import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

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 "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__