core/SkPathRef.h - platform/external/chromium_org/third_party/skia/src - Git at Google


 /*
  * 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 "SkRefCnt.h"
 #include <stddef.h> // ptrdiff_t

 /**
  * 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 multipls SkPaths. The caller passes the Editor's
  * constructor a SkAutoTUnref, 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 SkPathRef;

 class SkPathRef : public ::SkRefCnt {
 public:
     SK_DECLARE_INST_COUNT(SkPathRef);

     class Editor {
     public:
         Editor(SkAutoTUnref<SkPathRef>* pathRef,
                int incReserveVerbs = 0,
                int incReservePoints = 0)
         {
             if ((*pathRef)->unique()) {
                 (*pathRef)->incReserve(incReserveVerbs, incReservePoints);
             } else {
                 SkPathRef* copy = SkNEW(SkPathRef);
                 copy->copy(**pathRef, incReserveVerbs, incReservePoints);
                 pathRef->reset(copy);
             }
             fPathRef = *pathRef;
             fPathRef->fGenerationID = 0;
             SkDEBUGCODE(sk_atomic_inc(&fPathRef->fEditorsAttached);)
         }

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

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

         /**
          * Gets the ith point. Shortcut for this->points() + i
          */
         SkPoint* atPoint(int i) {
             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.
          */
         SkPoint* growForVerb(SkPath::Verb verb) {
             fPathRef->validate();
             return fPathRef->growForVerb(verb);
         }

         SkPoint* growForConic(SkScalar w) {
             fPathRef->validate();
             SkPoint* pts = fPathRef->growForVerb(SkPath::kConic_Verb);
             *fPathRef->fConicWeights.append() = w;
             return pts;
         }

         /**
          * Allocates space for additional verbs and points and returns pointers to the new verbs and
          * points. verbs will point one beyond the first new verb (index it using [~<i>]). pts points
          * at the first new point (indexed normally [<i>]).
          */
         void grow(int newVerbs, int newPts, uint8_t** verbs, SkPoint** pts) {
             SkASSERT(NULL != verbs);
             SkASSERT(NULL != pts);
             fPathRef->validate();
             int oldVerbCnt = fPathRef->fVerbCnt;
             int oldPointCnt = fPathRef->fPointCnt;
             SkASSERT(verbs && pts);
             fPathRef->grow(newVerbs, newPts);
             *verbs = fPathRef->fVerbs - oldVerbCnt;
             *pts = fPathRef->fPoints + oldPointCnt;
             fPathRef->validate();
         }

         /**
          * 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; }

     private:
         SkPathRef* fPathRef;
     };

 public:
     /**
      * Gets a path ref with no verbs or points.
      */
     static SkPathRef* CreateEmpty() {
         static SkPathRef* gEmptyPathRef;
         if (!gEmptyPathRef) {
             gEmptyPathRef = SkNEW(SkPathRef); // leak!
         }
         return SkRef(gEmptyPathRef);
     }

     /**
      * Transforms a path ref by a matrix, allocating a new one only if necessary.
      */
     static void CreateTransformedCopy(SkAutoTUnref<SkPathRef>* dst,
                                       const SkPathRef& src,
                                       const SkMatrix& matrix) {
         src.validate();
         if (matrix.isIdentity()) {
             if (*dst != &src) {
                 src.ref();
                 dst->reset(const_cast<SkPathRef*>(&src));
                 (*dst)->validate();
             }
             return;
         }
         bool dstUnique = (*dst)->unique();
         if (&src == *dst && dstUnique) {
             matrix.mapPoints((*dst)->fPoints, (*dst)->fPointCnt);
             return;
         } else if (!dstUnique) {
             dst->reset(SkNEW(SkPathRef));
         }
         (*dst)->resetToSize(src.fVerbCnt, src.fPointCnt, src.fConicWeights.count());
         memcpy((*dst)->verbsMemWritable(), src.verbsMemBegin(), src.fVerbCnt * sizeof(uint8_t));
         matrix.mapPoints((*dst)->fPoints, src.points(), src.fPointCnt);
         (*dst)->fConicWeights = src.fConicWeights;
         (*dst)->validate();
     }

     static SkPathRef* CreateFromBuffer(SkRBuffer* buffer) {
         SkPathRef* ref = SkNEW(SkPathRef);
         ref->fGenerationID = buffer->readU32();
         int32_t verbCount = buffer->readS32();
         int32_t pointCount = buffer->readS32();
         int32_t conicCount = buffer->readS32();
         ref->resetToSize(verbCount, pointCount, conicCount);

         SkASSERT(verbCount == ref->countVerbs());
         SkASSERT(pointCount == ref->countPoints());
         SkASSERT(conicCount == ref->fConicWeights.count());
         buffer->read(ref->verbsMemWritable(), verbCount * sizeof(uint8_t));
         buffer->read(ref->fPoints, pointCount * sizeof(SkPoint));
         buffer->read(ref->fConicWeights.begin(), conicCount * sizeof(SkScalar));
         return ref;
     }

     /**
      * 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(SkAutoTUnref<SkPathRef>* pathRef) {
         if ((*pathRef)->unique()) {
             (*pathRef)->validate();
             (*pathRef)->fVerbCnt = 0;
             (*pathRef)->fPointCnt = 0;
             (*pathRef)->fFreeSpace = (*pathRef)->currSize();
             (*pathRef)->fGenerationID = 0;
             (*pathRef)->fConicWeights.rewind();
             (*pathRef)->validate();
         } else {
             int oldVCnt = (*pathRef)->countVerbs();
             int oldPCnt = (*pathRef)->countPoints();
             pathRef->reset(SkNEW(SkPathRef));
             (*pathRef)->resetToSize(0, 0, 0, oldVCnt, oldPCnt);
         }
     }

     virtual ~SkPathRef() {
         this->validate();
         sk_free(fPoints);

         SkDEBUGCODE(fPoints = NULL;)
         SkDEBUGCODE(fVerbs = NULL;)
         SkDEBUGCODE(fVerbCnt = 0x9999999;)
         SkDEBUGCODE(fPointCnt = 0xAAAAAAA;)
         SkDEBUGCODE(fPointCnt = 0xBBBBBBB;)
         SkDEBUGCODE(fGenerationID = 0xEEEEEEEE;)
         SkDEBUGCODE(fEditorsAttached = 0x7777777;)
     }

     int countPoints() const { this->validate(); return fPointCnt; }
     int countVerbs() const { this->validate(); return fVerbCnt; }

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

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

     const SkScalar* conicWeights() const { this->validate(); return fConicWeights.begin(); }
     const SkScalar* conicWeightsEnd() const { this->validate(); return fConicWeights.end(); }

     /**
      * Convenience methods for getting to a verb or point by index.
      */
     uint8_t atVerb(int index) {
         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 {
         this->validate();
         ref.validate();
         bool genIDMatch = fGenerationID && fGenerationID == ref.fGenerationID;
 #ifdef SK_RELEASE
         if (genIDMatch) {
             return true;
         }
 #endif
         if (fPointCnt != ref.fPointCnt ||
             fVerbCnt != ref.fVerbCnt) {
             SkASSERT(!genIDMatch);
             return false;
         }
         if (0 != memcmp(this->verbsMemBegin(),
                         ref.verbsMemBegin(),
                         ref.fVerbCnt * sizeof(uint8_t))) {
             SkASSERT(!genIDMatch);
             return false;
         }
         if (0 != memcmp(this->points(),
                         ref.points(),
                         ref.fPointCnt * sizeof(SkPoint))) {
             SkASSERT(!genIDMatch);
             return false;
         }
         if (fConicWeights != ref.fConicWeights) {
             SkASSERT(!genIDMatch);
             return false;
         }
         // We've done the work to determine that these are equal. If either has a zero genID, copy
         // the other's. If both are 0 then genID() will compute the next ID.
         if (0 == fGenerationID) {
             fGenerationID = ref.genID();
         } else if (0 == ref.fGenerationID) {
             ref.fGenerationID = this->genID();
         }
         return true;
     }

     /**
      * Writes the path points and verbs to a buffer.
      */
     void writeToBuffer(SkWBuffer* buffer) {
         this->validate();
         SkDEBUGCODE(size_t beforePos = buffer->pos();)

         // TODO: write gen ID here. Problem: We don't know if we're cross process or not from
         // SkWBuffer. Until this is fixed we write 0.
         buffer->write32(0);
         buffer->write32(fVerbCnt);
         buffer->write32(fPointCnt);
         buffer->write32(fConicWeights.count());
         buffer->write(verbsMemBegin(), fVerbCnt * sizeof(uint8_t));
         buffer->write(fPoints, fPointCnt * sizeof(SkPoint));
         buffer->write(fConicWeights.begin(), fConicWeights.bytes());

         SkASSERT(buffer->pos() - beforePos == (size_t) this->writeSize());
     }

     /**
      * Gets the number of bytes that would be written in writeBuffer()
      */
     uint32_t writeSize() {
         return 4 * sizeof(uint32_t) +
                fVerbCnt * sizeof(uint8_t) +
                fPointCnt * sizeof(SkPoint) +
                fConicWeights.bytes();
     }

 private:
     SkPathRef() {
         fPointCnt = 0;
         fVerbCnt = 0;
         fVerbs = NULL;
         fPoints = NULL;
         fFreeSpace = 0;
         fGenerationID = kEmptyGenID;
         SkDEBUGCODE(fEditorsAttached = 0;)
         this->validate();
     }

     void copy(const SkPathRef& ref, int additionalReserveVerbs, int additionalReservePoints) {
         this->validate();
         this->resetToSize(ref.fVerbCnt, ref.fPointCnt, ref.fConicWeights.count(),
                           additionalReserveVerbs, additionalReservePoints);
         memcpy(this->verbsMemWritable(), ref.verbsMemBegin(), ref.fVerbCnt * sizeof(uint8_t));
         memcpy(this->fPoints, ref.fPoints, ref.fPointCnt * sizeof(SkPoint));
         fConicWeights = ref.fConicWeights;
         // We could call genID() here to force a real ID (instead of 0). However, if we're making
         // a copy then presumably we intend to make a modification immediately afterwards.
         fGenerationID = ref.fGenerationID;
         this->validate();
     }

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

     /** Resets the path ref with verbCount verbs and pointCount points, all unitialized. 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) {
         this->validate();
         fGenerationID = 0;

         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 = NULL;
             fVerbs = NULL;
             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);
         this->validate();
     }

     /**
      * Increases the verb count by newVerbs and the point count be newPoints. New verbs and points
      * are uninitialized.
      */
     void grow(int newVerbs, int newPoints) {
         this->validate();
         size_t space = newVerbs * sizeof(uint8_t) + newPoints * sizeof (SkPoint);
         this->makeSpace(space);
         fVerbCnt += newVerbs;
         fPointCnt += newPoints;
         fFreeSpace -= space;
         this->validate();
     }

     /**
      * 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(SkPath::Verb verb) {
         this->validate();
         int pCnt;
         switch (verb) {
             case SkPath::kMove_Verb:
                 pCnt = 1;
                 break;
             case SkPath::kLine_Verb:
                 pCnt = 1;
                 break;
             case SkPath::kQuad_Verb:
                 // fall through
             case SkPath::kConic_Verb:
                 pCnt = 2;
                 break;
             case SkPath::kCubic_Verb:
                 pCnt = 3;
                 break;
             case SkPath::kClose_Verb:
                 pCnt = 0;
                 break;
             case SkPath::kDone_Verb:
                 SkASSERT(!"growForVerb called for kDone");
                 // fall through
             default:
                 SkASSERT(!"default is not reached");
                 pCnt = 0;
         }
         size_t space = sizeof(uint8_t) + pCnt * sizeof (SkPoint);
         this->makeSpace(space);
         this->fVerbs[~fVerbCnt] = verb;
         SkPoint* ret = fPoints + fPointCnt;
         fVerbCnt += 1;
         fPointCnt += pCnt;
         fFreeSpace -= space;
         this->validate();
         return ret;
     }

     /**
      * 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) {
         this->validate();
         ptrdiff_t growSize = size - fFreeSpace;
         if (growSize <= 0) {
             return;
         }
         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 (static_cast<size_t>(growSize) < oldSize) {
             growSize = oldSize;
         }
         if (growSize < kMinSize) {
             growSize = kMinSize;
         }
         size_t newSize = oldSize + growSize;
         // 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 = reinterpret_cast<void*>(
                                 reinterpret_cast<intptr_t>(fPoints) + newSize - oldVerbSize);
         void* oldVerbsSrc = reinterpret_cast<void*>(
                                 reinterpret_cast<intptr_t>(fPoints) + oldSize - oldVerbSize);
         memmove(newVerbsDst, oldVerbsSrc, oldVerbSize);
         fVerbs = reinterpret_cast<uint8_t*>(reinterpret_cast<intptr_t>(fPoints) + newSize);
         fFreeSpace += growSize;
         this->validate();
     }

     /**
      * Private, non-const-ptr version of the public function verbsMemBegin().
      */
     uint8_t* verbsMemWritable() {
         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);
     }

     /**
      * 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. Zero is reserved and means an ID has not yet been determined
      * for the path ref.
      */
     int32_t genID() const {
         SkASSERT(!fEditorsAttached);
         if (!fGenerationID) {
             if (0 == fPointCnt && 0 == fVerbCnt) {
                 fGenerationID = kEmptyGenID;
             } else {
                 static int32_t  gPathRefGenerationID;
                 // do a loop in case our global wraps around, as we never want to return a 0 or the
                 // empty ID
                 do {
                     fGenerationID = sk_atomic_inc(&gPathRefGenerationID) + 1;
                 } while (fGenerationID <= kEmptyGenID);
             }
         }
         return fGenerationID;
     }

     void validate() const {
         SkASSERT(static_cast<ptrdiff_t>(fFreeSpace) >= 0);
         SkASSERT(reinterpret_cast<intptr_t>(fVerbs) - reinterpret_cast<intptr_t>(fPoints) >= 0);
         SkASSERT((NULL == fPoints) == (NULL == fVerbs));
         SkASSERT(!(NULL == fPoints && 0 != fFreeSpace));
         SkASSERT(!(NULL == fPoints && 0 != fFreeSpace));
         SkASSERT(!(NULL == fPoints && fPointCnt));
         SkASSERT(!(NULL == fVerbs && fVerbCnt));
         SkASSERT(this->currSize() ==
                  fFreeSpace + sizeof(SkPoint) * fPointCnt + sizeof(uint8_t) * fVerbCnt);
     }

     enum {
         kMinSize = 256,
     };

     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 int32_t     fGenerationID;
     SkDEBUGCODE(int32_t fEditorsAttached;) // assert that only one editor in use at any time.

     typedef SkRefCnt INHERITED;
 };

 SK_DEFINE_INST_COUNT(SkPathRef);

 #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 "SkRefCnt.h"
	#include <stddef.h> // ptrdiff_t

	/**
	* 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 multipls SkPaths. The caller passes the Editor's
	* constructor a SkAutoTUnref, 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 SkPathRef;

	class SkPathRef : public ::SkRefCnt {
	public:
	SK_DECLARE_INST_COUNT(SkPathRef);

	class Editor {
	public:
	Editor(SkAutoTUnref<SkPathRef>* pathRef,
	int incReserveVerbs = 0,
	int incReservePoints = 0)
	{
	if ((*pathRef)->unique()) {
	(*pathRef)->incReserve(incReserveVerbs, incReservePoints);
	} else {
	SkPathRef* copy = SkNEW(SkPathRef);
	copy->copy(**pathRef, incReserveVerbs, incReservePoints);
	pathRef->reset(copy);
	}
	fPathRef = *pathRef;
	fPathRef->fGenerationID = 0;
	SkDEBUGCODE(sk_atomic_inc(&fPathRef->fEditorsAttached);)
	}

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

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

	/**
	* Gets the ith point. Shortcut for this->points() + i
	*/
	SkPoint* atPoint(int i) {
	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.
	*/
	SkPoint* growForVerb(SkPath::Verb verb) {
	fPathRef->validate();
	return fPathRef->growForVerb(verb);
	}

	SkPoint* growForConic(SkScalar w) {
	fPathRef->validate();
	SkPoint* pts = fPathRef->growForVerb(SkPath::kConic_Verb);
	*fPathRef->fConicWeights.append() = w;
	return pts;
	}

	/**
	* Allocates space for additional verbs and points and returns pointers to the new verbs and
	* points. verbs will point one beyond the first new verb (index it using [~<i>]). pts points
	* at the first new point (indexed normally [<i>]).
	*/
	void grow(int newVerbs, int newPts, uint8_t verbs, SkPoint pts) {
	SkASSERT(NULL != verbs);
	SkASSERT(NULL != pts);
	fPathRef->validate();
	int oldVerbCnt = fPathRef->fVerbCnt;
	int oldPointCnt = fPathRef->fPointCnt;
	SkASSERT(verbs && pts);
	fPathRef->grow(newVerbs, newPts);
	*verbs = fPathRef->fVerbs - oldVerbCnt;
	*pts = fPathRef->fPoints + oldPointCnt;
	fPathRef->validate();
	}

	/**
	* 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; }

	private:
	SkPathRef* fPathRef;
	};

	public:
	/**
	* Gets a path ref with no verbs or points.
	*/
	static SkPathRef* CreateEmpty() {
	static SkPathRef* gEmptyPathRef;
	if (!gEmptyPathRef) {
	gEmptyPathRef = SkNEW(SkPathRef); // leak!
	}
	return SkRef(gEmptyPathRef);
	}

	/**
	* Transforms a path ref by a matrix, allocating a new one only if necessary.
	*/
	static void CreateTransformedCopy(SkAutoTUnref<SkPathRef>* dst,
	const SkPathRef& src,
	const SkMatrix& matrix) {
	src.validate();
	if (matrix.isIdentity()) {
	if (*dst != &src) {
	src.ref();
	dst->reset(const_cast<SkPathRef*>(&src));
	(*dst)->validate();
	}
	return;
	}
	bool dstUnique = (*dst)->unique();
	if (&src == *dst && dstUnique) {
	matrix.mapPoints((dst)->fPoints, (dst)->fPointCnt);
	return;
	} else if (!dstUnique) {
	dst->reset(SkNEW(SkPathRef));
	}
	(*dst)->resetToSize(src.fVerbCnt, src.fPointCnt, src.fConicWeights.count());
	memcpy((dst)->verbsMemWritable(), src.verbsMemBegin(), src.fVerbCnt sizeof(uint8_t));
	matrix.mapPoints((*dst)->fPoints, src.points(), src.fPointCnt);
	(*dst)->fConicWeights = src.fConicWeights;
	(*dst)->validate();
	}

	static SkPathRef* CreateFromBuffer(SkRBuffer* buffer) {
	SkPathRef* ref = SkNEW(SkPathRef);
	ref->fGenerationID = buffer->readU32();
	int32_t verbCount = buffer->readS32();
	int32_t pointCount = buffer->readS32();
	int32_t conicCount = buffer->readS32();
	ref->resetToSize(verbCount, pointCount, conicCount);

	SkASSERT(verbCount == ref->countVerbs());
	SkASSERT(pointCount == ref->countPoints());
	SkASSERT(conicCount == ref->fConicWeights.count());
	buffer->read(ref->verbsMemWritable(), verbCount * sizeof(uint8_t));
	buffer->read(ref->fPoints, pointCount * sizeof(SkPoint));
	buffer->read(ref->fConicWeights.begin(), conicCount * sizeof(SkScalar));
	return ref;
	}

	/**
	* 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(SkAutoTUnref<SkPathRef>* pathRef) {
	if ((*pathRef)->unique()) {
	(*pathRef)->validate();
	(*pathRef)->fVerbCnt = 0;
	(*pathRef)->fPointCnt = 0;
	(pathRef)->fFreeSpace = (pathRef)->currSize();
	(*pathRef)->fGenerationID = 0;
	(*pathRef)->fConicWeights.rewind();
	(*pathRef)->validate();
	} else {
	int oldVCnt = (*pathRef)->countVerbs();
	int oldPCnt = (*pathRef)->countPoints();
	pathRef->reset(SkNEW(SkPathRef));
	(*pathRef)->resetToSize(0, 0, 0, oldVCnt, oldPCnt);
	}
	}

	virtual ~SkPathRef() {
	this->validate();
	sk_free(fPoints);

	SkDEBUGCODE(fPoints = NULL;)
	SkDEBUGCODE(fVerbs = NULL;)
	SkDEBUGCODE(fVerbCnt = 0x9999999;)
	SkDEBUGCODE(fPointCnt = 0xAAAAAAA;)
	SkDEBUGCODE(fPointCnt = 0xBBBBBBB;)
	SkDEBUGCODE(fGenerationID = 0xEEEEEEEE;)
	SkDEBUGCODE(fEditorsAttached = 0x7777777;)
	}

	int countPoints() const { this->validate(); return fPointCnt; }
	int countVerbs() const { this->validate(); return fVerbCnt; }

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

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

	const SkScalar* conicWeights() const { this->validate(); return fConicWeights.begin(); }
	const SkScalar* conicWeightsEnd() const { this->validate(); return fConicWeights.end(); }

	/**
	* Convenience methods for getting to a verb or point by index.
	*/
	uint8_t atVerb(int index) {
	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 {
	this->validate();
	ref.validate();
	bool genIDMatch = fGenerationID && fGenerationID == ref.fGenerationID;
	#ifdef SK_RELEASE
	if (genIDMatch) {
	return true;
	}
	#endif
	if (fPointCnt != ref.fPointCnt \|\|
	fVerbCnt != ref.fVerbCnt) {
	SkASSERT(!genIDMatch);
	return false;
	}
	if (0 != memcmp(this->verbsMemBegin(),
	ref.verbsMemBegin(),
	ref.fVerbCnt * sizeof(uint8_t))) {
	SkASSERT(!genIDMatch);
	return false;
	}
	if (0 != memcmp(this->points(),
	ref.points(),
	ref.fPointCnt * sizeof(SkPoint))) {
	SkASSERT(!genIDMatch);
	return false;
	}
	if (fConicWeights != ref.fConicWeights) {
	SkASSERT(!genIDMatch);
	return false;
	}
	// We've done the work to determine that these are equal. If either has a zero genID, copy
	// the other's. If both are 0 then genID() will compute the next ID.
	if (0 == fGenerationID) {
	fGenerationID = ref.genID();
	} else if (0 == ref.fGenerationID) {
	ref.fGenerationID = this->genID();
	}
	return true;
	}

	/**
	* Writes the path points and verbs to a buffer.
	*/
	void writeToBuffer(SkWBuffer* buffer) {
	this->validate();
	SkDEBUGCODE(size_t beforePos = buffer->pos();)

	// TODO: write gen ID here. Problem: We don't know if we're cross process or not from
	// SkWBuffer. Until this is fixed we write 0.
	buffer->write32(0);
	buffer->write32(fVerbCnt);
	buffer->write32(fPointCnt);
	buffer->write32(fConicWeights.count());
	buffer->write(verbsMemBegin(), fVerbCnt * sizeof(uint8_t));
	buffer->write(fPoints, fPointCnt * sizeof(SkPoint));
	buffer->write(fConicWeights.begin(), fConicWeights.bytes());

	SkASSERT(buffer->pos() - beforePos == (size_t) this->writeSize());
	}

	/**
	* Gets the number of bytes that would be written in writeBuffer()
	*/
	uint32_t writeSize() {
	return 4 * sizeof(uint32_t) +
	fVerbCnt * sizeof(uint8_t) +
	fPointCnt * sizeof(SkPoint) +
	fConicWeights.bytes();
	}

	private:
	SkPathRef() {
	fPointCnt = 0;
	fVerbCnt = 0;
	fVerbs = NULL;
	fPoints = NULL;
	fFreeSpace = 0;
	fGenerationID = kEmptyGenID;
	SkDEBUGCODE(fEditorsAttached = 0;)
	this->validate();
	}

	void copy(const SkPathRef& ref, int additionalReserveVerbs, int additionalReservePoints) {
	this->validate();
	this->resetToSize(ref.fVerbCnt, ref.fPointCnt, ref.fConicWeights.count(),
	additionalReserveVerbs, additionalReservePoints);
	memcpy(this->verbsMemWritable(), ref.verbsMemBegin(), ref.fVerbCnt * sizeof(uint8_t));
	memcpy(this->fPoints, ref.fPoints, ref.fPointCnt * sizeof(SkPoint));
	fConicWeights = ref.fConicWeights;
	// We could call genID() here to force a real ID (instead of 0). However, if we're making
	// a copy then presumably we intend to make a modification immediately afterwards.
	fGenerationID = ref.fGenerationID;
	this->validate();
	}

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

	/** Resets the path ref with verbCount verbs and pointCount points, all unitialized. 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) {
	this->validate();
	fGenerationID = 0;

	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 = NULL;
	fVerbs = NULL;
	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);
	this->validate();
	}

	/**
	* Increases the verb count by newVerbs and the point count be newPoints. New verbs and points
	* are uninitialized.
	*/
	void grow(int newVerbs, int newPoints) {
	this->validate();
	size_t space = newVerbs * sizeof(uint8_t) + newPoints * sizeof (SkPoint);
	this->makeSpace(space);
	fVerbCnt += newVerbs;
	fPointCnt += newPoints;
	fFreeSpace -= space;
	this->validate();
	}

	/**
	* 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(SkPath::Verb verb) {
	this->validate();
	int pCnt;
	switch (verb) {
	case SkPath::kMove_Verb:
	pCnt = 1;
	break;
	case SkPath::kLine_Verb:
	pCnt = 1;
	break;
	case SkPath::kQuad_Verb:
	// fall through
	case SkPath::kConic_Verb:
	pCnt = 2;
	break;
	case SkPath::kCubic_Verb:
	pCnt = 3;
	break;
	case SkPath::kClose_Verb:
	pCnt = 0;
	break;
	case SkPath::kDone_Verb:
	SkASSERT(!"growForVerb called for kDone");
	// fall through
	default:
	SkASSERT(!"default is not reached");
	pCnt = 0;
	}
	size_t space = sizeof(uint8_t) + pCnt * sizeof (SkPoint);
	this->makeSpace(space);
	this->fVerbs[~fVerbCnt] = verb;
	SkPoint* ret = fPoints + fPointCnt;
	fVerbCnt += 1;
	fPointCnt += pCnt;
	fFreeSpace -= space;
	this->validate();
	return ret;
	}

	/**
	* 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) {
	this->validate();
	ptrdiff_t growSize = size - fFreeSpace;
	if (growSize <= 0) {
	return;
	}
	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 (static_cast<size_t>(growSize) < oldSize) {
	growSize = oldSize;
	}
	if (growSize < kMinSize) {
	growSize = kMinSize;
	}
	size_t newSize = oldSize + growSize;
	// 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 = reinterpret_cast<void*>(
	reinterpret_cast<intptr_t>(fPoints) + newSize - oldVerbSize);
	void* oldVerbsSrc = reinterpret_cast<void*>(
	reinterpret_cast<intptr_t>(fPoints) + oldSize - oldVerbSize);
	memmove(newVerbsDst, oldVerbsSrc, oldVerbSize);
	fVerbs = reinterpret_cast<uint8_t*>(reinterpret_cast<intptr_t>(fPoints) + newSize);
	fFreeSpace += growSize;
	this->validate();
	}

	/**
	* Private, non-const-ptr version of the public function verbsMemBegin().
	*/
	uint8_t* verbsMemWritable() {
	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);
	}

	/**
	* 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. Zero is reserved and means an ID has not yet been determined
	* for the path ref.
	*/
	int32_t genID() const {
	SkASSERT(!fEditorsAttached);
	if (!fGenerationID) {
	if (0 == fPointCnt && 0 == fVerbCnt) {
	fGenerationID = kEmptyGenID;
	} else {
	static int32_t gPathRefGenerationID;
	// do a loop in case our global wraps around, as we never want to return a 0 or the
	// empty ID
	do {
	fGenerationID = sk_atomic_inc(&gPathRefGenerationID) + 1;
	} while (fGenerationID <= kEmptyGenID);
	}
	}
	return fGenerationID;
	}

	void validate() const {
	SkASSERT(static_cast<ptrdiff_t>(fFreeSpace) >= 0);
	SkASSERT(reinterpret_cast<intptr_t>(fVerbs) - reinterpret_cast<intptr_t>(fPoints) >= 0);
	SkASSERT((NULL == fPoints) == (NULL == fVerbs));
	SkASSERT(!(NULL == fPoints && 0 != fFreeSpace));
	SkASSERT(!(NULL == fPoints && 0 != fFreeSpace));
	SkASSERT(!(NULL == fPoints && fPointCnt));
	SkASSERT(!(NULL == fVerbs && fVerbCnt));
	SkASSERT(this->currSize() ==
	fFreeSpace + sizeof(SkPoint) * fPointCnt + sizeof(uint8_t) * fVerbCnt);
	}

	enum {
	kMinSize = 256,
	};

	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 int32_t fGenerationID;
	SkDEBUGCODE(int32_t fEditorsAttached;) // assert that only one editor in use at any time.

	typedef SkRefCnt INHERITED;
	};

	SK_DEFINE_INST_COUNT(SkPathRef);

	#endif