text: /*
   * 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 "include/core/SkMatrix.h"
  #include "include/core/SkPathTypes.h"
  #include "include/core/SkPoint.h"
  #include "include/core/SkRRect.h"
  #include "include/core/SkRect.h"
  #include "include/core/SkRefCnt.h"
  #include "include/private/SkIDChangeListener.h"
  #include "include/private/SkMutex.h"
  #include "include/private/SkTDArray.h"
  #include "include/private/SkTemplates.h"
  #include "include/private/SkTo.h"
  
  #include <atomic>
  #include <limits>
  #include <tuple>
  
  struct SkPathView;
  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:
      SkPathRef(SkTDArray<SkPoint> points, SkTDArray<uint8_t> verbs, SkTDArray<SkScalar> weights,
                unsigned segmentMask)
          : fPoints(std::move(points))
          , fVerbs(std::move(verbs))
          , fConicWeights(std::move(weights))
      {
          fBoundsIsDirty = true;    // this also invalidates fIsFinite
          fGenerationID = 0;        // recompute
          fSegmentMask = segmentMask;
          fIsOval = false;
          fIsRRect = false;
          // The next two values don't matter unless fIsOval or fIsRRect are true.
          fRRectOrOvalIsCCW = false;
          fRRectOrOvalStartIdx = 0xAC;
          SkDEBUGCODE(fEditorsAttached.store(0);)
          SkDEBUGCODE(this->validate();)
      }
  
      class Editor {
      public:
          Editor(sk_sp<SkPathRef>* pathRef,
                 int incReserveVerbs = 0,
                 int incReservePoints = 0);
  
          ~Editor() { SkDEBUGCODE(fPathRef->fEditorsAttached--;) }
  
          /**
           * Returns the array of points.
           */
          SkPoint* writablePoints() { return fPathRef->getWritablePoints(); }
          const SkPoint* points() const { return fPathRef->points(); }
  
          /**
           * Gets the ith point. Shortcut for this->points() + i
           */
          SkPoint* atPoint(int i) { return fPathRef->getWritablePoints() + i; }
          const SkPoint* atPoint(int i) const { return &fPathRef->fPoints[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);
          }
  
          /**
           * Concatenates all verbs from 'path' onto the pathRef's verbs array. Increases the point
           * count by the number of points in 'path', and the conic weight count by the number of
           * conics in 'path'.
           *
           * Returns pointers to the uninitialized points and conic weights data.
           */
          std::tuple<SkPoint*, SkScalar*> growForVerbsInPath(const SkPathRef& path) {
              return fPathRef->growForVerbsInPath(path);
          }
  
          /**
           * 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 fPoints.count(); }
      int countVerbs() const { return fVerbs.count(); }
      int countWeights() const { return fConicWeights.count(); }
  
      /**
       * Returns a pointer one beyond the first logical verb (last verb in memory order).
       */
      const uint8_t* verbsBegin() const { return fVerbs.begin(); }
  
      /**
       * Returns a const pointer to the first verb in memory (which is the last logical verb).
       */
      const uint8_t* verbsEnd() const { return fVerbs.end(); }
  
      /**
       * Returns a const pointer to the first point.
       */
      const SkPoint* points() const { return fPoints.begin(); }
  
      /**
       * 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 { return fVerbs[index]; }
      const SkPoint& atPoint(int index) const { return fPoints[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;
  
      void addGenIDChangeListener(sk_sp<SkIDChangeListener>);   // Threadsafe.
      int genIDChangeListenerCount();                           // Threadsafe
  
      bool isValid() const;
      SkDEBUGCODE(void validate() const { SkASSERT(this->isValid()); } )
  
      SkPathView view(SkPathFillType, SkPathConvexityType) const;
  
  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
          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.store(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();)
          fPoints.setReserve(fPoints.count() + additionalPoints);
          fVerbs.setReserve(fVerbs.count() + additionalVerbs);
          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();)
          this->callGenIDChangeListeners();
          fBoundsIsDirty = true;      // this also invalidates fIsFinite
          fGenerationID = 0;
  
          fSegmentMask = 0;
          fIsOval = false;
          fIsRRect = false;
  
          fPoints.setReserve(pointCount + reservePoints);
          fPoints.setCount(pointCount);
          fVerbs.setReserve(verbCount + reserveVerbs);
          fVerbs.setCount(verbCount);
          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);
  
      /**
       * Concatenates all verbs from 'path' onto our own verbs array. Increases the point count by the
       * number of points in 'path', and the conic weight count by the number of conics in 'path'.
       *
       * Returns pointers to the uninitialized points and conic weights data.
       */
      std::tuple<SkPoint*, SkScalar*> growForVerbsInPath(const SkPathRef& path);
  
      /**
       * Private, non-const-ptr version of the public function verbsMemBegin().
       */
      uint8_t* verbsBeginWritable() { return fVerbs.begin(); }
  
      /**
       * 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* getWritablePoints() {
          SkDEBUGCODE(this->validate();)
          fIsOval = false;
          fIsRRect = false;
          return fPoints.begin();
      }
  
      const SkPoint* getPoints() const {
          SkDEBUGCODE(this->validate();)
          return fPoints.begin();
      }
  
      void callGenIDChangeListeners();
  
      enum {
          kMinSize = 256,
      };
  
      mutable SkRect   fBounds;
  
      SkTDArray<SkPoint>  fPoints;
      SkTDArray<uint8_t>  fVerbs;
      SkTDArray<SkScalar> fConicWeights;
  
      enum {
          kEmptyGenID = 1, // GenID reserved for path ref with zero points and zero verbs.
      };
      mutable uint32_t    fGenerationID;
      SkDEBUGCODE(std::atomic<int> fEditorsAttached;) // assert only one editor in use at any time.
  
      SkIDChangeListener::List fGenIDChangeListeners;
  
      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
      friend class SkPath;
      friend class SkPathBuilder;
      friend class SkPathPriv;
  };
  
  #endif
  