dom/svg/DOMSVGNumber.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_DOMSVGNUMBER_H_
   8 #define DOM_SVG_DOMSVGNUMBER_H_
   9
  10 #include "DOMSVGNumberList.h"
  11 #include "nsCOMPtr.h"
  12 #include "nsCycleCollectionParticipant.h"
  13 #include "nsTArray.h"
  14 #include "mozilla/Attributes.h"
  15 #include "mozilla/RefPtr.h"
  16 #include "nsWrapperCache.h"
  17
  18 #define MOZ_SVG_LIST_INDEX_BIT_COUNT 27  // supports > 134 million list items
  19
  20 namespace mozilla {
  21 class ErrorResult;
  22
  23 namespace dom {
  24 class SVGElement;
  25 class SVGSVGElement;
  26
  27 /**
  28  * Class DOMSVGNumber
  29  *
  30  * This class creates the DOM objects that wrap internal SVGNumber objects that
  31  * are in an SVGNumberList. It is also used to create the objects returned by
  32  * SVGSVGElement.createSVGNumber().
  33  *
  34  * For the DOM wrapper classes for non-list SVGNumber, see SVGAnimatedNumber.h.
  35  *
  36  * See the architecture comment in DOMSVGAnimatedNumberList.h.
  37  *
  38  * See the comment in DOMSVGLength.h (yes, LENGTH), which applies here too.
  39  */
  40 class DOMSVGNumber final : public nsWrapperCache {
  41   template <class T>
  42   friend class AutoChangeNumberListNotifier;
  43
  44   ~DOMSVGNumber() {
  45     // Our mList's weak ref to us must be nulled out when we die. If GC has
  46     // unlinked us using the cycle collector code, then that has already
  47     // happened, and mList is null.
  48     if (mList) {
  49       mList->mItems[mListIndex] = nullptr;
  50     }
  51   }
  52
  53  public:
  54   NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(DOMSVGNumber)
  55   NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_NATIVE_CLASS(DOMSVGNumber)
  56
  57   /**
  58    * Generic ctor for DOMSVGNumber objects that are created for an attribute.
  59    */
  60   DOMSVGNumber(DOMSVGNumberList* aList, uint8_t aAttrEnum, uint32_t aListIndex,
  61                bool aIsAnimValItem);
  62
  63   /**
  64    * Ctor for creating the objects returned by SVGSVGElement.createSVGNumber(),
  65    * which do not initially belong to an attribute.
  66    */
  67   explicit DOMSVGNumber(SVGSVGElement* aParent);
  68
  69  private:
  70   explicit DOMSVGNumber(nsISupports* aParent);
  71
  72  public:
  73   /**
  74    * Create an unowned copy. The caller is responsible for the first AddRef().
  75    */
  76   DOMSVGNumber* Clone() {
  77     DOMSVGNumber* clone = new DOMSVGNumber(mParent);
  78     clone->mValue = ToSVGNumber();
  79     return clone;
  80   }
  81
  82   bool IsInList() const { return !!mList; }
  83
  84   /**
  85    * Returns true if our attribute is animating.
  86    */
  87   bool IsAnimating() const { return mList && mList->IsAnimating(); }
  88
  89   /**
  90    * In future, if this class is used for non-list numbers, this will be
  91    * different to IsInList().
  92    */
  93   bool HasOwner() const { return !!mList; }
  94
  95   /**
  96    * This method is called to notify this DOM object that it is being inserted
  97    * into a list, and give it the information it needs as a result.
  98    *
  99    * This object MUST NOT already belong to a list when this method is called.
 100    * That's not to say that script can't move these DOM objects between
 101    * lists - it can - it's just that the logic to handle that (and send out
 102    * the necessary notifications) is located elsewhere (in DOMSVGNumberList).)
 103    */
 104   void InsertingIntoList(DOMSVGNumberList* aList, uint8_t aAttrEnum,
 105                          uint32_t aListIndex, bool aIsAnimValItem);
 106
 107   static uint32_t MaxListIndex() {
 108     return (1U << MOZ_SVG_LIST_INDEX_BIT_COUNT) - 1;
 109   }
 110
 111   /// This method is called to notify this object that its list index changed.
 112   void UpdateListIndex(uint32_t aListIndex) { mListIndex = aListIndex; }
 113
 114   /**
 115    * This method is called to notify this DOM object that it is about to be
 116    * removed from its current DOM list so that it can first make a copy of its
 117    * internal counterpart's value. (If it didn't do this, then it would
 118    * "lose" its value on being removed.)
 119    */
 120   void RemovingFromList();
 121
 122   float ToSVGNumber();
 123
 124   nsISupports* GetParentObject() { return mParent; }
 125
 126   JSObject* WrapObject(JSContext* aCx,
 127                        JS::Handle<JSObject*> aGivenProto) override;
 128
 129   float Value();
 130
 131   void SetValue(float aValue, ErrorResult& aRv);
 132
 133  private:
 134   dom::SVGElement* Element() { return mList->Element(); }
 135
 136   uint8_t AttrEnum() const { return mAttrEnum; }
 137
 138   /**
 139    * Get a reference to the internal SVGNumber list item that this DOM wrapper
 140    * object currently wraps.
 141    *
 142    * To simplify the code we just have this one method for obtaining both
 143    * baseVal and animVal internal items. This means that animVal items don't
 144    * get const protection, but then our setter methods guard against changing
 145    * animVal items.
 146    */
 147   float& InternalItem();
 148
 149 #ifdef DEBUG
 150   bool IndexIsValid();
 151 #endif
 152
 153   RefPtr<DOMSVGNumberList> mList;
 154   nsCOMPtr<nsISupports> mParent;
 155
 156   // Bounds for the following are checked in the ctor, so be sure to update
 157   // that if you change the capacity of any of the following.
 158
 159   uint32_t mListIndex : MOZ_SVG_LIST_INDEX_BIT_COUNT;
 160   uint32_t mAttrEnum : 4;  // supports up to 16 attributes
 161   uint32_t mIsAnimValItem : 1;
 162
 163   // The following member is only used when we're not in a list:
 164   float mValue;
 165 };
 166
 167 }  // namespace dom
 168 }  // namespace mozilla
 169
 170 #undef MOZ_SVG_LIST_INDEX_BIT_COUNT
 171
 172 #endif  // DOM_SVG_DOMSVGNUMBER_H_