include/private/SkPathRef.h - platform/external/skia - Gitiles

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */

 #ifndef SkPathRef_DEFINED
 #define SkPathRef_DEFINED

 #include "SkAtomics.h"
 #include "SkMatrix.h"
 #include "SkPoint.h"
 #include "SkRRect.h"
 #include "SkRect.h"
 #include "SkRefCnt.h"
 #include "SkTDArray.h"
 #include "SkTemplates.h"
 #include "SkTo.h"

 #include <limits>

 class SkRBuffer;
 class SkWBuffer;

 /**
  * Holds the path verbs and points. It is versioned by a generation ID. None of its public methods
  * modify the contents. To modify or append to the verbs/points wrap the SkPathRef in an
  * SkPathRef::Editor object. Installing the editor resets the generation ID. It also performs
  * copy-on-write if the SkPathRef is shared by multiple SkPaths. The caller passes the Editor's
  * constructor a pointer to a sk_sp<SkPathRef>, which may be updated to point to a new SkPathRef
  * after the editor's constructor returns.
  *
  * The points and verbs are stored in a single allocation. The points are at the begining of the
  * allocation while the verbs are stored at end of the allocation, in reverse order. Thus the points
  * and verbs both grow into the middle of the allocation until the meet. To access verb i in the
  * verb array use ref.verbs()[~i] (because verbs() returns a pointer just beyond the first
  * logical verb or the last verb in memory).
  */

 class SK_API SkPathRef final : public SkNVRefCnt<SkPathRef> {
 public:
     class Editor {
     public:
         Editor(sk_sp<SkPathRef>* pathRef,
                int incReserveVerbs = 0,
                int incReservePoints = 0);

         ~Editor() { SkDEBUGCODE(sk_atomic_dec(&fPathRef->fEditorsAttached);) }

         /**
          * Returns the array of points.
          */
         SkPoint* points() { return fPathRef->getPoints(); }
         const SkPoint* points() const { return fPathRef->points(); }

         /**
          * Gets the ith point. Shortcut for this->points() + i
          */
         SkPoint* atPoint(int i) {
             SkASSERT((unsigned) i < (unsigned) fPathRef->fPointCnt);
             return this->points() + i;
         }
         const SkPoint* atPoint(int i) const {
             SkASSERT((unsigned) i < (unsigned) fPathRef->fPointCnt);
             return this->points() + i;
         }

         /**
          * Adds the verb and allocates space for the number of points indicated by the verb. The
          * return value is a pointer to where the points for the verb should be written.
          * 'weight' is only used if 'verb' is kConic_Verb
          */
         SkPoint* growForVerb(int /*SkPath::Verb*/ verb, SkScalar weight = 0) {
             SkDEBUGCODE(fPathRef->validate();)
             return fPathRef->growForVerb(verb, weight);
         }

         /**
          * Allocates space for multiple instances of a particular verb and the
          * requisite points & weights.
          * The return pointer points at the first new point (indexed normally [<i>]).
          * If 'verb' is kConic_Verb, 'weights' will return a pointer to the
          * space for the conic weights (indexed normally).
          */
         SkPoint* growForRepeatedVerb(int /*SkPath::Verb*/ verb,
                                      int numVbs,
                                      SkScalar** weights = nullptr) {
             return fPathRef->growForRepeatedVerb(verb, numVbs, weights);
         }

         /**
          * Resets the path ref to a new verb and point count. The new verbs and points are
          * uninitialized.
          */
         void resetToSize(int newVerbCnt, int newPointCnt, int newConicCount) {
             fPathRef->resetToSize(newVerbCnt, newPointCnt, newConicCount);
         }

         /**
          * Gets the path ref that is wrapped in the Editor.
          */
         SkPathRef* pathRef() { return fPathRef; }

         void setIsOval(bool isOval, bool isCCW, unsigned start) {
             fPathRef->setIsOval(isOval, isCCW, start);
         }

         void setIsRRect(bool isRRect, bool isCCW, unsigned start) {
             fPathRef->setIsRRect(isRRect, isCCW, start);
         }

         void setBounds(const SkRect& rect) { fPathRef->setBounds(rect); }

     private:
         SkPathRef* fPathRef;
     };

     class SK_API Iter {
     public:
         Iter();
         Iter(const SkPathRef&);

         void setPathRef(const SkPathRef&);

         /** Return the next verb in this iteration of the path. When all
             segments have been visited, return kDone_Verb.

             If any point in the path is non-finite, return kDone_Verb immediately.

             @param  pts The points representing the current verb and/or segment
                         This must not be NULL.
             @return The verb for the current segment
         */
         uint8_t next(SkPoint pts[4]);
         uint8_t peek() const;

         SkScalar conicWeight() const { return *fConicWeights; }

     private:
         const SkPoint*  fPts;
         const uint8_t*  fVerbs;
         const uint8_t*  fVerbStop;
         const SkScalar* fConicWeights;
     };

 public:
     /**
      * Gets a path ref with no verbs or points.
      */
     static SkPathRef* CreateEmpty();

     /**
      *  Returns true if all of the points in this path are finite, meaning there
      *  are no infinities and no NaNs.
      */
     bool isFinite() const {
         if (fBoundsIsDirty) {
             this->computeBounds();
         }
         return SkToBool(fIsFinite);
     }

     /**
      *  Returns a mask, where each bit corresponding to a SegmentMask is
      *  set if the path contains 1 or more segments of that type.
      *  Returns 0 for an empty path (no segments).
      */
     uint32_t getSegmentMasks() const { return fSegmentMask; }

     /** Returns true if the path is an oval.
      *
      * @param rect      returns the bounding rect of this oval. It's a circle
      *                  if the height and width are the same.
      * @param isCCW     is the oval CCW (or CW if false).
      * @param start     indicates where the contour starts on the oval (see
      *                  SkPath::addOval for intepretation of the index).
      *
      * @return true if this path is an oval.
      *              Tracking whether a path is an oval is considered an
      *              optimization for performance and so some paths that are in
      *              fact ovals can report false.
      */
     bool isOval(SkRect* rect, bool* isCCW, unsigned* start) const {
         if (fIsOval) {
             if (rect) {
                 *rect = this->getBounds();
             }
             if (isCCW) {
                 *isCCW = SkToBool(fRRectOrOvalIsCCW);
             }
             if (start) {
                 *start = fRRectOrOvalStartIdx;
             }
         }

         return SkToBool(fIsOval);
     }

     bool isRRect(SkRRect* rrect, bool* isCCW, unsigned* start) const {
         if (fIsRRect) {
             if (rrect) {
                 *rrect = this->getRRect();
             }
             if (isCCW) {
                 *isCCW = SkToBool(fRRectOrOvalIsCCW);
             }
             if (start) {
                 *start = fRRectOrOvalStartIdx;
             }
         }
         return SkToBool(fIsRRect);
     }


     bool hasComputedBounds() const {
         return !fBoundsIsDirty;
     }

     /** Returns the bounds of the path's points. If the path contains 0 or 1
         points, the bounds is set to (0,0,0,0), and isEmpty() will return true.
         Note: this bounds may be larger than the actual shape, since curves
         do not extend as far as their control points.
     */
     const SkRect& getBounds() const {
         if (fBoundsIsDirty) {
             this->computeBounds();
         }
         return fBounds;
     }

     SkRRect getRRect() const;

     /**
      * Transforms a path ref by a matrix, allocating a new one only if necessary.
      */
     static void CreateTransformedCopy(sk_sp<SkPathRef>* dst,
                                       const SkPathRef& src,
                                       const SkMatrix& matrix);

     static SkPathRef* CreateFromBuffer(SkRBuffer* buffer);

     /**
      * Rollsback a path ref to zero verbs and points with the assumption that the path ref will be
      * repopulated with approximately the same number of verbs and points. A new path ref is created
      * only if necessary.
      */
     static void Rewind(sk_sp<SkPathRef>* pathRef);

     ~SkPathRef();
     int countPoints() const { return fPointCnt; }
     int countVerbs() const { return fVerbCnt; }
     int countWeights() const { return fConicWeights.count(); }

     /**
      * Returns a pointer one beyond the first logical verb (last verb in memory order).
      */
     const uint8_t* verbs() const { return fVerbs; }

     /**
      * Returns a const pointer to the first verb in memory (which is the last logical verb).
      */
     const uint8_t* verbsMemBegin() const { return this->verbs() - fVerbCnt; }

     /**
      * Returns a const pointer to the first point.
      */
     const SkPoint* points() const { return fPoints; }

     /**
      * Shortcut for this->points() + this->countPoints()
      */
     const SkPoint* pointsEnd() const { return this->points() + this->countPoints(); }

     const SkScalar* conicWeights() const { return fConicWeights.begin(); }
     const SkScalar* conicWeightsEnd() const { return fConicWeights.end(); }

     /**
      * Convenience methods for getting to a verb or point by index.
      */
     uint8_t atVerb(int index) const {
         SkASSERT((unsigned) index < (unsigned) fVerbCnt);
         return this->verbs()[~index];
     }
     const SkPoint& atPoint(int index) const {
         SkASSERT((unsigned) index < (unsigned) fPointCnt);
         return this->points()[index];
     }

     bool operator== (const SkPathRef& ref) const;

     /**
      * Writes the path points and verbs to a buffer.
      */
     void writeToBuffer(SkWBuffer* buffer) const;

     /**
      * Gets the number of bytes that would be written in writeBuffer()
      */
     uint32_t writeSize() const;

     void interpolate(const SkPathRef& ending, SkScalar weight, SkPathRef* out) const;

     /**
      * Gets an ID that uniquely identifies the contents of the path ref. If two path refs have the
      * same ID then they have the same verbs and points. However, two path refs may have the same
      * contents but different genIDs.
      */
     uint32_t genID() const;

     struct GenIDChangeListener : SkRefCnt {
         virtual ~GenIDChangeListener() {}
         virtual void onChange() = 0;
     };

     void addGenIDChangeListener(sk_sp<GenIDChangeListener>);

     bool isValid() const;
     SkDEBUGCODE(void validate() const { SkASSERT(this->isValid()); } )

 private:
     enum SerializationOffsets {
         kLegacyRRectOrOvalStartIdx_SerializationShift = 28, // requires 3 bits, ignored.
         kLegacyRRectOrOvalIsCCW_SerializationShift = 27,    // requires 1 bit, ignored.
         kLegacyIsRRect_SerializationShift = 26,             // requires 1 bit, ignored.
         kIsFinite_SerializationShift = 25,                  // requires 1 bit
         kLegacyIsOval_SerializationShift = 24,              // requires 1 bit, ignored.
         kSegmentMask_SerializationShift = 0                 // requires 4 bits (deprecated)
     };

     SkPathRef() {
         fBoundsIsDirty = true;    // this also invalidates fIsFinite
         fPointCnt = 0;
         fVerbCnt = 0;
         fVerbs = nullptr;
         fPoints = nullptr;
         fFreeSpace = 0;
         fGenerationID = kEmptyGenID;
         fSegmentMask = 0;
         fIsOval = false;
         fIsRRect = false;
         // The next two values don't matter unless fIsOval or fIsRRect are true.
         fRRectOrOvalIsCCW = false;
         fRRectOrOvalStartIdx = 0xAC;
         SkDEBUGCODE(fEditorsAttached = 0;)
         SkDEBUGCODE(this->validate();)
     }

     void copy(const SkPathRef& ref, int additionalReserveVerbs, int additionalReservePoints);

     // Doesn't read fSegmentMask, but (re)computes it from the verbs array
     unsigned computeSegmentMask() const;

     // Return true if the computed bounds are finite.
     static bool ComputePtBounds(SkRect* bounds, const SkPathRef& ref) {
         return bounds->setBoundsCheck(ref.points(), ref.countPoints());
     }

     // called, if dirty, by getBounds()
     void computeBounds() const {
         SkDEBUGCODE(this->validate();)
         // TODO(mtklein): remove fBoundsIsDirty and fIsFinite,
         // using an inverted rect instead of fBoundsIsDirty and always recalculating fIsFinite.
         SkASSERT(fBoundsIsDirty);

         fIsFinite = ComputePtBounds(&fBounds, *this);
         fBoundsIsDirty = false;
     }

     void setBounds(const SkRect& rect) {
         SkASSERT(rect.fLeft <= rect.fRight && rect.fTop <= rect.fBottom);
         fBounds = rect;
         fBoundsIsDirty = false;
         fIsFinite = fBounds.isFinite();
     }

     /** Makes additional room but does not change the counts or change the genID */
     void incReserve(int additionalVerbs, int additionalPoints) {
         SkDEBUGCODE(this->validate();)
         size_t space = additionalVerbs * sizeof(uint8_t) + additionalPoints * sizeof (SkPoint);
         this->makeSpace(space);
         SkDEBUGCODE(this->validate();)
     }

     /** Resets the path ref with verbCount verbs and pointCount points, all uninitialized. Also
      *  allocates space for reserveVerb additional verbs and reservePoints additional points.*/
     void resetToSize(int verbCount, int pointCount, int conicCount,
                      int reserveVerbs = 0, int reservePoints = 0) {
         SkDEBUGCODE(this->validate();)
         fBoundsIsDirty = true;      // this also invalidates fIsFinite
         fGenerationID = 0;

         fSegmentMask = 0;
         fIsOval = false;
         fIsRRect = false;

         size_t newSize = sizeof(uint8_t) * verbCount + sizeof(SkPoint) * pointCount;
         size_t newReserve = sizeof(uint8_t) * reserveVerbs + sizeof(SkPoint) * reservePoints;
         size_t minSize = newSize + newReserve;

         ptrdiff_t sizeDelta = this->currSize() - minSize;

         if (sizeDelta < 0 || static_cast<size_t>(sizeDelta) >= 3 * minSize) {
             sk_free(fPoints);
             fPoints = nullptr;
             fVerbs = nullptr;
             fFreeSpace = 0;
             fVerbCnt = 0;
             fPointCnt = 0;
             this->makeSpace(minSize);
             fVerbCnt = verbCount;
             fPointCnt = pointCount;
             fFreeSpace -= newSize;
         } else {
             fPointCnt = pointCount;
             fVerbCnt = verbCount;
             fFreeSpace = this->currSize() - minSize;
         }
         fConicWeights.setCount(conicCount);
         SkDEBUGCODE(this->validate();)
     }

     /**
      * Increases the verb count by numVbs and point count by the required amount.
      * The new points are uninitialized. All the new verbs are set to the specified
      * verb. If 'verb' is kConic_Verb, 'weights' will return a pointer to the
      * uninitialized conic weights.
      */
     SkPoint* growForRepeatedVerb(int /*SkPath::Verb*/ verb, int numVbs, SkScalar** weights);

     /**
      * Increases the verb count 1, records the new verb, and creates room for the requisite number
      * of additional points. A pointer to the first point is returned. Any new points are
      * uninitialized.
      */
     SkPoint* growForVerb(int /*SkPath::Verb*/ verb, SkScalar weight);

     /**
      * Ensures that the free space available in the path ref is >= size. The verb and point counts
      * are not changed.
      */
     void makeSpace(size_t size) {
         SkDEBUGCODE(this->validate();)
         if (size <= fFreeSpace) {
             return;
         }
         size_t growSize = size - fFreeSpace;
         size_t oldSize = this->currSize();
         // round to next multiple of 8 bytes
         growSize = (growSize + 7) & ~static_cast<size_t>(7);
         // we always at least double the allocation
         if (growSize < oldSize) {
             growSize = oldSize;
         }
         if (growSize < kMinSize) {
             growSize = kMinSize;
         }
         constexpr size_t maxSize = std::numeric_limits<size_t>::max();
         size_t newSize;
         if (growSize <= maxSize - oldSize) {
             newSize = oldSize + growSize;
         } else {
             SK_ABORT("Path too big.");
         }
         // Note that realloc could memcpy more than we need. It seems to be a win anyway. TODO:
         // encapsulate this.
         fPoints = reinterpret_cast<SkPoint*>(sk_realloc_throw(fPoints, newSize));
         size_t oldVerbSize = fVerbCnt * sizeof(uint8_t);
         void* newVerbsDst = SkTAddOffset<void>(fPoints, newSize - oldVerbSize);
         void* oldVerbsSrc = SkTAddOffset<void>(fPoints, oldSize - oldVerbSize);
         memmove(newVerbsDst, oldVerbsSrc, oldVerbSize);
         fVerbs = SkTAddOffset<uint8_t>(fPoints, newSize);
         fFreeSpace += growSize;
         SkDEBUGCODE(this->validate();)
     }

     /**
      * Private, non-const-ptr version of the public function verbsMemBegin().
      */
     uint8_t* verbsMemWritable() {
         SkDEBUGCODE(this->validate();)
         return fVerbs - fVerbCnt;
     }

     /**
      * Gets the total amount of space allocated for verbs, points, and reserve.
      */
     size_t currSize() const {
         return reinterpret_cast<intptr_t>(fVerbs) - reinterpret_cast<intptr_t>(fPoints);
     }

     /**
      * Called the first time someone calls CreateEmpty to actually create the singleton.
      */
     friend SkPathRef* sk_create_empty_pathref();

     void setIsOval(bool isOval, bool isCCW, unsigned start) {
         fIsOval = isOval;
         fRRectOrOvalIsCCW = isCCW;
         fRRectOrOvalStartIdx = SkToU8(start);
     }

     void setIsRRect(bool isRRect, bool isCCW, unsigned start) {
         fIsRRect = isRRect;
         fRRectOrOvalIsCCW = isCCW;
         fRRectOrOvalStartIdx = SkToU8(start);
     }

     // called only by the editor. Note that this is not a const function.
     SkPoint* getPoints() {
         SkDEBUGCODE(this->validate();)
         fIsOval = false;
         fIsRRect = false;
         return fPoints;
     }

     const SkPoint* getPoints() const {
         SkDEBUGCODE(this->validate();)
         return fPoints;
     }

     void callGenIDChangeListeners();

     enum {
         kMinSize = 256,
     };

     mutable SkRect   fBounds;

     SkPoint*            fPoints; // points to begining of the allocation
     uint8_t*            fVerbs; // points just past the end of the allocation (verbs grow backwards)
     int                 fVerbCnt;
     int                 fPointCnt;
     size_t              fFreeSpace; // redundant but saves computation
     SkTDArray<SkScalar> fConicWeights;

     enum {
         kEmptyGenID = 1, // GenID reserved for path ref with zero points and zero verbs.
     };
     mutable uint32_t    fGenerationID;
     SkDEBUGCODE(int32_t fEditorsAttached;) // assert that only one editor in use at any time.

     SkTDArray<GenIDChangeListener*> fGenIDChangeListeners;  // pointers are reffed

     mutable uint8_t  fBoundsIsDirty;
     mutable bool     fIsFinite;    // only meaningful if bounds are valid

     bool     fIsOval;
     bool     fIsRRect;
     // Both the circle and rrect special cases have a notion of direction and starting point
     // The next two variables store that information for either.
     bool     fRRectOrOvalIsCCW;
     uint8_t  fRRectOrOvalStartIdx;
     uint8_t  fSegmentMask;

     friend class PathRefTest_Private;
     friend class ForceIsRRect_Private; // unit test isRRect
 };

 #endif
	/*
	* Copyright 2012 Google Inc.
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/

	#ifndef SkPathRef_DEFINED
	#define SkPathRef_DEFINED

	#include "SkAtomics.h"
	#include "SkMatrix.h"
	#include "SkPoint.h"
	#include "SkRRect.h"
	#include "SkRect.h"
	#include "SkRefCnt.h"
	#include "SkTDArray.h"
	#include "SkTemplates.h"
	#include "SkTo.h"

	#include <limits>

	class SkRBuffer;
	class SkWBuffer;

	/**
	* Holds the path verbs and points. It is versioned by a generation ID. None of its public methods
	* modify the contents. To modify or append to the verbs/points wrap the SkPathRef in an
	* SkPathRef::Editor object. Installing the editor resets the generation ID. It also performs
	* copy-on-write if the SkPathRef is shared by multiple SkPaths. The caller passes the Editor's
	* constructor a pointer to a sk_sp<SkPathRef>, which may be updated to point to a new SkPathRef
	* after the editor's constructor returns.
	*
	* The points and verbs are stored in a single allocation. The points are at the begining of the
	* allocation while the verbs are stored at end of the allocation, in reverse order. Thus the points
	* and verbs both grow into the middle of the allocation until the meet. To access verb i in the
	* verb array use ref.verbs()[~i] (because verbs() returns a pointer just beyond the first
	* logical verb or the last verb in memory).
	*/

	class SK_API SkPathRef final : public SkNVRefCnt<SkPathRef> {
	public:
	class Editor {
	public:
	Editor(sk_sp<SkPathRef>* pathRef,
	int incReserveVerbs = 0,
	int incReservePoints = 0);

	~Editor() { SkDEBUGCODE(sk_atomic_dec(&fPathRef->fEditorsAttached);) }

	/**
	* Returns the array of points.
	*/
	SkPoint* points() { return fPathRef->getPoints(); }
	const SkPoint* points() const { return fPathRef->points(); }

	/**
	* Gets the ith point. Shortcut for this->points() + i
	*/
	SkPoint* atPoint(int i) {
	SkASSERT((unsigned) i < (unsigned) fPathRef->fPointCnt);
	return this->points() + i;
	}
	const SkPoint* atPoint(int i) const {
	SkASSERT((unsigned) i < (unsigned) fPathRef->fPointCnt);
	return this->points() + i;
	}

	/**
	* Adds the verb and allocates space for the number of points indicated by the verb. The
	* return value is a pointer to where the points for the verb should be written.
	* 'weight' is only used if 'verb' is kConic_Verb
	*/
	SkPoint* growForVerb(int /SkPath::Verb/ verb, SkScalar weight = 0) {
	SkDEBUGCODE(fPathRef->validate();)
	return fPathRef->growForVerb(verb, weight);
	}

	/**
	* Allocates space for multiple instances of a particular verb and the
	* requisite points & weights.
	* The return pointer points at the first new point (indexed normally [<i>]).
	* If 'verb' is kConic_Verb, 'weights' will return a pointer to the
	* space for the conic weights (indexed normally).
	*/
	SkPoint* growForRepeatedVerb(int /SkPath::Verb/ verb,
	int numVbs,
	SkScalar** weights = nullptr) {
	return fPathRef->growForRepeatedVerb(verb, numVbs, weights);
	}

	/**
	* Resets the path ref to a new verb and point count. The new verbs and points are
	* uninitialized.
	*/
	void resetToSize(int newVerbCnt, int newPointCnt, int newConicCount) {
	fPathRef->resetToSize(newVerbCnt, newPointCnt, newConicCount);
	}

	/**
	* Gets the path ref that is wrapped in the Editor.
	*/
	SkPathRef* pathRef() { return fPathRef; }

	void setIsOval(bool isOval, bool isCCW, unsigned start) {
	fPathRef->setIsOval(isOval, isCCW, start);
	}

	void setIsRRect(bool isRRect, bool isCCW, unsigned start) {
	fPathRef->setIsRRect(isRRect, isCCW, start);
	}

	void setBounds(const SkRect& rect) { fPathRef->setBounds(rect); }

	private:
	SkPathRef* fPathRef;
	};

	class SK_API Iter {
	public:
	Iter();
	Iter(const SkPathRef&);

	void setPathRef(const SkPathRef&);

	/** Return the next verb in this iteration of the path. When all
	segments have been visited, return kDone_Verb.

	If any point in the path is non-finite, return kDone_Verb immediately.

	@param pts The points representing the current verb and/or segment
	This must not be NULL.
	@return The verb for the current segment
	*/
	uint8_t next(SkPoint pts[4]);
	uint8_t peek() const;

	SkScalar conicWeight() const { return *fConicWeights; }

	private:
	const SkPoint* fPts;
	const uint8_t* fVerbs;
	const uint8_t* fVerbStop;
	const SkScalar* fConicWeights;
	};

	public:
	/**
	* Gets a path ref with no verbs or points.
	*/
	static SkPathRef* CreateEmpty();

	/**
	* Returns true if all of the points in this path are finite, meaning there
	* are no infinities and no NaNs.
	*/
	bool isFinite() const {
	if (fBoundsIsDirty) {
	this->computeBounds();
	}
	return SkToBool(fIsFinite);
	}

	/**
	* Returns a mask, where each bit corresponding to a SegmentMask is
	* set if the path contains 1 or more segments of that type.
	* Returns 0 for an empty path (no segments).
	*/
	uint32_t getSegmentMasks() const { return fSegmentMask; }

	/** Returns true if the path is an oval.
	*
	* @param rect returns the bounding rect of this oval. It's a circle
	* if the height and width are the same.
	* @param isCCW is the oval CCW (or CW if false).
	* @param start indicates where the contour starts on the oval (see
	* SkPath::addOval for intepretation of the index).
	*
	* @return true if this path is an oval.
	* Tracking whether a path is an oval is considered an
	* optimization for performance and so some paths that are in
	* fact ovals can report false.
	*/
	bool isOval(SkRect* rect, bool* isCCW, unsigned* start) const {
	if (fIsOval) {
	if (rect) {
	*rect = this->getBounds();
	}
	if (isCCW) {
	*isCCW = SkToBool(fRRectOrOvalIsCCW);
	}
	if (start) {
	*start = fRRectOrOvalStartIdx;
	}
	}

	return SkToBool(fIsOval);
	}

	bool isRRect(SkRRect* rrect, bool* isCCW, unsigned* start) const {
	if (fIsRRect) {
	if (rrect) {
	*rrect = this->getRRect();
	}
	if (isCCW) {
	*isCCW = SkToBool(fRRectOrOvalIsCCW);
	}
	if (start) {
	*start = fRRectOrOvalStartIdx;
	}
	}
	return SkToBool(fIsRRect);
	}


	bool hasComputedBounds() const {
	return !fBoundsIsDirty;
	}

	/** Returns the bounds of the path's points. If the path contains 0 or 1
	points, the bounds is set to (0,0,0,0), and isEmpty() will return true.
	Note: this bounds may be larger than the actual shape, since curves
	do not extend as far as their control points.
	*/
	const SkRect& getBounds() const {
	if (fBoundsIsDirty) {
	this->computeBounds();
	}
	return fBounds;
	}

	SkRRect getRRect() const;

	/**
	* Transforms a path ref by a matrix, allocating a new one only if necessary.
	*/
	static void CreateTransformedCopy(sk_sp<SkPathRef>* dst,
	const SkPathRef& src,
	const SkMatrix& matrix);

	static SkPathRef* CreateFromBuffer(SkRBuffer* buffer);

	/**
	* Rollsback a path ref to zero verbs and points with the assumption that the path ref will be
	* repopulated with approximately the same number of verbs and points. A new path ref is created
	* only if necessary.
	*/
	static void Rewind(sk_sp<SkPathRef>* pathRef);

	~SkPathRef();
	int countPoints() const { return fPointCnt; }
	int countVerbs() const { return fVerbCnt; }
	int countWeights() const { return fConicWeights.count(); }

	/**
	* Returns a pointer one beyond the first logical verb (last verb in memory order).
	*/
	const uint8_t* verbs() const { return fVerbs; }

	/**
	* Returns a const pointer to the first verb in memory (which is the last logical verb).
	*/
	const uint8_t* verbsMemBegin() const { return this->verbs() - fVerbCnt; }

	/**
	* Returns a const pointer to the first point.
	*/
	const SkPoint* points() const { return fPoints; }

	/**
	* Shortcut for this->points() + this->countPoints()
	*/
	const SkPoint* pointsEnd() const { return this->points() + this->countPoints(); }

	const SkScalar* conicWeights() const { return fConicWeights.begin(); }
	const SkScalar* conicWeightsEnd() const { return fConicWeights.end(); }

	/**
	* Convenience methods for getting to a verb or point by index.
	*/
	uint8_t atVerb(int index) const {
	SkASSERT((unsigned) index < (unsigned) fVerbCnt);
	return this->verbs()[~index];
	}
	const SkPoint& atPoint(int index) const {
	SkASSERT((unsigned) index < (unsigned) fPointCnt);
	return this->points()[index];
	}

	bool operator== (const SkPathRef& ref) const;

	/**
	* Writes the path points and verbs to a buffer.
	*/
	void writeToBuffer(SkWBuffer* buffer) const;

	/**
	* Gets the number of bytes that would be written in writeBuffer()
	*/
	uint32_t writeSize() const;

	void interpolate(const SkPathRef& ending, SkScalar weight, SkPathRef* out) const;

	/**
	* Gets an ID that uniquely identifies the contents of the path ref. If two path refs have the
	* same ID then they have the same verbs and points. However, two path refs may have the same
	* contents but different genIDs.
	*/
	uint32_t genID() const;

	struct GenIDChangeListener : SkRefCnt {
	virtual ~GenIDChangeListener() {}
	virtual void onChange() = 0;
	};

	void addGenIDChangeListener(sk_sp<GenIDChangeListener>);

	bool isValid() const;
	SkDEBUGCODE(void validate() const { SkASSERT(this->isValid()); } )

	private:
	enum SerializationOffsets {
	kLegacyRRectOrOvalStartIdx_SerializationShift = 28, // requires 3 bits, ignored.
	kLegacyRRectOrOvalIsCCW_SerializationShift = 27, // requires 1 bit, ignored.
	kLegacyIsRRect_SerializationShift = 26, // requires 1 bit, ignored.
	kIsFinite_SerializationShift = 25, // requires 1 bit
	kLegacyIsOval_SerializationShift = 24, // requires 1 bit, ignored.
	kSegmentMask_SerializationShift = 0 // requires 4 bits (deprecated)
	};

	SkPathRef() {
	fBoundsIsDirty = true; // this also invalidates fIsFinite
	fPointCnt = 0;
	fVerbCnt = 0;
	fVerbs = nullptr;
	fPoints = nullptr;
	fFreeSpace = 0;
	fGenerationID = kEmptyGenID;
	fSegmentMask = 0;
	fIsOval = false;
	fIsRRect = false;
	// The next two values don't matter unless fIsOval or fIsRRect are true.
	fRRectOrOvalIsCCW = false;
	fRRectOrOvalStartIdx = 0xAC;
	SkDEBUGCODE(fEditorsAttached = 0;)
	SkDEBUGCODE(this->validate();)
	}

	void copy(const SkPathRef& ref, int additionalReserveVerbs, int additionalReservePoints);

	// Doesn't read fSegmentMask, but (re)computes it from the verbs array
	unsigned computeSegmentMask() const;

	// Return true if the computed bounds are finite.
	static bool ComputePtBounds(SkRect* bounds, const SkPathRef& ref) {
	return bounds->setBoundsCheck(ref.points(), ref.countPoints());
	}

	// called, if dirty, by getBounds()
	void computeBounds() const {
	SkDEBUGCODE(this->validate();)
	// TODO(mtklein): remove fBoundsIsDirty and fIsFinite,
	// using an inverted rect instead of fBoundsIsDirty and always recalculating fIsFinite.
	SkASSERT(fBoundsIsDirty);

	fIsFinite = ComputePtBounds(&fBounds, *this);
	fBoundsIsDirty = false;
	}

	void setBounds(const SkRect& rect) {
	SkASSERT(rect.fLeft <= rect.fRight && rect.fTop <= rect.fBottom);
	fBounds = rect;
	fBoundsIsDirty = false;
	fIsFinite = fBounds.isFinite();
	}

	/** Makes additional room but does not change the counts or change the genID */
	void incReserve(int additionalVerbs, int additionalPoints) {
	SkDEBUGCODE(this->validate();)
	size_t space = additionalVerbs * sizeof(uint8_t) + additionalPoints * sizeof (SkPoint);
	this->makeSpace(space);
	SkDEBUGCODE(this->validate();)
	}

	/** Resets the path ref with verbCount verbs and pointCount points, all uninitialized. Also
	* allocates space for reserveVerb additional verbs and reservePoints additional points.*/
	void resetToSize(int verbCount, int pointCount, int conicCount,
	int reserveVerbs = 0, int reservePoints = 0) {
	SkDEBUGCODE(this->validate();)
	fBoundsIsDirty = true; // this also invalidates fIsFinite
	fGenerationID = 0;

	fSegmentMask = 0;
	fIsOval = false;
	fIsRRect = false;

	size_t newSize = sizeof(uint8_t) * verbCount + sizeof(SkPoint) * pointCount;
	size_t newReserve = sizeof(uint8_t) * reserveVerbs + sizeof(SkPoint) * reservePoints;
	size_t minSize = newSize + newReserve;

	ptrdiff_t sizeDelta = this->currSize() - minSize;

	if (sizeDelta < 0 \|\| static_cast<size_t>(sizeDelta) >= 3 * minSize) {
	sk_free(fPoints);
	fPoints = nullptr;
	fVerbs = nullptr;
	fFreeSpace = 0;
	fVerbCnt = 0;
	fPointCnt = 0;
	this->makeSpace(minSize);
	fVerbCnt = verbCount;
	fPointCnt = pointCount;
	fFreeSpace -= newSize;
	} else {
	fPointCnt = pointCount;
	fVerbCnt = verbCount;
	fFreeSpace = this->currSize() - minSize;
	}
	fConicWeights.setCount(conicCount);
	SkDEBUGCODE(this->validate();)
	}

	/**
	* Increases the verb count by numVbs and point count by the required amount.
	* The new points are uninitialized. All the new verbs are set to the specified
	* verb. If 'verb' is kConic_Verb, 'weights' will return a pointer to the
	* uninitialized conic weights.
	*/
	SkPoint* growForRepeatedVerb(int /SkPath::Verb/ verb, int numVbs, SkScalar** weights);

	/**
	* Increases the verb count 1, records the new verb, and creates room for the requisite number
	* of additional points. A pointer to the first point is returned. Any new points are
	* uninitialized.
	*/
	SkPoint* growForVerb(int /SkPath::Verb/ verb, SkScalar weight);

	/**
	* Ensures that the free space available in the path ref is >= size. The verb and point counts
	* are not changed.
	*/
	void makeSpace(size_t size) {
	SkDEBUGCODE(this->validate();)
	if (size <= fFreeSpace) {
	return;
	}
	size_t growSize = size - fFreeSpace;
	size_t oldSize = this->currSize();
	// round to next multiple of 8 bytes
	growSize = (growSize + 7) & ~static_cast<size_t>(7);
	// we always at least double the allocation
	if (growSize < oldSize) {
	growSize = oldSize;
	}
	if (growSize < kMinSize) {
	growSize = kMinSize;
	}
	constexpr size_t maxSize = std::numeric_limits<size_t>::max();
	size_t newSize;
	if (growSize <= maxSize - oldSize) {
	newSize = oldSize + growSize;
	} else {
	SK_ABORT("Path too big.");
	}
	// Note that realloc could memcpy more than we need. It seems to be a win anyway. TODO:
	// encapsulate this.
	fPoints = reinterpret_cast<SkPoint*>(sk_realloc_throw(fPoints, newSize));
	size_t oldVerbSize = fVerbCnt * sizeof(uint8_t);
	void* newVerbsDst = SkTAddOffset<void>(fPoints, newSize - oldVerbSize);
	void* oldVerbsSrc = SkTAddOffset<void>(fPoints, oldSize - oldVerbSize);
	memmove(newVerbsDst, oldVerbsSrc, oldVerbSize);
	fVerbs = SkTAddOffset<uint8_t>(fPoints, newSize);
	fFreeSpace += growSize;
	SkDEBUGCODE(this->validate();)
	}

	/**
	* Private, non-const-ptr version of the public function verbsMemBegin().
	*/
	uint8_t* verbsMemWritable() {
	SkDEBUGCODE(this->validate();)
	return fVerbs - fVerbCnt;
	}

	/**
	* Gets the total amount of space allocated for verbs, points, and reserve.
	*/
	size_t currSize() const {
	return reinterpret_cast<intptr_t>(fVerbs) - reinterpret_cast<intptr_t>(fPoints);
	}

	/**
	* Called the first time someone calls CreateEmpty to actually create the singleton.
	*/
	friend SkPathRef* sk_create_empty_pathref();

	void setIsOval(bool isOval, bool isCCW, unsigned start) {
	fIsOval = isOval;
	fRRectOrOvalIsCCW = isCCW;
	fRRectOrOvalStartIdx = SkToU8(start);
	}

	void setIsRRect(bool isRRect, bool isCCW, unsigned start) {
	fIsRRect = isRRect;
	fRRectOrOvalIsCCW = isCCW;
	fRRectOrOvalStartIdx = SkToU8(start);
	}

	// called only by the editor. Note that this is not a const function.
	SkPoint* getPoints() {
	SkDEBUGCODE(this->validate();)
	fIsOval = false;
	fIsRRect = false;
	return fPoints;
	}

	const SkPoint* getPoints() const {
	SkDEBUGCODE(this->validate();)
	return fPoints;
	}

	void callGenIDChangeListeners();

	enum {
	kMinSize = 256,
	};

	mutable SkRect fBounds;

	SkPoint* fPoints; // points to begining of the allocation
	uint8_t* fVerbs; // points just past the end of the allocation (verbs grow backwards)
	int fVerbCnt;
	int fPointCnt;
	size_t fFreeSpace; // redundant but saves computation
	SkTDArray<SkScalar> fConicWeights;

	enum {
	kEmptyGenID = 1, // GenID reserved for path ref with zero points and zero verbs.
	};
	mutable uint32_t fGenerationID;
	SkDEBUGCODE(int32_t fEditorsAttached;) // assert that only one editor in use at any time.

	SkTDArray<GenIDChangeListener*> fGenIDChangeListeners; // pointers are reffed

	mutable uint8_t fBoundsIsDirty;
	mutable bool fIsFinite; // only meaningful if bounds are valid

	bool fIsOval;
	bool fIsRRect;
	// Both the circle and rrect special cases have a notion of direction and starting point
	// The next two variables store that information for either.
	bool fRRectOrOvalIsCCW;
	uint8_t fRRectOrOvalStartIdx;
	uint8_t fSegmentMask;

	friend class PathRefTest_Private;
	friend class ForceIsRRect_Private; // unit test isRRect
	};

	#endif