src/third_party/skia/src/core/SkPoint.cpp - cobalt - Git at Google

 /*
  * Copyright 2008 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.
  */


 #include "SkMathPriv.h"
 #include "SkPoint.h"

 void SkIPoint::rotateCW(SkIPoint* dst) const {
     SkASSERT(dst);

     // use a tmp in case this == dst
     int32_t tmp = fX;
     dst->fX = -fY;
     dst->fY = tmp;
 }

 void SkIPoint::rotateCCW(SkIPoint* dst) const {
     SkASSERT(dst);

     // use a tmp in case this == dst
     int32_t tmp = fX;
     dst->fX = fY;
     dst->fY = -tmp;
 }

 ///////////////////////////////////////////////////////////////////////////////

 void SkPoint::setIRectFan(int l, int t, int r, int b, size_t stride) {
     SkASSERT(stride >= sizeof(SkPoint));

     ((SkPoint*)((intptr_t)this + 0 * stride))->set(SkIntToScalar(l),
                                                    SkIntToScalar(t));
     ((SkPoint*)((intptr_t)this + 1 * stride))->set(SkIntToScalar(l),
                                                    SkIntToScalar(b));
     ((SkPoint*)((intptr_t)this + 2 * stride))->set(SkIntToScalar(r),
                                                    SkIntToScalar(b));
     ((SkPoint*)((intptr_t)this + 3 * stride))->set(SkIntToScalar(r),
                                                    SkIntToScalar(t));
 }

 void SkPoint::rotateCW(SkPoint* dst) const {
     SkASSERT(dst);

     // use a tmp in case this == dst
     SkScalar tmp = fX;
     dst->fX = -fY;
     dst->fY = tmp;
 }

 void SkPoint::rotateCCW(SkPoint* dst) const {
     SkASSERT(dst);

     // use a tmp in case this == dst
     SkScalar tmp = fX;
     dst->fX = fY;
     dst->fY = -tmp;
 }

 void SkPoint::scale(SkScalar scale, SkPoint* dst) const {
     SkASSERT(dst);
     dst->set(fX * scale, fY * scale);
 }

 bool SkPoint::normalize() {
     return this->setLength(fX, fY, SK_Scalar1);
 }

 bool SkPoint::setNormalize(SkScalar x, SkScalar y) {
     return this->setLength(x, y, SK_Scalar1);
 }

 bool SkPoint::setLength(SkScalar length) {
     return this->setLength(fX, fY, length);
 }

 // Returns the square of the Euclidian distance to (dx,dy).
 static inline float getLengthSquared(float dx, float dy) {
     return dx * dx + dy * dy;
 }

 // Calculates the square of the Euclidian distance to (dx,dy) and stores it in
 // *lengthSquared.  Returns true if the distance is judged to be "nearly zero".
 //
 // This logic is encapsulated in a helper method to make it explicit that we
 // always perform this check in the same manner, to avoid inconsistencies
 // (see http://code.google.com/p/skia/issues/detail?id=560 ).
 static inline bool is_length_nearly_zero(float dx, float dy,
                                          float *lengthSquared) {
     *lengthSquared = getLengthSquared(dx, dy);
     return *lengthSquared <= (SK_ScalarNearlyZero * SK_ScalarNearlyZero);
 }

 SkScalar SkPoint::Normalize(SkPoint* pt) {
     float x = pt->fX;
     float y = pt->fY;
     float mag2;
     if (is_length_nearly_zero(x, y, &mag2)) {
         pt->set(0, 0);
         return 0;
     }

     float mag, scale;
     if (SkScalarIsFinite(mag2)) {
         mag = sk_float_sqrt(mag2);
         scale = 1 / mag;
     } else {
         // our mag2 step overflowed to infinity, so use doubles instead.
         // much slower, but needed when x or y are very large, other wise we
         // divide by inf. and return (0,0) vector.
         double xx = x;
         double yy = y;
         double magmag = sqrt(xx * xx + yy * yy);
         mag = (float)magmag;
         // we perform the divide with the double magmag, to stay exactly the
         // same as setLength. It would be faster to perform the divide with
         // mag, but it is possible that mag has overflowed to inf. but still
         // have a non-zero value for scale (thanks to denormalized numbers).
         scale = (float)(1 / magmag);
     }
     pt->set(x * scale, y * scale);
     return mag;
 }

 SkScalar SkPoint::Length(SkScalar dx, SkScalar dy) {
     float mag2 = dx * dx + dy * dy;
     if (SkScalarIsFinite(mag2)) {
         return sk_float_sqrt(mag2);
     } else {
         double xx = dx;
         double yy = dy;
         return (float)sqrt(xx * xx + yy * yy);
     }
 }

 /*
  *  We have to worry about 2 tricky conditions:
  *  1. underflow of mag2 (compared against nearlyzero^2)
  *  2. overflow of mag2 (compared w/ isfinite)
  *
  *  If we underflow, we return false. If we overflow, we compute again using
  *  doubles, which is much slower (3x in a desktop test) but will not overflow.
  */
 bool SkPoint::setLength(float x, float y, float length) {
     float mag2;
     if (is_length_nearly_zero(x, y, &mag2)) {
         this->set(0, 0);
         return false;
     }

     float scale;
     if (SkScalarIsFinite(mag2)) {
         scale = length / sk_float_sqrt(mag2);
     } else {
         // our mag2 step overflowed to infinity, so use doubles instead.
         // much slower, but needed when x or y are very large, other wise we
         // divide by inf. and return (0,0) vector.
         double xx = x;
         double yy = y;
     #ifdef SK_CPU_FLUSH_TO_ZERO
         // The iOS ARM processor discards small denormalized numbers to go faster.
         // Casting this to a float would cause the scale to go to zero. Keeping it
         // as a double for the multiply keeps the scale non-zero.
         double dscale = length / sqrt(xx * xx + yy * yy);
         fX = x * dscale;
         fY = y * dscale;
         return true;
     #else
         scale = (float)(length / sqrt(xx * xx + yy * yy));
     #endif
     }
     fX = x * scale;
     fY = y * scale;
     return true;
 }

 bool SkPoint::setLengthFast(float length) {
     return this->setLengthFast(fX, fY, length);
 }

 bool SkPoint::setLengthFast(float x, float y, float length) {
     float mag2;
     if (is_length_nearly_zero(x, y, &mag2)) {
         this->set(0, 0);
         return false;
     }

     float scale;
     if (SkScalarIsFinite(mag2)) {
         scale = length * sk_float_rsqrt(mag2);  // <--- this is the difference
     } else {
         // our mag2 step overflowed to infinity, so use doubles instead.
         // much slower, but needed when x or y are very large, other wise we
         // divide by inf. and return (0,0) vector.
         double xx = x;
         double yy = y;
         scale = (float)(length / sqrt(xx * xx + yy * yy));
     }
     fX = x * scale;
     fY = y * scale;
     return true;
 }


 ///////////////////////////////////////////////////////////////////////////////

 SkScalar SkPoint::distanceToLineBetweenSqd(const SkPoint& a,
                                            const SkPoint& b,
                                            Side* side) const {

     SkVector u = b - a;
     SkVector v = *this - a;

     SkScalar uLengthSqd = u.lengthSqd();
     SkScalar det = u.cross(v);
     if (side) {
         SkASSERT(-1 == SkPoint::kLeft_Side &&
                   0 == SkPoint::kOn_Side &&
                   1 == kRight_Side);
         *side = (Side) SkScalarSignAsInt(det);
     }
     SkScalar temp = det / uLengthSqd;
     temp *= det;
     return temp;
 }

 SkScalar SkPoint::distanceToLineSegmentBetweenSqd(const SkPoint& a,
                                                   const SkPoint& b) const {
     // See comments to distanceToLineBetweenSqd. If the projection of c onto
     // u is between a and b then this returns the same result as that
     // function. Otherwise, it returns the distance to the closer of a and
     // b. Let the projection of v onto u be v'.  There are three cases:
     //    1. v' points opposite to u. c is not between a and b and is closer
     //       to a than b.
     //    2. v' points along u and has magnitude less than y. c is between
     //       a and b and the distance to the segment is the same as distance
     //       to the line ab.
     //    3. v' points along u and has greater magnitude than u. c is not
     //       not between a and b and is closer to b than a.
     // v' = (u dot v) * u / |u|. So if (u dot v)/|u| is less than zero we're
     // in case 1. If (u dot v)/|u| is > |u| we are in case 3. Otherwise
     // we're in case 2. We actually compare (u dot v) to 0 and |u|^2 to
     // avoid a sqrt to compute |u|.

     SkVector u = b - a;
     SkVector v = *this - a;

     SkScalar uLengthSqd = u.lengthSqd();
     SkScalar uDotV = SkPoint::DotProduct(u, v);

     if (uDotV <= 0) {
         return v.lengthSqd();
     } else if (uDotV > uLengthSqd) {
         return b.distanceToSqd(*this);
     } else {
         SkScalar det = u.cross(v);
         SkScalar temp = det / uLengthSqd;
         temp *= det;
         return temp;
     }
 }
	/*
	* Copyright 2008 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.
	*/


	#include "SkMathPriv.h"
	#include "SkPoint.h"

	void SkIPoint::rotateCW(SkIPoint* dst) const {
	SkASSERT(dst);

	// use a tmp in case this == dst
	int32_t tmp = fX;
	dst->fX = -fY;
	dst->fY = tmp;
	}

	void SkIPoint::rotateCCW(SkIPoint* dst) const {
	SkASSERT(dst);

	// use a tmp in case this == dst
	int32_t tmp = fX;
	dst->fX = fY;
	dst->fY = -tmp;
	}

	///////////////////////////////////////////////////////////////////////////////

	void SkPoint::setIRectFan(int l, int t, int r, int b, size_t stride) {
	SkASSERT(stride >= sizeof(SkPoint));

	((SkPoint)((intptr_t)this + 0 stride))->set(SkIntToScalar(l),
	SkIntToScalar(t));
	((SkPoint)((intptr_t)this + 1 stride))->set(SkIntToScalar(l),
	SkIntToScalar(b));
	((SkPoint)((intptr_t)this + 2 stride))->set(SkIntToScalar(r),
	SkIntToScalar(b));
	((SkPoint)((intptr_t)this + 3 stride))->set(SkIntToScalar(r),
	SkIntToScalar(t));
	}

	void SkPoint::rotateCW(SkPoint* dst) const {
	SkASSERT(dst);

	// use a tmp in case this == dst
	SkScalar tmp = fX;
	dst->fX = -fY;
	dst->fY = tmp;
	}

	void SkPoint::rotateCCW(SkPoint* dst) const {
	SkASSERT(dst);

	// use a tmp in case this == dst
	SkScalar tmp = fX;
	dst->fX = fY;
	dst->fY = -tmp;
	}

	void SkPoint::scale(SkScalar scale, SkPoint* dst) const {
	SkASSERT(dst);
	dst->set(fX * scale, fY * scale);
	}

	bool SkPoint::normalize() {
	return this->setLength(fX, fY, SK_Scalar1);
	}

	bool SkPoint::setNormalize(SkScalar x, SkScalar y) {
	return this->setLength(x, y, SK_Scalar1);
	}

	bool SkPoint::setLength(SkScalar length) {
	return this->setLength(fX, fY, length);
	}

	// Returns the square of the Euclidian distance to (dx,dy).
	static inline float getLengthSquared(float dx, float dy) {
	return dx * dx + dy * dy;
	}

	// Calculates the square of the Euclidian distance to (dx,dy) and stores it in
	// *lengthSquared. Returns true if the distance is judged to be "nearly zero".
	//
	// This logic is encapsulated in a helper method to make it explicit that we
	// always perform this check in the same manner, to avoid inconsistencies
	// (see http://code.google.com/p/skia/issues/detail?id=560 ).
	static inline bool is_length_nearly_zero(float dx, float dy,
	float *lengthSquared) {
	*lengthSquared = getLengthSquared(dx, dy);
	return lengthSquared <= (SK_ScalarNearlyZero SK_ScalarNearlyZero);
	}

	SkScalar SkPoint::Normalize(SkPoint* pt) {
	float x = pt->fX;
	float y = pt->fY;
	float mag2;
	if (is_length_nearly_zero(x, y, &mag2)) {
	pt->set(0, 0);
	return 0;
	}

	float mag, scale;
	if (SkScalarIsFinite(mag2)) {
	mag = sk_float_sqrt(mag2);
	scale = 1 / mag;
	} else {
	// our mag2 step overflowed to infinity, so use doubles instead.
	// much slower, but needed when x or y are very large, other wise we
	// divide by inf. and return (0,0) vector.
	double xx = x;
	double yy = y;
	double magmag = sqrt(xx * xx + yy * yy);
	mag = (float)magmag;
	// we perform the divide with the double magmag, to stay exactly the
	// same as setLength. It would be faster to perform the divide with
	// mag, but it is possible that mag has overflowed to inf. but still
	// have a non-zero value for scale (thanks to denormalized numbers).
	scale = (float)(1 / magmag);
	}
	pt->set(x * scale, y * scale);
	return mag;
	}

	SkScalar SkPoint::Length(SkScalar dx, SkScalar dy) {
	float mag2 = dx * dx + dy * dy;
	if (SkScalarIsFinite(mag2)) {
	return sk_float_sqrt(mag2);
	} else {
	double xx = dx;
	double yy = dy;
	return (float)sqrt(xx * xx + yy * yy);
	}
	}

	/*
	* We have to worry about 2 tricky conditions:
	* 1. underflow of mag2 (compared against nearlyzero^2)
	* 2. overflow of mag2 (compared w/ isfinite)
	*
	* If we underflow, we return false. If we overflow, we compute again using
	* doubles, which is much slower (3x in a desktop test) but will not overflow.
	*/
	bool SkPoint::setLength(float x, float y, float length) {
	float mag2;
	if (is_length_nearly_zero(x, y, &mag2)) {
	this->set(0, 0);
	return false;
	}

	float scale;
	if (SkScalarIsFinite(mag2)) {
	scale = length / sk_float_sqrt(mag2);
	} else {
	// our mag2 step overflowed to infinity, so use doubles instead.
	// much slower, but needed when x or y are very large, other wise we
	// divide by inf. and return (0,0) vector.
	double xx = x;
	double yy = y;
	#ifdef SK_CPU_FLUSH_TO_ZERO
	// The iOS ARM processor discards small denormalized numbers to go faster.
	// Casting this to a float would cause the scale to go to zero. Keeping it
	// as a double for the multiply keeps the scale non-zero.
	double dscale = length / sqrt(xx * xx + yy * yy);
	fX = x * dscale;
	fY = y * dscale;
	return true;
	#else
	scale = (float)(length / sqrt(xx * xx + yy * yy));
	#endif
	}
	fX = x * scale;
	fY = y * scale;
	return true;
	}

	bool SkPoint::setLengthFast(float length) {
	return this->setLengthFast(fX, fY, length);
	}

	bool SkPoint::setLengthFast(float x, float y, float length) {
	float mag2;
	if (is_length_nearly_zero(x, y, &mag2)) {
	this->set(0, 0);
	return false;
	}

	float scale;
	if (SkScalarIsFinite(mag2)) {
	scale = length * sk_float_rsqrt(mag2); // <--- this is the difference
	} else {
	// our mag2 step overflowed to infinity, so use doubles instead.
	// much slower, but needed when x or y are very large, other wise we
	// divide by inf. and return (0,0) vector.
	double xx = x;
	double yy = y;
	scale = (float)(length / sqrt(xx * xx + yy * yy));
	}
	fX = x * scale;
	fY = y * scale;
	return true;
	}


	///////////////////////////////////////////////////////////////////////////////

	SkScalar SkPoint::distanceToLineBetweenSqd(const SkPoint& a,
	const SkPoint& b,
	Side* side) const {

	SkVector u = b - a;
	SkVector v = *this - a;

	SkScalar uLengthSqd = u.lengthSqd();
	SkScalar det = u.cross(v);
	if (side) {
	SkASSERT(-1 == SkPoint::kLeft_Side &&
	0 == SkPoint::kOn_Side &&
	1 == kRight_Side);
	*side = (Side) SkScalarSignAsInt(det);
	}
	SkScalar temp = det / uLengthSqd;
	temp *= det;
	return temp;
	}

	SkScalar SkPoint::distanceToLineSegmentBetweenSqd(const SkPoint& a,
	const SkPoint& b) const {
	// See comments to distanceToLineBetweenSqd. If the projection of c onto
	// u is between a and b then this returns the same result as that
	// function. Otherwise, it returns the distance to the closer of a and
	// b. Let the projection of v onto u be v'. There are three cases:
	// 1. v' points opposite to u. c is not between a and b and is closer
	// to a than b.
	// 2. v' points along u and has magnitude less than y. c is between
	// a and b and the distance to the segment is the same as distance
	// to the line ab.
	// 3. v' points along u and has greater magnitude than u. c is not
	// not between a and b and is closer to b than a.
	// v' = (u dot v) * u / \|u\|. So if (u dot v)/\|u\| is less than zero we're
	// in case 1. If (u dot v)/\|u\| is > \|u\| we are in case 3. Otherwise
	// we're in case 2. We actually compare (u dot v) to 0 and \|u\|^2 to
	// avoid a sqrt to compute \|u\|.

	SkVector u = b - a;
	SkVector v = *this - a;

	SkScalar uLengthSqd = u.lengthSqd();
	SkScalar uDotV = SkPoint::DotProduct(u, v);

	if (uDotV <= 0) {
	return v.lengthSqd();
	} else if (uDotV > uLengthSqd) {
	return b.distanceToSqd(*this);
	} else {
	SkScalar det = u.cross(v);
	SkScalar temp = det / uLengthSqd;
	temp *= det;
	return temp;
	}
	}