include/core/SkPoint.h - skia - Git at Google

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */

 #ifndef SkPoint_DEFINED
 #define SkPoint_DEFINED

 #include "SkMath.h"
 #include "SkScalar.h"

 /** \struct SkIPoint16

     SkIPoint holds two 16 bit integer coordinates
 */
 struct SkIPoint16 {
     int16_t fX, fY;

     static SkIPoint16 Make(int x, int y) {
         SkIPoint16 pt;
         pt.set(x, y);
         return pt;
     }

     int16_t x() const { return fX; }
     int16_t y() const { return fY; }

     void set(int x, int y) {
         fX = SkToS16(x);
         fY = SkToS16(y);
     }
 };

 /** \struct SkIPoint

     SkIPoint holds two 32 bit integer coordinates
 */
 struct SkIPoint {
     int32_t fX, fY;

     static SkIPoint Make(int32_t x, int32_t y) {
         SkIPoint pt;
         pt.set(x, y);
         return pt;
     }

     int32_t x() const { return fX; }
     int32_t y() const { return fY; }
     void setX(int32_t x) { fX = x; }
     void setY(int32_t y) { fY = y; }

     /**
      *  Returns true iff fX and fY are both zero.
      */
     bool isZero() const { return (fX | fY) == 0; }

     /**
      *  Set both fX and fY to zero. Same as set(0, 0)
      */
     void setZero() { fX = fY = 0; }

     /** Set the x and y values of the point. */
     void set(int32_t x, int32_t y) { fX = x; fY = y; }

     /** Rotate the point clockwise, writing the new point into dst
         It is legal for dst == this
     */
     void rotateCW(SkIPoint* dst) const;

     /** Rotate the point clockwise, writing the new point back into the point
     */

     void rotateCW() { this->rotateCW(this); }

     /** Rotate the point counter-clockwise, writing the new point into dst.
         It is legal for dst == this
     */
     void rotateCCW(SkIPoint* dst) const;

     /** Rotate the point counter-clockwise, writing the new point back into
         the point
     */
     void rotateCCW() { this->rotateCCW(this); }

     /** Negate the X and Y coordinates of the point.
     */
     void negate() { fX = -fX; fY = -fY; }

     /** Return a new point whose X and Y coordinates are the negative of the
         original point's
     */
     SkIPoint operator-() const {
         SkIPoint neg;
         neg.fX = -fX;
         neg.fY = -fY;
         return neg;
     }

     /** Add v's coordinates to this point's */
     void operator+=(const SkIPoint& v) {
         fX += v.fX;
         fY += v.fY;
     }

     /** Subtract v's coordinates from this point's */
     void operator-=(const SkIPoint& v) {
         fX -= v.fX;
         fY -= v.fY;
     }

     /** Returns true if the point's coordinates equal (x,y) */
     bool equals(int32_t x, int32_t y) const {
         return fX == x && fY == y;
     }

     friend bool operator==(const SkIPoint& a, const SkIPoint& b) {
         return a.fX == b.fX && a.fY == b.fY;
     }

     friend bool operator!=(const SkIPoint& a, const SkIPoint& b) {
         return a.fX != b.fX || a.fY != b.fY;
     }

     /** Returns a new point whose coordinates are the difference between
         a and b (i.e. a - b)
     */
     friend SkIPoint operator-(const SkIPoint& a, const SkIPoint& b) {
         SkIPoint v;
         v.set(a.fX - b.fX, a.fY - b.fY);
         return v;
     }

     /** Returns a new point whose coordinates are the sum of a and b (a + b)
     */
     friend SkIPoint operator+(const SkIPoint& a, const SkIPoint& b) {
         SkIPoint v;
         v.set(a.fX + b.fX, a.fY + b.fY);
         return v;
     }

     /** Returns the dot product of a and b, treating them as 2D vectors
     */
     static int32_t DotProduct(const SkIPoint& a, const SkIPoint& b) {
         return a.fX * b.fX + a.fY * b.fY;
     }

     /** Returns the cross product of a and b, treating them as 2D vectors
     */
     static int32_t CrossProduct(const SkIPoint& a, const SkIPoint& b) {
         return a.fX * b.fY - a.fY * b.fX;
     }
 };

 struct SK_API SkPoint {
     SkScalar    fX, fY;

     static SkPoint Make(SkScalar x, SkScalar y) {
         SkPoint pt;
         pt.set(x, y);
         return pt;
     }

     SkScalar x() const { return fX; }
     SkScalar y() const { return fY; }

     /**
      *  Returns true iff fX and fY are both zero.
      */
     bool isZero() const { return (0 == fX) & (0 == fY); }

     /** Set the point's X and Y coordinates */
     void set(SkScalar x, SkScalar y) { fX = x; fY = y; }

     /** Set the point's X and Y coordinates by automatically promoting (x,y) to
         SkScalar values.
     */
     void iset(int32_t x, int32_t y) {
         fX = SkIntToScalar(x);
         fY = SkIntToScalar(y);
     }

     /** Set the point's X and Y coordinates by automatically promoting p's
         coordinates to SkScalar values.
     */
     void iset(const SkIPoint& p) {
         fX = SkIntToScalar(p.fX);
         fY = SkIntToScalar(p.fY);
     }

     void setAbs(const SkPoint& pt) {
         fX = SkScalarAbs(pt.fX);
         fY = SkScalarAbs(pt.fY);
     }

     // counter-clockwise fan
     void setIRectFan(int l, int t, int r, int b) {
         SkPoint* v = this;
         v[0].set(SkIntToScalar(l), SkIntToScalar(t));
         v[1].set(SkIntToScalar(l), SkIntToScalar(b));
         v[2].set(SkIntToScalar(r), SkIntToScalar(b));
         v[3].set(SkIntToScalar(r), SkIntToScalar(t));
     }
     void setIRectFan(int l, int t, int r, int b, size_t stride);

     // counter-clockwise fan
     void setRectFan(SkScalar l, SkScalar t, SkScalar r, SkScalar b) {
         SkPoint* v = this;
         v[0].set(l, t);
         v[1].set(l, b);
         v[2].set(r, b);
         v[3].set(r, t);
     }
     void setRectFan(SkScalar l, SkScalar t, SkScalar r, SkScalar b, size_t stride);

     static void Offset(SkPoint points[], int count, const SkPoint& offset) {
         Offset(points, count, offset.fX, offset.fY);
     }

     static void Offset(SkPoint points[], int count, SkScalar dx, SkScalar dy) {
         for (int i = 0; i < count; ++i) {
             points[i].offset(dx, dy);
         }
     }

     void offset(SkScalar dx, SkScalar dy) {
         fX += dx;
         fY += dy;
     }

     /** Return the euclidian distance from (0,0) to the point
     */
     SkScalar length() const { return SkPoint::Length(fX, fY); }
     SkScalar distanceToOrigin() const { return this->length(); }

     /**
      *  Return true if the computed length of the vector is >= the internal
      *  tolerance (used to avoid dividing by tiny values).
      */
     static bool CanNormalize(SkScalar dx, SkScalar dy) {
         // Simple enough (and performance critical sometimes) so we inline it.
         return (dx*dx + dy*dy) > (SK_ScalarNearlyZero * SK_ScalarNearlyZero);
     }

     bool canNormalize() const {
         return CanNormalize(fX, fY);
     }

     /** Set the point (vector) to be unit-length in the same direction as it
         already points.  If the point has a degenerate length (i.e. nearly 0)
         then return false and do nothing; otherwise return true.
     */
     bool normalize();

     /** Set the point (vector) to be unit-length in the same direction as the
         x,y params. If the vector (x,y) has a degenerate length (i.e. nearly 0)
         then return false and do nothing, otherwise return true.
     */
     bool setNormalize(SkScalar x, SkScalar y);

     /** Scale the point (vector) to have the specified length, and return that
         length. If the original length is degenerately small (nearly zero),
         do nothing and return false, otherwise return true.
     */
     bool setLength(SkScalar length);

     /** Set the point (vector) to have the specified length in the same
      direction as (x,y). If the vector (x,y) has a degenerate length
      (i.e. nearly 0) then return false and do nothing, otherwise return true.
     */
     bool setLength(SkScalar x, SkScalar y, SkScalar length);

     /** Same as setLength, but favoring speed over accuracy.
     */
     bool setLengthFast(SkScalar length);

     /** Same as setLength, but favoring speed over accuracy.
     */
     bool setLengthFast(SkScalar x, SkScalar y, SkScalar length);

     /** Scale the point's coordinates by scale, writing the answer into dst.
         It is legal for dst == this.
     */
     void scale(SkScalar scale, SkPoint* dst) const;

     /** Scale the point's coordinates by scale, writing the answer back into
         the point.
     */
     void scale(SkScalar value) { this->scale(value, this); }

     /** Rotate the point clockwise by 90 degrees, writing the answer into dst.
         It is legal for dst == this.
     */
     void rotateCW(SkPoint* dst) const;

     /** Rotate the point clockwise by 90 degrees, writing the answer back into
         the point.
     */
     void rotateCW() { this->rotateCW(this); }

     /** Rotate the point counter-clockwise by 90 degrees, writing the answer
         into dst. It is legal for dst == this.
     */
     void rotateCCW(SkPoint* dst) const;

     /** Rotate the point counter-clockwise by 90 degrees, writing the answer
         back into the point.
     */
     void rotateCCW() { this->rotateCCW(this); }

     /** Negate the point's coordinates
     */
     void negate() {
         fX = -fX;
         fY = -fY;
     }

     /** Returns a new point whose coordinates are the negative of the point's
     */
     SkPoint operator-() const {
         SkPoint neg;
         neg.fX = -fX;
         neg.fY = -fY;
         return neg;
     }

     /** Add v's coordinates to the point's
     */
     void operator+=(const SkPoint& v) {
         fX += v.fX;
         fY += v.fY;
     }

     /** Subtract v's coordinates from the point's
     */
     void operator-=(const SkPoint& v) {
         fX -= v.fX;
         fY -= v.fY;
     }

     /**
      *  Returns true if both X and Y are finite (not infinity or NaN)
      */
     bool isFinite() const {
         SkScalar accum = 0;
         accum *= fX;
         accum *= fY;

         // accum is either NaN or it is finite (zero).
         SkASSERT(0 == accum || !(accum == accum));

         // value==value will be true iff value is not NaN
         // TODO: is it faster to say !accum or accum==accum?
         return accum == accum;
     }

     /**
      *  Returns true if the point's coordinates equal (x,y)
      */
     bool equals(SkScalar x, SkScalar y) const {
         return fX == x && fY == y;
     }

     friend bool operator==(const SkPoint& a, const SkPoint& b) {
         return a.fX == b.fX && a.fY == b.fY;
     }

     friend bool operator!=(const SkPoint& a, const SkPoint& b) {
         return a.fX != b.fX || a.fY != b.fY;
     }

     /** Return true if this point and the given point are far enough apart
         such that a vector between them would be non-degenerate.

         WARNING: Unlike the explicit tolerance version,
         this method does not use componentwise comparison.  Instead, it
         uses a comparison designed to match judgments elsewhere regarding
         degeneracy ("points A and B are so close that the vector between them
         is essentially zero").
     */
     bool equalsWithinTolerance(const SkPoint& p) const {
         return !CanNormalize(fX - p.fX, fY - p.fY);
     }

     /** WARNING: There is no guarantee that the result will reflect judgments
         elsewhere regarding degeneracy ("points A and B are so close that the
         vector between them is essentially zero").
     */
     bool equalsWithinTolerance(const SkPoint& p, SkScalar tol) const {
         return SkScalarNearlyZero(fX - p.fX, tol)
                && SkScalarNearlyZero(fY - p.fY, tol);
     }

     /** Returns a new point whose coordinates are the difference between
         a's and b's (a - b)
     */
     friend SkPoint operator-(const SkPoint& a, const SkPoint& b) {
         SkPoint v;
         v.set(a.fX - b.fX, a.fY - b.fY);
         return v;
     }

     /** Returns a new point whose coordinates are the sum of a's and b's (a + b)
     */
     friend SkPoint operator+(const SkPoint& a, const SkPoint& b) {
         SkPoint v;
         v.set(a.fX + b.fX, a.fY + b.fY);
         return v;
     }

     /** Returns the euclidian distance from (0,0) to (x,y)
     */
     static SkScalar Length(SkScalar x, SkScalar y);

     /** Normalize pt, returning its previous length. If the prev length is too
         small (degenerate), return 0 and leave pt unchanged. This uses the same
         tolerance as CanNormalize.

         Note that this method may be significantly more expensive than
         the non-static normalize(), because it has to return the previous length
         of the point.  If you don't need the previous length, call the
         non-static normalize() method instead.
      */
     static SkScalar Normalize(SkPoint* pt);

     /** Returns the euclidian distance between a and b
     */
     static SkScalar Distance(const SkPoint& a, const SkPoint& b) {
         return Length(a.fX - b.fX, a.fY - b.fY);
     }

     /** Returns the dot product of a and b, treating them as 2D vectors
     */
     static SkScalar DotProduct(const SkPoint& a, const SkPoint& b) {
         return a.fX * b.fX + a.fY * b.fY;
     }

     /** Returns the cross product of a and b, treating them as 2D vectors
     */
     static SkScalar CrossProduct(const SkPoint& a, const SkPoint& b) {
         return a.fX * b.fY - a.fY * b.fX;
     }

     SkScalar cross(const SkPoint& vec) const {
         return CrossProduct(*this, vec);
     }

     SkScalar dot(const SkPoint& vec) const {
         return DotProduct(*this, vec);
     }

     SkScalar lengthSqd() const {
         return DotProduct(*this, *this);
     }

     SkScalar distanceToSqd(const SkPoint& pt) const {
         SkScalar dx = fX - pt.fX;
         SkScalar dy = fY - pt.fY;
         return dx * dx + dy * dy;
     }

     /**
      * The side of a point relative to a line. If the line is from a to b then
      * the values are consistent with the sign of (b-a) cross (pt-a)
      */
     enum Side {
         kLeft_Side  = -1,
         kOn_Side    =  0,
         kRight_Side =  1
     };

     /**
      * Returns the squared distance to the infinite line between two pts. Also
      * optionally returns the side of the line that the pt falls on (looking
      * along line from a to b)
      */
     SkScalar distanceToLineBetweenSqd(const SkPoint& a,
                                       const SkPoint& b,
                                       Side* side = NULL) const;

     /**
      * Returns the distance to the infinite line between two pts. Also
      * optionally returns the side of the line that the pt falls on (looking
      * along the line from a to b)
      */
     SkScalar distanceToLineBetween(const SkPoint& a,
                                    const SkPoint& b,
                                    Side* side = NULL) const {
         return SkScalarSqrt(this->distanceToLineBetweenSqd(a, b, side));
     }

     /**
      * Returns the squared distance to the line segment between pts a and b
      */
     SkScalar distanceToLineSegmentBetweenSqd(const SkPoint& a,
                                              const SkPoint& b) const;

     /**
      * Returns the distance to the line segment between pts a and b.
      */
     SkScalar distanceToLineSegmentBetween(const SkPoint& a,
                                           const SkPoint& b) const {
         return SkScalarSqrt(this->distanceToLineSegmentBetweenSqd(a, b));
     }

     /**
      * Make this vector be orthogonal to vec. Looking down vec the
      * new vector will point in direction indicated by side (which
      * must be kLeft_Side or kRight_Side).
      */
     void setOrthog(const SkPoint& vec, Side side = kLeft_Side) {
         // vec could be this
         SkScalar tmp = vec.fX;
         if (kRight_Side == side) {
             fX = -vec.fY;
             fY = tmp;
         } else {
             SkASSERT(kLeft_Side == side);
             fX = vec.fY;
             fY = -tmp;
         }
     }

     /**
      *  cast-safe way to treat the point as an array of (2) SkScalars.
      */
     const SkScalar* asScalars() const { return &fX; }
 };

 typedef SkPoint SkVector;

 #endif
	/*
	* Copyright 2006 The Android Open Source Project
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/

	#ifndef SkPoint_DEFINED
	#define SkPoint_DEFINED

	#include "SkMath.h"
	#include "SkScalar.h"

	/** \struct SkIPoint16

	SkIPoint holds two 16 bit integer coordinates
	*/
	struct SkIPoint16 {
	int16_t fX, fY;

	static SkIPoint16 Make(int x, int y) {
	SkIPoint16 pt;
	pt.set(x, y);
	return pt;
	}

	int16_t x() const { return fX; }
	int16_t y() const { return fY; }

	void set(int x, int y) {
	fX = SkToS16(x);
	fY = SkToS16(y);
	}
	};

	/** \struct SkIPoint

	SkIPoint holds two 32 bit integer coordinates
	*/
	struct SkIPoint {
	int32_t fX, fY;

	static SkIPoint Make(int32_t x, int32_t y) {
	SkIPoint pt;
	pt.set(x, y);
	return pt;
	}

	int32_t x() const { return fX; }
	int32_t y() const { return fY; }
	void setX(int32_t x) { fX = x; }
	void setY(int32_t y) { fY = y; }

	/**
	* Returns true iff fX and fY are both zero.
	*/
	bool isZero() const { return (fX \| fY) == 0; }

	/**
	* Set both fX and fY to zero. Same as set(0, 0)
	*/
	void setZero() { fX = fY = 0; }

	/** Set the x and y values of the point. */
	void set(int32_t x, int32_t y) { fX = x; fY = y; }

	/** Rotate the point clockwise, writing the new point into dst
	It is legal for dst == this
	*/
	void rotateCW(SkIPoint* dst) const;

	/** Rotate the point clockwise, writing the new point back into the point
	*/

	void rotateCW() { this->rotateCW(this); }

	/** Rotate the point counter-clockwise, writing the new point into dst.
	It is legal for dst == this
	*/
	void rotateCCW(SkIPoint* dst) const;

	/** Rotate the point counter-clockwise, writing the new point back into
	the point
	*/
	void rotateCCW() { this->rotateCCW(this); }

	/** Negate the X and Y coordinates of the point.
	*/
	void negate() { fX = -fX; fY = -fY; }

	/** Return a new point whose X and Y coordinates are the negative of the
	original point's
	*/
	SkIPoint operator-() const {
	SkIPoint neg;
	neg.fX = -fX;
	neg.fY = -fY;
	return neg;
	}

	/** Add v's coordinates to this point's */
	void operator+=(const SkIPoint& v) {
	fX += v.fX;
	fY += v.fY;
	}

	/** Subtract v's coordinates from this point's */
	void operator-=(const SkIPoint& v) {
	fX -= v.fX;
	fY -= v.fY;
	}

	/** Returns true if the point's coordinates equal (x,y) */
	bool equals(int32_t x, int32_t y) const {
	return fX == x && fY == y;
	}

	friend bool operator==(const SkIPoint& a, const SkIPoint& b) {
	return a.fX == b.fX && a.fY == b.fY;
	}

	friend bool operator!=(const SkIPoint& a, const SkIPoint& b) {
	return a.fX != b.fX \|\| a.fY != b.fY;
	}

	/** Returns a new point whose coordinates are the difference between
	a and b (i.e. a - b)
	*/
	friend SkIPoint operator-(const SkIPoint& a, const SkIPoint& b) {
	SkIPoint v;
	v.set(a.fX - b.fX, a.fY - b.fY);
	return v;
	}

	/** Returns a new point whose coordinates are the sum of a and b (a + b)
	*/
	friend SkIPoint operator+(const SkIPoint& a, const SkIPoint& b) {
	SkIPoint v;
	v.set(a.fX + b.fX, a.fY + b.fY);
	return v;
	}

	/** Returns the dot product of a and b, treating them as 2D vectors
	*/
	static int32_t DotProduct(const SkIPoint& a, const SkIPoint& b) {
	return a.fX * b.fX + a.fY * b.fY;
	}

	/** Returns the cross product of a and b, treating them as 2D vectors
	*/
	static int32_t CrossProduct(const SkIPoint& a, const SkIPoint& b) {
	return a.fX * b.fY - a.fY * b.fX;
	}
	};

	struct SK_API SkPoint {
	SkScalar fX, fY;

	static SkPoint Make(SkScalar x, SkScalar y) {
	SkPoint pt;
	pt.set(x, y);
	return pt;
	}

	SkScalar x() const { return fX; }
	SkScalar y() const { return fY; }

	/**
	* Returns true iff fX and fY are both zero.
	*/
	bool isZero() const { return (0 == fX) & (0 == fY); }

	/** Set the point's X and Y coordinates */
	void set(SkScalar x, SkScalar y) { fX = x; fY = y; }

	/** Set the point's X and Y coordinates by automatically promoting (x,y) to
	SkScalar values.
	*/
	void iset(int32_t x, int32_t y) {
	fX = SkIntToScalar(x);
	fY = SkIntToScalar(y);
	}

	/** Set the point's X and Y coordinates by automatically promoting p's
	coordinates to SkScalar values.
	*/
	void iset(const SkIPoint& p) {
	fX = SkIntToScalar(p.fX);
	fY = SkIntToScalar(p.fY);
	}

	void setAbs(const SkPoint& pt) {
	fX = SkScalarAbs(pt.fX);
	fY = SkScalarAbs(pt.fY);
	}

	// counter-clockwise fan
	void setIRectFan(int l, int t, int r, int b) {
	SkPoint* v = this;
	v[0].set(SkIntToScalar(l), SkIntToScalar(t));
	v[1].set(SkIntToScalar(l), SkIntToScalar(b));
	v[2].set(SkIntToScalar(r), SkIntToScalar(b));
	v[3].set(SkIntToScalar(r), SkIntToScalar(t));
	}
	void setIRectFan(int l, int t, int r, int b, size_t stride);

	// counter-clockwise fan
	void setRectFan(SkScalar l, SkScalar t, SkScalar r, SkScalar b) {
	SkPoint* v = this;
	v[0].set(l, t);
	v[1].set(l, b);
	v[2].set(r, b);
	v[3].set(r, t);
	}
	void setRectFan(SkScalar l, SkScalar t, SkScalar r, SkScalar b, size_t stride);

	static void Offset(SkPoint points[], int count, const SkPoint& offset) {
	Offset(points, count, offset.fX, offset.fY);
	}

	static void Offset(SkPoint points[], int count, SkScalar dx, SkScalar dy) {
	for (int i = 0; i < count; ++i) {
	points[i].offset(dx, dy);
	}
	}

	void offset(SkScalar dx, SkScalar dy) {
	fX += dx;
	fY += dy;
	}

	/** Return the euclidian distance from (0,0) to the point
	*/
	SkScalar length() const { return SkPoint::Length(fX, fY); }
	SkScalar distanceToOrigin() const { return this->length(); }

	/**
	* Return true if the computed length of the vector is >= the internal
	* tolerance (used to avoid dividing by tiny values).
	*/
	static bool CanNormalize(SkScalar dx, SkScalar dy) {
	// Simple enough (and performance critical sometimes) so we inline it.
	return (dxdx + dydy) > (SK_ScalarNearlyZero * SK_ScalarNearlyZero);
	}

	bool canNormalize() const {
	return CanNormalize(fX, fY);
	}

	/** Set the point (vector) to be unit-length in the same direction as it
	already points. If the point has a degenerate length (i.e. nearly 0)
	then return false and do nothing; otherwise return true.
	*/
	bool normalize();

	/** Set the point (vector) to be unit-length in the same direction as the
	x,y params. If the vector (x,y) has a degenerate length (i.e. nearly 0)
	then return false and do nothing, otherwise return true.
	*/
	bool setNormalize(SkScalar x, SkScalar y);

	/** Scale the point (vector) to have the specified length, and return that
	length. If the original length is degenerately small (nearly zero),
	do nothing and return false, otherwise return true.
	*/
	bool setLength(SkScalar length);

	/** Set the point (vector) to have the specified length in the same
	direction as (x,y). If the vector (x,y) has a degenerate length
	(i.e. nearly 0) then return false and do nothing, otherwise return true.
	*/
	bool setLength(SkScalar x, SkScalar y, SkScalar length);

	/** Same as setLength, but favoring speed over accuracy.
	*/
	bool setLengthFast(SkScalar length);

	/** Same as setLength, but favoring speed over accuracy.
	*/
	bool setLengthFast(SkScalar x, SkScalar y, SkScalar length);

	/** Scale the point's coordinates by scale, writing the answer into dst.
	It is legal for dst == this.
	*/
	void scale(SkScalar scale, SkPoint* dst) const;

	/** Scale the point's coordinates by scale, writing the answer back into
	the point.
	*/
	void scale(SkScalar value) { this->scale(value, this); }

	/** Rotate the point clockwise by 90 degrees, writing the answer into dst.
	It is legal for dst == this.
	*/
	void rotateCW(SkPoint* dst) const;

	/** Rotate the point clockwise by 90 degrees, writing the answer back into
	the point.
	*/
	void rotateCW() { this->rotateCW(this); }

	/** Rotate the point counter-clockwise by 90 degrees, writing the answer
	into dst. It is legal for dst == this.
	*/
	void rotateCCW(SkPoint* dst) const;

	/** Rotate the point counter-clockwise by 90 degrees, writing the answer
	back into the point.
	*/
	void rotateCCW() { this->rotateCCW(this); }

	/** Negate the point's coordinates
	*/
	void negate() {
	fX = -fX;
	fY = -fY;
	}

	/** Returns a new point whose coordinates are the negative of the point's
	*/
	SkPoint operator-() const {
	SkPoint neg;
	neg.fX = -fX;
	neg.fY = -fY;
	return neg;
	}

	/** Add v's coordinates to the point's
	*/
	void operator+=(const SkPoint& v) {
	fX += v.fX;
	fY += v.fY;
	}

	/** Subtract v's coordinates from the point's
	*/
	void operator-=(const SkPoint& v) {
	fX -= v.fX;
	fY -= v.fY;
	}

	/**
	* Returns true if both X and Y are finite (not infinity or NaN)
	*/
	bool isFinite() const {
	SkScalar accum = 0;
	accum *= fX;
	accum *= fY;

	// accum is either NaN or it is finite (zero).
	SkASSERT(0 == accum \|\| !(accum == accum));

	// value==value will be true iff value is not NaN
	// TODO: is it faster to say !accum or accum==accum?
	return accum == accum;
	}

	/**
	* Returns true if the point's coordinates equal (x,y)
	*/
	bool equals(SkScalar x, SkScalar y) const {
	return fX == x && fY == y;
	}

	friend bool operator==(const SkPoint& a, const SkPoint& b) {
	return a.fX == b.fX && a.fY == b.fY;
	}

	friend bool operator!=(const SkPoint& a, const SkPoint& b) {
	return a.fX != b.fX \|\| a.fY != b.fY;
	}

	/** Return true if this point and the given point are far enough apart
	such that a vector between them would be non-degenerate.

	WARNING: Unlike the explicit tolerance version,
	this method does not use componentwise comparison. Instead, it
	uses a comparison designed to match judgments elsewhere regarding
	degeneracy ("points A and B are so close that the vector between them
	is essentially zero").
	*/
	bool equalsWithinTolerance(const SkPoint& p) const {
	return !CanNormalize(fX - p.fX, fY - p.fY);
	}

	/** WARNING: There is no guarantee that the result will reflect judgments
	elsewhere regarding degeneracy ("points A and B are so close that the
	vector between them is essentially zero").
	*/
	bool equalsWithinTolerance(const SkPoint& p, SkScalar tol) const {
	return SkScalarNearlyZero(fX - p.fX, tol)
	&& SkScalarNearlyZero(fY - p.fY, tol);
	}

	/** Returns a new point whose coordinates are the difference between
	a's and b's (a - b)
	*/
	friend SkPoint operator-(const SkPoint& a, const SkPoint& b) {
	SkPoint v;
	v.set(a.fX - b.fX, a.fY - b.fY);
	return v;
	}

	/** Returns a new point whose coordinates are the sum of a's and b's (a + b)
	*/
	friend SkPoint operator+(const SkPoint& a, const SkPoint& b) {
	SkPoint v;
	v.set(a.fX + b.fX, a.fY + b.fY);
	return v;
	}

	/** Returns the euclidian distance from (0,0) to (x,y)
	*/
	static SkScalar Length(SkScalar x, SkScalar y);

	/** Normalize pt, returning its previous length. If the prev length is too
	small (degenerate), return 0 and leave pt unchanged. This uses the same
	tolerance as CanNormalize.

	Note that this method may be significantly more expensive than
	the non-static normalize(), because it has to return the previous length
	of the point. If you don't need the previous length, call the
	non-static normalize() method instead.
	*/
	static SkScalar Normalize(SkPoint* pt);

	/** Returns the euclidian distance between a and b
	*/
	static SkScalar Distance(const SkPoint& a, const SkPoint& b) {
	return Length(a.fX - b.fX, a.fY - b.fY);
	}

	/** Returns the dot product of a and b, treating them as 2D vectors
	*/
	static SkScalar DotProduct(const SkPoint& a, const SkPoint& b) {
	return a.fX * b.fX + a.fY * b.fY;
	}

	/** Returns the cross product of a and b, treating them as 2D vectors
	*/
	static SkScalar CrossProduct(const SkPoint& a, const SkPoint& b) {
	return a.fX * b.fY - a.fY * b.fX;
	}

	SkScalar cross(const SkPoint& vec) const {
	return CrossProduct(*this, vec);
	}

	SkScalar dot(const SkPoint& vec) const {
	return DotProduct(*this, vec);
	}

	SkScalar lengthSqd() const {
	return DotProduct(this, this);
	}

	SkScalar distanceToSqd(const SkPoint& pt) const {
	SkScalar dx = fX - pt.fX;
	SkScalar dy = fY - pt.fY;
	return dx * dx + dy * dy;
	}

	/**
	* The side of a point relative to a line. If the line is from a to b then
	* the values are consistent with the sign of (b-a) cross (pt-a)
	*/
	enum Side {
	kLeft_Side = -1,
	kOn_Side = 0,
	kRight_Side = 1
	};

	/**
	* Returns the squared distance to the infinite line between two pts. Also
	* optionally returns the side of the line that the pt falls on (looking
	* along line from a to b)
	*/
	SkScalar distanceToLineBetweenSqd(const SkPoint& a,
	const SkPoint& b,
	Side* side = NULL) const;

	/**
	* Returns the distance to the infinite line between two pts. Also
	* optionally returns the side of the line that the pt falls on (looking
	* along the line from a to b)
	*/
	SkScalar distanceToLineBetween(const SkPoint& a,
	const SkPoint& b,
	Side* side = NULL) const {
	return SkScalarSqrt(this->distanceToLineBetweenSqd(a, b, side));
	}

	/**
	* Returns the squared distance to the line segment between pts a and b
	*/
	SkScalar distanceToLineSegmentBetweenSqd(const SkPoint& a,
	const SkPoint& b) const;

	/**
	* Returns the distance to the line segment between pts a and b.
	*/
	SkScalar distanceToLineSegmentBetween(const SkPoint& a,
	const SkPoint& b) const {
	return SkScalarSqrt(this->distanceToLineSegmentBetweenSqd(a, b));
	}

	/**
	* Make this vector be orthogonal to vec. Looking down vec the
	* new vector will point in direction indicated by side (which
	* must be kLeft_Side or kRight_Side).
	*/
	void setOrthog(const SkPoint& vec, Side side = kLeft_Side) {
	// vec could be this
	SkScalar tmp = vec.fX;
	if (kRight_Side == side) {
	fX = -vec.fY;
	fY = tmp;
	} else {
	SkASSERT(kLeft_Side == side);
	fX = vec.fY;
	fY = -tmp;
	}
	}

	/**
	* cast-safe way to treat the point as an array of (2) SkScalars.
	*/
	const SkScalar* asScalars() const { return &fX; }
	};

	typedef SkPoint SkVector;

	#endif