/* -*- 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_SVGPATHDATA_H__

#define MOZILLA_SVGPATHDATA_H__

#include "nsCOMPtr.h"

#include "nsDebug.h"

#include "nsIContent.h"

#include "nsINode.h"

#include "nsIWeakReferenceUtils.h"

#include "mozilla/gfx/2D.h"

#include "mozilla/gfx/Types.h"

#include "mozilla/MemoryReporting.h"

#include "mozilla/RefPtr.h"

#include "nsSVGElement.h"

#include "nsTArray.h"

#include <string.h>

class nsSVGPathDataParser; // IWYU pragma: keep

struct nsSVGMark;

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 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 DOMSVGPathSegList;

  friend class DOMSVGPathSeg;

  friend class ::nsSVGPathDataParser;

  // nsSVGPathDataParser will not keep wrappers in sync, so consumers

  // are responsible for that!

  typedef gfx::DrawTarget DrawTarget;

  typedef gfx::Path Path;

  typedef gfx::PathBuilder PathBuilder;

  typedef gfx::FillRule FillRule;

  typedef gfx::Float Float;

  typedef gfx::CapStyle CapStyle;

public:

  typedef const float* const_iterator;

  SVGPathData(){}

  ~SVGPathData(){}

  // 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 float& operator[](uint32_t aIndex) const {

    return mData[aIndex];

  }

  // Used by nsSMILCompositor 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 aLength) const;

  void GetMarkerPositioningData(nsTArray<nsSVGMark> *aMarks) const;

  /**

   * Returns true, except on OOM, in which case returns false.

   */

  bool GetSegmentLengths(nsTArray<double> *aLengths) const;

  /**

   * Returns true, except on OOM, in which case returns false.

   */

  bool GetDistancesFromOriginToEndsOfVisibleSegments(FallibleTArray<double> *aArray) const;

  /**

   * 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,

                               uint8_t aCapStyle,

                               Float aStrokeWidth) const;

  /**

   * This function tries to build the path by 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(const nsTArray<StylePathCommand>& aPath,

            PathBuilder* aBuilder,

            uint8_t aCapStyle,

            Float aStrokeWidth,

            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:

  typedef float* iterator;

  /**

   * 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);

  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(nsSVGElement *aElement = nullptr)

    : mElement(do_GetWeakReference(static_cast<nsINode*>(aElement)))

  {}

  void SetElement(nsSVGElement *aElement) {

    mElement = do_GetWeakReference(static_cast<nsINode*>(aElement));

  }

  nsSVGElement* Element() const {

    nsCOMPtr<nsIContent> e = do_QueryReferent(mElement);

    return static_cast<nsSVGElement*>(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::SetLength;

  using SVGPathData::begin;

  using SVGPathData::end;

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;

};

} // namespace mozilla

#endif // MOZILLA_SVGPATHDATA_H__