gecko-dev/dom/base/ResizeObserver.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* 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 mozilla_dom_ResizeObserver_h
#define mozilla_dom_ResizeObserver_h
#include "js/TypeDecls.h"
#include "mozilla/AppUnits.h"
#include "mozilla/Attributes.h"
#include "mozilla/LinkedList.h"
#include "mozilla/WritingModes.h"
#include "mozilla/dom/DOMRect.h"
#include "mozilla/dom/BindingDeclarations.h"
#include "mozilla/dom/ResizeObserverBinding.h"
#include "nsCoord.h"
#include "nsCycleCollectionParticipant.h"
#include "nsRefPtrHashtable.h"
#include "nsTArray.h"
#include "nsWrapperCache.h"
// XXX Avoid including this here by moving function bodies to the cpp file
#include "nsPIDOMWindow.h"
namespace mozilla {
class ErrorResult;
namespace dom {
class Element;
} // namespace dom
} // namespace mozilla
namespace mozilla {
namespace dom {
// For the internal implementation in ResizeObserver. Normally, this is owned by
// ResizeObserver.
class ResizeObservation final : public LinkedListElement<ResizeObservation> {
public:
NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(ResizeObservation)
NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS(ResizeObservation)
ResizeObservation(Element& aTarget, ResizeObserverBoxOptions aBox,
const WritingMode aWM)
: mTarget(&aTarget),
mObservedBox(aBox),
// This starts us with a 0,0 last-reported-size:
mLastReportedSize(aWM),
mLastReportedWM(aWM) {
MOZ_ASSERT(mTarget, "Need a non-null target element");
}
Element* Target() const { return mTarget; }
ResizeObserverBoxOptions BoxOptions() const { return mObservedBox; }
/**
* Returns whether the observed target element size differs from the saved
* mLastReportedSize.
*/
bool IsActive() const;
/**
* Update current mLastReportedSize with size from aSize.
*/
void UpdateLastReportedSize(const nsSize& aSize);
protected:
~ResizeObservation() = default;
nsCOMPtr<Element> mTarget;
const ResizeObserverBoxOptions mObservedBox;
// The latest recorded size of observed target.
// Per the spec, observation.lastReportedSize should be entry.borderBoxSize
// or entry.contentBoxSize (i.e. logical size), instead of entry.contentRect
// (i.e. physical rect), so we store this as LogicalSize.
LogicalSize mLastReportedSize;
WritingMode mLastReportedWM;
};
/**
* ResizeObserver interfaces and algorithms are based on
* https://drafts.csswg.org/resize-observer/#api
*/
class ResizeObserver final : public nsISupports, public nsWrapperCache {
public:
NS_DECL_CYCLE_COLLECTING_ISUPPORTS
NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(ResizeObserver)
ResizeObserver(nsCOMPtr<nsPIDOMWindowInner>&& aOwner, Document* aDocument,
ResizeObserverCallback& aCb)
: mOwner(std::move(aOwner)), mDocument(aDocument), mCallback(&aCb) {
MOZ_ASSERT(mOwner, "Need a non-null owner window");
MOZ_ASSERT(mDocument, "Need a non-null doc");
MOZ_ASSERT(mDocument == mOwner->GetExtantDoc());
}
nsISupports* GetParentObject() const { return mOwner; }
JSObject* WrapObject(JSContext* aCx,
JS::Handle<JSObject*> aGivenProto) override {
return ResizeObserver_Binding::Wrap(aCx, this, aGivenProto);
}
static already_AddRefed<ResizeObserver> Constructor(
const GlobalObject& aGlobal, ResizeObserverCallback& aCb,
ErrorResult& aRv);
void Observe(Element& aTarget, const ResizeObserverOptions& aOptions,
ErrorResult& aRv);
void Unobserve(Element& target, ErrorResult& aRv);
void Disconnect();
/**
* Gather all observations which have an observed target with size changed
* since last BroadcastActiveObservations() in this ResizeObserver.
* An observation will be skipped if the depth of its observed target is less
* or equal than aDepth. All gathered observations will be added to
* mActiveTargets.
*/
void GatherActiveObservations(uint32_t aDepth);
/**
* Returns whether this ResizeObserver has any active observations
* since last GatherActiveObservations().
*/
bool HasActiveObservations() const { return !mActiveTargets.IsEmpty(); }
/**
* Returns whether this ResizeObserver has any skipped observations
* since last GatherActiveObservations().
*/
bool HasSkippedObservations() const { return mHasSkippedTargets; }
/**
* Invoke the callback function in JavaScript for all active observations
* and pass the sequence of ResizeObserverEntry so JavaScript can access them.
* The active observations' mLastReportedSize fields will be updated, and
* mActiveTargets will be cleared. It also returns the shallowest depth of
* elements from active observations or numeric_limits<uint32_t>::max() if
* there are not any active observations.
*/
MOZ_CAN_RUN_SCRIPT uint32_t BroadcastActiveObservations();
protected:
~ResizeObserver() { mObservationList.clear(); }
nsCOMPtr<nsPIDOMWindowInner> mOwner;
// The window's document at the time of ResizeObserver creation.
RefPtr<Document> mDocument;
RefPtr<ResizeObserverCallback> mCallback;
nsTArray<RefPtr<ResizeObservation>> mActiveTargets;
// The spec uses a list to store the skipped targets. However, it seems what
// we want is to check if there are any skipped targets (i.e. existence).
// Therefore, we use a boolean value to represent the existence of skipped
// targets.
bool mHasSkippedTargets;
// Combination of HashTable and LinkedList so we can iterate through
// the elements of HashTable in order of insertion time, so we can deliver
// observations in the correct order
// FIXME: it will be nice if we have our own data structure for this in the
// future, and mObservationMap should be considered the "owning" storage for
// the observations, so it'd be better to drop mObservationList later.
nsRefPtrHashtable<nsPtrHashKey<Element>, ResizeObservation> mObservationMap;
LinkedList<ResizeObservation> mObservationList;
};
/**
* ResizeObserverEntry is the entry that contains the information for observed
* elements. This object is the one that's visible to JavaScript in callback
* function that is fired by ResizeObserver.
*/
class ResizeObserverEntry final : public nsISupports, public nsWrapperCache {
public:
NS_DECL_CYCLE_COLLECTING_ISUPPORTS
NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(ResizeObserverEntry)
ResizeObserverEntry(nsISupports* aOwner, Element& aTarget,
const nsSize& aBorderBoxSize,
const nsSize& aContentBoxSize)
: mOwner(aOwner), mTarget(&aTarget) {
MOZ_ASSERT(mOwner, "Need a non-null owner");
MOZ_ASSERT(mTarget, "Need a non-null target element");
SetBorderBoxSize(aBorderBoxSize);
SetContentRectAndSize(aContentBoxSize);
}
nsISupports* GetParentObject() const { return mOwner; }
JSObject* WrapObject(JSContext* aCx,
JS::Handle<JSObject*> aGivenProto) override {
return ResizeObserverEntry_Binding::Wrap(aCx, this, aGivenProto);
}
Element* Target() const { return mTarget; }
/**
* Returns the DOMRectReadOnly of target's content rect so it can be
* accessed from JavaScript in callback function of ResizeObserver.
*/
DOMRectReadOnly* ContentRect() const { return mContentRect; }
/**
* Returns target's logical border-box size and content-box size as
* ResizeObserverSize.
*/
ResizeObserverSize* BorderBoxSize() const { return mBorderBoxSize; }
ResizeObserverSize* ContentBoxSize() const { return mContentBoxSize; }
private:
~ResizeObserverEntry() = default;
// Set borderBoxSize.
void SetBorderBoxSize(const nsSize& aSize);
// Set contentRect and contentBoxSize.
void SetContentRectAndSize(const nsSize& aSize);
nsCOMPtr<nsISupports> mOwner;
nsCOMPtr<Element> mTarget;
RefPtr<DOMRectReadOnly> mContentRect;
RefPtr<ResizeObserverSize> mBorderBoxSize;
RefPtr<ResizeObserverSize> mContentBoxSize;
};
class ResizeObserverSize final : public nsISupports, public nsWrapperCache {
public:
NS_DECL_CYCLE_COLLECTING_ISUPPORTS
NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(ResizeObserverSize)
// Note: the unit of |aSize| is app unit, and we convert it into css pixel in
// the public JS APIs.
ResizeObserverSize(nsISupports* aOwner, const nsSize& aSize,
const WritingMode aWM)
: mOwner(aOwner), mSize(aWM, aSize), mWM(aWM) {
MOZ_ASSERT(mOwner, "Need a non-null owner");
}
nsISupports* GetParentObject() const { return mOwner; }
JSObject* WrapObject(JSContext* aCx,
JS::Handle<JSObject*> aGivenProto) override {
return ResizeObserverSize_Binding::Wrap(aCx, this, aGivenProto);
}
double InlineSize() const {
return NSAppUnitsToDoublePixels(mSize.ISize(mWM), AppUnitsPerCSSPixel());
}
double BlockSize() const {
return NSAppUnitsToDoublePixels(mSize.BSize(mWM), AppUnitsPerCSSPixel());
}
protected:
~ResizeObserverSize() = default;
nsCOMPtr<nsISupports> mOwner;
const LogicalSize mSize;
const WritingMode mWM;
};
} // namespace dom
} // namespace mozilla
#endif // mozilla_dom_ResizeObserver_h