dom/svg/DOMSVGAnimatedNumberList.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef DOM_SVG_DOMSVGANIMATEDNUMBERLIST_H_
   8 #define DOM_SVG_DOMSVGANIMATEDNUMBERLIST_H_
   9
  10 #include "nsCycleCollectionParticipant.h"
  11 #include "SVGElement.h"
  12 #include "nsWrapperCache.h"
  13 #include "mozilla/Attributes.h"
  14 #include "mozilla/RefPtr.h"
  15
  16 namespace mozilla {
  17
  18 class SVGAnimatedNumberList;
  19 class SVGNumberList;
  20
  21 namespace dom {
  22
  23 class DOMSVGNumberList;
  24
  25 /**
  26  * Class DOMSVGAnimatedNumberList
  27  *
  28  * This class is used to create the DOM tearoff objects that wrap internal
  29  * SVGAnimatedNumberList objects.
  30  *
  31  * See the architecture comment in DOMSVGAnimatedLengthList.h (that's
  32  * LENGTH list). The comment for that class largly applies to this one too
  33  * and will go a long way to helping you understand the architecture here.
  34  *
  35  * This class is strongly intertwined with DOMSVGNumberList and DOMSVGNumber.
  36  * Our DOMSVGNumberList base and anim vals are friends and take care of nulling
  37  * out our pointers to them when they die (making our pointers to them true
  38  * weak refs).
  39  */
  40 class DOMSVGAnimatedNumberList final : public nsWrapperCache {
  41   friend class DOMSVGNumberList;
  42
  43  public:
  44   NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(DOMSVGAnimatedNumberList)
  45   NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_NATIVE_CLASS(DOMSVGAnimatedNumberList)
  46
  47   /**
  48    * Factory method to create and return a DOMSVGAnimatedNumberList wrapper
  49    * for a given internal SVGAnimatedNumberList object. The factory takes care
  50    * of caching the object that it returns so that the same object can be
  51    * returned for the given SVGAnimatedNumberList each time it is requested.
  52    * The cached object is only removed from the cache when it is destroyed due
  53    * to there being no more references to it or to any of its descendant
  54    * objects. If that happens, any subsequent call requesting the DOM wrapper
  55    * for the SVGAnimatedNumberList will naturally result in a new
  56    * DOMSVGAnimatedNumberList being returned.
  57    */
  58   static already_AddRefed<DOMSVGAnimatedNumberList> GetDOMWrapper(
  59       SVGAnimatedNumberList* aList, dom::SVGElement* aElement,
  60       uint8_t aAttrEnum);
  61
  62   /**
  63    * This method returns the DOMSVGAnimatedNumberList wrapper for an internal
  64    * SVGAnimatedNumberList object if it currently has a wrapper. If it does
  65    * not, then nullptr is returned.
  66    */
  67   static DOMSVGAnimatedNumberList* GetDOMWrapperIfExists(
  68       SVGAnimatedNumberList* aList);
  69
  70   /**
  71    * Called by internal code to notify us when we need to sync the length of
  72    * our baseVal DOM list with its internal list. This is called just prior to
  73    * the length of the internal baseVal list being changed so that any DOM list
  74    * items that need to be removed from the DOM list can first get their values
  75    * from their internal counterpart.
  76    *
  77    * The only time this method could fail is on OOM when trying to increase the
  78    * length of the DOM list. If that happens then this method simply clears the
  79    * list and returns. Callers just proceed as normal, and we simply accept
  80    * that the DOM list will be empty (until successfully set to a new value).
  81    */
  82   void InternalBaseValListWillChangeTo(const SVGNumberList& aNewValue);
  83   void InternalAnimValListWillChangeTo(const SVGNumberList& aNewValue);
  84
  85   /**
  86    * Returns true if our attribute is animating (in which case our animVal is
  87    * not simply a mirror of our baseVal).
  88    */
  89   bool IsAnimating() const;
  90
  91   // WebIDL
  92   dom::SVGElement* GetParentObject() const { return mElement; }
  93   virtual JSObject* WrapObject(JSContext* aCx,
  94                                JS::Handle<JSObject*> aGivenProto) override;
  95   // These aren't weak refs because mBaseVal and mAnimVal are weak
  96   already_AddRefed<DOMSVGNumberList> BaseVal();
  97   already_AddRefed<DOMSVGNumberList> AnimVal();
  98
  99  private:
 100   /**
 101    * Only our static GetDOMWrapper() factory method may create objects of our
 102    * type.
 103    */
 104   DOMSVGAnimatedNumberList(dom::SVGElement* aElement, uint8_t aAttrEnum)
 105       : mBaseVal(nullptr),
 106         mAnimVal(nullptr),
 107         mElement(aElement),
 108         mAttrEnum(aAttrEnum) {}
 109
 110   ~DOMSVGAnimatedNumberList();
 111
 112   /// Get a reference to this DOM wrapper object's internal counterpart.
 113   SVGAnimatedNumberList& InternalAList();
 114   const SVGAnimatedNumberList& InternalAList() const;
 115
 116   // Weak refs to our DOMSVGNumberList baseVal/animVal objects. These objects
 117   // are friends and take care of clearing these pointers when they die, making
 118   // these true weak references.
 119   DOMSVGNumberList* mBaseVal;
 120   DOMSVGNumberList* mAnimVal;
 121
 122   // Strong ref to our element to keep it alive. We hold this not only for
 123   // ourself, but also for our base/animVal and all of their items.
 124   RefPtr<dom::SVGElement> mElement;
 125
 126   uint8_t mAttrEnum;
 127 };
 128
 129 }  // namespace dom
 130 }  // namespace mozilla
 131
 132 #endif  // DOM_SVG_DOMSVGANIMATEDNUMBERLIST_H_