gecko-dev/dom/svg/SVGTransformList.h

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ :
 * 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_SVGTRANSFORMLIST_H__
#define MOZILLA_SVGTRANSFORMLIST_H__

#include "gfxMatrix.h"
#include "nsDebug.h"
#include "nsTArray.h"
#include "nsSVGTransform.h"

namespace mozilla {

namespace dom {
class SVGTransform;
}

/**
 * ATTENTION! WARNING! WATCH OUT!!
 *
 * Consumers that modify objects of this type absolutely MUST keep the DOM
 * wrappers for those lists (if any) in sync!! That's why this class is so
 * locked down.
 *
 * The DOM wrapper class for this class is DOMSVGTransformList.
 */
class SVGTransformList
{
  friend class nsSVGAnimatedTransformList;
  friend class DOMSVGTransformList;
  friend class dom::SVGTransform;

public:
  SVGTransformList() {}
  ~SVGTransformList() {}

  // Only methods that don't make/permit modification to this list are public.
  // Only our friend classes can access methods that may change us.

  /// This may return an incomplete string on OOM, but that's acceptable.
  void GetValueAsString(nsAString& aValue) const;

  bool IsEmpty() const {
    return mItems.IsEmpty();
  }

  uint32_t Length() const {
    return mItems.Length();
  }

  const nsSVGTransform& operator[](uint32_t aIndex) const {
    return mItems[aIndex];
  }

  bool operator==(const SVGTransformList& rhs) const {
    return mItems == rhs.mItems;
  }

  bool SetCapacity(uint32_t size) {
    return mItems.SetCapacity(size);
  }

  void Compact() {
    mItems.Compact();
  }

  gfxMatrix GetConsolidationMatrix() const;

  // Access to methods that can modify objects of this type is deliberately
  // limited. This is to reduce the chances of someone modifying objects of
  // this type without taking the necessary steps to keep DOM wrappers in sync.
  // If you need wider access to these methods, consider adding a method to
  // SVGAnimatedTransformList and having that class act as an intermediary so it
  // can take care of keeping DOM wrappers in sync.

protected:

  /**
   * These may fail on OOM if the internal capacity needs to be increased, in
   * which case the list will be left unmodified.
   */
  nsresult CopyFrom(const SVGTransformList& rhs);
  nsresult CopyFrom(const nsTArray<nsSVGTransform>& aTransformArray);

  nsSVGTransform& operator[](uint32_t aIndex) {
    return mItems[aIndex];
  }

  /**
   * This may fail (return false) on OOM if the internal capacity is being
   * increased, in which case the list will be left unmodified.
   */
  bool SetLength(uint32_t aNumberOfItems) {
    return mItems.SetLength(aNumberOfItems);
  }

private:

  // Marking the following private only serves to show which methods are only
  // used by our friend classes (as opposed to our subclasses) - it doesn't
  // really provide additional safety.

  nsresult SetValueFromString(const nsAString& aValue);

  void Clear() {
    mItems.Clear();
  }

  bool InsertItem(uint32_t aIndex, const nsSVGTransform& aTransform) {
    if (aIndex >= mItems.Length()) {
      aIndex = mItems.Length();
    }
    return !!mItems.InsertElementAt(aIndex, aTransform);
  }

  void ReplaceItem(uint32_t aIndex, const nsSVGTransform& aTransform) {
    MOZ_ASSERT(aIndex < mItems.Length(),
               "DOM wrapper caller should have raised INDEX_SIZE_ERR");
    mItems[aIndex] = aTransform;
  }

  void RemoveItem(uint32_t aIndex) {
    MOZ_ASSERT(aIndex < mItems.Length(),
               "DOM wrapper caller should have raised INDEX_SIZE_ERR");
    mItems.RemoveElementAt(aIndex);
  }

  bool AppendItem(const nsSVGTransform& aTransform) {
    return !!mItems.AppendElement(aTransform);
  }

protected:
  /*
   * See SVGLengthList for the rationale for using FallibleTArray<nsSVGTransform>
   * instead of FallibleTArray<nsSVGTransform, 1>.
   */
  FallibleTArray<nsSVGTransform> mItems;
};

} // namespace mozilla

#endif // MOZILLA_SVGTRANSFORMLIST_H__