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DOMSVGNumber.h (5300B)

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