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/* -*- 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,
#include "DOMIntersectionObserver.h"
#include "nsCSSPropertyID.h"
#include "nsIFrame.h"
#include "nsContainerFrame.h"
#include "nsIScrollableFrame.h"
#include "nsContentUtils.h"
#include "nsLayoutUtils.h"
#include "nsRefreshDriver.h"
#include "mozilla/PresShell.h"
#include "mozilla/StaticPrefs_dom.h"
#include "mozilla/StaticPrefs_layout.h"
#include "mozilla/ServoBindings.h"
#include "mozilla/dom/BrowserChild.h"
#include "mozilla/dom/BrowsingContext.h"
#include "mozilla/dom/DocumentInlines.h"
#include "mozilla/dom/HTMLImageElement.h"
#include "mozilla/dom/HTMLIFrameElement.h"
#include "Units.h"
namespace mozilla::dom {
NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(DOMIntersectionObserverEntry)
NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
NS_INTERFACE_MAP_ENTRY(nsISupports)
NS_INTERFACE_MAP_END
NS_IMPL_CYCLE_COLLECTING_ADDREF(DOMIntersectionObserverEntry)
NS_IMPL_CYCLE_COLLECTING_RELEASE(DOMIntersectionObserverEntry)
NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(DOMIntersectionObserverEntry, mOwner,
mRootBounds, mBoundingClientRect,
mIntersectionRect, mTarget)
NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(DOMIntersectionObserver)
NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
NS_INTERFACE_MAP_ENTRY(nsISupports)
NS_INTERFACE_MAP_ENTRY(DOMIntersectionObserver)
NS_INTERFACE_MAP_END
NS_IMPL_CYCLE_COLLECTING_ADDREF(DOMIntersectionObserver)
NS_IMPL_CYCLE_COLLECTING_RELEASE(DOMIntersectionObserver)
NS_IMPL_CYCLE_COLLECTION_CLASS(DOMIntersectionObserver)
NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(DOMIntersectionObserver)
NS_IMPL_CYCLE_COLLECTION_TRACE_PRESERVED_WRAPPER
NS_IMPL_CYCLE_COLLECTION_TRACE_END
NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(DOMIntersectionObserver)
NS_IMPL_CYCLE_COLLECTION_UNLINK_PRESERVED_WRAPPER
tmp->Disconnect();
NS_IMPL_CYCLE_COLLECTION_UNLINK(mOwner)
NS_IMPL_CYCLE_COLLECTION_UNLINK(mDocument)
if (tmp->mCallback.is<RefPtr<dom::IntersectionCallback>>()) {
ImplCycleCollectionUnlink(
tmp->mCallback.as<RefPtr<dom::IntersectionCallback>>());
}
NS_IMPL_CYCLE_COLLECTION_UNLINK(mRoot)
NS_IMPL_CYCLE_COLLECTION_UNLINK(mQueuedEntries)
NS_IMPL_CYCLE_COLLECTION_UNLINK_END
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(DOMIntersectionObserver)
NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mOwner)
NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mDocument)
if (tmp->mCallback.is<RefPtr<dom::IntersectionCallback>>()) {
ImplCycleCollectionTraverse(
cb, tmp->mCallback.as<RefPtr<dom::IntersectionCallback>>(), "mCallback",
0);
}
NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mRoot)
NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mQueuedEntries)
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
DOMIntersectionObserver::DOMIntersectionObserver(
already_AddRefed<nsPIDOMWindowInner>&& aOwner,
dom::IntersectionCallback& aCb)
: mOwner(aOwner),
mDocument(mOwner->GetExtantDoc()),
mCallback(RefPtr<dom::IntersectionCallback>(&aCb)) {}
already_AddRefed<DOMIntersectionObserver> DOMIntersectionObserver::Constructor(
const GlobalObject& aGlobal, dom::IntersectionCallback& aCb,
ErrorResult& aRv) {
return Constructor(aGlobal, aCb, IntersectionObserverInit(), aRv);
}
already_AddRefed<DOMIntersectionObserver> DOMIntersectionObserver::Constructor(
const GlobalObject& aGlobal, dom::IntersectionCallback& aCb,
const IntersectionObserverInit& aOptions, ErrorResult& aRv) {
nsCOMPtr<nsPIDOMWindowInner> window =
do_QueryInterface(aGlobal.GetAsSupports());
if (!window) {
aRv.Throw(NS_ERROR_FAILURE);
return nullptr;
}
RefPtr<DOMIntersectionObserver> observer =
new DOMIntersectionObserver(window.forget(), aCb);
if (!aOptions.mRoot.IsNull()) {
if (aOptions.mRoot.Value().IsElement()) {
observer->mRoot = aOptions.mRoot.Value().GetAsElement();
} else {
MOZ_ASSERT(aOptions.mRoot.Value().IsDocument());
observer->mRoot = aOptions.mRoot.Value().GetAsDocument();
}
}
if (!observer->SetRootMargin(aOptions.mRootMargin)) {
aRv.ThrowSyntaxError("rootMargin must be specified in pixels or percent.");
return nullptr;
}
if (aOptions.mThreshold.IsDoubleSequence()) {
const Sequence<double>& thresholds =
aOptions.mThreshold.GetAsDoubleSequence();
observer->mThresholds.SetCapacity(thresholds.Length());
for (const auto& thresh : thresholds) {
if (thresh < 0.0 || thresh > 1.0) {
aRv.ThrowRangeError<dom::MSG_THRESHOLD_RANGE_ERROR>();
return nullptr;
}
observer->mThresholds.AppendElement(thresh);
}
observer->mThresholds.Sort();
if (observer->mThresholds.IsEmpty()) {
observer->mThresholds.AppendElement(0.0);
}
} else {
double thresh = aOptions.mThreshold.GetAsDouble();
if (thresh < 0.0 || thresh > 1.0) {
aRv.ThrowRangeError<dom::MSG_THRESHOLD_RANGE_ERROR>();
return nullptr;
}
observer->mThresholds.AppendElement(thresh);
}
return observer.forget();
}
static void LazyLoadCallback(
const Sequence<OwningNonNull<DOMIntersectionObserverEntry>>& aEntries) {
for (const auto& entry : aEntries) {
Element* target = entry->Target();
if (entry->IsIntersecting()) {
if (auto* image = HTMLImageElement::FromNode(target)) {
image->StopLazyLoading(HTMLImageElement::StartLoading::Yes);
} else if (auto* iframe = HTMLIFrameElement::FromNode(target)) {
iframe->StopLazyLoading();
} else {
MOZ_ASSERT_UNREACHABLE(
"Only <img> and <iframe> should be observed by lazy load observer");
}
}
}
}
static LengthPercentage PrefMargin(float aValue, bool aIsPercentage) {
return aIsPercentage ? LengthPercentage::FromPercentage(aValue / 100.0f)
: LengthPercentage::FromPixels(aValue);
}
DOMIntersectionObserver::DOMIntersectionObserver(Document& aDocument,
NativeCallback aCallback)
: mOwner(aDocument.GetInnerWindow()),
mDocument(&aDocument),
mCallback(aCallback) {}
already_AddRefed<DOMIntersectionObserver>
DOMIntersectionObserver::CreateLazyLoadObserver(Document& aDocument) {
RefPtr<DOMIntersectionObserver> observer =
new DOMIntersectionObserver(aDocument, LazyLoadCallback);
observer->mThresholds.AppendElement(0.0f);
#define SET_MARGIN(side_, side_lower_) \
observer->mRootMargin.Get(eSide##side_) = PrefMargin( \
StaticPrefs::dom_image_lazy_loading_root_margin_##side_lower_(), \
StaticPrefs:: \
dom_image_lazy_loading_root_margin_##side_lower_##_percentage());
SET_MARGIN(Top, top);
SET_MARGIN(Right, right);
SET_MARGIN(Bottom, bottom);
SET_MARGIN(Left, left);
#undef SET_MARGIN
return observer.forget();
}
bool DOMIntersectionObserver::SetRootMargin(const nsACString& aString) {
return Servo_IntersectionObserverRootMargin_Parse(&aString, &mRootMargin);
}
nsISupports* DOMIntersectionObserver::GetParentObject() const { return mOwner; }
void DOMIntersectionObserver::GetRootMargin(nsACString& aRetVal) {
Servo_IntersectionObserverRootMargin_ToString(&mRootMargin, &aRetVal);
}
void DOMIntersectionObserver::GetThresholds(nsTArray<double>& aRetVal) {
aRetVal = mThresholds.Clone();
}
void DOMIntersectionObserver::Observe(Element& aTarget) {
if (!mObservationTargetSet.EnsureInserted(&aTarget)) {
return;
}
aTarget.RegisterIntersectionObserver(this);
mObservationTargets.AppendElement(&aTarget);
MOZ_ASSERT(mObservationTargets.Length() == mObservationTargetSet.Count());
Connect();
if (mDocument) {
if (nsPresContext* pc = mDocument->GetPresContext()) {
pc->RefreshDriver()->EnsureIntersectionObservationsUpdateHappens();
}
}
}
void DOMIntersectionObserver::Unobserve(Element& aTarget) {
if (!mObservationTargetSet.EnsureRemoved(&aTarget)) {
return;
}
mObservationTargets.RemoveElement(&aTarget);
aTarget.UnregisterIntersectionObserver(this);
MOZ_ASSERT(mObservationTargets.Length() == mObservationTargetSet.Count());
if (mObservationTargets.IsEmpty()) {
Disconnect();
}
}
void DOMIntersectionObserver::UnlinkTarget(Element& aTarget) {
mObservationTargets.RemoveElement(&aTarget);
mObservationTargetSet.Remove(&aTarget);
if (mObservationTargets.IsEmpty()) {
Disconnect();
}
}
void DOMIntersectionObserver::Connect() {
if (mConnected) {
return;
}
mConnected = true;
if (mDocument) {
mDocument->AddIntersectionObserver(this);
}
}
void DOMIntersectionObserver::Disconnect() {
if (!mConnected) {
return;
}
mConnected = false;
for (Element* target : mObservationTargets) {
target->UnregisterIntersectionObserver(this);
}
mObservationTargets.Clear();
mObservationTargetSet.Clear();
if (mDocument) {
mDocument->RemoveIntersectionObserver(this);
}
}
void DOMIntersectionObserver::TakeRecords(
nsTArray<RefPtr<DOMIntersectionObserverEntry>>& aRetVal) {
aRetVal = std::move(mQueuedEntries);
}
enum class BrowsingContextOrigin { Similar, Different };
// NOTE(emilio): Checking docgroup as per discussion in:
static BrowsingContextOrigin SimilarOrigin(const Element& aTarget,
const nsINode* aRoot) {
if (!aRoot) {
return BrowsingContextOrigin::Different;
}
return aTarget.OwnerDoc()->GetDocGroup() == aRoot->OwnerDoc()->GetDocGroup()
? BrowsingContextOrigin::Similar
: BrowsingContextOrigin::Different;
}
// NOTE: This returns nullptr if |aDocument| is in another process from the top
// level content document.
static const Document* GetTopLevelContentDocumentInThisProcess(
const Document& aDocument) {
auto* wc = aDocument.GetTopLevelWindowContext();
return wc ? wc->GetExtantDoc() : nullptr;
}
//
// TODO(emilio): Proof of this being equivalent to the spec welcome, seems
// reasonably close.
//
// Also, it's unclear to me why the spec talks about browsing context while
// discarding observations of targets of different documents.
//
// Both aRootBounds and the return value are relative to
// nsLayoutUtils::GetContainingBlockForClientRect(aRoot).
//
// In case of out-of-process document, aRemoteDocumentVisibleRect is a rectangle
// in the out-of-process document's coordinate system.
static Maybe<nsRect> ComputeTheIntersection(
nsIFrame* aTarget, nsIFrame* aRoot, const nsRect& aRootBounds,
const Maybe<nsRect>& aRemoteDocumentVisibleRect,
DOMIntersectionObserver::IsForProximityToViewport
aIsForProximityToViewport) {
nsIFrame* target = aTarget;
// 1. Let intersectionRect be the result of running the
// getBoundingClientRect() algorithm on the target.
//
// `intersectionRect` is kept relative to `target` during the loop.
auto inflowRect = nsLayoutUtils::GetAllInFlowRectsUnion(
target, target, nsLayoutUtils::RECTS_ACCOUNT_FOR_TRANSFORMS);
// For content-visibility, we need to observe the overflow clip edge,
if (aIsForProximityToViewport ==
DOMIntersectionObserver::IsForProximityToViewport::Yes) {
const auto& disp = *target->StyleDisplay();
auto clipAxes = target->ShouldApplyOverflowClipping(&disp);
if (clipAxes != PhysicalAxes::None) {
inflowRect = OverflowAreas::GetOverflowClipRect(
inflowRect, inflowRect, clipAxes,
target->OverflowClipMargin(clipAxes));
}
}
Maybe<nsRect> intersectionRect = Some(inflowRect);
// 2. Let container be the containing block of the target.
// (We go through the parent chain and only look at scroll frames)
//
// FIXME(emilio): Spec uses containing blocks, we use scroll frames, but we
// only apply overflow-clipping, not clip-path, so it's ~fine. We do need to
// apply clip-path.
//
// 3. While container is not the intersection root:
nsIFrame* containerFrame =
nsLayoutUtils::GetCrossDocParentFrameInProcess(target);
while (containerFrame && containerFrame != aRoot) {
// FIXME(emilio): What about other scroll frames that inherit from
// nsHTMLScrollFrame but have a different type, like nsListControlFrame?
// This looks bogus in that case, but different bug.
if (nsIScrollableFrame* scrollFrame = do_QueryFrame(containerFrame)) {
if (containerFrame->GetParent() == aRoot && !aRoot->GetParent()) {
// This is subtle: if we're computing the intersection against the
// viewport (the root frame), and this is its scroll frame, we really
// want to skip this intersection (because we want to account for the
// root margin, which is already in aRootBounds).
break;
}
nsRect subFrameRect = scrollFrame->GetScrollPortRect();
// 3.1 Map intersectionRect to the coordinate space of container.
nsRect intersectionRectRelativeToContainer =
nsLayoutUtils::TransformFrameRectToAncestor(
target, intersectionRect.value(), containerFrame);
// 3.2 If container has overflow clipping or a css clip-path property,
// update intersectionRect by applying container's clip.
//
// 3.3 is handled, looks like, by this same clipping, given the root
// scroll-frame cannot escape the viewport, probably?
intersectionRect =
intersectionRectRelativeToContainer.EdgeInclusiveIntersection(
subFrameRect);
if (!intersectionRect) {
return Nothing();
}
target = containerFrame;
} else {
const auto& disp = *containerFrame->StyleDisplay();
auto clipAxes = containerFrame->ShouldApplyOverflowClipping(&disp);
// 3.2 TODO: Apply clip-path.
if (clipAxes != PhysicalAxes::None) {
// 3.1 Map intersectionRect to the coordinate space of container.
const nsRect intersectionRectRelativeToContainer =
nsLayoutUtils::TransformFrameRectToAncestor(
target, intersectionRect.value(), containerFrame);
const nsRect clipRect = OverflowAreas::GetOverflowClipRect(
intersectionRectRelativeToContainer,
containerFrame->GetRectRelativeToSelf(), clipAxes,
containerFrame->OverflowClipMargin(clipAxes));
intersectionRect =
intersectionRectRelativeToContainer.EdgeInclusiveIntersection(
clipRect);
if (!intersectionRect) {
return Nothing();
}
target = containerFrame;
}
}
containerFrame =
nsLayoutUtils::GetCrossDocParentFrameInProcess(containerFrame);
}
MOZ_ASSERT(intersectionRect);
// 4. Map intersectionRect to the coordinate space of the intersection root.
nsRect intersectionRectRelativeToRoot =
nsLayoutUtils::TransformFrameRectToAncestor(
target, intersectionRect.value(),
nsLayoutUtils::GetContainingBlockForClientRect(aRoot));
// 5.Update intersectionRect by intersecting it with the root intersection
// rectangle.
intersectionRect =
intersectionRectRelativeToRoot.EdgeInclusiveIntersection(aRootBounds);
if (intersectionRect.isNothing()) {
return Nothing();
}
// 6. Map intersectionRect to the coordinate space of the viewport of the
// Document containing the target.
//
// FIXME(emilio): I think this may not be correct if the root is explicit
// and in the same document, since then the rectangle may not be relative to
// the viewport already (but it's in the same document).
nsRect rect = intersectionRect.value();
if (aTarget->PresContext() != aRoot->PresContext()) {
if (nsIFrame* rootScrollFrame =
aTarget->PresShell()->GetRootScrollFrame()) {
nsLayoutUtils::TransformRect(aRoot, rootScrollFrame, rect);
}
}
// In out-of-process iframes we need to take an intersection with the remote
// document visible rect which was already clipped by ancestor document's
// viewports.
if (aRemoteDocumentVisibleRect) {
MOZ_ASSERT(aRoot->PresContext()->IsRootContentDocumentInProcess() &&
!aRoot->PresContext()->IsRootContentDocumentCrossProcess());
intersectionRect =
rect.EdgeInclusiveIntersection(*aRemoteDocumentVisibleRect);
if (intersectionRect.isNothing()) {
return Nothing();
}
rect = intersectionRect.value();
}
return Some(rect);
}
struct OopIframeMetrics {
nsIFrame* mInProcessRootFrame = nullptr;
nsRect mInProcessRootRect;
nsRect mRemoteDocumentVisibleRect;
};
static Maybe<OopIframeMetrics> GetOopIframeMetrics(
const Document& aDocument, const Document* aRootDocument) {
const Document* rootDoc =
nsContentUtils::GetInProcessSubtreeRootDocument(&aDocument);
MOZ_ASSERT(rootDoc);
if (rootDoc->IsTopLevelContentDocument()) {
return Nothing();
}
if (aRootDocument &&
rootDoc ==
nsContentUtils::GetInProcessSubtreeRootDocument(aRootDocument)) {
// aRootDoc, if non-null, is either the implicit root
// (top-level-content-document) or a same-origin document passed explicitly.
//
// In the former case, we should've returned above if there are no iframes
// in between. This condition handles the explicit, same-origin root
// document, when both are embedded in an OOP iframe.
return Nothing();
}
PresShell* rootPresShell = rootDoc->GetPresShell();
if (!rootPresShell || rootPresShell->IsDestroying()) {
return Some(OopIframeMetrics{});
}
nsIFrame* inProcessRootFrame = rootPresShell->GetRootFrame();
if (!inProcessRootFrame) {
return Some(OopIframeMetrics{});
}
BrowserChild* browserChild = BrowserChild::GetFrom(rootDoc->GetDocShell());
if (!browserChild) {
return Some(OopIframeMetrics{});
}
if (MOZ_UNLIKELY(browserChild->IsTopLevel())) {
// have a top-level BrowserChild for a document that isn't a top-level
// content document?
MOZ_ASSERT_UNREACHABLE("Top level BrowserChild w/ non-top level Document?");
return Nothing();
}
nsRect inProcessRootRect;
if (nsIScrollableFrame* scrollFrame =
rootPresShell->GetRootScrollFrameAsScrollable()) {
inProcessRootRect = scrollFrame->GetScrollPortRect();
}
Maybe<LayoutDeviceRect> remoteDocumentVisibleRect =
browserChild->GetTopLevelViewportVisibleRectInSelfCoords();
if (!remoteDocumentVisibleRect) {
return Some(OopIframeMetrics{});
}
return Some(OopIframeMetrics{
inProcessRootFrame,
inProcessRootRect,
LayoutDeviceRect::ToAppUnits(
*remoteDocumentVisibleRect,
rootPresShell->GetPresContext()->AppUnitsPerDevPixel()),
});
}
// step 2.1
IntersectionInput DOMIntersectionObserver::ComputeInput(
const Document& aDocument, const nsINode* aRoot,
const StyleRect<LengthPercentage>* aRootMargin) {
// 1 - Let rootBounds be observer's root intersection rectangle.
// ... but since the intersection rectangle depends on the target, we defer
// the inflation until later.
// NOTE: |rootRect| and |rootFrame| will be root in the same process. In
// out-of-process iframes, they are NOT root ones of the top level content
// document.
nsRect rootRect;
nsIFrame* rootFrame = nullptr;
const nsINode* root = aRoot;
const bool isImplicitRoot = !aRoot;
Maybe<nsRect> remoteDocumentVisibleRect;
if (aRoot && aRoot->IsElement()) {
if ((rootFrame = aRoot->AsElement()->GetPrimaryFrame())) {
nsRect rootRectRelativeToRootFrame;
if (nsIScrollableFrame* scrollFrame = do_QueryFrame(rootFrame)) {
// rootRectRelativeToRootFrame should be the content rect of rootFrame,
// not including the scrollbars.
rootRectRelativeToRootFrame = scrollFrame->GetScrollPortRect();
} else {
// rootRectRelativeToRootFrame should be the border rect of rootFrame.
rootRectRelativeToRootFrame = rootFrame->GetRectRelativeToSelf();
}
nsIFrame* containingBlock =
nsLayoutUtils::GetContainingBlockForClientRect(rootFrame);
rootRect = nsLayoutUtils::TransformFrameRectToAncestor(
rootFrame, rootRectRelativeToRootFrame, containingBlock);
}
} else {
MOZ_ASSERT(!aRoot || aRoot->IsDocument());
const Document* rootDocument =
aRoot ? aRoot->AsDocument()
: GetTopLevelContentDocumentInThisProcess(aDocument);
root = rootDocument;
if (rootDocument) {
// We're in the same process as the root document, though note that there
// could be an out-of-process iframe in between us and the root. Grab the
// root frame and the root rect.
//
// Note that the root rect is always good (we assume no DPI changes in
// between the two documents, and we don't need to convert coordinates).
//
// The root frame however we may need to tweak in the block below, if
// there's any OOP iframe in between `rootDocument` and `aDocument`, to
// handle the OOP iframe positions.
if (PresShell* presShell = rootDocument->GetPresShell()) {
rootFrame = presShell->GetRootFrame();
// We use the root scrollable frame's scroll port to account the
// scrollbars in rootRect, if needed.
if (nsIScrollableFrame* scrollFrame =
presShell->GetRootScrollFrameAsScrollable()) {
rootRect = scrollFrame->GetScrollPortRect();
} else if (rootFrame) {
rootRect = rootFrame->GetRectRelativeToSelf();
}
}
}
if (Maybe<OopIframeMetrics> metrics =
GetOopIframeMetrics(aDocument, rootDocument)) {
rootFrame = metrics->mInProcessRootFrame;
if (!rootDocument) {
rootRect = metrics->mInProcessRootRect;
}
remoteDocumentVisibleRect = Some(metrics->mRemoteDocumentVisibleRect);
}
}
nsMargin rootMargin; // This root margin is NOT applied in `implicit root`
// case, e.g. in out-of-process iframes.
if (aRootMargin) {
for (const auto side : mozilla::AllPhysicalSides()) {
nscoord basis = side == eSideTop || side == eSideBottom
? rootRect.Height()
: rootRect.Width();
rootMargin.Side(side) = aRootMargin->Get(side).Resolve(
basis, static_cast<nscoord (*)(float)>(NSToCoordRoundWithClamp));
}
}
return {isImplicitRoot, root, rootFrame,
rootRect, rootMargin, remoteDocumentVisibleRect};
}
// (steps 2.1 - 2.5)
IntersectionOutput DOMIntersectionObserver::Intersect(
const IntersectionInput& aInput, const Element& aTarget,
IsForProximityToViewport aIsForProximityToViewport) {
const bool isSimilarOrigin = SimilarOrigin(aTarget, aInput.mRootNode) ==
BrowsingContextOrigin::Similar;
nsIFrame* targetFrame = aTarget.GetPrimaryFrame();
if (!targetFrame || !aInput.mRootFrame) {
return {isSimilarOrigin};
}
// "From the perspective of an IntersectionObserver, the skipped contents
// of an element are never intersecting the intersection root. This is
// true even if both the root and the target elements are in the skipped
// contents."
//
// Skip the intersection if the element is hidden, unless this is the
// specifically to determine the proximity to the viewport for
// `content-visibility: auto` elements.
if (aIsForProximityToViewport == IsForProximityToViewport::No &&
targetFrame->IsHiddenByContentVisibilityOnAnyAncestor()) {
return {isSimilarOrigin};
}
// 2.2. If the intersection root is not the implicit root, and target is
// not in the same Document as the intersection root, skip to step 11.
if (!aInput.mIsImplicitRoot &&
aInput.mRootNode->OwnerDoc() != aTarget.OwnerDoc()) {
return {isSimilarOrigin};
}
// 2.3. If the intersection root is an element and target is not a descendant
// of the intersection root in the containing block chain, skip to step 11.
//
// NOTE(emilio): We also do this if target is the implicit root, pending
// clarification in
if (aInput.mRootFrame == targetFrame ||
!nsLayoutUtils::IsAncestorFrameCrossDocInProcess(aInput.mRootFrame,
targetFrame)) {
return {isSimilarOrigin};
}
nsRect rootBounds = aInput.mRootRect;
if (isSimilarOrigin) {
rootBounds.Inflate(aInput.mRootMargin);
}
// 2.4. Set targetRect to the DOMRectReadOnly obtained by running the
// getBoundingClientRect() algorithm on target.
nsRect targetRect = targetFrame->GetBoundingClientRect();
// For content-visibility, we need to observe the overflow clip edge,
if (aIsForProximityToViewport == IsForProximityToViewport::Yes) {
const auto& disp = *targetFrame->StyleDisplay();
auto clipAxes = targetFrame->ShouldApplyOverflowClipping(&disp);
if (clipAxes != PhysicalAxes::None) {
targetRect = OverflowAreas::GetOverflowClipRect(
targetRect, targetRect, clipAxes,
targetFrame->OverflowClipMargin(clipAxes));
}
}
// 2.5. Let intersectionRect be the result of running the compute the
// intersection algorithm on target and observer’s intersection root.
Maybe<nsRect> intersectionRect = ComputeTheIntersection(
targetFrame, aInput.mRootFrame, rootBounds,
aInput.mRemoteDocumentVisibleRect, aIsForProximityToViewport);
return {isSimilarOrigin, rootBounds, targetRect, intersectionRect};
}
IntersectionOutput DOMIntersectionObserver::Intersect(
const IntersectionInput& aInput, const nsRect& aTargetRect) {
nsRect rootBounds = aInput.mRootRect;
rootBounds.Inflate(aInput.mRootMargin);
auto intersectionRect =
aInput.mRootRect.EdgeInclusiveIntersection(aTargetRect);
if (intersectionRect && aInput.mRemoteDocumentVisibleRect) {
intersectionRect = intersectionRect->EdgeInclusiveIntersection(
*aInput.mRemoteDocumentVisibleRect);
}
return {true, rootBounds, aTargetRect, intersectionRect};
}
// (step 2)
void DOMIntersectionObserver::Update(Document& aDocument,
DOMHighResTimeStamp time) {
auto input = ComputeInput(aDocument, mRoot, &mRootMargin);
// 2. For each target in observer’s internal [[ObservationTargets]] slot,
// processed in the same order that observe() was called on each target:
for (Element* target : mObservationTargets) {
// 2.1 - 2.4.
IntersectionOutput output = Intersect(input, *target);
// 2.5. Let targetArea be targetRect’s area.
int64_t targetArea = (int64_t)output.mTargetRect.Width() *
(int64_t)output.mTargetRect.Height();
// 2.6. Let intersectionArea be intersectionRect’s area.
int64_t intersectionArea =
!output.mIntersectionRect
? 0
: (int64_t)output.mIntersectionRect->Width() *
(int64_t)output.mIntersectionRect->Height();
// 2.7. Let isIntersecting be true if targetRect and rootBounds intersect or
// are edge-adjacent, even if the intersection has zero area (because
// rootBounds or targetRect have zero area); otherwise, let isIntersecting
// be false.
const bool isIntersecting = output.Intersects();
// 2.8. If targetArea is non-zero, let intersectionRatio be intersectionArea
// divided by targetArea. Otherwise, let intersectionRatio be 1 if
// isIntersecting is true, or 0 if isIntersecting is false.
double intersectionRatio;
if (targetArea > 0.0) {
intersectionRatio =
std::min((double)intersectionArea / (double)targetArea, 1.0);
} else {
intersectionRatio = isIntersecting ? 1.0 : 0.0;
}
// 2.9 Let thresholdIndex be the index of the first entry in
// observer.thresholds whose value is greater than intersectionRatio, or the
// length of observer.thresholds if intersectionRatio is greater than or
// equal to the last entry in observer.thresholds.
int32_t thresholdIndex = -1;
// If not intersecting, we can just shortcut, as we know that the thresholds
// are always between 0 and 1.
if (isIntersecting) {
thresholdIndex = mThresholds.IndexOfFirstElementGt(intersectionRatio);
if (thresholdIndex == 0) {
// Per the spec, we should leave threshold at 0 and distinguish between
// "less than all thresholds and intersecting" and "not intersecting"
// (queuing observer entries as both cases come to pass). However,
// neither Chrome nor the WPT tests expect this behavior, so treat these
// two cases as one.
//
// this.
thresholdIndex = -1;
}
}
// Steps 2.10 - 2.15.
if (target->UpdateIntersectionObservation(this, thresholdIndex)) {
// why we use thresholdIndex > 0 rather than isIntersecting for the
// entry's isIntersecting value.
QueueIntersectionObserverEntry(
target, time,
output.mIsSimilarOrigin ? Some(output.mRootBounds) : Nothing(),
output.mTargetRect, output.mIntersectionRect, thresholdIndex > 0,
intersectionRatio);
}
}
}
void DOMIntersectionObserver::QueueIntersectionObserverEntry(
Element* aTarget, DOMHighResTimeStamp time, const Maybe<nsRect>& aRootRect,
const nsRect& aTargetRect, const Maybe<nsRect>& aIntersectionRect,
bool aIsIntersecting, double aIntersectionRatio) {
RefPtr<DOMRect> rootBounds;
if (aRootRect.isSome()) {
rootBounds = new DOMRect(mOwner);
rootBounds->SetLayoutRect(aRootRect.value());
}
RefPtr<DOMRect> boundingClientRect = new DOMRect(mOwner);
boundingClientRect->SetLayoutRect(aTargetRect);
RefPtr<DOMRect> intersectionRect = new DOMRect(mOwner);
if (aIntersectionRect.isSome()) {
intersectionRect->SetLayoutRect(aIntersectionRect.value());
}
RefPtr<DOMIntersectionObserverEntry> entry = new DOMIntersectionObserverEntry(
mOwner, time, rootBounds.forget(), boundingClientRect.forget(),
intersectionRect.forget(), aIsIntersecting, aTarget, aIntersectionRatio);
mQueuedEntries.AppendElement(entry.forget());
}
void DOMIntersectionObserver::Notify() {
if (!mQueuedEntries.Length()) {
return;
}
Sequence<OwningNonNull<DOMIntersectionObserverEntry>> entries;
if (entries.SetCapacity(mQueuedEntries.Length(), mozilla::fallible)) {
for (size_t i = 0; i < mQueuedEntries.Length(); ++i) {
RefPtr<DOMIntersectionObserverEntry> next = mQueuedEntries[i];
*entries.AppendElement(mozilla::fallible) = next;
}
}
mQueuedEntries.Clear();
if (mCallback.is<RefPtr<dom::IntersectionCallback>>()) {
RefPtr<dom::IntersectionCallback> callback(
mCallback.as<RefPtr<dom::IntersectionCallback>>());
callback->Call(this, entries, *this);
} else {
mCallback.as<NativeCallback>()(entries);
}
}
} // namespace mozilla::dom