gfxMatrix
nsSVGGraphicElement::PrependLocalTransformsTo(const gfxMatrix &aMatrix,
                                              TransformTypes aWhich) const
{
  NS_ABORT_IF_FALSE(aWhich != eChildToUserSpace || aMatrix.IsIdentity(),
                    "Skipping eUserSpaceToParent transforms makes no sense");

  gfxMatrix result(aMatrix);

  if (aWhich == eChildToUserSpace) {
    // We don't have anything to prepend.
    // eChildToUserSpace is not the common case, which is why we return
    // 'result' to benefit from NRVO rather than returning aMatrix before
    // creating 'result'.
    return result;
  }

  NS_ABORT_IF_FALSE(aWhich == eAllTransforms || aWhich == eUserSpaceToParent,
                    "Unknown TransformTypes");

  // animateMotion's resulting transform is supposed to apply *on top of*
  // any transformations from the |transform| attribute. So since we're
  // PRE-multiplying, we need to apply the animateMotion transform *first*.
  if (mAnimateMotionTransform) {
    result.PreMultiply(*mAnimateMotionTransform);
  }

  if (mTransforms) {
    result.PreMultiply(mTransforms->GetAnimValue().GetConsolidationMatrix());
  }

  return result;
}
/* virtual */ gfxMatrix
SVGUseElement::PrependLocalTransformsTo(const gfxMatrix &aMatrix,
                                        TransformTypes aWhich) const
{
  NS_ABORT_IF_FALSE(aWhich != eChildToUserSpace || aMatrix.IsIdentity(),
                    "Skipping eUserSpaceToParent transforms makes no sense");

  // 'transform' attribute:
  gfxMatrix fromUserSpace =
    SVGUseElementBase::PrependLocalTransformsTo(aMatrix, aWhich);
  if (aWhich == eUserSpaceToParent) {
    return fromUserSpace;
  }
  // our 'x' and 'y' attributes:
  float x, y;
  const_cast<SVGUseElement*>(this)->GetAnimatedLengthValues(&x, &y, nullptr);
  gfxMatrix toUserSpace = gfxMatrix().Translate(gfxPoint(x, y));
  if (aWhich == eChildToUserSpace) {
    return toUserSpace;
  }
  NS_ABORT_IF_FALSE(aWhich == eAllTransforms, "Unknown TransformTypes");
  return toUserSpace * fromUserSpace;
}