gecko-dev/dom/svg/DOMSVGLength.h

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/* -*- 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_DOMSVGLENGTH_H__
#define MOZILLA_DOMSVGLENGTH_H__
#include "DOMSVGLengthList.h"
#include "nsCycleCollectionParticipant.h"
#include "nsDebug.h"
#include "nsTArray.h"
#include "SVGLength.h"
#include "mozilla/Attributes.h"
#include "nsWrapperCache.h"
class nsSVGElement;
// We make DOMSVGLength a pseudo-interface to allow us to QI to it in order to
// check that the objects that scripts pass to DOMSVGLengthList methods are our
// *native* length objects.
//
// {A8468350-7F7B-4976-9A7E-3765A1DADF9A}
#define MOZILLA_DOMSVGLENGTH_IID \
{ 0xA8468350, 0x7F7B, 0x4976, { 0x9A, 0x7E, 0x37, 0x65, 0xA1, 0xDA, 0xDF, 0x9A } }
#define MOZ_SVG_LIST_INDEX_BIT_COUNT 22 // supports > 4 million list items
namespace mozilla {
class ErrorResult;
/**
* Class DOMSVGLength
*
* This class creates the DOM objects that wrap internal SVGLength objects that
* are in an SVGLengthList. It is also used to create the objects returned by
* SVGSVGElement.createSVGLength().
*
* For the DOM wrapper classes for non-list SVGLength, see nsSVGLength2.h.
*
* See the architecture comment in DOMSVGAnimatedLengthList.h.
*
* This class is strongly intertwined with DOMSVGAnimatedLengthList and
* DOMSVGLengthList. We are a friend of DOMSVGLengthList, and are responsible
* for nulling out our DOMSVGLengthList's pointer to us when we die, making it
* a real weak pointer.
*
* When objects of this type are in a DOMSVGLengthList they belong to an
* attribute. While they belong to an attribute, the objects' values come from
* their corresponding internal SVGLength objects in the internal SVGLengthList
* objects for the attribute. Getting and setting values of a DOMSVGLength
* requires reading and writing to its internal SVGLength. However, if the
* DOMSVGLength is detached from its DOMSVGLengthList then it first makes a
* copy of its internal SVGLength's value and unit so that it doesn't appear to
* "lose" its value from script's perspective on being removed from the list.
* This means that these DOM tearoffs have space to store these values, even
* though they're not used in the common case.
*
* Objects of this type are also used to reflect the baseVal and animVal of
* a single, non-list SVGLength attribute. Getting and settings values of the
* DOMSVGLength in this case requires reading and writing to the corresponding
* nsSVGLength2 object.
*
* This class also stores its current list index, attribute enum, and whether
* it belongs to a baseVal or animVal list. This is so that objects of this
* type can find their corresponding internal SVGLength.
*
* To use these classes for <length> attributes as well as <list-of-length>
* attributes, we would need to take a bit from mListIndex and use that to
* indicate whether the object belongs to a list or non-list attribute, then
* if-else as appropriate. The bug for doing that work is:
* https://bugzilla.mozilla.org/show_bug.cgi?id=571734
*/
class DOMSVGLength final : public nsISupports,
public nsWrapperCache
{
friend class AutoChangeLengthNotifier;
/**
* Ctor for creating the object returned by nsSVGLength2::ToDOMBaseVal/ToDOMAnimVal
*/
DOMSVGLength(nsSVGLength2* aVal, nsSVGElement* aSVGElement, bool aAnimVal);
~DOMSVGLength();
public:
NS_DECLARE_STATIC_IID_ACCESSOR(MOZILLA_DOMSVGLENGTH_IID)
NS_DECL_CYCLE_COLLECTING_ISUPPORTS
NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(DOMSVGLength)
/**
* Generic ctor for DOMSVGLength objects that are created for an attribute.
*/
DOMSVGLength(DOMSVGLengthList *aList,
uint8_t aAttrEnum,
uint32_t aListIndex,
bool aIsAnimValItem);
/**
* Ctor for creating the objects returned by SVGSVGElement.createSVGLength(),
* which do not initially belong to an attribute.
*/
DOMSVGLength();
static already_AddRefed<DOMSVGLength> GetTearOff(nsSVGLength2* aVal,
nsSVGElement* aSVGElement,
bool aAnimVal);
/**
* Create an unowned copy of a length that is owned or is reflecting a single
* attribute. The caller is responsible for the first AddRef().
*/
DOMSVGLength* Copy();
bool IsInList() const {
return !!mList;
}
/**
* In future, if this class is used for non-list lengths, this will be
* different to IsInList().
*/
bool HasOwner() const {
return !!mList;
}
/**
* Returns whether this length object is reflecting a single SVG element
* attribute. This includes the baseVal or animVal of SVGRectElement.x, for
* example, but not an item in an SVGLengthList, such as those in the
* baseVal or animVal of SVGTextElement.x.
*/
bool IsReflectingAttribute() const {
return mVal;
}
/**
* This method is called to notify this DOM object that it is being inserted
* into a list, and give it the information it needs as a result.
*
* This object MUST NOT already belong to a list when this method is called.
* That's not to say that script can't move these DOM objects between
* lists - it can - it's just that the logic to handle that (and send out
* the necessary notifications) is located elsewhere (in DOMSVGLengthList).)
*/
void InsertingIntoList(DOMSVGLengthList *aList,
uint8_t aAttrEnum,
uint32_t aListIndex,
bool aIsAnimValItem);
static uint32_t MaxListIndex() {
return (1U << MOZ_SVG_LIST_INDEX_BIT_COUNT) - 1;
}
/// This method is called to notify this object that its list index changed.
void UpdateListIndex(uint32_t aListIndex) {
mListIndex = aListIndex;
}
/**
* This method is called to notify this DOM object that it is about to be
* removed from its current DOM list so that it can first make a copy of its
* internal counterpart's values. (If it didn't do this, then it would
* "lose" its value on being removed.)
*/
void RemovingFromList();
SVGLength ToSVGLength();
// WebIDL
uint16_t UnitType();
float GetValue(ErrorResult& aRv);
void SetValue(float aValue, ErrorResult& aRv);
float ValueInSpecifiedUnits();
void SetValueInSpecifiedUnits(float aValue, ErrorResult& aRv);
void GetValueAsString(nsAString& aValue);
void SetValueAsString(const nsAString& aValue, ErrorResult& aRv);
void NewValueSpecifiedUnits(uint16_t aUnit, float aValue,
ErrorResult& aRv);
void ConvertToSpecifiedUnits(uint16_t aUnit, ErrorResult& aRv);
nsISupports* GetParentObject() const {
auto svgElement = mList ? Element() : mSVGElement.get();
return svgElement;
}
JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;
private:
nsSVGElement* Element() const {
return mList->Element();
}
uint8_t AttrEnum() const {
return mAttrEnum;
}
/**
* Get the axis that this length lies along. This method must only be called
* when this object is associated with an element (HasOwner() returns true).
*/
uint8_t Axis() const {
return mList->Axis();
}
/**
* Get a reference to the internal SVGLength list item that this DOM wrapper
* object currently wraps.
*
* To simplify the code we just have this one method for obtaining both
* baseVal and animVal internal items. This means that animVal items don't
* get const protection, but then our setter methods guard against changing
* animVal items.
*/
SVGLength& InternalItem();
#ifdef DEBUG
bool IndexIsValid();
#endif
/**
* Clears soon-to-be-invalid weak references in external objects that were
* set up during the creation of this object. This should be called during
* destruction and during cycle collection.
*/
void CleanupWeakRefs();
RefPtr<DOMSVGLengthList> mList;
// Bounds for the following are checked in the ctor, so be sure to update
// that if you change the capacity of any of the following.
uint32_t mListIndex:MOZ_SVG_LIST_INDEX_BIT_COUNT;
uint32_t mAttrEnum:4; // supports up to 16 attributes
uint32_t mIsAnimValItem:1;
// The following members are only used when we're not in a list:
uint32_t mUnit:5; // can handle 31 units (the 10 SVG 1.1 units + rem, vw, vh, wm, calc + future additions)
float mValue;
// The following members are only used when we have an nsSVGLength2
nsSVGLength2* mVal; // kept alive because it belongs to mSVGElement
RefPtr<nsSVGElement> mSVGElement;
};
NS_DEFINE_STATIC_IID_ACCESSOR(DOMSVGLength, MOZILLA_DOMSVGLENGTH_IID)
} // namespace mozilla
#undef MOZ_SVG_LIST_INDEX_BIT_COUNT
#endif // MOZILLA_DOMSVGLENGTH_H__