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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 "nsIDOMSVGLength.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 nsIDOMSVGLength,
+ 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)
+ NS_DECL_NSIDOMSVGLENGTH
+
+ /**
+ * 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);
+ // The XPCOM GetValueAsString is good
+ 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 static_cast<nsIDOMSVGElement*> (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__