gecko-dev/dom/base/DOMIntersectionObserver.h

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
 * You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef DOMIntersectionObserver_h
#define DOMIntersectionObserver_h

#include "mozilla/Attributes.h"
#include "mozilla/dom/IntersectionObserverBinding.h"
#include "nsStyleCoord.h"
#include "nsTArray.h"

using mozilla::dom::DOMRect;
using mozilla::dom::Element;

namespace mozilla {
namespace dom {

class DOMIntersectionObserver;

class DOMIntersectionObserverEntry final : public nsISupports,
                                           public nsWrapperCache {
  ~DOMIntersectionObserverEntry() {}

 public:
  DOMIntersectionObserverEntry(nsISupports* aOwner, DOMHighResTimeStamp aTime,
                               RefPtr<DOMRect> aRootBounds,
                               RefPtr<DOMRect> aBoundingClientRect,
                               RefPtr<DOMRect> aIntersectionRect,
                               bool aIsIntersecting, Element* aTarget,
                               double aIntersectionRatio)
      : mOwner(aOwner),
        mTime(aTime),
        mRootBounds(aRootBounds),
        mBoundingClientRect(aBoundingClientRect),
        mIntersectionRect(aIntersectionRect),
        mIsIntersecting(aIsIntersecting),
        mTarget(aTarget),
        mIntersectionRatio(aIntersectionRatio) {}
  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(DOMIntersectionObserverEntry)

  nsISupports* GetParentObject() const { return mOwner; }

  virtual JSObject* WrapObject(JSContext* aCx,
                               JS::Handle<JSObject*> aGivenProto) override {
    return mozilla::dom::IntersectionObserverEntry_Binding::Wrap(aCx, this,
                                                                 aGivenProto);
  }

  DOMHighResTimeStamp Time() { return mTime; }

  DOMRect* GetRootBounds() { return mRootBounds; }

  DOMRect* BoundingClientRect() { return mBoundingClientRect; }

  DOMRect* IntersectionRect() { return mIntersectionRect; }

  bool IsIntersecting() { return mIsIntersecting; }

  double IntersectionRatio() { return mIntersectionRatio; }

  Element* Target() { return mTarget; }

 protected:
  nsCOMPtr<nsISupports> mOwner;
  DOMHighResTimeStamp mTime;
  RefPtr<DOMRect> mRootBounds;
  RefPtr<DOMRect> mBoundingClientRect;
  RefPtr<DOMRect> mIntersectionRect;
  bool mIsIntersecting;
  RefPtr<Element> mTarget;
  double mIntersectionRatio;
};

#define NS_DOM_INTERSECTION_OBSERVER_IID             \
  {                                                  \
    0x8570a575, 0xe303, 0x4d18, {                    \
      0xb6, 0xb1, 0x4d, 0x2b, 0x49, 0xd8, 0xef, 0x94 \
    }                                                \
  }

class DOMIntersectionObserver final : public nsISupports,
                                      public nsWrapperCache {
  virtual ~DOMIntersectionObserver() { Disconnect(); }

 public:
  DOMIntersectionObserver(already_AddRefed<nsPIDOMWindowInner>&& aOwner,
                          mozilla::dom::IntersectionCallback& aCb)
      : mOwner(aOwner),
        mDocument(mOwner->GetExtantDoc()),
        mCallback(&aCb),
        mConnected(false) {}
  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(DOMIntersectionObserver)
  NS_DECLARE_STATIC_IID_ACCESSOR(NS_DOM_INTERSECTION_OBSERVER_IID)

  static already_AddRefed<DOMIntersectionObserver> Constructor(
      const mozilla::dom::GlobalObject& aGlobal,
      mozilla::dom::IntersectionCallback& aCb, mozilla::ErrorResult& aRv);
  static already_AddRefed<DOMIntersectionObserver> Constructor(
      const mozilla::dom::GlobalObject& aGlobal,
      mozilla::dom::IntersectionCallback& aCb,
      const mozilla::dom::IntersectionObserverInit& aOptions,
      mozilla::ErrorResult& aRv);

  virtual JSObject* WrapObject(JSContext* aCx,
                               JS::Handle<JSObject*> aGivenProto) override {
    return mozilla::dom::IntersectionObserver_Binding::Wrap(aCx, this,
                                                            aGivenProto);
  }

  nsISupports* GetParentObject() const { return mOwner; }

  Element* GetRoot() const { return mRoot; }

  void GetRootMargin(mozilla::dom::DOMString& aRetVal);
  void GetThresholds(nsTArray<double>& aRetVal);
  void Observe(Element& aTarget);
  void Unobserve(Element& aTarget);

  void UnlinkTarget(Element& aTarget);
  void Disconnect();

  void TakeRecords(nsTArray<RefPtr<DOMIntersectionObserverEntry>>& aRetVal);

  mozilla::dom::IntersectionCallback* IntersectionCallback() {
    return mCallback;
  }

  bool SetRootMargin(const nsAString& aString);

  void Update(Document* aDocument, DOMHighResTimeStamp time);
  MOZ_CAN_RUN_SCRIPT void Notify();

 protected:
  void Connect();
  void QueueIntersectionObserverEntry(Element* aTarget,
                                      DOMHighResTimeStamp time,
                                      const Maybe<nsRect>& aRootRect,
                                      const nsRect& aTargetRect,
                                      const Maybe<nsRect>& aIntersectionRect,
                                      double aIntersectionRatio);

  nsCOMPtr<nsPIDOMWindowInner> mOwner;
  RefPtr<Document> mDocument;
  RefPtr<mozilla::dom::IntersectionCallback> mCallback;
  RefPtr<Element> mRoot;
  StyleRect<LengthPercentage> mRootMargin;
  nsTArray<double> mThresholds;

  // Holds raw pointers which are explicitly cleared by UnlinkTarget().
  nsTArray<Element*> mObservationTargets;

  nsTArray<RefPtr<DOMIntersectionObserverEntry>> mQueuedEntries;
  bool mConnected;
};

NS_DEFINE_STATIC_IID_ACCESSOR(DOMIntersectionObserver,
                              NS_DOM_INTERSECTION_OBSERVER_IID)

}  // namespace dom
}  // namespace mozilla

#endif