dom/svg/SVGAnimatedTransformList.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  * vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ :
   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 mozilla_dom_SVGAnimatedTransformList_h
   8 #define mozilla_dom_SVGAnimatedTransformList_h
   9
  10 #include "nsAutoPtr.h"
  11 #include "nsCOMPtr.h"
  12 #include "nsCycleCollectionParticipant.h"
  13 #include "nsSVGElement.h"
  14 #include "nsWrapperCache.h"
  15 #include "mozilla/Attributes.h"
  16
  17 namespace mozilla {
  18
  19 class DOMSVGTransformList;
  20 class nsSVGAnimatedTransformList;
  21
  22 namespace dom {
  23
  24 /**
  25  * Class SVGAnimatedTransformList
  26  *
  27  * This class is used to create the DOM tearoff objects that wrap internal
  28  * nsSVGAnimatedTransformList objects.
  29  *
  30  * See the architecture comment in DOMSVGAnimatedLengthList.h (that's
  31  * LENGTH list). The comment for that class largly applies to this one too
  32  * and will go a long way to helping you understand the architecture here.
  33  *
  34  * This class is strongly intertwined with DOMSVGTransformList and
  35  * DOMSVGTransform.
  36  * Our DOMSVGTransformList base and anim vals are friends and take care of
  37  * nulling out our pointers to them when they die (making our pointers to them
  38  * true weak refs).
  39  */
  40 class SVGAnimatedTransformList MOZ_FINAL : public nsWrapperCache
  41 {
  42   friend class mozilla::DOMSVGTransformList;
  43
  44 public:
  45   NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(SVGAnimatedTransformList)
  46   NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_NATIVE_CLASS(SVGAnimatedTransformList)
  47
  48   /**
  49    * Factory method to create and return a SVGAnimatedTransformList wrapper
  50    * for a given internal nsSVGAnimatedTransformList object. The factory takes
  51    * care of caching the object that it returns so that the same object can be
  52    * returned for the given nsSVGAnimatedTransformList each time it is requested.
  53    * The cached object is only removed from the cache when it is destroyed due
  54    * to there being no more references to it or to any of its descendant
  55    * objects. If that happens, any subsequent call requesting the DOM wrapper
  56    * for the nsSVGAnimatedTransformList will naturally result in a new
  57    * SVGAnimatedTransformList being returned.
  58    */
  59   static already_AddRefed<SVGAnimatedTransformList>
  60     GetDOMWrapper(nsSVGAnimatedTransformList *aList, nsSVGElement *aElement);
  61
  62   /**
  63    * This method returns the SVGAnimatedTransformList wrapper for an internal
  64    * nsSVGAnimatedTransformList object if it currently has a wrapper. If it does
  65    * not, then nullptr is returned.
  66    */
  67   static SVGAnimatedTransformList*
  68     GetDOMWrapperIfExists(nsSVGAnimatedTransformList *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 InternalBaseValListWillChangeLengthTo(uint32_t aNewLength);
  83   void InternalAnimValListWillChangeLengthTo(uint32_t aNewLength);
  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   nsSVGElement* GetParentObject() const { return mElement; }
  93   virtual JSObject* WrapObject(JSContext* aCx) MOZ_OVERRIDE;
  94   // These aren't weak refs because mBaseVal and mAnimVal are weak
  95   already_AddRefed<DOMSVGTransformList> BaseVal();
  96   already_AddRefed<DOMSVGTransformList> AnimVal();
  97
  98 private:
  99
 100   /**
 101    * Only our static GetDOMWrapper() factory method may create objects of our
 102    * type.
 103    */
 104   explicit SVGAnimatedTransformList(nsSVGElement *aElement)
 105     : mBaseVal(nullptr)
 106     , mAnimVal(nullptr)
 107     , mElement(aElement)
 108   {
 109   }
 110
 111   ~SVGAnimatedTransformList();
 112
 113   /// Get a reference to this DOM wrapper object's internal counterpart.
 114   nsSVGAnimatedTransformList& InternalAList();
 115   const nsSVGAnimatedTransformList& InternalAList() const;
 116
 117   // Weak refs to our DOMSVGTransformList baseVal/animVal objects. These objects
 118   // are friends and take care of clearing these pointers when they die, making
 119   // these true weak references.
 120   DOMSVGTransformList *mBaseVal;
 121   DOMSVGTransformList *mAnimVal;
 122
 123   // Strong ref to our element to keep it alive. We hold this not only for
 124   // ourself, but also for our base/animVal and all of their items.
 125   nsRefPtr<nsSVGElement> mElement;
 126 };
 127
 128 } // namespace dom
 129 } // namespace mozilla
 130
 131 #endif // mozilla_dom_SVGAnimatedTransformList_h