tor-browser

SVGPointList.h (7113B)

---

/* -*- 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 DOM_SVG_SVGPOINTLIST_H_
#define DOM_SVG_SVGPOINTLIST_H_

#include <string.h>

#include "SVGElement.h"
#include "SVGPoint.h"
#include "nsCOMPtr.h"
#include "nsDebug.h"
#include "nsIContent.h"
#include "nsINode.h"
#include "nsIWeakReferenceUtils.h"
#include "nsTArray.h"

namespace mozilla {

namespace dom {
class DOMSVGPoint;
class DOMSVGPointList;
}  // namespace dom

/**
* 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 DOMSVGPointList.
*/
class SVGPointList {
 friend class SVGAnimatedPointList;
 friend class dom::DOMSVGPointList;
 friend class dom::DOMSVGPoint;

public:
 SVGPointList() = default;
 ~SVGPointList() = default;

 SVGPointList& operator=(const SVGPointList& aOther) {
   mItems.ClearAndRetainStorage();
   // Best-effort, really.
   (void)mItems.AppendElements(aOther.mItems, fallible);
   return *this;
 }

 SVGPointList(const SVGPointList& aOther) { *this = aOther; }

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

 bool operator==(const SVGPointList& rhs) const {
   // memcmp can be faster than |mItems == rhs.mItems|
   return mItems.Length() == rhs.mItems.Length() &&
          memcmp(mItems.Elements(), rhs.mItems.Elements(),
                 mItems.Length() * sizeof(SVGPoint)) == 0;
 }

 bool SetCapacity(uint32_t aSize) {
   return mItems.SetCapacity(aSize, fallible);
 }

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

 // 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
 // SVGAnimatedPointList and having that class act as an intermediary so it
 // can take care of keeping DOM wrappers in sync.

protected:
 /**
  * This may fail on OOM if the internal capacity needs to be increased, in
  * which case the list will be left unmodified.
  */
 nsresult CopyFrom(const SVGPointList& rhs);
 void SwapWith(SVGPointList& aRhs) { mItems.SwapElements(aRhs.mItems); }

 SVGPoint& 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, fallible);
 }

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 SVGPoint& aPoint) {
   if (aIndex >= mItems.Length()) {
     aIndex = mItems.Length();
   }
   return !!mItems.InsertElementAt(aIndex, aPoint, fallible);
 }

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

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

 bool AppendItem(SVGPoint aPoint) {
   return !!mItems.AppendElement(aPoint, fallible);
 }

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

/**
* This SVGPointList subclass is for SVGPointListSMILType which needs a
* mutable version of SVGPointList. Instances of this class do not have
* DOM wrappers that need to be kept in sync, so we can safely expose any
* protected base class methods required by the SMIL code.
*
* This class contains a strong reference to the element that instances of
* this class are being used to animate. This is because the SMIL code stores
* instances of this class in SMILValue objects, some of which are cached.
* Holding a strong reference to the element here prevents the element from
* disappearing out from under the SMIL code unexpectedly.
*/
class SVGPointListAndInfo : public SVGPointList {
public:
 explicit SVGPointListAndInfo(dom::SVGElement* aElement = nullptr)
     : mElement(do_GetWeakReference(static_cast<nsINode*>(aElement))) {}

 void SetInfo(dom::SVGElement* aElement) {
   mElement = do_GetWeakReference(static_cast<nsINode*>(aElement));
 }

 dom::SVGElement* Element() const {
   nsCOMPtr<nsIContent> e = do_QueryReferent(mElement);
   return static_cast<dom::SVGElement*>(e.get());
 }

 /**
  * Returns true if this object is an "identity" value, from the perspective
  * of SMIL. In other words, returns true until the initial value set up in
  * SVGPointListSMILType::InitValue() has been changed with a SetInfo() call.
  */
 bool IsIdentity() const {
   if (!mElement) {
     MOZ_ASSERT(IsEmpty(), "target element propagation failure");
     return true;
   }
   return false;
 }

 nsresult CopyFrom(const SVGPointListAndInfo& rhs) {
   mElement = rhs.mElement;
   return SVGPointList::CopyFrom(rhs);
 }

 /**
  * Exposed so that SVGPointList baseVals can be copied to
  * SVGPointListAndInfo objects. Note that callers should also call
  * SetElement() when using this method!
  */
 nsresult CopyFrom(const SVGPointList& rhs) {
   return SVGPointList::CopyFrom(rhs);
 }
 const SVGPoint& operator[](uint32_t aIndex) const {
   return SVGPointList::operator[](aIndex);
 }
 SVGPoint& operator[](uint32_t aIndex) {
   return SVGPointList::operator[](aIndex);
 }
 bool SetLength(uint32_t aNumberOfItems) {
   return SVGPointList::SetLength(aNumberOfItems);
 }

private:
 // We must keep a weak reference to our element because we may belong to a
 // cached baseVal SMILValue. See the comments starting at:
 // https://bugzilla.mozilla.org/show_bug.cgi?id=515116#c15
 // See also https://bugzilla.mozilla.org/show_bug.cgi?id=653497
 nsWeakPtr mElement;
};

}  // namespace mozilla

#endif  // DOM_SVG_SVGPOINTLIST_H_