DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Implementation

Mercurial (b6d82b1a6b02)

VCS Links

Line Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231
/* -*- 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 MOZILLA_DOMSVGPATHSEGLIST_H__
#define MOZILLA_DOMSVGPATHSEGLIST_H__

#include "nsCycleCollectionParticipant.h"
#include "nsDebug.h"
#include "SVGElement.h"
#include "nsTArray.h"
#include "SVGPathData.h"  // IWYU pragma: keep
#include "mozilla/Attributes.h"
#include "mozilla/ErrorResult.h"
#include "mozilla/RefPtr.h"

namespace mozilla {

class DOMSVGPathSeg;
class SVGAnimatedPathSegList;

/**
 * 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 {
  friend class AutoChangePathSegListNotifier;
  friend class DOMSVGPathSeg;

 public:
  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(DOMSVGPathSegList)

  virtual 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::SVGElement* aElement, bool aIsAnimValList);

  /**
   * 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; }

  /**
   * 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 mozilla

#endif  // MOZILLA_DOMSVGPATHSEGLIST_H__