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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, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#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_