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diff --git a/dom/svg/SVGLengthList.h b/dom/svg/SVGLengthList.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_SVGLENGTHLIST_H__
+#define MOZILLA_SVGLENGTHLIST_H__
+
+#include "nsCOMPtr.h"
+#include "nsDebug.h"
+#include "nsIContent.h"
+#include "nsINode.h"
+#include "nsIWeakReferenceUtils.h"
+#include "nsSVGElement.h"
+#include "nsTArray.h"
+#include "SVGLength.h"
+
+namespace mozilla {
+
+/**
+ * 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 DOMSVGLengthList.
+ */
+class SVGLengthList
+{
+ friend class SVGAnimatedLengthList;
+ friend class DOMSVGLengthList;
+ friend class DOMSVGLength;
+
+public:
+
+ SVGLengthList(){}
+ ~SVGLengthList(){}
+
+ // 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 mLengths.IsEmpty();
+ }
+
+ uint32_t Length() const {
+ return mLengths.Length();
+ }
+
+ const SVGLength& operator[](uint32_t aIndex) const {
+ return mLengths[aIndex];
+ }
+
+ bool operator==(const SVGLengthList& rhs) const;
+
+ bool SetCapacity(uint32_t size) {
+ return mLengths.SetCapacity(size, fallible);
+ }
+
+ void Compact() {
+ mLengths.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
+ // SVGAnimatedLengthList 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 SVGLengthList& rhs);
+
+ SVGLength& operator[](uint32_t aIndex) {
+ return mLengths[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 mLengths.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() {
+ mLengths.Clear();
+ }
+
+ bool InsertItem(uint32_t aIndex, const SVGLength &aLength) {
+ if (aIndex >= mLengths.Length()) aIndex = mLengths.Length();
+ return !!mLengths.InsertElementAt(aIndex, aLength, fallible);
+ }
+
+ void ReplaceItem(uint32_t aIndex, const SVGLength &aLength) {
+ MOZ_ASSERT(aIndex < mLengths.Length(),
+ "DOM wrapper caller should have raised INDEX_SIZE_ERR");
+ mLengths[aIndex] = aLength;
+ }
+
+ void RemoveItem(uint32_t aIndex) {
+ MOZ_ASSERT(aIndex < mLengths.Length(),
+ "DOM wrapper caller should have raised INDEX_SIZE_ERR");
+ mLengths.RemoveElementAt(aIndex);
+ }
+
+ bool AppendItem(SVGLength aLength) {
+ return !!mLengths.AppendElement(aLength, fallible);
+ }
+
+protected:
+
+ /* Rationale for using nsTArray<SVGLength> and not nsTArray<SVGLength, 1>:
+ *
+ * It might seem like we should use AutoTArray<SVGLength, 1> instead of
+ * nsTArray<SVGLength>. That would preallocate space for one SVGLength and
+ * avoid an extra memory allocation call in the common case of the 'x'
+ * and 'y' attributes each containing a single length (and the 'dx' and 'dy'
+ * attributes being empty). However, consider this:
+ *
+ * An empty nsTArray uses sizeof(Header*). An AutoTArray<class E,
+ * uint32_t N> on the other hand uses sizeof(Header*) +
+ * (2 * sizeof(uint32_t)) + (N * sizeof(E)), which for one SVGLength is
+ * sizeof(Header*) + 16 bytes.
+ *
+ * Now consider that for text elements we have four length list attributes
+ * (x, y, dx, dy), each of which can have a baseVal and an animVal list. If
+ * we were to go the AutoTArray<SVGLength, 1> route for each of these, we'd
+ * end up using at least 160 bytes for these four attributes alone, even
+ * though we only need storage for two SVGLengths (16 bytes) in the common
+ * case!!
+ *
+ * A compromise might be to template SVGLengthList to allow
+ * SVGAnimatedLengthList to preallocate space for an SVGLength for the
+ * baseVal lists only, and that would cut the space used by the four
+ * attributes to 96 bytes. Taking that even further and templating
+ * SVGAnimatedLengthList too in order to only use nsTArray for 'dx' and 'dy'
+ * would reduce the storage further to 64 bytes. Having different types makes
+ * things more complicated for code that needs to look at the lists though.
+ * In fact it also makes things more complicated when it comes to storing the
+ * lists.
+ *
+ * It may be worth considering using nsAttrValue for length lists instead of
+ * storing them directly on the element.
+ */
+ FallibleTArray<SVGLength> mLengths;
+};
+
+
+/**
+ * This SVGLengthList subclass is for SVGLengthListSMILType which needs to know
+ * which element and attribute a length list belongs to so that it can convert
+ * between unit types if necessary.
+ */
+class SVGLengthListAndInfo : public SVGLengthList
+{
+public:
+
+ SVGLengthListAndInfo()
+ : mElement(nullptr)
+ , mAxis(0)
+ , mCanZeroPadList(false)
+ {}
+
+ SVGLengthListAndInfo(nsSVGElement *aElement, uint8_t aAxis, bool aCanZeroPadList)
+ : mElement(do_GetWeakReference(static_cast<nsINode*>(aElement)))
+ , mAxis(aAxis)
+ , mCanZeroPadList(aCanZeroPadList)
+ {}
+
+ void SetInfo(nsSVGElement *aElement, uint8_t aAxis, bool aCanZeroPadList) {
+ mElement = do_GetWeakReference(static_cast<nsINode*>(aElement));
+ mAxis = aAxis;
+ mCanZeroPadList = aCanZeroPadList;
+ }
+
+ nsSVGElement* Element() const {
+ nsCOMPtr<nsIContent> e = do_QueryReferent(mElement);
+ return static_cast<nsSVGElement*>(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
+ * SVGLengthListSMILType::Init() has been changed with a SetInfo() call.
+ */
+ bool IsIdentity() const {
+ if (!mElement) {
+ MOZ_ASSERT(IsEmpty(), "target element propagation failure");
+ return true;
+ }
+ return false;
+ }
+
+ uint8_t Axis() const {
+ MOZ_ASSERT(mElement, "Axis() isn't valid");
+ return mAxis;
+ }
+
+ /**
+ * The value returned by this function depends on which attribute this object
+ * is for. If appending a list of zeros to the attribute's list would have no
+ * effect on rendering (e.g. the attributes 'dx' and 'dy' on <text>), then
+ * this method will return true. If appending a list of zeros to the
+ * attribute's list could *change* rendering (e.g. the attributes 'x' and 'y'
+ * on <text>), then this method will return false.
+ *
+ * The reason that this method exists is because the SMIL code needs to know
+ * what to do when it's asked to animate between lists of different length.
+ * If this method returns true, then it can zero pad the short list before
+ * carrying out its operations. However, in the case of the 'x' and 'y'
+ * attributes on <text>, zero would mean "zero in the current coordinate
+ * system", whereas we would want to pad shorter lists with the coordinates
+ * at which glyphs would otherwise lie, which is almost certainly not zero!
+ * Animating from/to zeros in this case would produce terrible results.
+ *
+ * Currently SVGLengthListSMILType simply disallows (drops) animation between
+ * lists of different length if it can't zero pad a list. This is to avoid
+ * having some authors create content that depends on undesirable behaviour
+ * (which would make it difficult for us to fix the behavior in future). At
+ * some point it would be nice to implement a callback to allow this code to
+ * determine padding values for lists that can't be zero padded. See
+ * https://bugzilla.mozilla.org/show_bug.cgi?id=573431
+ */
+ bool CanZeroPadList() const {
+ //NS_ASSERTION(mElement, "CanZeroPadList() isn't valid");
+ return mCanZeroPadList;
+ }
+
+ // For the SMIL code. See comment in SVGLengthListSMILType::Add().
+ void SetCanZeroPadList(bool aCanZeroPadList) {
+ mCanZeroPadList = aCanZeroPadList;
+ }
+
+ nsresult CopyFrom(const SVGLengthListAndInfo& rhs) {
+ mElement = rhs.mElement;
+ mAxis = rhs.mAxis;
+ mCanZeroPadList = rhs.mCanZeroPadList;
+ return SVGLengthList::CopyFrom(rhs);
+ }
+
+ // Instances of this special subclass do not have DOM wrappers that we need
+ // to worry about keeping in sync, so it's safe to expose any hidden base
+ // class methods required by the SMIL code, as we do below.
+
+ /**
+ * Exposed so that SVGLengthList baseVals can be copied to
+ * SVGLengthListAndInfo objects. Note that callers should also call
+ * SetInfo() when using this method!
+ */
+ nsresult CopyFrom(const SVGLengthList& rhs) {
+ return SVGLengthList::CopyFrom(rhs);
+ }
+ const SVGLength& operator[](uint32_t aIndex) const {
+ return SVGLengthList::operator[](aIndex);
+ }
+ SVGLength& operator[](uint32_t aIndex) {
+ return SVGLengthList::operator[](aIndex);
+ }
+ bool SetLength(uint32_t aNumberOfItems) {
+ return SVGLengthList::SetLength(aNumberOfItems);
+ }
+
+private:
+ // We must keep a weak reference to our element because we may belong to a
+ // cached baseVal nsSMILValue. 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;
+ uint8_t mAxis;
+ bool mCanZeroPadList;
+};
+
+
+/**
+ * This class wraps SVGLengthList objects to allow frame consumers to process
+ * SVGLengthList objects as if they were simply a list of float values in user
+ * units. When consumers request the value at a given index, this class
+ * dynamically converts the corresponding SVGLength from its actual unit and
+ * returns its value in user units.
+ *
+ * Consumers should check that the user unit values returned are finite. Even
+ * if the consumer can guarantee the list's element has a valid viewport
+ * ancestor to resolve percentage units against, and a valid presContext and
+ * styleContext to resolve absolute and em/ex units against, unit conversions
+ * could still overflow. In that case the value returned will be
+ * numeric_limits<float>::quiet_NaN().
+ */
+class MOZ_STACK_CLASS SVGUserUnitList
+{
+public:
+
+ SVGUserUnitList()
+ : mList(nullptr)
+ {}
+
+ void Init(const SVGLengthList *aList, nsSVGElement *aElement, uint8_t aAxis) {
+ mList = aList;
+ mElement = aElement;
+ mAxis = aAxis;
+ }
+
+ void Clear() {
+ mList = nullptr;
+ }
+
+ bool IsEmpty() const {
+ return !mList || mList->IsEmpty();
+ }
+
+ uint32_t Length() const {
+ return mList ? mList->Length() : 0;
+ }
+
+ /// This may return a non-finite value
+ float operator[](uint32_t aIndex) const {
+ return (*mList)[aIndex].GetValueInUserUnits(mElement, mAxis);
+ }
+
+ bool HasPercentageValueAt(uint32_t aIndex) const {
+ const SVGLength& length = (*mList)[aIndex];
+ return length.GetUnit() == nsIDOMSVGLength::SVG_LENGTHTYPE_PERCENTAGE;
+ }
+
+private:
+ const SVGLengthList *mList;
+ nsSVGElement *mElement;
+ uint8_t mAxis;
+};
+
+} // namespace mozilla
+
+#endif // MOZILLA_SVGLENGTHLIST_H__