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Diffstat (limited to 'dom/svg/SVGPathData.h')
| -rw-r--r-- | dom/svg/SVGPathData.h | 320 |
1 files changed, 320 insertions, 0 deletions
diff --git a/dom/svg/SVGPathData.h b/dom/svg/SVGPathData.h new file mode 100644 index 0000000000..4aa60de3cb --- /dev/null +++ b/dom/svg/SVGPathData.h @@ -0,0 +1,320 @@ +/* -*- 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_SVGPATHDATA_H_ +#define DOM_SVG_SVGPATHDATA_H_ + +#include "nsCOMPtr.h" +#include "nsDebug.h" +#include "nsIContent.h" +#include "nsINode.h" +#include "nsIWeakReferenceUtils.h" +#include "mozilla/dom/SVGElement.h" +#include "mozilla/gfx/2D.h" +#include "mozilla/gfx/Types.h" +#include "mozilla/MemoryReporting.h" +#include "mozilla/RefPtr.h" +#include "nsTArray.h" + +#include <string.h> + +namespace mozilla { + +struct StylePathCommand; +struct SVGMark; +enum class StyleStrokeLinecap : uint8_t; + +class SVGPathDataParser; // IWYU pragma: keep + +namespace dom { +class DOMSVGPathSeg; +class DOMSVGPathSegList; +} // 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 DOMSVGPathSegList. + * + * This class is not called |class SVGPathSegList| for one very good reason; + * this class does not provide a list of "SVGPathSeg" items, it provides an + * array of floats into which path segments are encoded. See the paragraphs + * that follow for why. Note that the Length() method returns the number of + * floats in our array, not the number of encoded segments, and the index + * operator indexes floats in the array, not segments. If this class were + * called SVGPathSegList the names of these methods would be very misleading. + * + * The reason this class is designed in this way is because there are many + * different types of path segment, each taking a different numbers of + * arguments. We want to store the segments in an nsTArray to avoid individual + * allocations for each item, but the different size of segments means we can't + * have one single segment type for the nsTArray (not without using a space + * wasteful union or something similar). Since the internal code does not need + * to index into the list (the DOM wrapper does, but it handles that itself) + * the obvious solution is to have the items in this class take up variable + * width and have the internal code iterate over these lists rather than index + * into them. + * + * Implementing indexing to segments with O(1) performance would require us to + * allocate and maintain a separate segment index table (keeping that table in + * sync when items are inserted or removed from the list). So long as the + * internal code doesn't require indexing to segments, we can avoid that + * overhead and additional complexity. + * + * Segment encoding: the first float in the encoding of a segment contains the + * segment's type. The segment's type is encoded to/decoded from this float + * using the static methods SVGPathSegUtils::EncodeType(uint32_t)/ + * SVGPathSegUtils::DecodeType(float). If the path segment type in question + * takes any arguments then these follow the first float, and are in the same + * order as they are given in a <path> element's 'd' attribute (NOT in the + * order of the createSVGPathSegXxx() methods' arguments from the SVG DOM + * interface SVGPathElement, which are different...grr). Consumers can use + * SVGPathSegUtils::ArgCountForType(type) to determine how many arguments + * there are (if any), and thus where the current encoded segment ends, and + * where the next segment (if any) begins. + */ +class SVGPathData { + friend class SVGAnimatedPathSegList; + friend class dom::DOMSVGPathSeg; + friend class dom::DOMSVGPathSegList; + friend class SVGPathDataParser; + // SVGPathDataParser will not keep wrappers in sync, so consumers + // are responsible for that! + + using DrawTarget = gfx::DrawTarget; + using Path = gfx::Path; + using PathBuilder = gfx::PathBuilder; + using FillRule = gfx::FillRule; + using Float = gfx::Float; + using CapStyle = gfx::CapStyle; + + public: + using const_iterator = const float*; + + SVGPathData() = default; + ~SVGPathData() = default; + + SVGPathData& operator=(const SVGPathData& aOther) { + mData.ClearAndRetainStorage(); + // Best-effort, really. + Unused << mData.AppendElements(aOther.mData, fallible); + return *this; + } + + SVGPathData(const SVGPathData& 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 mData.IsEmpty(); } + +#ifdef DEBUG + /** + * This method iterates over the encoded segment data and counts the number + * of segments we currently have. + */ + uint32_t CountItems() const; +#endif + + /** + * Returns the number of *floats* in the encoding array, and NOT the number + * of segments encoded in this object. (For that, see CountItems() above.) + */ + uint32_t Length() const { return mData.Length(); } + + const nsTArray<float>& RawData() const { return mData; } + + const float& operator[](uint32_t aIndex) const { return mData[aIndex]; } + + // Used by SMILCompositor to check if the cached base val is out of date + bool operator==(const SVGPathData& rhs) const { + // We use memcmp so that we don't need to worry that the data encoded in + // the first float may have the same bit pattern as a NaN. + return mData.Length() == rhs.mData.Length() && + memcmp(mData.Elements(), rhs.mData.Elements(), + mData.Length() * sizeof(float)) == 0; + } + + bool SetCapacity(uint32_t aSize) { + return mData.SetCapacity(aSize, fallible); + } + + void Compact() { mData.Compact(); } + + float GetPathLength() const; + + uint32_t GetPathSegAtLength(float aDistance) const; + + static uint32_t GetPathSegAtLength(Span<const StylePathCommand> aPath, + float aDistance); + + void GetMarkerPositioningData(nsTArray<SVGMark>* aMarks) const; + + static void GetMarkerPositioningData(Span<const StylePathCommand> aPath, + nsTArray<SVGMark>* aMarks); + + /** + * Returns true, except on OOM, in which case returns false. + */ + bool GetDistancesFromOriginToEndsOfVisibleSegments( + FallibleTArray<double>* aOutput) const; + + /** + * This is identical to the above one but accepts StylePathCommand. + */ + static bool GetDistancesFromOriginToEndsOfVisibleSegments( + Span<const StylePathCommand> aPath, FallibleTArray<double>* aOutput); + + /** + * This returns a path without the extra little line segments that + * ApproximateZeroLengthSubpathSquareCaps can insert if we have square-caps. + * See the comment for that function for more info on that. + */ + already_AddRefed<Path> BuildPathForMeasuring() const; + + already_AddRefed<Path> BuildPath(PathBuilder* aBuilder, + StyleStrokeLinecap aStrokeLineCap, + Float aStrokeWidth) const; + + static already_AddRefed<Path> BuildPathForMeasuring( + Span<const StylePathCommand> aPath); + + /** + * This function tries to build the path from an array of StylePathCommand, + * which is generated by cbindgen from Rust (see ServoStyleConsts.h). + * Basically, this is a variant of the above BuildPath() functions. + */ + static already_AddRefed<Path> BuildPath( + Span<const StylePathCommand> aPath, PathBuilder* aBuilder, + StyleStrokeLinecap aStrokeLineCap, Float aStrokeWidth, + const gfx::Point& aOffset = gfx::Point(), float aZoomFactor = 1.0); + + const_iterator begin() const { return mData.Elements(); } + const_iterator end() const { return mData.Elements() + mData.Length(); } + + // memory reporting methods + size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const; + size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const; + + // 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 + // SVGAnimatedPathSegList and having that class act as an intermediary so it + // can take care of keeping DOM wrappers in sync. + + protected: + using iterator = float*; + + /** + * 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 SVGPathData& rhs); + void SwapWith(SVGPathData& aRhs) { mData.SwapElements(aRhs.mData); } + + float& operator[](uint32_t aIndex) { return mData[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 aLength) { + return mData.SetLength(aLength, fallible); + } + + nsresult SetValueFromString(const nsAString& aValue); + + void Clear() { mData.Clear(); } + + // Our DOM wrappers have direct access to our mData, so they directly + // manipulate it rather than us implementing: + // + // * InsertItem(uint32_t aDataIndex, uint32_t aType, const float *aArgs); + // * ReplaceItem(uint32_t aDataIndex, uint32_t aType, const float *aArgs); + // * RemoveItem(uint32_t aDataIndex); + // * bool AppendItem(uint32_t aType, const float *aArgs); + + nsresult AppendSeg(uint32_t aType, ...); // variable number of float args + + iterator begin() { return mData.Elements(); } + iterator end() { return mData.Elements() + mData.Length(); } + + FallibleTArray<float> mData; +}; + +/** + * This SVGPathData subclass is for SVGPathSegListSMILType which needs to + * have write access to the lists it works with. + * + * 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. + */ +class SVGPathDataAndInfo final : public SVGPathData { + public: + explicit SVGPathDataAndInfo(dom::SVGElement* aElement = nullptr) + : mElement(do_GetWeakReference(static_cast<nsINode*>(aElement))) {} + + void SetElement(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()); + } + + nsresult CopyFrom(const SVGPathDataAndInfo& rhs) { + mElement = rhs.mElement; + return SVGPathData::CopyFrom(rhs); + } + + /** + * 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 + * SVGPathSegListSMILType::Init() has been changed with a SetElement() call. + */ + bool IsIdentity() const { + if (!mElement) { + MOZ_ASSERT(IsEmpty(), "target element propagation failure"); + return true; + } + return false; + } + + /** + * Exposed so that SVGPathData baseVals can be copied to + * SVGPathDataAndInfo objects. Note that callers should also call + * SetElement() when using this method! + */ + using SVGPathData::CopyFrom; + + // Exposed since SVGPathData objects can be modified. + using SVGPathData::iterator; + using SVGPathData::operator[]; + using SVGPathData::begin; + using SVGPathData::end; + using SVGPathData::SetLength; + + 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_SVGPATHDATA_H_ |