result);

  result = nscoord(0);

  return result;

/* virtual */
nscoord nsSVGOuterSVGFrame::GetPrefISize(gfxContext* aRenderingContext) {
  nscoord result;

  SVGSVGElement* svg = static_cast<SVGSVGElement*>(GetContent());
  WritingMode wm = GetWritingMode();
  const nsSVGLength2& isize =
      wm.IsVertical() ? svg->mLengthAttributes[SVGSVGElement::ATTR_HEIGHT]
                      : svg->mLengthAttributes[SVGSVGElement::ATTR_WIDTH];

  if (isize.IsPercentage()) {
    // It looks like our containing block's isize may depend on our isize. In
    // that case our behavior is undefined according to CSS 2.1 section 10.3.2.
    // As a last resort, we'll fall back to returning zero.
    result = nscoord(0);

    // Returning zero may be unhelpful, however, as it leads to unexpected
    // disappearance of %-sized SVGs in orthogonal contexts, where our
    // containing block wants to shrink-wrap. So let's look for an ancestor
    // with non-zero size in this dimension, and use that as a (somewhat
    // arbitrary) result instead.
    nsIFrame* parent = GetParent();
    while (parent) {
      nscoord parentISize = parent->GetLogicalSize(wm).ISize(wm);
      if (parentISize > 0 && parentISize != NS_UNCONSTRAINEDSIZE) {
        result = parentISize;
      parent = parent->GetParent();
  } else {
    result = nsPresContext::CSSPixelsToAppUnits(isize.GetAnimValue(svg));
    if (result < 0) {
      result = nscoord(0);

  return result;

/* virtual */
IntrinsicSize nsSVGOuterSVGFrame::GetIntrinsicSize() {
  // XXXjwatt Note that here we want to return the CSS width/height if they're
  // specified and we're embedded inside an nsIObjectLoadingContent.

  IntrinsicSize intrinsicSize;

  SVGSVGElement* content = static_cast<SVGSVGElement*>(GetContent());
  const nsSVGLength2& width =
  const nsSVGLength2& height =

  if (!width.IsPercentage()) {
    nscoord val =
    if (val < 0) val = 0;

  if (!height.IsPercentage()) {
    nscoord val =
    if (val < 0) val = 0;

  return intrinsicSize;

/* virtual */
nsSize nsSVGOuterSVGFrame::GetIntrinsicRatio() {
  // We only have an intrinsic size/ratio if our width and height attributes
  // are both specified and set to non-percentage values, or we have a viewBox
  // rect:
  // Unfortunately we have to return the ratio as two nscoords whereas what
  // we have are two floats. Using app units allows for some floating point
  // values to work but really small or large numbers will fail.

  SVGSVGElement* content = static_cast<SVGSVGElement*>(GetContent());
  const nsSVGLength2& width =
  const nsSVGLength2& height =

  if (!width.IsPercentage() && !height.IsPercentage()) {
    nsSize ratio(
    if (ratio.width < 0) {
      ratio.width = 0;
    if (ratio.height < 0) {
      ratio.height = 0;
    return ratio;

  SVGViewElement* viewElement = content->GetCurrentViewElement();
  const SVGViewBoxRect* viewbox = nullptr;

  // The logic here should match HasViewBox().
  if (viewElement && viewElement->mViewBox.HasRect()) {
    viewbox = &viewElement->mViewBox.GetAnimValue();
  } else if (content->mViewBox.HasRect()) {
    viewbox = &content->mViewBox.GetAnimValue();

  if (viewbox) {
    float viewBoxWidth = viewbox->width;
    float viewBoxHeight = viewbox->height;

    if (viewBoxWidth < 0.0f) {
      viewBoxWidth = 0.0f;
    if (viewBoxHeight < 0.0f) {
      viewBoxHeight = 0.0f;
    return nsSize(nsPresContext::CSSPixelsToAppUnits(viewBoxWidth),

  return nsSVGDisplayContainerFrame::GetIntrinsicRatio();

/* virtual */
LogicalSize nsSVGOuterSVGFrame::ComputeSize(
    gfxContext* aRenderingContext, WritingMode aWM, const LogicalSize& aCBSize,
    nscoord aAvailableISize, const LogicalSize& aMargin,
    const LogicalSize& aBorder, const LogicalSize& aPadding,
    ComputeSizeFlags aFlags) {
  if (IsRootOfImage() || IsRootOfReplacedElementSubDoc()) {
    // The embedding element has sized itself using the CSS replaced element
    // sizing rules, using our intrinsic dimensions as necessary. The SVG spec
    // says that the width and height of embedded SVG is overridden by the
    // width and height of the embedding element, so we just need to size to
    // the viewport that the embedding element has established for us.
    return aCBSize;

  LogicalSize cbSize = aCBSize;
  IntrinsicSize intrinsicSize = GetIntrinsicSize();

  if (!mContent->GetParent()) {
    // We're the root of the outermost browsing context, so we need to scale
    // cbSize by the full-zoom so that SVGs with percentage width/height zoom:

                     aCBSize.BSize(aWM) != NS_AUTOHEIGHT,
                 "root should not have auto-width/height containing block");
    cbSize.ISize(aWM) *= PresContext()->GetFullZoom();
    cbSize.BSize(aWM) *= PresContext()->GetFullZoom();

    // We also need to honour the width and height attributes' default values
    // of 100% when we're the root of a browsing context.  (GetIntrinsicSize()
    // doesn't report these since there's no such thing as a percentage
    // intrinsic size.  Also note that explicit percentage values are mapped
    // into style, so the following isn't for them.)

    SVGSVGElement* content = static_cast<SVGSVGElement*>(GetContent());

    const nsSVGLength2& width =
    if (width.IsPercentage()) {
      MOZ_ASSERT(intrinsicSize.width.GetUnit() == eStyleUnit_None,
                 "GetIntrinsicSize should have reported no intrinsic width");
      float val = width.GetAnimValInSpecifiedUnits() / 100.0f;
      if (val < 0.0f) val = 0.0f;
      intrinsicSize.width.SetCoordValue(val * cbSize.Width(aWM));

    const nsSVGLength2& height =
                 "root should not have auto-height containing block");
    if (height.IsPercentage()) {
      MOZ_ASSERT(intrinsicSize.height.GetUnit() == eStyleUnit_None,
                 "GetIntrinsicSize should have reported no intrinsic height");
      float val = height.GetAnimValInSpecifiedUnits() / 100.0f;
      if (val < 0.0f) val = 0.0f;
      intrinsicSize.height.SetCoordValue(val * cbSize.Height(aWM));
    MOZ_ASSERT(intrinsicSize.height.GetUnit() == eStyleUnit_Coord &&
                   intrinsicSize.width.GetUnit() == eStyleUnit_Coord,
               "We should have just handled the only situation where"
               "we lack an intrinsic height or width.");

  return ComputeSizeWithIntrinsicDimensions(
      aRenderingContext, aWM, intrinsicSize, GetIntrinsicRatio(), cbSize,
      aMargin, aBorder, aPadding, aFlags);

void nsSVGOuterSVGFrame::Reflow(nsPresContext* aPresContext,
                                ReflowOutput& aDesiredSize,
                                const ReflowInput& aReflowInput,
                                nsReflowStatus& aStatus) {
  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
  MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
      ("enter nsSVGOuterSVGFrame::Reflow: availSize=%d,%d",
       aReflowInput.AvailableWidth(), aReflowInput.AvailableHeight()));

  MOZ_ASSERT(mState & NS_FRAME_IN_REFLOW, "frame is not in reflow");

  aDesiredSize.Width() =
      aReflowInput.ComputedWidth() +
  aDesiredSize.Height() =
      aReflowInput.ComputedHeight() +

  NS_ASSERTION(!GetPrevInFlow(), "SVG can't currently be broken across pages.");

  SVGSVGElement* svgElem = static_cast<SVGSVGElement*>(GetContent());

  nsSVGOuterSVGAnonChildFrame* anonKid =

  if (mState & NS_FRAME_FIRST_REFLOW) {
    // Initialize

  // If our SVG viewport has changed, update our content and notify.

  svgFloatSize newViewportSize(

  svgFloatSize oldViewportSize = svgElem->GetViewportSize();

  uint32_t changeBits = 0;
  if (newViewportSize != oldViewportSize) {
    // When our viewport size changes, we may need to update the overflow rects
    // of our child frames. This is the case if:
    //  * We have a real/synthetic viewBox (a children-only transform), since
    //    the viewBox transform will change as the viewport dimensions change.
    //  * We do not have a real/synthetic viewBox, but the last time we
    //    reflowed (or the last time UpdateOverflow() was called) we did.
    // We only handle the former case here, in which case we mark all our child
    // frames as dirty so that we reflow them below and update their overflow
    // rects.
    // In the latter case, updating of overflow rects is handled for removal of
    // real viewBox (the viewBox attribute) in AttributeChanged. Synthetic
    // viewBox "removal" (e.g. a document references the same SVG via both an
    // <svg:image> and then as a CSS background image (a synthetic viewBox is
    // used when painting the former, but not when painting the latter)) is
    // handled in SVGSVGElement::FlushImageTransformInvalidation.
    if (svgElem->HasViewBoxOrSyntheticViewBox()) {
      nsIFrame* anonChild = PrincipalChildList().FirstChild();
      for (nsIFrame* child : anonChild->PrincipalChildList()) {
    changeBits |= COORD_CONTEXT_CHANGED;
  if (mFullZoom != PresContext()->GetFullZoom()) {
    changeBits |= FULL_ZOOM_CHANGED;
    mFullZoom = PresContext()->GetFullZoom();
  if (changeBits) {
  mViewportInitialized = true;

  // Now that we've marked the necessary children as dirty, call
  // ReflowSVG() or ReflowSVGNonDisplayText() on them, depending
  // on whether we are non-display.
  mCallingReflowSVG = true;
  if (GetStateBits() & NS_FRAME_IS_NONDISPLAY) {
  } else {
    // Update the mRects and visual overflow rects of all our descendants,
    // including our anonymous wrapper kid:
    anonKid->AddStateBits(mState & NS_FRAME_IS_DIRTY);
               "We should have one anonymous child frame wrapping our real "
  mCallingReflowSVG = false;

  // Set our anonymous kid's offset from our border box:

  // Including our size in our overflow rects regardless of the value of
  // 'background', 'border', etc. makes sure that we usually (when we clip to
  // our content area) don't have to keep changing our overflow rects as our
  // descendants move about (see perf comment below). Including our size in our
  // scrollable overflow rect also makes sure that we scroll if we're too big
  // for our viewport.
  // <svg> never allows scrolling to anything outside its mRect (only panning),
  // so we must always keep our scrollable overflow set to our size.
  // With regards to visual overflow, we always clip root-<svg> (see our
  // BuildDisplayList method) regardless of the value of the 'overflow'
  // property since that is per-spec, even for the initial 'visible' value. For
  // that reason there's no point in adding descendant visual overflow to our
  // own when this frame is for a root-<svg>. That said, there's also a very
  // good performance reason for us wanting to avoid doing so. If we did, then
  // the frame's overflow would often change as descendants that are partially
  // or fully outside its rect moved (think animation on/off screen), and that
  // would cause us to do a full NS_FRAME_IS_DIRTY reflow and repaint of the
  // entire document tree each such move (see bug 875175).
  // So it's only non-root outer-<svg> that has the visual overflow of its
  // descendants added to its own. (Note that the default user-agent style
  // sheet makes 'hidden' the default value for :not(root(svg)), so usually
  // FinishAndStoreOverflow will still clip this back to the frame's rect.)
  // WARNING!! Keep UpdateBounds below in sync with whatever we do for our
  // overflow rects here! (Again, see bug 875175.)
  if (!mIsRootContent) {
        anonKid->GetVisualOverflowRect() + anonKid->GetPosition());

                 ("exit nsSVGOuterSVGFrame::Reflow: size=%d,%d",
                  aDesiredSize.Width(), aDesiredSize.Height()));
  NS_FRAME_SET_TRUNCATION(aStatus, aReflowInput, aDesiredSize);

void nsSVGOuterSVGFrame::DidReflow(nsPresContext* aPresContext,
                                   const ReflowInput* aReflowInput) {
  nsSVGDisplayContainerFrame::DidReflow(aPresContext, aReflowInput);

  // Make sure elements styled by :hover get updated if script/animation moves
  // them under or out from under the pointer:

/* virtual */
void nsSVGOuterSVGFrame::UnionChildOverflow(nsOverflowAreas& aOverflowAreas) {
  // See the comments in Reflow above.

  // WARNING!! Keep this in sync with Reflow above!

  if (!mIsRootContent) {
    nsIFrame* anonKid = PrincipalChildList().FirstChild();
        anonKid->GetVisualOverflowRect() + anonKid->GetPosition());

// container methods

 * Used to paint/hit-test SVG when SVG display lists are disabled.
class nsDisplayOuterSVG final : public nsDisplayItem {
  nsDisplayOuterSVG(nsDisplayListBuilder* aBuilder, nsSVGOuterSVGFrame* aFrame)
      : nsDisplayItem(aBuilder, aFrame) {
  virtual ~nsDisplayOuterSVG() { MOZ_COUNT_DTOR(nsDisplayOuterSVG); }

  virtual void HitTest(nsDisplayListBuilder* aBuilder, const nsRect& aRect,
                       HitTestState* aState,
                       nsTArray<nsIFrame*>* aOutFrames) override;
  virtual void Paint(nsDisplayListBuilder* aBuilder, gfxContext* aCtx) override;

  virtual void ComputeInvalidationRegion(
      nsDisplayListBuilder* aBuilder, const nsDisplayItemGeometry* aGeometry,
      nsRegion* aInvalidRegion) const override;

  nsDisplayItemGeometry* AllocateGeometry(
      nsDisplayListBuilder* aBuilder) override {
    return new nsDisplayItemGenericImageGeometry(this, aBuilder);


void nsDisplayOuterSVG::HitTest(nsDisplayListBuilder* aBuilder,
                                const nsRect& aRect, HitTestState* aState,
                                nsTArray<nsIFrame*>* aOutFrames) {
  nsSVGOuterSVGFrame* outerSVGFrame = static_cast<nsSVGOuterSVGFrame*>(mFrame);

  nsPoint refFrameToContentBox =
      ToReferenceFrame() +

  nsPoint pointRelativeToContentBox =
      nsPoint(aRect.x + aRect.width / 2, aRect.y + aRect.height / 2) -

  gfxPoint svgViewportRelativePoint =
      gfxPoint(pointRelativeToContentBox.x, pointRelativeToContentBox.y) /

  nsSVGOuterSVGAnonChildFrame* anonKid =

  nsIFrame* frame =
      nsSVGUtils::HitTestChildren(anonKid, svgViewportRelativePoint);
  if (frame) {

void nsDisplayOuterSVG::Paint(nsDisplayListBuilder* aBuilder,
                              gfxContext* aContext) {
#if defined(DEBUG) && defined(SVG_DEBUG_PAINT_TIMING)
  PRTime start = PR_Now();

  // Create an SVGAutoRenderState so we can call SetPaintingToWindow on it.
  SVGAutoRenderState state(aContext->GetDrawTarget());

  if (aBuilder->IsPaintingToWindow()) {

  nsRect viewportRect =
      mFrame->GetContentRectRelativeToSelf() + ToReferenceFrame();

  nsRect clipRect = GetPaintRect().Intersect(viewportRect);

  uint32_t appUnitsPerDevPixel = mFrame->PresContext()->AppUnitsPerDevPixel();

  nsIntRect contentAreaDirtyRect =
      (clipRect - viewportRect.TopLeft()).ToOutsidePixels(appUnitsPerDevPixel);

  gfxPoint devPixelOffset = nsLayoutUtils::PointToGfxPoint(
      viewportRect.TopLeft(), appUnitsPerDevPixel);

  imgDrawingParams imgParams(aBuilder->GetImageDecodeFlags());
  // We include the offset of our frame and a scale from device pixels to user
  // units (i.e. CSS px) in the matrix that we pass to our children):
  gfxMatrix tm = nsSVGUtils::GetCSSPxToDevPxMatrix(mFrame) *
  nsSVGUtils::PaintFrameWithEffects(mFrame, *aContext, tm, imgParams,
  nsDisplayItemGenericImageGeometry::UpdateDrawResult(this, imgParams.result);

#if defined(DEBUG) && defined(SVG_DEBUG_PAINT_TIMING)
  PRTime end = PR_Now();
  printf("SVG Paint Timing: %f ms\n", (end - start) / 1000.0);

nsRegion nsSVGOuterSVGFrame::FindInvalidatedForeignObjectFrameChildren(
    nsIFrame* aFrame) {
  nsRegion result;
  if (mForeignObjectHash && mForeignObjectHash->Count()) {
    for (auto it = mForeignObjectHash->Iter(); !it.Done(); it.Next()) {
      result.Or(result, it.Get()->GetKey()->GetInvalidRegion());
  return result;

void nsDisplayOuterSVG::ComputeInvalidationRegion(
    nsDisplayListBuilder* aBuilder, const nsDisplayItemGeometry* aGeometry,
    nsRegion* aInvalidRegion) const {
  nsSVGOuterSVGFrame* frame = static_cast<nsSVGOuterSVGFrame*>(mFrame);

  nsRegion result = frame->GetInvalidRegion();

  nsDisplayItem::ComputeInvalidationRegion(aBuilder, aGeometry, aInvalidRegion);
  aInvalidRegion->Or(*aInvalidRegion, result);

  auto geometry =
      static_cast<const nsDisplayItemGenericImageGeometry*>(aGeometry);

  if (aBuilder->ShouldSyncDecodeImages() &&
      geometry->ShouldInvalidateToSyncDecodeImages()) {
    bool snap;
    aInvalidRegion->Or(*aInvalidRegion, GetBounds(aBuilder, &snap));

nsresult nsSVGOuterSVGFrame::AttributeChanged(int32_t aNameSpaceID,
                                              nsAtom* aAttribute,
                                              int32_t aModType) {
  if (aNameSpaceID == kNameSpaceID_None &&
    if (aAttribute == nsGkAtoms::viewBox ||
        aAttribute == nsGkAtoms::preserveAspectRatio ||
        aAttribute == nsGkAtoms::transform) {
      // make sure our cached transform matrix gets (lazily) updated
      mCanvasTM = nullptr;

          aAttribute == nsGkAtoms::viewBox
              : TRANSFORM_CHANGED);

      if (aAttribute != nsGkAtoms::transform) {

    } else if (aAttribute == nsGkAtoms::width ||
               aAttribute == nsGkAtoms::height) {
      // Don't call ChildrenOnlyTransformChanged() here, since we call it
      // under Reflow if the width/height actually changed.

      nsIFrame* embeddingFrame;
      if (IsRootOfReplacedElementSubDoc(&embeddingFrame) && embeddingFrame) {
        if (DependsOnIntrinsicSize(embeddingFrame)) {
          // Tell embeddingFrame's presShell it needs to be reflowed (which
          // takes care of reflowing us too).
              embeddingFrame, nsIPresShell::eStyleChange, NS_FRAME_IS_DIRTY);
        // else our width and height is overridden - don't reflow anything
      } else {
        // We are not embedded by reference, so our 'width' and 'height'
        // attributes are not overridden - we need to reflow.
        PresShell()->FrameNeedsReflow(this, nsIPresShell::eStyleChange,

  return NS_OK;

bool nsSVGOuterSVGFrame::IsSVGTransformed(Matrix* aOwnTransform,
                                          Matrix* aFromParentTransform) const {
  // Our anonymous child's HasChildrenOnlyTransform() implementation makes sure
  // our children-only transforms are applied to our children.  We only care
  // about transforms that transform our own frame here.

  bool foundTransform = false;

  SVGSVGElement* content = static_cast<SVGSVGElement*>(GetContent());
  SVGAnimatedTransformList* transformList = content->GetAnimatedTransformList();
  if ((transformList && transformList->HasTransform()) ||
      content->GetAnimateMotionTransform()) {
    if (aOwnTransform) {
      *aOwnTransform = gfx::ToMatrix(
          content->PrependLocalTransformsTo(gfxMatrix(), eUserSpaceToParent));
    foundTransform = true;

  return foundTransform;

// painting

void nsSVGOuterSVGFrame::BuildDisplayList(nsDisplayListBuilder* aBuilder,
                                          const nsDisplayListSet& aLists) {
  if (GetStateBits() & NS_FRAME_IS_NONDISPLAY) {

  DisplayBorderBackgroundOutline(aBuilder, aLists);

  // Per-spec, we always clip root-<svg> even when 'overflow' has its initial
  // value of 'visible'. See also the "visual overflow" comments in Reflow.
  DisplayListClipState::AutoSaveRestore autoSR(aBuilder);
  if (mIsRootContent || StyleDisplay()->IsScrollableOverflow()) {
    autoSR.ClipContainingBlockDescendantsToContentBox(aBuilder, this);

  if ((aBuilder->IsForEventDelivery() &&
       NS_SVGDisplayListHitTestingEnabled()) ||
      (!aBuilder->IsForEventDelivery() && NS_SVGDisplayListPaintingEnabled())) {
    nsDisplayList* contentList = aLists.Content();
    nsDisplayListSet set(contentList, contentList, contentList, contentList,
                         contentList, contentList);
    BuildDisplayListForNonBlockChildren(aBuilder, set);
  } else if (IsVisibleForPainting() || !aBuilder->IsForPainting()) {
        MakeDisplayItem<nsDisplayOuterSVG>(aBuilder, this));

// nsISVGSVGFrame methods:

void nsSVGOuterSVGFrame::NotifyViewportOrTransformChanged(uint32_t aFlags) {
             "Unexpected aFlags value");

  // No point in doing anything when were not init'ed yet:
  if (!mViewportInitialized) {

  SVGSVGElement* content = static_cast<SVGSVGElement*>(GetContent());

    if (content->HasViewBoxRect()) {
      // Percentage lengths on children resolve against the viewBox rect so we
      // don't need to notify them of the viewport change, but the viewBox
      // transform will have changed, so we need to notify them of that instead.
    } else if (content->ShouldSynthesizeViewBox()) {
      // In the case of a synthesized viewBox, the synthetic viewBox's rect
      // changes as the viewport changes. As a result we need to maintain the
      aFlags |= TRANSFORM_CHANGED;
    } else if (mCanvasTM && mCanvasTM->IsSingular()) {
      // A width/height of zero will result in us having a singular mCanvasTM
      // even when we don't have a viewBox. So we also want to recompute our
      // mCanvasTM for this width/height change even though we don't have a
      // viewBox.
      aFlags |= TRANSFORM_CHANGED;

  bool haveNonFulLZoomTransformChange = (aFlags & TRANSFORM_CHANGED);

  if (aFlags & FULL_ZOOM_CHANGED) {

  if (aFlags & TRANSFORM_CHANGED) {
    // Make sure our canvas transform matrix gets (lazily) recalculated:
    mCanvasTM = nullptr;

    if (haveNonFulLZoomTransformChange && !(mState & NS_FRAME_IS_NONDISPLAY)) {
      uint32_t flags =
          (mState & NS_FRAME_IN_REFLOW) ? SVGSVGElement::eDuringReflow : 0;


// nsSVGDisplayableFrame methods:

void nsSVGOuterSVGFrame::PaintSVG(gfxContext& aContext,
                                  const gfxMatrix& aTransform,
                                  imgDrawingParams& aImgParams,
                                  const nsIntRect* aDirtyRect) {
      PrincipalChildList().FirstChild()->IsSVGOuterSVGAnonChildFrame() &&
      "We should have a single, anonymous, child");
  nsSVGOuterSVGAnonChildFrame* anonKid =
  anonKid->PaintSVG(aContext, aTransform, aImgParams, aDirtyRect);

SVGBBox nsSVGOuterSVGFrame::GetBBoxContribution(
    const gfx::Matrix& aToBBoxUserspace, uint32_t aFlags) {
      PrincipalChildList().FirstChild()->IsSVGOuterSVGAnonChildFrame() &&
      "We should have a single, anonymous, child");
  // We must defer to our child so that we don't include our
  // content->PrependLocalTransformsTo() transforms.
  nsSVGOuterSVGAnonChildFrame* anonKid =
  return anonKid->GetBBoxContribution(aToBBoxUserspace, aFlags);

// nsSVGContainerFrame methods:

gfxMatrix nsSVGOuterSVGFrame::GetCanvasTM() {
  if (!mCanvasTM) {
    SVGSVGElement* content = static_cast<SVGSVGElement*>(GetContent());

    float devPxPerCSSPx = 1.0f / PresContext()->AppUnitsToFloatCSSPixels(

    gfxMatrix tm = content->PrependLocalTransformsTo(
        gfxMatrix::Scaling(devPxPerCSSPx, devPxPerCSSPx));
    mCanvasTM = new gfxMatrix(tm);
  return *mCanvasTM;

// Implementation helpers

bool nsSVGOuterSVGFrame::IsRootOfReplacedElementSubDoc(
    nsIFrame** aEmbeddingFrame) {
  if (!mContent->GetParent()) {
    // Our content is the document element
    nsCOMPtr<nsIDocShell> docShell = PresContext()->GetDocShell();
    nsCOMPtr<nsPIDOMWindowOuter> window;
    if (docShell) {
      window = docShell->GetWindow();

    if (window) {
      RefPtr<Element> frameElement = window->GetFrameElement();
      if (frameElement &&
          frameElement->IsAnyOfHTMLElements(nsGkAtoms::object, nsGkAtoms::embed,
                                            nsGkAtoms::iframe)) {
        // Our document is inside an HTML 'object', 'embed' or 'iframe' element
        if (aEmbeddingFrame) {
          *aEmbeddingFrame = frameElement->GetPrimaryFrame();
          NS_ASSERTION(*aEmbeddingFrame, "Yikes, no embedding frame!");
        return true;
  if (aEmbeddingFrame) {
    *aEmbeddingFrame = nullptr;
  return false;

bool nsSVGOuterSVGFrame::IsRootOfImage() {
  if (!mContent->GetParent()) {
    // Our content is the document element
    Document* doc = mContent->GetUncomposedDoc();
    if (doc && doc->IsBeingUsedAsImage()) {
      // Our document is being used as an image
      return true;

  return false;

bool nsSVGOuterSVGFrame::VerticalScrollbarNotNeeded() const {
  const nsSVGLength2& height =
  return height.IsPercentage() && height.GetBaseValInSpecifiedUnits() <= 100;

void nsSVGOuterSVGFrame::AppendDirectlyOwnedAnonBoxes(
    nsTArray<OwnedAnonBox>& aResult) {
  nsIFrame* anonKid = PrincipalChildList().FirstChild();

// Implementation of nsSVGOuterSVGAnonChildFrame

nsContainerFrame* NS_NewSVGOuterSVGAnonChildFrame(nsIPresShell* aPresShell,
                                                  ComputedStyle* aStyle) {
  return new (aPresShell)
      nsSVGOuterSVGAnonChildFrame(aStyle, aPresShell->GetPresContext());


#ifdef DEBUG
void nsSVGOuterSVGAnonChildFrame::Init(nsIContent* aContent,
                                       nsContainerFrame* aParent,
                                       nsIFrame* aPrevInFlow) {
  MOZ_ASSERT(aParent->IsSVGOuterSVGFrame(), "Unexpected parent");
  nsSVGDisplayContainerFrame::Init(aContent, aParent, aPrevInFlow);

void nsSVGOuterSVGAnonChildFrame::BuildDisplayList(
    nsDisplayListBuilder* aBuilder, const nsDisplayListSet& aLists) {
  // Wrap our contents into an nsDisplaySVGWrapper.
  // We wrap this frame instead of the nsSVGOuterSVGFrame so that the wrapper
  // doesn't contain the <svg> element's CSS styles, like backgrounds or
  // borders. Creating the nsDisplaySVGWrapper here also means that it'll be
  // inside the nsDisplayTransform for our viewbox transform. The
  // nsDisplaySVGWrapper's reference frame is this frame, because this frame
  // always returns true from IsSVGTransformed.
  nsDisplayList newList;
  nsDisplayListSet set(&newList, &newList, &newList, &newList, &newList,
  BuildDisplayListForNonBlockChildren(aBuilder, set);
      MakeDisplayItem<nsDisplaySVGWrapper>(aBuilder, this, &newList));

static Matrix ComputeOuterSVGAnonChildFrameTransform(
    const nsSVGOuterSVGAnonChildFrame* aFrame) {
  // Our elements 'transform' attribute is applied to our nsSVGOuterSVGFrame
  // parent, and the element's children-only transforms are applied to us, the
  // anonymous child frame. Since we are the child frame, we apply the
  // children-only transforms as if they are our own transform.
  SVGSVGElement* content = static_cast<SVGSVGElement*>(aFrame->GetContent());

  if (!content->HasChildrenOnlyTransform()) {
    return Matrix();

  // Outer-<svg> doesn't use x/y, so we can pass eChildToUserSpace here.
  gfxMatrix ownMatrix =
      content->PrependLocalTransformsTo(gfxMatrix(), eChildToUserSpace);

  if (ownMatrix.HasNonTranslation()) {
    // viewBox, currentScale and currentTranslate should only produce a
    // rectilinear transform.
               "Non-rectilinear transform will break the following logic");

    // The nsDisplayTransform code will apply this transform to our frame,
    // including to our frame position.  We don't want our frame position to
    // be scaled though, so we need to correct for that in the transform.
    // XXX Yeah, this is a bit hacky.
    CSSPoint pos = CSSPixel::FromAppUnits(aFrame->GetPosition());
    CSSPoint scaledPos = CSSPoint(ownMatrix._11 * pos.x, ownMatrix._22 * pos.y);
    CSSPoint deltaPos = scaledPos - pos;
    ownMatrix *= gfxMatrix::Translation(-deltaPos.x, -deltaPos.y);

  return gfx::ToMatrix(ownMatrix);

// We want this frame to be a reference frame. An easy way to achieve that is
// to always return true from this method, even for identity transforms.
// This frame being a reference frame ensures that the offset between this
// <svg> element and the parent reference frame is completely absorbed by the
// nsDisplayTransform that's created for this frame, and that this offset does
// not affect our descendants' transforms. Consequently, if the <svg> element
// moves, e.g. during scrolling, the transform matrices of our contents are
// unaffected. This simplifies invalidation.
bool nsSVGOuterSVGAnonChildFrame::IsSVGTransformed(
    Matrix* aOwnTransform, Matrix* aFromParentTransform) const {
  if (aOwnTransform) {
    *aOwnTransform = ComputeOuterSVGAnonChildFrameTransform(this);

  return true;