Mypal/dom/svg/DOMSVGTransformList.h

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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_DOMSVGTRANSFORMLIST_H__
#define MOZILLA_DOMSVGTRANSFORMLIST_H__

#include "mozilla/dom/SVGAnimatedTransformList.h"
#include "nsCycleCollectionParticipant.h"
#include "nsDebug.h"
#include "nsTArray.h"
#include "SVGTransformList.h"
#include "mozilla/Attributes.h"
#include "mozilla/ErrorResult.h"

class nsSVGElement;

namespace mozilla {

namespace dom {
class SVGMatrix;
class SVGTransform;
} // namespace dom

/**
 * Class DOMSVGTransformList
 *
 * This class is used to create the DOM tearoff objects that wrap internal
 * SVGTransformList objects.
 *
 * See the architecture comment in SVGAnimatedTransformList.h.
 */
class DOMSVGTransformList final : public nsISupports,
                                  public nsWrapperCache
{
  friend class AutoChangeTransformListNotifier;
  friend class dom::SVGTransform;

  ~DOMSVGTransformList() {
    // Our mAList's weak ref to us must be nulled out when we die. If GC has
    // unlinked us using the cycle collector code, then that has already
    // happened, and mAList is null.
    if (mAList) {
      ( IsAnimValList() ? mAList->mAnimVal : mAList->mBaseVal ) = nullptr;
    }
  }

public:
  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(DOMSVGTransformList)

  DOMSVGTransformList(dom::SVGAnimatedTransformList *aAList,
                      const SVGTransformList &aInternalList)
    : mAList(aAList)
  {
    // aInternalList must be passed in explicitly because we can't use
    // InternalList() here. (Because it depends on IsAnimValList, which depends
    // on this object having been assigned to aAList's mBaseVal or mAnimVal,
    // which hasn't happend yet.)

    InternalListLengthWillChange(aInternalList.Length()); // Sync mItems
  }

  virtual JSObject* WrapObject(JSContext *cx, JS::Handle<JSObject*> aGivenProto) override;

  nsISupports* GetParentObject()
  {
    return static_cast<nsIContent*>(Element());
  }

  /**
   * This will normally be the same as InternalList().Length(), except if we've
   * hit OOM in which case our length will be zero.
   */
  uint32_t LengthNoFlush() const {
    MOZ_ASSERT(mItems.IsEmpty() || mItems.Length() == InternalList().Length(),
               "DOM wrapper's list length is out of sync");
    return mItems.Length();
  }

  /// Called to notify us to synchronize our length and detach excess items.
  void InternalListLengthWillChange(uint32_t aNewLength);

  /**
   * Returns true if our attribute is animating (in which case our animVal is
   * not simply a mirror of our baseVal).
   */
  bool IsAnimating() const {
    return mAList->IsAnimating();
  }
  /**
   * Returns true if there is an animated list mirroring the base list.
   */
  bool AnimListMirrorsBaseList() const {
    return mAList->mAnimVal && !mAList->IsAnimating();
  }

  uint32_t NumberOfItems() const
  {
    if (IsAnimValList()) {
      Element()->FlushAnimations();
    }
    return LengthNoFlush();
  }
  void Clear(ErrorResult& error);
  already_AddRefed<dom::SVGTransform> Initialize(dom::SVGTransform& newItem,
                                                 ErrorResult& error);
  already_AddRefed<dom::SVGTransform> GetItem(uint32_t index,
                                              ErrorResult& error);
  already_AddRefed<dom::SVGTransform> IndexedGetter(uint32_t index, bool& found,
                                                    ErrorResult& error);
  already_AddRefed<dom::SVGTransform> InsertItemBefore(dom::SVGTransform& newItem,
                                                       uint32_t index,
                                                       ErrorResult& error);
  already_AddRefed<dom::SVGTransform> ReplaceItem(dom::SVGTransform& newItem,
                                                  uint32_t index,
                                                  ErrorResult& error);
  already_AddRefed<dom::SVGTransform> RemoveItem(uint32_t index,
                                                 ErrorResult& error);
  already_AddRefed<dom::SVGTransform> AppendItem(dom::SVGTransform& newItem,
                                                 ErrorResult& error)
  {
    return InsertItemBefore(newItem, LengthNoFlush(), error);
  }
  already_AddRefed<dom::SVGTransform> CreateSVGTransformFromMatrix(dom::SVGMatrix& matrix);
  already_AddRefed<dom::SVGTransform> Consolidate(ErrorResult& error);
  uint32_t Length() const
  {
    return NumberOfItems();
  }

private:

  nsSVGElement* Element() const {
    return mAList->mElement;
  }

  /// Used to determine if this list is the baseVal or animVal list.
  bool IsAnimValList() const {
    MOZ_ASSERT(this == mAList->mBaseVal || this == mAList->mAnimVal,
               "Calling IsAnimValList() too early?!");
    return this == mAList->mAnimVal;
  }

  /**
   * Get a reference to this object's corresponding internal SVGTransformList.
   *
   * To simplify the code we just have this one method for obtaining both
   * baseVal and animVal internal lists. This means that animVal lists don't
   * get const protection, but our setter methods guard against changing
   * animVal lists.
   */
  SVGTransformList& InternalList() const;

  /// Returns the SVGTransform at aIndex, creating it if necessary.
  already_AddRefed<dom::SVGTransform> GetItemAt(uint32_t aIndex);

  void MaybeInsertNullInAnimValListAt(uint32_t aIndex);
  void MaybeRemoveItemFromAnimValListAt(uint32_t aIndex);

  // Weak refs to our SVGTransform items. The items are friends and take care
  // of clearing our pointer to them when they die.
  FallibleTArray<dom::SVGTransform*> mItems;

  RefPtr<dom::SVGAnimatedTransformList> mAList;
};

} // namespace mozilla

#endif // MOZILLA_DOMSVGTRANSFORMLIST_H__