gecko-dev/dom/svg/nsSVGAnimatedTransformList.h

/* -*- 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_SVGANIMATEDTRANSFORMLIST_H__
#define MOZILLA_SVGANIMATEDTRANSFORMLIST_H__

#include "mozilla/Attributes.h"
#include "nsAutoPtr.h"
#include "nsISMILAttr.h"
#include "SVGTransformList.h"

class nsIAtom;
class nsSMILValue;
class nsSVGElement;

namespace mozilla {

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

/**
 * Class nsSVGAnimatedTransformList
 *
 * This class is very different to the SVG DOM interface of the same name found
 * in the SVG specification. This is a lightweight internal class - see
 * SVGAnimatedTransformList for the heavier DOM class that wraps instances of
 * this class and implements the SVG specification's SVGAnimatedTransformList
 * DOM interface.
 *
 * Except where noted otherwise, this class' methods take care of keeping the
 * appropriate DOM wrappers in sync (see the comment in
 * SVGAnimatedTransformList::InternalBaseValListWillChangeTo) so that their
 * consumers don't need to concern themselves with that.
 */
class nsSVGAnimatedTransformList
{
  // friends so that they can get write access to mBaseVal
  friend class dom::SVGTransform;
  friend class DOMSVGTransformList;

public:
  nsSVGAnimatedTransformList()
    : mIsAttrSet(false),
      mHadTransformBeforeLastBaseValChange(false) { }

  /**
   * Because it's so important that mBaseVal and its DOMSVGTransformList wrapper
   * (if any) be kept in sync (see the comment in
   * SVGAnimatedTransformList::InternalBaseValListWillChangeTo), this method
   * returns a const reference. Only our friend classes may get mutable
   * references to mBaseVal.
   */
  const SVGTransformList& GetBaseValue() const {
    return mBaseVal;
  }

  nsresult SetBaseValue(const SVGTransformList& aValue);

  nsresult SetBaseValueString(const nsAString& aValue);

  void ClearBaseValue();

  const SVGTransformList& GetAnimValue() const {
    return mAnimVal ? *mAnimVal : mBaseVal;
  }

  nsresult SetAnimValue(const SVGTransformList& aNewAnimValue,
                        nsSVGElement *aElement);

  void ClearAnimValue(nsSVGElement *aElement);

  /**
   * Returns true if the corresponding transform attribute is set (or animated)
   * to a valid value. Unlike HasTransform it will return true for an empty
   * transform.
   */
  bool IsExplicitlySet() const;

  /**
   * Returns true if the corresponding transform attribute is set (or animated)
   * to a valid value, such that we have at least one transform in our list.
   * Returns false otherwise (e.g. if the transform attribute is missing or empty
   * or invalid).
   */
  bool HasTransform() const
    { return (mAnimVal && !mAnimVal->IsEmpty()) || !mBaseVal.IsEmpty(); }

  bool IsAnimating() const {
    return !!mAnimVal;
  }

  /**
   * Returns true iff "HasTransform" returned true just before our most recent
   * SetBaseValue/SetBaseValueString/ClearBaseValue change.
   *
   * (This is used as part of an optimization in
   * SVGTransformableElement::GetAttributeChangeHint. That function reports an
   * inexpensive nsChangeHint when a transform has just modified -- but this
   * accessor lets it detect cases where the "modification" is actually adding
   * a transform where we previously had none. These cases require a more
   * thorough nsChangeHint.)
   */
  bool HadTransformBeforeLastBaseValChange() const {
    return mHadTransformBeforeLastBaseValChange;
  }

  /// Callers own the returned nsISMILAttr
  nsISMILAttr* ToSMILAttr(nsSVGElement* aSVGElement);

private:

  // mAnimVal is a pointer to allow us to determine if we're being animated or
  // not. Making it a non-pointer member and using mAnimVal.IsEmpty() to check
  // if we're animating is not an option, since that would break animation *to*
  // the empty string (<set to="">).

  SVGTransformList mBaseVal;
  nsAutoPtr<SVGTransformList> mAnimVal;
  bool mIsAttrSet;
   // (See documentation for accessor, HadTransformBeforeLastBaseValChange.)
  bool mHadTransformBeforeLastBaseValChange;

  struct SMILAnimatedTransformList : public nsISMILAttr
  {
  public:
    SMILAnimatedTransformList(nsSVGAnimatedTransformList* aVal,
                              nsSVGElement* aSVGElement)
      : mVal(aVal)
      , mElement(aSVGElement)
    {}

    // nsISMILAttr methods
    virtual nsresult ValueFromString(const nsAString& aStr,
                                     const dom::SVGAnimationElement* aSrcElement,
                                     nsSMILValue& aValue,
                                     bool& aPreventCachingOfSandwich) const override;
    virtual nsSMILValue GetBaseValue() const override;
    virtual void ClearAnimValue() override;
    virtual nsresult SetAnimValue(const nsSMILValue& aValue) override;

  protected:
    static void ParseValue(const nsAString& aSpec,
                           const nsIAtom* aTransformType,
                           nsSMILValue& aResult);
    static int32_t ParseParameterList(const nsAString& aSpec, float* aVars,
                                      int32_t aNVars);

    // These will stay alive because a nsISMILAttr only lives as long
    // as the Compositing step, and DOM elements don't get a chance to
    // die during that.
    nsSVGAnimatedTransformList* mVal;
    nsSVGElement* mElement;
  };
};

} // namespace mozilla

#endif // MOZILLA_SVGANIMATEDTRANSFORMLIST_H__