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Diffstat (limited to 'dom/svg/DOMSVGPathSegList.h')
| -rw-r--r-- | dom/svg/DOMSVGPathSegList.h | 256 |
1 files changed, 256 insertions, 0 deletions
diff --git a/dom/svg/DOMSVGPathSegList.h b/dom/svg/DOMSVGPathSegList.h new file mode 100644 index 000000000..150c92035 --- /dev/null +++ b/dom/svg/DOMSVGPathSegList.h @@ -0,0 +1,256 @@ +/* -*- 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 MOZILLA_DOMSVGPATHSEGLIST_H__ +#define MOZILLA_DOMSVGPATHSEGLIST_H__ + +#include "nsCOMPtr.h" +#include "nsCycleCollectionParticipant.h" +#include "nsDebug.h" +#include "nsSVGElement.h" +#include "nsTArray.h" +#include "SVGPathData.h" // IWYU pragma: keep +#include "mozilla/Attributes.h" +#include "mozilla/ErrorResult.h" + +namespace mozilla { + +class DOMSVGPathSeg; +class SVGAnimatedPathSegList; + +/** + * 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 +{ + friend class AutoChangePathSegListNotifier; + friend class DOMSVGPathSeg; + +public: + NS_DECL_CYCLE_COLLECTING_ISUPPORTS + NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(DOMSVGPathSegList) + + virtual 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, + nsSVGElement *aElement, + bool aIsAnimValList); + + /** + * 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(nsSVGElement *aElement, bool aIsAnimValList) + : mElement(aElement) + , mIsAnimValList(aIsAnimValList) + { + InternalListWillChangeTo(InternalList()); // Sync mItems + } + + ~DOMSVGPathSegList(); + + nsSVGElement* 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 returs 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; + } + + /** + * 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(){} + 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<nsSVGElement> mElement; + + bool mIsAnimValList; +}; + +} // namespace mozilla + +#endif // MOZILLA_DOMSVGPATHSEGLIST_H__ |