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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
#ifndef DOM_SVG_DOMSVGPATHSEGLIST_H_
#define DOM_SVG_DOMSVGPATHSEGLIST_H_
#include "mozAutoDocUpdate.h"
#include "nsCycleCollectionParticipant.h"
#include "nsDebug.h"
#include "nsTArray.h"
#include "SVGPathData.h" // IWYU pragma: keep
#include "mozilla/Attributes.h"
#include "mozilla/RefPtr.h"
#include "mozilla/dom/SVGElement.h"
namespace mozilla {
class ErrorResult;
class SVGAnimatedPathSegList;
namespace dom {
class DOMSVGPathSeg;
class SVGPathElement;
//----------------------------------------------------------------------
// Helper class: AutoChangePathSegListNotifier
// Stack-based helper class to pair calls to WillChangePathSegList and
// DidChangePathSegList. Used by DOMSVGPathSeg and DOMSVGPathSegList.
template <class T>
class MOZ_RAII AutoChangePathSegListNotifier : public mozAutoDocUpdate {
public:
explicit AutoChangePathSegListNotifier(T* aValue)
: mozAutoDocUpdate(aValue->Element()->GetComposedDoc(), true),
mValue(aValue) {
MOZ_ASSERT(mValue, "Expecting non-null value");
mEmptyOrOldValue = mValue->Element()->WillChangePathSegList(*this);
}
~AutoChangePathSegListNotifier() {
mValue->Element()->DidChangePathSegList(mEmptyOrOldValue, *this);
if (mValue->AttrIsAnimating()) {
mValue->Element()->AnimationNeedsResample();
}
}
private:
T* const mValue;
nsAttrValue mEmptyOrOldValue;
};
/**
* Class DOMSVGPathSegList
*
* This class is used to create the DOM tearoff objects that wrap internal
* SVGPathData objects.
*
* See the architecture comment in DOMSVGAnimatedLengthList.h first (that's
* LENGTH list), then continue reading the remainder of this comment.
*
* The architecture of this class is very similar to that of DOMSVGLengthList
* except that, since there is no nsIDOMSVGAnimatedPathSegList interface
* in SVG, we have no parent DOMSVGAnimatedPathSegList (unlike DOMSVGLengthList
* which has a parent DOMSVGAnimatedLengthList class). (There is an
* SVGAnimatedPathData interface, but that is quite different to
* DOMSVGAnimatedLengthList, since it is inherited by elements rather than
* elements having members of that type.) As a consequence, much of the logic
* that would otherwise be in DOMSVGAnimatedPathSegList (and is in
* DOMSVGAnimatedLengthList) is contained in this class.
*
* This class is strongly intertwined with DOMSVGPathSeg. Our DOMSVGPathSeg
* items are friends of us and responsible for nulling out our pointers to
* them when they die.
*
* Our DOM items are created lazily on demand as and when script requests them.
*/
class DOMSVGPathSegList final : public nsISupports, public nsWrapperCache {
template <class T>
friend class AutoChangePathSegListNotifier;
friend class DOMSVGPathSeg;
public:
NS_DECL_CYCLE_COLLECTING_ISUPPORTS
NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(DOMSVGPathSegList)
JSObject* WrapObject(JSContext* cx,
JS::Handle<JSObject*> aGivenProto) override;
nsISupports* GetParentObject() { return static_cast<nsIContent*>(mElement); }
/**
* Factory method to create and return a DOMSVGPathSegList wrapper
* for a given internal SVGPathData object. The factory takes care
* of caching the object that it returns so that the same object can be
* returned for the given SVGPathData each time it is requested.
* The cached object is only removed from the cache when it is destroyed due
* to there being no more references to it or to any of its descendant
* objects. If that happens, any subsequent call requesting the DOM wrapper
* for the SVGPathData will naturally result in a new
* DOMSVGPathSegList being returned.
*
* It's unfortunate that aList is a void* instead of a typed argument. This
* is because the mBaseVal and mAnimVal members of SVGAnimatedPathSegList are
* of different types - a plain SVGPathData, and a SVGPathData*. We
* use the addresses of these members as the key for the hash table, and
* clearly SVGPathData* and a SVGPathData** are not the same type.
*/
static already_AddRefed<DOMSVGPathSegList> GetDOMWrapper(
void* aList, dom::SVGPathElement* aElement);
/**
* This method returns the DOMSVGPathSegList wrapper for an internal
* SVGPathData object if it currently has a wrapper. If it does
* not, then nullptr is returned.
*/
static DOMSVGPathSegList* GetDOMWrapperIfExists(void* aList);
/**
* This will normally be the same as InternalList().CountItems(), except if
* we've hit OOM, in which case our length will be zero.
*/
uint32_t LengthNoFlush() const {
MOZ_ASSERT(
mItems.Length() == 0 || mItems.Length() == InternalList().CountItems(),
"DOM wrapper's list length is out of sync");
return mItems.Length();
}
/**
* WATCH OUT! If you add code to call this on a baseVal wrapper, then you
* must also call it on the animVal wrapper too if necessary!! See other
* callers!
*
* Called by internal code to notify us when we need to sync the length of
* this DOM list with its internal list. This is called immediately prior to
* the length of the internal list being changed so that any DOM list items
* that need to be removed from the DOM list can first copy their values from
* their internal counterpart.
*
* The only time this method could fail is on OOM when trying to increase the
* length of the DOM list. If that happens then this method simply clears the
* list and returns. Callers just proceed as normal, and we simply accept
* that the DOM list will be empty (until successfully set to a new value).
*/
void InternalListWillChangeTo(const SVGPathData& aNewValue);
/**
* Returns true if our attribute is animating (in which case our animVal is
* not simply a mirror of our baseVal).
*/
bool AttrIsAnimating() const;
/**
* Returns true if there is an animated list mirroring the base list.
*/
bool AnimListMirrorsBaseList() const;
uint32_t NumberOfItems() const {
if (IsAnimValList()) {
Element()->FlushAnimations();
}
return LengthNoFlush();
}
void Clear(ErrorResult& aError);
already_AddRefed<DOMSVGPathSeg> Initialize(DOMSVGPathSeg& aNewItem,
ErrorResult& aError);
already_AddRefed<DOMSVGPathSeg> GetItem(uint32_t index, ErrorResult& error);
already_AddRefed<DOMSVGPathSeg> IndexedGetter(uint32_t index, bool& found,
ErrorResult& error);
already_AddRefed<DOMSVGPathSeg> InsertItemBefore(DOMSVGPathSeg& aNewItem,
uint32_t aIndex,
ErrorResult& aError);
already_AddRefed<DOMSVGPathSeg> ReplaceItem(DOMSVGPathSeg& aNewItem,
uint32_t aIndex,
ErrorResult& aError);
already_AddRefed<DOMSVGPathSeg> RemoveItem(uint32_t aIndex,
ErrorResult& aError);
already_AddRefed<DOMSVGPathSeg> AppendItem(DOMSVGPathSeg& aNewItem,
ErrorResult& aError) {
return InsertItemBefore(aNewItem, LengthNoFlush(), aError);
}
uint32_t Length() const { return NumberOfItems(); }
private:
/**
* Only our static GetDOMWrapper() factory method may create objects of our
* type.
*/
DOMSVGPathSegList(dom::SVGElement* aElement, bool aIsAnimValList)
: mElement(aElement), mIsAnimValList(aIsAnimValList) {
InternalListWillChangeTo(InternalList()); // Sync mItems
}
~DOMSVGPathSegList();
dom::SVGElement* Element() const { return mElement.get(); }
/// Used to determine if this list is the baseVal or animVal list.
bool IsAnimValList() const { return mIsAnimValList; }
/**
* Get a reference to this object's corresponding internal SVGPathData.
*
* To simplify the code we just have this one method for obtaining both
* base val and anim val internal lists. This means that anim val lists don't
* get const protection, but our setter methods guard against changing
* anim val lists.
*/
SVGPathData& InternalList() const;
SVGAnimatedPathSegList& InternalAList() const;
/// Creates an instance of the appropriate DOMSVGPathSeg sub-class for
// aIndex, if it doesn't already exist, and then returns it.
already_AddRefed<DOMSVGPathSeg> GetItemAt(uint32_t aIndex);
void MaybeInsertNullInAnimValListAt(uint32_t aIndex, uint32_t aInternalIndex,
uint32_t aArgCountForItem);
void MaybeRemoveItemFromAnimValListAt(uint32_t aIndex,
int32_t aArgCountForItem);
// Calls UpdateListIndex on all elements in |mItems| that satisfy ItemAt(),
// from |aStartingIndex| to the end of |mItems|. Also adjusts
// |mItems.mInternalDataIndex| by the requested amount.
void UpdateListIndicesFromIndex(uint32_t aStartingIndex,
int32_t aInternalDataIndexDelta);
DOMSVGPathSeg*& ItemAt(uint32_t aIndex) { return mItems[aIndex].mItem; }
void RemoveFromTearoffTable();
/**
* This struct is used in our array of mItems to provide us with somewhere to
* store the indexes into the internal SVGPathData of the internal seg data
* that our DOMSVGPathSeg items wrap (the internal segment data is or varying
* length, so we can't just use the index of our DOMSVGPathSeg items
* themselves). The reason that we have this separate struct rather than
* just storing the internal indexes in the DOMSVGPathSeg items is because we
* want to create the DOMSVGPathSeg items lazily on demand.
*/
struct ItemProxy {
ItemProxy() : mItem(nullptr), mInternalDataIndex(0) {}
ItemProxy(DOMSVGPathSeg* aItem, uint32_t aInternalDataIndex)
: mItem(aItem), mInternalDataIndex(aInternalDataIndex) {}
DOMSVGPathSeg* mItem;
uint32_t mInternalDataIndex;
};
// Weak refs to our DOMSVGPathSeg items. The items are friends and take care
// of clearing our pointer to them when they die.
FallibleTArray<ItemProxy> mItems;
// Strong ref to our element to keep it alive. We hold this not only for
// ourself, but also for our DOMSVGPathSeg items too.
RefPtr<dom::SVGElement> mElement;
bool mIsAnimValList;
};
} // namespace dom
} // namespace mozilla
#endif // DOM_SVG_DOMSVGPATHSEGLIST_H_