gd_interpolation.c

/*
 * The two pass scaling function is based on:
 * Filtered Image Rescaling
 * Based on Gems III
 *  - Schumacher general filtered image rescaling
 * (pp. 414-424)
 * by Dale Schumacher
 *
 * 	Additional changes by Ray Gardener, Daylon Graphics Ltd.
 * 	December 4, 1999
 *
 * 	Ported to libgd by Pierre Joye. Support for multiple channels
 * 	added (argb for now).
 *
 * 	Initial sources code is avaibable in the Gems Source Code Packages:
 * 	http://www.acm.org/pubs/tog/GraphicsGems/GGemsIII.tar.gz
 *
 */

/*
	Summary:

		- Horizontal filter contributions are calculated on the fly,
		  as each column is mapped from src to dst image. This lets
		  us omit having to allocate a temporary full horizontal stretch
		  of the src image.

		- If none of the src pixels within a sampling region differ,
		  then the output pixel is forced to equal (any of) the source pixel.
		  This ensures that filters do not corrupt areas of constant color.

		- Filter weight contribution results, after summing, are
		  rounded to the nearest pixel color value instead of
		  being casted to ILubyte (usually an int or char). Otherwise,
		  artifacting occurs.

*/

/*
	Additional functions are available for simple rotation or up/downscaling.
	downscaling using the fixed point implementations are usually much faster
	than the existing gdImageCopyResampled while having a similar or better
	quality.

	For image rotations, the optimized versions have a lazy antialiasing for
	the edges of the images. For a much better antialiased result, the affine
	function is recommended.
*/

/*
TODO:
 - Optimize pixel accesses and loops once we have continuous buffer
 - Add scale support for a portion only of an image (equivalent of copyresized/resampled)
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

#include <gd.h>
#include "gdhelpers.h"

#ifdef _MSC_VER
# pragma optimize("t", on)
# include <emmintrin.h>
#endif

#ifndef MIN
#define MIN(a,b) ((a)<(b)?(a):(b))
#endif
#define MIN3(a,b,c) ((a)<(b)?(MIN(a,c)):(MIN(b,c)))
#ifndef MAX
#define MAX(a,b) ((a)<(b)?(b):(a))
#endif
#define MAX3(a,b,c) ((a)<(b)?(MAX(b,c)):(MAX(a,c)))

#define CLAMP(x, low, high)  (((x) > (high)) ? (high) : (((x) < (low)) ? (low) : (x)))

/* only used here, let do a generic fixed point integers later if required by other
   part of GD */
typedef long gdFixed;
/* Integer to fixed point */
#define gd_itofx(x) ((x) << 8)

/* Float to fixed point */
#define gd_ftofx(x) (long)((x) * 256)

/*  Double to fixed point */
#define gd_dtofx(x) (long)((x) * 256)

/* Fixed point to integer */
#define gd_fxtoi(x) ((x) >> 8)

/* Fixed point to float */
# define gd_fxtof(x) ((float)(x) / 256)

/* Fixed point to double */
#define gd_fxtod(x) ((double)(x) / 256)

/* Multiply a fixed by a fixed */
#define gd_mulfx(x,y) (((x) * (y)) >> 8)

/* Divide a fixed by a fixed */
#define gd_divfx(x,y) (((x) << 8) / (y))

typedef struct
{
   double *Weights;  /* Normalized weights of neighboring pixels */
   int Left,Right;   /* Bounds of source pixels window */
} ContributionType;  /* Contirbution information for a single pixel */

typedef struct
{
   ContributionType *ContribRow; /* Row (or column) of contribution weights */
   unsigned int WindowSize,      /* Filter window size (of affecting source pixels) */
				LineLength;      /* Length of line (no. or rows / cols) */
} LineContribType;

/* Each core filter has its own radius */
#define DEFAULT_FILTER_BICUBIC				3.0
#define DEFAULT_FILTER_BOX					0.5
#define DEFAULT_FILTER_GENERALIZED_CUBIC	0.5
#define DEFAULT_FILTER_RADIUS				1.0
#define DEFAULT_LANCZOS8_RADIUS				8.0
#define DEFAULT_LANCZOS3_RADIUS				3.0
#define DEFAULT_HERMITE_RADIUS				1.0
#define DEFAULT_BOX_RADIUS					0.5
#define DEFAULT_TRIANGLE_RADIUS				1.0
#define DEFAULT_BELL_RADIUS					1.5
#define DEFAULT_CUBICSPLINE_RADIUS			2.0
#define DEFAULT_MITCHELL_RADIUS				2.0
#define DEFAULT_COSINE_RADIUS				1.0
#define DEFAULT_CATMULLROM_RADIUS			2.0
#define DEFAULT_QUADRATIC_RADIUS			1.5
#define DEFAULT_QUADRATICBSPLINE_RADIUS		1.5
#define DEFAULT_CUBICCONVOLUTION_RADIUS		3.0
#define DEFAULT_GAUSSIAN_RADIUS				1.0
#define DEFAULT_HANNING_RADIUS				1.0
#define DEFAULT_HAMMING_RADIUS				1.0
#define DEFAULT_SINC_RADIUS					1.0
#define DEFAULT_WELSH_RADIUS				1.0

enum GD_RESIZE_FILTER_TYPE{
	FILTER_DEFAULT          = 0,
	FILTER_BELL,
	FILTER_BESSEL,
	FILTER_BLACKMAN,
	FILTER_BOX,
	FILTER_BSPLINE,
	FILTER_CATMULLROM,
	FILTER_COSINE,
	FILTER_CUBICCONVOLUTION,
	FILTER_CUBICSPLINE,
	FILTER_HERMITE,
	FILTER_LANCZOS3,
	FILTER_LANCZOS8,
	FILTER_MITCHELL,
	FILTER_QUADRATIC,
	FILTER_QUADRATICBSPLINE,
	FILTER_TRIANGLE,
	FILTER_GAUSSIAN,
	FILTER_HANNING,
	FILTER_HAMMING,
	FILTER_SINC,
	FILTER_WELSH,

	FILTER_CALLBACK        = 999
};

typedef enum GD_RESIZE_FILTER_TYPE gdResizeFilterType;

static double KernelBessel_J1(const double x)
{
	double p, q;

	register long i;

	static const double
	Pone[] =
	{
		0.581199354001606143928050809e+21,
		-0.6672106568924916298020941484e+20,
		0.2316433580634002297931815435e+19,
		-0.3588817569910106050743641413e+17,
		0.2908795263834775409737601689e+15,
		-0.1322983480332126453125473247e+13,
		0.3413234182301700539091292655e+10,
		-0.4695753530642995859767162166e+7,
		0.270112271089232341485679099e+4
	},
	Qone[] =
	{
		0.11623987080032122878585294e+22,
		0.1185770712190320999837113348e+20,
		0.6092061398917521746105196863e+17,
		0.2081661221307607351240184229e+15,
		0.5243710262167649715406728642e+12,
		0.1013863514358673989967045588e+10,
		0.1501793594998585505921097578e+7,
		0.1606931573481487801970916749e+4,
		0.1e+1
	};

	p = Pone[8];
	q = Qone[8];
	for (i=7; i >= 0; i--)
	{
		p = p*x*x+Pone[i];
		q = q*x*x+Qone[i];
	}
	return (double)(p/q);
}

static double KernelBessel_P1(const double x)
{
	double p, q;

	register long i;

	static const double
	Pone[] =
	{
		0.352246649133679798341724373e+5,
		0.62758845247161281269005675e+5,
		0.313539631109159574238669888e+5,
		0.49854832060594338434500455e+4,
		0.2111529182853962382105718e+3,
		0.12571716929145341558495e+1
	},
	Qone[] =
	{
		0.352246649133679798068390431e+5,
		0.626943469593560511888833731e+5,
		0.312404063819041039923015703e+5,
		0.4930396490181088979386097e+4,
		0.2030775189134759322293574e+3,
		0.1e+1
	};

	p = Pone[5];
	q = Qone[5];
	for (i=4; i >= 0; i--)
	{
		p = p*(8.0/x)*(8.0/x)+Pone[i];
		q = q*(8.0/x)*(8.0/x)+Qone[i];
	}
	return (double)(p/q);
}

static double KernelBessel_Q1(const double x)
{
	double p, q;

	register long i;

	static const double
	Pone[] =
	{
		0.3511751914303552822533318e+3,
		0.7210391804904475039280863e+3,
		0.4259873011654442389886993e+3,
		0.831898957673850827325226e+2,
		0.45681716295512267064405e+1,
		0.3532840052740123642735e-1
	},
	Qone[] =
	{
		0.74917374171809127714519505e+4,
		0.154141773392650970499848051e+5,
		0.91522317015169922705904727e+4,
		0.18111867005523513506724158e+4,
		0.1038187585462133728776636e+3,
		0.1e+1
	};

	p = Pone[5];
	q = Qone[5];
	for (i=4; i >= 0; i--)
	{
		p = p*(8.0/x)*(8.0/x)+Pone[i];
		q = q*(8.0/x)*(8.0/x)+Qone[i];
	}
	return (double)(p/q);
}

static double KernelBessel_Order1(double x)
{
	double p, q;

	if (x == 0.0)
		return (0.0f);
	p = x;
	if (x < 0.0)
		x=(-x);
	if (x < 8.0)
		return (p*KernelBessel_J1(x));
	q = (double)sqrt(2.0f/(M_PI*x))*(double)(KernelBessel_P1(x)*(1.0f/sqrt(2.0f)*(sin(x)-cos(x)))-8.0f/x*KernelBessel_Q1(x)*
		(-1.0f/sqrt(2.0f)*(sin(x)+cos(x))));
	if (p < 0.0f)
		q = (-q);
	return (q);
}

static double filter_bessel(const double x)
{
	if (x == 0.0f)
		return (double)(M_PI/4.0f);
	return (KernelBessel_Order1((double)M_PI*x)/(2.0f*x));
}


static double filter_blackman(const double x)
{
	return (0.42f+0.5f*(double)cos(M_PI*x)+0.08f*(double)cos(2.0f*M_PI*x));
}

/**
 * Bicubic interpolation kernel (a=-1):
  \verbatim
          /
         | 1-2|t|**2+|t|**3          , if |t| < 1
  h(t) = | 4-8|t|+5|t|**2-|t|**3     , if 1<=|t|<2
         | 0                         , otherwise
          \
  \endverbatim
 * ***bd*** 2.2004
 */
static double filter_bicubic(const double t)
{
  const double abs_t = (double)fabs(t);
  const double abs_t_sq = abs_t * abs_t;
  if (abs_t<1) return 1-2*abs_t_sq+abs_t_sq*abs_t;
  if (abs_t<2) return 4 - 8*abs_t +5*abs_t_sq - abs_t_sq*abs_t;
  return 0;
}

/**
 * Generalized cubic kernel (for a=-1 it is the same as BicubicKernel):
  \verbatim
          /
         | (a+2)|t|**3 - (a+3)|t|**2 + 1     , |t| <= 1
  h(t) = | a|t|**3 - 5a|t|**2 + 8a|t| - 4a   , 1 < |t| <= 2
         | 0                                 , otherwise
          \
  \endverbatim
 * Often used values for a are -1 and -1/2.
 */
static double filter_generalized_cubic(const double t)
{
	const double a = -DEFAULT_FILTER_GENERALIZED_CUBIC;
	double abs_t = (double)fabs(t);
	double abs_t_sq = abs_t * abs_t;
	if (abs_t < 1) return (a + 2) * abs_t_sq * abs_t - (a + 3) * abs_t_sq + 1;
	if (abs_t < 2) return a * abs_t_sq * abs_t - 5 * a * abs_t_sq + 8 * a * abs_t - 4 * a;
	return 0;
}

/* CubicSpline filter, default radius 2 */
static double filter_cubic_spline(const double x1)
{
	const double x = x1 < 0.0 ? -x1 : x1;

	if (x < 1.0 ) {
		const double x2 = x*x;

		return (0.5 * x2 * x - x2 + 2.0 / 3.0);
	}
	if (x < 2.0) {
		return (pow(2.0 - x, 3.0)/6.0);
	}
	return 0;
}

/* CubicConvolution filter, default radius 3 */
static double filter_cubic_convolution(const double x1)
{
	const double x = x1 < 0.0 ? -x1 : x1;
	const double x2 = x1 * x1;
	const double x2_x = x2 * x;

	if (x <= 1.0) return ((4.0 / 3.0)* x2_x - (7.0 / 3.0) * x2 + 1.0);
	if (x <= 2.0) return (- (7.0 / 12.0) * x2_x + 3 * x2 - (59.0 / 12.0) * x + 2.5);
	if (x <= 3.0) return ( (1.0/12.0) * x2_x - (2.0 / 3.0) * x2 + 1.75 * x - 1.5);
	return 0;
}

static double filter_box(double x) {
	if (x < - DEFAULT_FILTER_BOX)
		return 0.0f;
	if (x < DEFAULT_FILTER_BOX)
		return 1.0f;
	return 0.0f;
}

static double filter_catmullrom(const double x)
{
	if (x < -2.0)
		return(0.0f);
	if (x < -1.0)
		return(0.5f*(4.0f+x*(8.0f+x*(5.0f+x))));
	if (x < 0.0)
		return(0.5f*(2.0f+x*x*(-5.0f-3.0f*x)));
	if (x < 1.0)
		return(0.5f*(2.0f+x*x*(-5.0f+3.0f*x)));
	if (x < 2.0)
		return(0.5f*(4.0f+x*(-8.0f+x*(5.0f-x))));
	return(0.0f);
}

static double filter_filter(double t)
{
	/* f(t) = 2|t|^3 - 3|t|^2 + 1, -1 <= t <= 1 */
	if(t < 0.0) t = -t;
	if(t < 1.0) return((2.0 * t - 3.0) * t * t + 1.0);
	return(0.0);
}


/* Lanczos8 filter, default radius 8 */
static double filter_lanczos8(const double x1)
{
	const double x = x1 < 0.0 ? -x1 : x1;
#define R DEFAULT_LANCZOS8_RADIUS

	if ( x == 0.0) return 1;

	if ( x < R) {
		return R * sin(x*M_PI) * sin(x * M_PI/ R) / (x * M_PI * x * M_PI);
	}
	return 0.0;
#undef R
}


/* Lanczos3 filter, default radius 3 */
static double filter_lanczos3(const double x1)
{
	const double x = x1 < 0.0 ? -x1 : x1;
#define R DEFAULT_LANCZOS3_RADIUS

	if ( x == 0.0) return 1;

	if ( x < R)
	{
		return R * sin(x*M_PI) * sin(x * M_PI / R) / (x * M_PI * x * M_PI);
	}
	return 0.0;
#undef R
}

/* Hermite filter, default radius 1 */
static double filter_hermite(const double x1)
{
	const double x = x1 < 0.0 ? -x1 : x1;

	if (x < 1.0) return ((2.0 * x - 3) * x * x + 1.0 );

	return 0.0;
}

/* Trangle filter, default radius 1 */
static double filter_triangle(const double x1)
{
	const double x = x1 < 0.0 ? -x1 : x1;
	if (x < 1.0) return (1.0 - x);
	return 0.0;
}

/* Bell filter, default radius 1.5 */
static double filter_bell(const double x1)
{
	const double x = x1 < 0.0 ? -x1 : x1;

	if (x < 0.5) return (0.75 - x*x);
	if (x < 1.5) return (0.5 * pow(x - 1.5, 2.0));
	return 0.0;
}

/* Mitchell filter, default radius 2.0 */
static double filter_mitchell(const double x)
{
#define KM_B (1.0f/3.0f)
#define KM_C (1.0f/3.0f)
#define KM_P0 ((  6.0f - 2.0f * KM_B ) / 6.0f)
#define KM_P2 ((-18.0f + 12.0f * KM_B + 6.0f * KM_C) / 6.0f)
#define KM_P3 (( 12.0f - 9.0f  * KM_B - 6.0f * KM_C) / 6.0f)
#define KM_Q0 ((  8.0f * KM_B + 24.0f * KM_C) / 6.0f)
#define KM_Q1 ((-12.0f * KM_B - 48.0f * KM_C) / 6.0f)
#define KM_Q2 ((  6.0f * KM_B + 30.0f * KM_C) / 6.0f)
#define KM_Q3 (( -1.0f * KM_B -  6.0f * KM_C) / 6.0f)

	if (x < -2.0)
		return(0.0f);
	if (x < -1.0)
		return(KM_Q0-x*(KM_Q1-x*(KM_Q2-x*KM_Q3)));
	if (x < 0.0f)
		return(KM_P0+x*x*(KM_P2-x*KM_P3));
	if (x < 1.0f)
		return(KM_P0+x*x*(KM_P2+x*KM_P3));
	if (x < 2.0f)
		return(KM_Q0+x*(KM_Q1+x*(KM_Q2+x*KM_Q3)));
	return(0.0f);
}



/* Cosine filter, default radius 1 */
static double filter_cosine(const double x)
{
	if ((x >= -1.0) && (x <= 1.0)) return ((cos(x * M_PI) + 1.0)/2.0);

	return 0;
}

/* Quadratic filter, default radius 1.5 */
static double filter_quadratic(const double x1)
{
	const double x = x1 < 0.0 ? -x1 : x1;

	if (x <= 0.5) return (- 2.0 * x * x + 1);
	if (x <= 1.5) return (x * x - 2.5* x + 1.5);
	return 0.0;
}

static double filter_bspline(const double x)
{
	if (x>2.0f) {
		return 0.0f;
	} else {
		double a, b, c, d;
		/* Was calculated anyway cause the "if((x-1.0f) < 0)" */
		const double xm1 = x - 1.0f;
		const double xp1 = x + 1.0f;
		const double xp2 = x + 2.0f;

		if ((xp2) <= 0.0f) a = 0.0f; else a = xp2*xp2*xp2;
		if ((xp1) <= 0.0f) b = 0.0f; else b = xp1*xp1*xp1;
		if (x <= 0) c = 0.0f; else c = x*x*x;
		if ((xm1) <= 0.0f) d = 0.0f; else d = xm1*xm1*xm1;

		return (0.16666666666666666667f * (a - (4.0f * b) + (6.0f * c) - (4.0f * d)));
	}
}

/* QuadraticBSpline filter, default radius 1.5 */
static double filter_quadratic_bspline(const double x1)
{
	const double x = x1 < 0.0 ? -x1 : x1;

	if (x <= 0.5) return (- x * x + 0.75);
	if (x <= 1.5) return (0.5 * x * x - 1.5 * x + 1.125);
	return 0.0;
}

static double filter_gaussian(const double x)
{
	/* return(exp((double) (-2.0 * x * x)) * sqrt(2.0 / M_PI)); */
	return (double)(exp(-2.0f * x * x) * 0.79788456080287f);
}

static double filter_hanning(const double x)
{
	/* A Cosine windowing function */
	return(0.5 + 0.5 * cos(M_PI * x));
}

static double filter_hamming(const double x)
{
	/* should be
	(0.54+0.46*cos(M_PI*(double) x));
	but this approximation is sufficient */
	if (x < -1.0f)
		return 0.0f;
	if (x < 0.0f)
		return 0.92f*(-2.0f*x-3.0f)*x*x+1.0f;
	if (x < 1.0f)
		return 0.92f*(2.0f*x-3.0f)*x*x+1.0f;
	return 0.0f;
}

static double filter_power(const double x)
{
	const double a = 2.0f;
	if (fabs(x)>1) return 0.0f;
	return (1.0f - (double)fabs(pow(x,a)));
}

static double filter_sinc(const double x)
{
	/* X-scaled Sinc(x) function. */
	if (x == 0.0) return(1.0);
	return (sin(M_PI * (double) x) / (M_PI * (double) x));
}

static double filter_welsh(const double x)
{
	/* Welsh parabolic windowing filter */
	if (x <  1.0)
		return(1 - x*x);
	return(0.0);
}


/* Copied from upstream's libgd */
static inline int _color_blend (const int dst, const int src)
{
    const int src_alpha = gdTrueColorGetAlpha(src);

    if( src_alpha == gdAlphaOpaque ) {
		return src;
	} else {
		const int dst_alpha = gdTrueColorGetAlpha(dst);

		if( src_alpha == gdAlphaTransparent ) return dst;
		if( dst_alpha == gdAlphaTransparent ) {
			return src;
		} else {
			register int alpha, red, green, blue;
			const int src_weight = gdAlphaTransparent - src_alpha;
			const int dst_weight = (gdAlphaTransparent - dst_alpha) * src_alpha / gdAlphaMax;
			const int tot_weight = src_weight + dst_weight;

			alpha = src_alpha * dst_alpha / gdAlphaMax;

			red = (gdTrueColorGetRed(src) * src_weight
				   + gdTrueColorGetRed(dst) * dst_weight) / tot_weight;
			green = (gdTrueColorGetGreen(src) * src_weight
				   + gdTrueColorGetGreen(dst) * dst_weight) / tot_weight;
			blue = (gdTrueColorGetBlue(src) * src_weight
				   + gdTrueColorGetBlue(dst) * dst_weight) / tot_weight;

			return ((alpha << 24) + (red << 16) + (green << 8) + blue);
		}
	}
}

static inline int _setEdgePixel(const gdImagePtr src, unsigned int x, unsigned int y, gdFixed coverage, const int bgColor)
{
	const gdFixed f_127 = gd_itofx(127);
	register int c = src->tpixels[y][x];
	c = c | (( (int) (gd_fxtof(gd_mulfx(coverage, f_127)) + 50.5f)) << 24);
	return _color_blend(bgColor, c);
}

static inline int getPixelOverflowTC(gdImagePtr im, const int x, const int y, const int bgColor)
{
	if (gdImageBoundsSafe(im, x, y)) {
		const int c = im->tpixels[y][x];
		if (c == im->transparent) {
			return bgColor == -1 ? gdTrueColorAlpha(0, 0, 0, 127) : bgColor;
		}
		return c;
	} else {
		register int border = 0;

		if (y < im->cy1) {
			border = im->tpixels[0][im->cx1];
			goto processborder;
		}

		if (y < im->cy1) {
			border = im->tpixels[0][im->cx1];
			goto processborder;
		}

		if (y > im->cy2) {
			if (x >= im->cx1 && x <= im->cx1) {
				border = im->tpixels[im->cy2][x];
				goto processborder;
			} else {
				return gdTrueColorAlpha(0, 0, 0, 127);
			}
		}

		/* y is bound safe at this point */
		if (x < im->cx1) {
			border = im->tpixels[y][im->cx1];
			goto processborder;
		}

		if (x > im->cx2) {
			border = im->tpixels[y][im->cx2];
		}

processborder:
		if (border == im->transparent) {
			return gdTrueColorAlpha(0, 0, 0, 127);
		} else{
			return gdTrueColorAlpha(gdTrueColorGetRed(border), gdTrueColorGetGreen(border), gdTrueColorGetBlue(border), 127);
		}
	}
}

#define colorIndex2RGBA(c) gdTrueColorAlpha(im->red[(c)], im->green[(c)], im->blue[(c)], im->alpha[(c)])
#define colorIndex2RGBcustomA(c, a) gdTrueColorAlpha(im->red[(c)], im->green[(c)], im->blue[(c)], im->alpha[(a)])
static inline int getPixelOverflowPalette(gdImagePtr im, const int x, const int y, const int bgColor)
{
	if (gdImageBoundsSafe(im, x, y)) {
		const int c = im->pixels[y][x];
		if (c == im->transparent) {
			return bgColor == -1 ? gdTrueColorAlpha(0, 0, 0, 127) : bgColor;
		}
		return colorIndex2RGBA(c);
	} else {
		register int border = 0;
		if (y < im->cy1) {
			border = gdImageGetPixel(im, im->cx1, 0);
			goto processborder;
		}

		if (y < im->cy1) {
			border = gdImageGetPixel(im, im->cx1, 0);
			goto processborder;
		}

		if (y > im->cy2) {
			if (x >= im->cx1 && x <= im->cx1) {
				border = gdImageGetPixel(im, x,  im->cy2);
				goto processborder;
			} else {
				return gdTrueColorAlpha(0, 0, 0, 127);
			}
		}

		/* y is bound safe at this point */
		if (x < im->cx1) {
			border = gdImageGetPixel(im, im->cx1, y);
			goto processborder;
		}

		if (x > im->cx2) {
			border = gdImageGetPixel(im, im->cx2, y);
		}

processborder:
		if (border == im->transparent) {
			return gdTrueColorAlpha(0, 0, 0, 127);
		} else{
			return colorIndex2RGBcustomA(border, 127);
		}
	}
}

static int getPixelInterpolateWeight(gdImagePtr im, const double x, const double y, const int bgColor)
{
	/* Closest pixel <= (xf,yf) */
	int sx = (int)(x);
	int sy = (int)(y);
	const double xf = x - (double)sx;
	const double yf = y - (double)sy;
	const double nxf = (double) 1.0 - xf;
	const double nyf = (double) 1.0 - yf;
	const double m1 = xf * yf;
	const double m2 = nxf * yf;
	const double m3 = xf * nyf;
	const double m4 = nxf * nyf;

	/* get color values of neighbouring pixels */
	const int c1 = im->trueColor == 1 ? getPixelOverflowTC(im, sx, sy, bgColor)         : getPixelOverflowPalette(im, sx, sy, bgColor);
	const int c2 = im->trueColor == 1 ? getPixelOverflowTC(im, sx - 1, sy, bgColor)     : getPixelOverflowPalette(im, sx - 1, sy, bgColor);
	const int c3 = im->trueColor == 1 ? getPixelOverflowTC(im, sx, sy - 1, bgColor)     : getPixelOverflowPalette(im, sx, sy - 1, bgColor);
	const int c4 = im->trueColor == 1 ? getPixelOverflowTC(im, sx - 1, sy - 1, bgColor) : getPixelOverflowPalette(im, sx, sy - 1, bgColor);
	int r, g, b, a;

	if (x < 0) sx--;
	if (y < 0) sy--;

	/* component-wise summing-up of color values */
	if (im->trueColor) {
		r = (int)(m1*gdTrueColorGetRed(c1)   + m2*gdTrueColorGetRed(c2)   + m3*gdTrueColorGetRed(c3)   + m4*gdTrueColorGetRed(c4));
		g = (int)(m1*gdTrueColorGetGreen(c1) + m2*gdTrueColorGetGreen(c2) + m3*gdTrueColorGetGreen(c3) + m4*gdTrueColorGetGreen(c4));
		b = (int)(m1*gdTrueColorGetBlue(c1)  + m2*gdTrueColorGetBlue(c2)  + m3*gdTrueColorGetBlue(c3)  + m4*gdTrueColorGetBlue(c4));
		a = (int)(m1*gdTrueColorGetAlpha(c1) + m2*gdTrueColorGetAlpha(c2) + m3*gdTrueColorGetAlpha(c3) + m4*gdTrueColorGetAlpha(c4));
	} else {
		r = (int)(m1*im->red[(c1)]   + m2*im->red[(c2)]   + m3*im->red[(c3)]   + m4*im->red[(c4)]);
		g = (int)(m1*im->green[(c1)] + m2*im->green[(c2)] + m3*im->green[(c3)] + m4*im->green[(c4)]);
		b = (int)(m1*im->blue[(c1)]  + m2*im->blue[(c2)]  + m3*im->blue[(c3)]  + m4*im->blue[(c4)]);
		a = (int)(m1*im->alpha[(c1)] + m2*im->alpha[(c2)] + m3*im->alpha[(c3)] + m4*im->alpha[(c4)]);
	}

	r = CLAMP(r, 0, 255);
	g = CLAMP(g, 0, 255);
	b = CLAMP(b, 0, 255);
	a = CLAMP(a, 0, gdAlphaMax);
	return gdTrueColorAlpha(r, g, b, a);
}

/**
 * Function: getPixelInterpolated
 *  Returns the interpolated color value using the default interpolation
 *  method. The returned color is always in the ARGB format (truecolor).
 *
 * Parameters:
 * 	im - Image to set the default interpolation method
 *  y - X value of the ideal position
 *  y - Y value of the ideal position
 *  method - Interpolation method <gdInterpolationMethod>
 *
 * Returns:
 *  GD_TRUE if the affine is rectilinear or GD_FALSE
 *
 * See also:
 *  <gdSetInterpolationMethod>
 */
int getPixelInterpolated(gdImagePtr im, const double x, const double y, const int bgColor)
{
	const int xi=(int)((x) < 0 ? x - 1: x);
	const int yi=(int)((y) < 0 ? y - 1: y);
	int yii;
	int i;
	double kernel, kernel_cache_y;
	double kernel_x[12], kernel_y[4];
	double new_r = 0.0f, new_g = 0.0f, new_b = 0.0f, new_a = 0.0f;

	/* These methods use special implementations */
	if (im->interpolation_id == GD_BILINEAR_FIXED || im->interpolation_id == GD_BICUBIC_FIXED || im->interpolation_id == GD_NEAREST_NEIGHBOUR) {
		return -1;
	}

	if (im->interpolation_id == GD_WEIGHTED4) {
		return getPixelInterpolateWeight(im, x, y, bgColor);
	}

	if (im->interpolation_id == GD_NEAREST_NEIGHBOUR) {
		if (im->trueColor == 1) {
			return getPixelOverflowTC(im, xi, yi, bgColor);
		} else {
			return getPixelOverflowPalette(im, xi, yi, bgColor);
		}
	}
	if (im->interpolation) {
		for (i=0; i<4; i++) {
			kernel_x[i] = (double) im->interpolation((double)(xi+i-1-x));
			kernel_y[i] = (double) im->interpolation((double)(yi+i-1-y));
		}
	} else {
		return -1;
	}

	/*
	 * TODO: use the known fast rgba multiplication implementation once
	 * the new formats are in place
	 */
	for (yii = yi-1; yii < yi+3; yii++) {
		int xii;
		kernel_cache_y = kernel_y[yii-(yi-1)];
		if (im->trueColor) {
			for (xii=xi-1; xii<xi+3; xii++) {
				const int rgbs = getPixelOverflowTC(im, xii, yii, bgColor);

				kernel = kernel_cache_y * kernel_x[xii-(xi-1)];
				new_r += kernel * gdTrueColorGetRed(rgbs);
				new_g += kernel * gdTrueColorGetGreen(rgbs);
				new_b += kernel * gdTrueColorGetBlue(rgbs);
				new_a += kernel * gdTrueColorGetAlpha(rgbs);
			}
		} else {
			for (xii=xi-1; xii<xi+3; xii++) {
				const int rgbs = getPixelOverflowPalette(im, xii, yii, bgColor);

				kernel = kernel_cache_y * kernel_x[xii-(xi-1)];
				new_r += kernel * gdTrueColorGetRed(rgbs);
				new_g += kernel * gdTrueColorGetGreen(rgbs);
				new_b += kernel * gdTrueColorGetBlue(rgbs);
				new_a += kernel * gdTrueColorGetAlpha(rgbs);
			}
		}
	}

	new_r = CLAMP(new_r, 0, 255);
	new_g = CLAMP(new_g, 0, 255);
	new_b = CLAMP(new_b, 0, 255);
	new_a = CLAMP(new_a, 0, gdAlphaMax);

	return gdTrueColorAlpha(((int)new_r), ((int)new_g), ((int)new_b), ((int)new_a));
}

static inline LineContribType * _gdContributionsAlloc(unsigned int line_length, unsigned int windows_size)
{
	unsigned int u = 0;
    LineContribType *res;

	res = (LineContribType *) gdMalloc(sizeof(LineContribType));
	if (!res) {
		return NULL;
	}
    res->WindowSize = windows_size;
    res->LineLength = line_length;
    res->ContribRow = (ContributionType *) gdMalloc(line_length * sizeof(ContributionType));

    for (u = 0 ; u < line_length ; u++) {
        res->ContribRow[u].Weights = (double *) gdMalloc(windows_size * sizeof(double));
    }
    return res;
}

static inline void _gdContributionsFree(LineContribType * p)
{
	unsigned int u;
	for (u = 0; u < p->LineLength; u++)  {
		gdFree(p->ContribRow[u].Weights);
	}
	gdFree(p->ContribRow);
	gdFree(p);
}

static inline LineContribType *_gdContributionsCalc(unsigned int line_size, unsigned int src_size, double scale_d,  const interpolation_method pFilter)
{
    double width_d;
    double scale_f_d = 1.0;
    const double filter_width_d = DEFAULT_BOX_RADIUS;
	int windows_size;
	unsigned int u;
	LineContribType *res;

    if (scale_d < 1.0) {
        width_d = filter_width_d / scale_d;
        scale_f_d = scale_d;
    }  else {
        width_d= filter_width_d;
    }

    windows_size = 2 * (int)ceil(width_d) + 1;
    res = _gdContributionsAlloc(line_size, windows_size);

    for (u = 0; u < line_size; u++) {
        const double dCenter = (double)u / scale_d;
        /* get the significant edge points affecting the pixel */
        register int iLeft = MAX(0, (int)floor (dCenter - width_d));
        int iRight = MIN((int)ceil(dCenter + width_d), (int)src_size - 1);
        double dTotalWeight = 0.0;
		int iSrc;

        res->ContribRow[u].Left = iLeft;
        res->ContribRow[u].Right = iRight;

        /* Cut edge points to fit in filter window in case of spill-off */
        if (iRight - iLeft + 1 > windows_size)  {
            if (iLeft < ((int)src_size - 1 / 2))  {
                iLeft++;
            } else {
                iRight--;
            }
        }

        for (iSrc = iLeft; iSrc <= iRight; iSrc++) {
            dTotalWeight += (res->ContribRow[u].Weights[iSrc-iLeft] =  scale_f_d * (*pFilter)(scale_f_d * (dCenter - (double)iSrc)));
        }

		if (dTotalWeight < 0.0) {
			_gdContributionsFree(res);
			return NULL;
		}

        if (dTotalWeight > 0.0) {
            for (iSrc = iLeft; iSrc <= iRight; iSrc++) {
                res->ContribRow[u].Weights[iSrc-iLeft] /= dTotalWeight;
            }
        }
   }
   return res;
}

static inline void _gdScaleRow(gdImagePtr pSrc,  unsigned int src_width, gdImagePtr dst, unsigned int dst_width, unsigned int row, LineContribType *contrib)
{
    int *p_src_row = pSrc->tpixels[row];
    int *p_dst_row = dst->tpixels[row];
	unsigned int x;

    for (x = 0; x < dst_width - 1; x++) {
		register unsigned char r = 0, g = 0, b = 0, a = 0;
        const int left = contrib->ContribRow[x].Left;
        const int right = contrib->ContribRow[x].Right;
		int i;

		/* Accumulate each channel */
        for (i = left; i <= right; i++) {
			const int left_channel = i - left;
            r += (unsigned char)(contrib->ContribRow[x].Weights[left_channel] * (double)(gdTrueColorGetRed(p_src_row[i])));
            g += (unsigned char)(contrib->ContribRow[x].Weights[left_channel] * (double)(gdTrueColorGetGreen(p_src_row[i])));
            b += (unsigned char)(contrib->ContribRow[x].Weights[left_channel] * (double)(gdTrueColorGetBlue(p_src_row[i])));
			a += (unsigned char)(contrib->ContribRow[x].Weights[left_channel] * (double)(gdTrueColorGetAlpha(p_src_row[i])));
        }
        p_dst_row[x] = gdTrueColorAlpha(r, g, b, a);
    }
}

static inline void _gdScaleHoriz(gdImagePtr pSrc, unsigned int src_width, unsigned int src_height, gdImagePtr pDst,  unsigned int dst_width, unsigned int dst_height)
{
	unsigned int u;
	LineContribType * contrib;

	/* same width, just copy it */
	if (dst_width == src_width) {
		unsigned int y;
		for (y = 0; y < src_height - 1; ++y) {
			memcpy(pDst->tpixels[y], pSrc->tpixels[y], src_width);
		}
	}

	contrib = _gdContributionsCalc(dst_width, src_width, (double)dst_width / (double)src_width, pSrc->interpolation);
	if (contrib == NULL) {
		return;
	}
	/* Scale each row */
	for (u = 0; u < dst_height - 1; u++) {
		_gdScaleRow(pSrc, src_width, pDst, dst_width, u, contrib);
	}
	_gdContributionsFree (contrib);
}

static inline void _gdScaleCol (gdImagePtr pSrc,  unsigned int src_width, gdImagePtr pRes, unsigned int dst_width, unsigned int dst_height, unsigned int uCol, LineContribType *contrib)
{
	unsigned int y;
	for (y = 0; y < dst_height - 1; y++) {
		register unsigned char r = 0, g = 0, b = 0, a = 0;
		const int iLeft = contrib->ContribRow[y].Left;
		const int iRight = contrib->ContribRow[y].Right;
		int i;
		int *row = pRes->tpixels[y];

		/* Accumulate each channel */
		for (i = iLeft; i <= iRight; i++) {
			const int pCurSrc = pSrc->tpixels[i][uCol];
			const int i_iLeft = i - iLeft;
			r += (unsigned char)(contrib->ContribRow[y].Weights[i_iLeft] * (double)(gdTrueColorGetRed(pCurSrc)));
			g += (unsigned char)(contrib->ContribRow[y].Weights[i_iLeft] * (double)(gdTrueColorGetGreen(pCurSrc)));
			b += (unsigned char)(contrib->ContribRow[y].Weights[i_iLeft] * (double)(gdTrueColorGetBlue(pCurSrc)));
			a += (unsigned char)(contrib->ContribRow[y].Weights[i_iLeft] * (double)(gdTrueColorGetAlpha(pCurSrc)));
		}
		pRes->tpixels[y][uCol] = gdTrueColorAlpha(r, g, b, a);
	}
}

static inline void _gdScaleVert (const gdImagePtr pSrc, const unsigned int src_width, const unsigned int src_height, const gdImagePtr pDst, const unsigned int dst_width, const unsigned int dst_height)
{
	unsigned int u;
	LineContribType * contrib;

	/* same height, copy it */
	if (src_height == dst_height) {
		unsigned int y;
		for (y = 0; y < src_height - 1; ++y) {
			memcpy(pDst->tpixels[y], pSrc->tpixels[y], src_width);
		}
	}

	contrib = _gdContributionsCalc(dst_height, src_height, (double)(dst_height) / (double)(src_height), pSrc->interpolation);
	/* scale each column */
	for (u = 0; u < dst_width - 1; u++) {
		_gdScaleCol(pSrc, src_width, pDst, dst_width, dst_height, u, contrib);
	}
	_gdContributionsFree(contrib);
}

gdImagePtr gdImageScaleTwoPass(const gdImagePtr src, const unsigned int src_width, const unsigned int src_height, const unsigned int new_width, const unsigned int new_height)
{
	gdImagePtr tmp_im;
	gdImagePtr dst;

	/* Convert to truecolor if it isn't; this code requires it. */
	if (!src->trueColor) {
		gdImagePaletteToTrueColor(src);
	}

	tmp_im = gdImageCreateTrueColor(new_width, src_height);
	if (tmp_im == NULL) {
		return NULL;
	}
	gdImageSetInterpolationMethod(tmp_im, src->interpolation_id);
	_gdScaleHoriz(src, src_width, src_height, tmp_im, new_width, src_height);

	dst = gdImageCreateTrueColor(new_width, new_height);
	if (dst == NULL) {
		gdImageDestroy(tmp_im);
		return NULL;
	}
	gdImageSetInterpolationMethod(dst, src->interpolation_id);
	_gdScaleVert(tmp_im, new_width, src_height, dst, new_width, new_height);
	gdImageDestroy(tmp_im);

	return dst;
}

gdImagePtr Scale(const gdImagePtr src, const unsigned int src_width, const unsigned int src_height, const gdImagePtr dst, const unsigned int new_width, const unsigned int new_height)
{
	gdImagePtr tmp_im;

	tmp_im = gdImageCreateTrueColor(new_width, src_height);
	if (tmp_im == NULL) {
		return NULL;
	}
	gdImageSetInterpolationMethod(tmp_im, src->interpolation_id);

	_gdScaleHoriz(src, src_width, src_height, tmp_im, new_width, src_height);
	_gdScaleVert(tmp_im, new_width, src_height, dst, new_width, new_height);

	gdFree(tmp_im);
	return dst;
}

/*
	BilinearFixed, BicubicFixed and nearest implementations are rewamped versions of the implementation in CBitmapEx
	http://www.codeproject.com/Articles/29121/CBitmapEx-Free-C-Bitmap-Manipulation-Class
	Integer only implementation, good to have for common usages like pre scale very large
	images before using another interpolation methods for the last step.
*/
gdImagePtr gdImageScaleNearestNeighbour(gdImagePtr im, const unsigned int width, const unsigned int height)
{
	const unsigned long new_width = MAX(1, width);
	const unsigned long new_height = MAX(1, height);
	const float dx = (float)im->sx / (float)new_width;
	const float dy = (float)im->sy / (float)new_height;
	const gdFixed f_dx = gd_ftofx(dx);
	const gdFixed f_dy = gd_ftofx(dy);

	gdImagePtr dst_img;
	unsigned long  dst_offset_x;
	unsigned long  dst_offset_y = 0;
	unsigned int i;

	dst_img = gdImageCreateTrueColor(new_width, new_height);

	if (dst_img == NULL) {
		return NULL;
	}

	for (i=0; i<new_height; i++) {
		unsigned int j;
		dst_offset_x = 0;
		if (im->trueColor) {
			for (j=0; j<new_width; j++) {
				const gdFixed f_i = gd_itofx(i);
				const gdFixed f_j = gd_itofx(j);
				const gdFixed f_a = gd_mulfx(f_i, f_dy);
				const gdFixed f_b = gd_mulfx(f_j, f_dx);
				const long m = gd_fxtoi(f_a);
				const long n = gd_fxtoi(f_b);

				dst_img->tpixels[dst_offset_y][dst_offset_x++] = im->tpixels[m][n];
			}
		} else {
			for (j=0; j<new_width; j++) {
				const gdFixed f_i = gd_itofx(i);
				const gdFixed f_j = gd_itofx(j);
				const gdFixed f_a = gd_mulfx(f_i, f_dy);
				const gdFixed f_b = gd_mulfx(f_j, f_dx);
				const long m = gd_fxtoi(f_a);
				const long n = gd_fxtoi(f_b);

				dst_img->tpixels[dst_offset_y][dst_offset_x++] = colorIndex2RGBA(im->pixels[m][n]);
			}
		}
		dst_offset_y++;
	}
	return dst_img;
}

static inline int getPixelOverflowColorTC(gdImagePtr im, const int x, const int y, const int color)
{
	if (gdImageBoundsSafe(im, x, y)) {
		const int c = im->tpixels[y][x];
		if (c == im->transparent) {
			return gdTrueColorAlpha(0, 0, 0, 127);
		}
		return c;
	} else {
		register int border = 0;
		if (y < im->cy1) {
			border = im->tpixels[0][im->cx1];
			goto processborder;
		}

		if (y < im->cy1) {
			border = im->tpixels[0][im->cx1];
			goto processborder;
		}

		if (y > im->cy2) {
			if (x >= im->cx1 && x <= im->cx1) {
				border = im->tpixels[im->cy2][x];
				goto processborder;
			} else {
				return gdTrueColorAlpha(0, 0, 0, 127);
			}
		}

		/* y is bound safe at this point */
		if (x < im->cx1) {
			border = im->tpixels[y][im->cx1];
			goto processborder;
		}

		if (x > im->cx2) {
			border = im->tpixels[y][im->cx2];
		}

processborder:
		if (border == im->transparent) {
			return gdTrueColorAlpha(0, 0, 0, 127);
		} else{
			return gdTrueColorAlpha(gdTrueColorGetRed(border), gdTrueColorGetGreen(border), gdTrueColorGetBlue(border), 127);
		}
	}
}

static gdImagePtr gdImageScaleBilinearPalette(gdImagePtr im, const unsigned int new_width, const unsigned int new_height)
{
	long _width = MAX(1, new_width);
	long _height = MAX(1, new_height);
	float dx = (float)gdImageSX(im) / (float)_width;
	float dy = (float)gdImageSY(im) / (float)_height;
	gdFixed f_dx = gd_ftofx(dx);
	gdFixed f_dy = gd_ftofx(dy);
	gdFixed f_1 = gd_itofx(1);

	int dst_offset_h;
	int dst_offset_v = 0;
	long i;
	gdImagePtr new_img;
	const int transparent = im->transparent;

	new_img = gdImageCreateTrueColor(new_width, new_height);
	if (new_img == NULL) {
		return NULL;
	}
	new_img->transparent = gdTrueColorAlpha(im->red[transparent], im->green[transparent], im->blue[transparent], im->alpha[transparent]);

	for (i=0; i < _height; i++) {
		long j;
		const gdFixed f_i = gd_itofx(i);
		const gdFixed f_a = gd_mulfx(f_i, f_dy);
		register long m = gd_fxtoi(f_a);

		dst_offset_h = 0;

		for (j=0; j < _width; j++) {
			/* Update bitmap */
			gdFixed f_j = gd_itofx(j);
			gdFixed f_b = gd_mulfx(f_j, f_dx);

			const long n = gd_fxtoi(f_b);
			gdFixed f_f = f_a - gd_itofx(m);
			gdFixed f_g = f_b - gd_itofx(n);

			const gdFixed f_w1 = gd_mulfx(f_1-f_f, f_1-f_g);
			const gdFixed f_w2 = gd_mulfx(f_1-f_f, f_g);
			const gdFixed f_w3 = gd_mulfx(f_f, f_1-f_g);
			const gdFixed f_w4 = gd_mulfx(f_f, f_g);
			unsigned int pixel1;
			unsigned int pixel2;
			unsigned int pixel3;
			unsigned int pixel4;
			register gdFixed f_r1, f_r2, f_r3, f_r4,
					f_g1, f_g2, f_g3, f_g4,
					f_b1, f_b2, f_b3, f_b4,
					f_a1, f_a2, f_a3, f_a4;

			/* zero for the background color, nothig gets outside anyway */
			pixel1 = getPixelOverflowPalette(im, n, m, 0);
			pixel2 = getPixelOverflowPalette(im, n + 1, m, 0);
			pixel3 = getPixelOverflowPalette(im, n, m + 1, 0);
			pixel4 = getPixelOverflowPalette(im, n + 1, m + 1, 0);

			f_r1 = gd_itofx(gdTrueColorGetRed(pixel1));
			f_r2 = gd_itofx(gdTrueColorGetRed(pixel2));
			f_r3 = gd_itofx(gdTrueColorGetRed(pixel3));
			f_r4 = gd_itofx(gdTrueColorGetRed(pixel4));
			f_g1 = gd_itofx(gdTrueColorGetGreen(pixel1));
			f_g2 = gd_itofx(gdTrueColorGetGreen(pixel2));
			f_g3 = gd_itofx(gdTrueColorGetGreen(pixel3));
			f_g4 = gd_itofx(gdTrueColorGetGreen(pixel4));
			f_b1 = gd_itofx(gdTrueColorGetBlue(pixel1));
			f_b2 = gd_itofx(gdTrueColorGetBlue(pixel2));
			f_b3 = gd_itofx(gdTrueColorGetBlue(pixel3));
			f_b4 = gd_itofx(gdTrueColorGetBlue(pixel4));
			f_a1 = gd_itofx(gdTrueColorGetAlpha(pixel1));
			f_a2 = gd_itofx(gdTrueColorGetAlpha(pixel2));
			f_a3 = gd_itofx(gdTrueColorGetAlpha(pixel3));
			f_a4 = gd_itofx(gdTrueColorGetAlpha(pixel4));

			{
				const char red = (char) gd_fxtoi(gd_mulfx(f_w1, f_r1) + gd_mulfx(f_w2, f_r2) + gd_mulfx(f_w3, f_r3) + gd_mulfx(f_w4, f_r4));
				const char green = (char) gd_fxtoi(gd_mulfx(f_w1, f_g1) + gd_mulfx(f_w2, f_g2) + gd_mulfx(f_w3, f_g3) + gd_mulfx(f_w4, f_g4));
				const char blue = (char) gd_fxtoi(gd_mulfx(f_w1, f_b1) + gd_mulfx(f_w2, f_b2) + gd_mulfx(f_w3, f_b3) + gd_mulfx(f_w4, f_b4));
				const char alpha = (char) gd_fxtoi(gd_mulfx(f_w1, f_a1) + gd_mulfx(f_w2, f_a2) + gd_mulfx(f_w3, f_a3) + gd_mulfx(f_w4, f_a4));

				new_img->tpixels[dst_offset_v][dst_offset_h] = gdTrueColorAlpha(red, green, blue, alpha);
			}

			dst_offset_h++;
		}

		dst_offset_v++;
	}
	return new_img;
}

static gdImagePtr gdImageScaleBilinearTC(gdImagePtr im, const unsigned int new_width, const unsigned int new_height)
{
	long dst_w = MAX(1, new_width);
	long dst_h = MAX(1, new_height);
	float dx = (float)gdImageSX(im) / (float)dst_w;
	float dy = (float)gdImageSY(im) / (float)dst_h;
	gdFixed f_dx = gd_ftofx(dx);
	gdFixed f_dy = gd_ftofx(dy);
	gdFixed f_1 = gd_itofx(1);

	int dst_offset_h;
	int dst_offset_v = 0;
	int dwSrcTotalOffset;
	long i;
	gdImagePtr new_img;

	new_img = gdImageCreateTrueColor(new_width, new_height);
	if (!new_img){
		return NULL;
	}

	for (i=0; i < dst_h; i++) {
		long j;
		dst_offset_h = 0;
		for (j=0; j < dst_w; j++) {
			/* Update bitmap */
			gdFixed f_i = gd_itofx(i);
			gdFixed f_j = gd_itofx(j);
			gdFixed f_a = gd_mulfx(f_i, f_dy);
			gdFixed f_b = gd_mulfx(f_j, f_dx);
			const gdFixed m = gd_fxtoi(f_a);
			const gdFixed n = gd_fxtoi(f_b);
			gdFixed f_f = f_a - gd_itofx(m);
			gdFixed f_g = f_b - gd_itofx(n);

			const gdFixed f_w1 = gd_mulfx(f_1-f_f, f_1-f_g);
			const gdFixed f_w2 = gd_mulfx(f_1-f_f, f_g);
			const gdFixed f_w3 = gd_mulfx(f_f, f_1-f_g);
			const gdFixed f_w4 = gd_mulfx(f_f, f_g);
			unsigned int pixel1;
			unsigned int pixel2;
			unsigned int pixel3;
			unsigned int pixel4;
			register gdFixed f_r1, f_r2, f_r3, f_r4,
					f_g1, f_g2, f_g3, f_g4,
					f_b1, f_b2, f_b3, f_b4,
					f_a1, f_a2, f_a3, f_a4;
			dwSrcTotalOffset = m + n;
			/* 0 for bgColor, nothing gets outside anyway */
			pixel1 = getPixelOverflowTC(im, n, m, 0);
			pixel2 = getPixelOverflowTC(im, n + 1, m, 0);
			pixel3 = getPixelOverflowTC(im, n, m + 1, 0);
			pixel4 = getPixelOverflowTC(im, n + 1, m + 1, 0);

			f_r1 = gd_itofx(gdTrueColorGetRed(pixel1));
			f_r2 = gd_itofx(gdTrueColorGetRed(pixel2));
			f_r3 = gd_itofx(gdTrueColorGetRed(pixel3));
			f_r4 = gd_itofx(gdTrueColorGetRed(pixel4));
			f_g1 = gd_itofx(gdTrueColorGetGreen(pixel1));
			f_g2 = gd_itofx(gdTrueColorGetGreen(pixel2));
			f_g3 = gd_itofx(gdTrueColorGetGreen(pixel3));
			f_g4 = gd_itofx(gdTrueColorGetGreen(pixel4));
			f_b1 = gd_itofx(gdTrueColorGetBlue(pixel1));
			f_b2 = gd_itofx(gdTrueColorGetBlue(pixel2));
			f_b3 = gd_itofx(gdTrueColorGetBlue(pixel3));
			f_b4 = gd_itofx(gdTrueColorGetBlue(pixel4));
			f_a1 = gd_itofx(gdTrueColorGetAlpha(pixel1));
			f_a2 = gd_itofx(gdTrueColorGetAlpha(pixel2));
			f_a3 = gd_itofx(gdTrueColorGetAlpha(pixel3));
			f_a4 = gd_itofx(gdTrueColorGetAlpha(pixel4));
			{
				const unsigned char red   = (unsigned char) gd_fxtoi(gd_mulfx(f_w1, f_r1) + gd_mulfx(f_w2, f_r2) + gd_mulfx(f_w3, f_r3) + gd_mulfx(f_w4, f_r4));
				const unsigned char green = (unsigned char) gd_fxtoi(gd_mulfx(f_w1, f_g1) + gd_mulfx(f_w2, f_g2) + gd_mulfx(f_w3, f_g3) + gd_mulfx(f_w4, f_g4));
				const unsigned char blue  = (unsigned char) gd_fxtoi(gd_mulfx(f_w1, f_b1) + gd_mulfx(f_w2, f_b2) + gd_mulfx(f_w3, f_b3) + gd_mulfx(f_w4, f_b4));
				const unsigned char alpha = (unsigned char) gd_fxtoi(gd_mulfx(f_w1, f_a1) + gd_mulfx(f_w2, f_a2) + gd_mulfx(f_w3, f_a3) + gd_mulfx(f_w4, f_a4));

				new_img->tpixels[dst_offset_v][dst_offset_h] = gdTrueColorAlpha(red, green, blue, alpha);
			}

			dst_offset_h++;
		}

		dst_offset_v++;
	}
	return new_img;
}

gdImagePtr gdImageScaleBilinear(gdImagePtr im, const unsigned int new_width, const unsigned int new_height)
{
	if (im->trueColor) {
		return gdImageScaleBilinearTC(im, new_width, new_height);
	} else {
		return gdImageScaleBilinearPalette(im, new_width, new_height);
	}
}

gdImagePtr gdImageScaleBicubicFixed(gdImagePtr src, const unsigned int width, const unsigned int height)
{
	const long new_width = MAX(1, width);
	const long new_height = MAX(1, height);
	const int src_w = gdImageSX(src);
	const int src_h = gdImageSY(src);
	const gdFixed f_dx = gd_ftofx((float)src_w / (float)new_width);
	const gdFixed f_dy = gd_ftofx((float)src_h / (float)new_height);
	const gdFixed f_1 = gd_itofx(1);
	const gdFixed f_2 = gd_itofx(2);
	const gdFixed f_4 = gd_itofx(4);
	const gdFixed f_6 = gd_itofx(6);
	const gdFixed f_gamma = gd_ftofx(1.04f);
	gdImagePtr dst;

	unsigned int dst_offset_x;
	unsigned int dst_offset_y = 0;
	long i;

	/* impact perf a bit, but not that much. Implementation for palette
	   images can be done at a later point.
	*/
	if (src->trueColor == 0) {
		gdImagePaletteToTrueColor(src);
	}

	dst = gdImageCreateTrueColor(new_width, new_height);
	if (!dst) {
		return NULL;
	}

	dst->saveAlphaFlag = 1;

	for (i=0; i < new_height; i++) {
		long j;
		dst_offset_x = 0;

		for (j=0; j < new_width; j++) {
			const gdFixed f_a = gd_mulfx(gd_itofx(i), f_dy);
			const gdFixed f_b = gd_mulfx(gd_itofx(j), f_dx);
			const long m = gd_fxtoi(f_a);
			const long n = gd_fxtoi(f_b);
			const gdFixed f_f = f_a - gd_itofx(m);
			const gdFixed f_g = f_b - gd_itofx(n);
			unsigned int src_offset_x[16], src_offset_y[16];
			long k;
			register gdFixed f_red = 0, f_green = 0, f_blue = 0, f_alpha = 0;
			unsigned char red, green, blue, alpha = 0;
			int *dst_row = dst->tpixels[dst_offset_y];

			if ((m < 1) || (n < 1)) {
				src_offset_x[0] = n;
				src_offset_y[0] = m;
			} else {
				src_offset_x[0] = n - 1;
				src_offset_y[0] = m;
			}

			if (m < 1) {
				src_offset_x[1] = n;
				src_offset_y[1] = m;
			} else {
				src_offset_x[1] = n;
				src_offset_y[1] = m;
			}

			if ((m < 1) || (n >= src_w - 1)) {
				src_offset_x[2] = n;
				src_offset_y[2] = m;
			} else {
				src_offset_x[2] = n + 1;
				src_offset_y[2] = m;
			}

			if ((m < 1) || (n >= src_w - 2)) {
				src_offset_x[3] = n;
				src_offset_y[3] = m;
			} else {
				src_offset_x[3] = n + 1 + 1;
				src_offset_y[3] = m;
			}

			if (n < 1) {
				src_offset_x[4] = n;
				src_offset_y[4] = m;
			} else {
				src_offset_x[4] = n - 1;
				src_offset_y[4] = m;
			}

			src_offset_x[5] = n;
			src_offset_y[5] = m;
			if (n >= src_w-1) {
				src_offset_x[6] = n;
				src_offset_y[6] = m;
			} else {
				src_offset_x[6] = n + 1;
				src_offset_y[6] = m;
			}

			if (n >= src_w - 2) {
				src_offset_x[7] = n;
				src_offset_y[7] = m;
			} else {
				src_offset_x[7] = n + 1 + 1;
				src_offset_y[7] = m;
			}

			if ((m >= src_h - 1) || (n < 1)) {
				src_offset_x[8] = n;
				src_offset_y[8] = m;
			} else {
				src_offset_x[8] = n - 1;
				src_offset_y[8] = m;
			}

			if (m >= src_h - 1) {
				src_offset_x[8] = n;
				src_offset_y[8] = m;
			} else {
				src_offset_x[9] = n;
				src_offset_y[9] = m;
			}

			if ((m >= src_h-1) || (n >= src_w-1)) {
				src_offset_x[10] = n;
				src_offset_y[10] = m;
			} else {
				src_offset_x[10] = n + 1;
				src_offset_y[10] = m;
			}

			if ((m >= src_h - 1) || (n >= src_w - 2)) {
				src_offset_x[11] = n;
				src_offset_y[11] = m;
			} else {
				src_offset_x[11] = n + 1 + 1;
				src_offset_y[11] = m;
			}

			if ((m >= src_h - 2) || (n < 1)) {
				src_offset_x[12] = n;
				src_offset_y[12] = m;
			} else {
				src_offset_x[12] = n - 1;
				src_offset_y[12] = m;
			}

			if (m >= src_h - 2) {
				src_offset_x[13] = n;
				src_offset_y[13] = m;
			} else {
				src_offset_x[13] = n;
				src_offset_y[13] = m;
			}

			if ((m >= src_h - 2) || (n >= src_w - 1)) {
				src_offset_x[14] = n;
				src_offset_y[14] = m;
			} else {
				src_offset_x[14] = n + 1;
				src_offset_y[14] = m;
			}

			if ((m >= src_h - 2) || (n >= src_w - 2)) {
				src_offset_x[15] = n;
				src_offset_y[15] = m;
			} else {
				src_offset_x[15] = n  + 1 + 1;
				src_offset_y[15] = m;
			}

			for (k = -1; k < 3; k++) {
				const gdFixed f = gd_itofx(k)-f_f;
				const gdFixed f_fm1 = f - f_1;
				const gdFixed f_fp1 = f + f_1;
				const gdFixed f_fp2 = f + f_2;
				register gdFixed f_a = 0, f_b = 0, f_d = 0, f_c = 0;
				register gdFixed f_RY;
				int l;

				if (f_fp2 > 0) f_a = gd_mulfx(f_fp2, gd_mulfx(f_fp2,f_fp2));
				if (f_fp1 > 0) f_b = gd_mulfx(f_fp1, gd_mulfx(f_fp1,f_fp1));
				if (f > 0)     f_c = gd_mulfx(f, gd_mulfx(f,f));
				if (f_fm1 > 0) f_d = gd_mulfx(f_fm1, gd_mulfx(f_fm1,f_fm1));

				f_RY = gd_divfx((f_a - gd_mulfx(f_4,f_b) + gd_mulfx(f_6,f_c) - gd_mulfx(f_4,f_d)),f_6);

				for (l = -1; l < 3; l++) {
					const gdFixed f = gd_itofx(l) - f_g;
					const gdFixed f_fm1 = f - f_1;
					const gdFixed f_fp1 = f + f_1;
					const gdFixed f_fp2 = f + f_2;
					register gdFixed f_a = 0, f_b = 0, f_c = 0, f_d = 0;
					register gdFixed f_RX, f_R, f_rs, f_gs, f_bs, f_ba;
					register int c;
					const int _k = ((k+1)*4) + (l+1);

					if (f_fp2 > 0) f_a = gd_mulfx(f_fp2,gd_mulfx(f_fp2,f_fp2));

					if (f_fp1 > 0) f_b = gd_mulfx(f_fp1,gd_mulfx(f_fp1,f_fp1));

					if (f > 0) f_c = gd_mulfx(f,gd_mulfx(f,f));

					if (f_fm1 > 0) f_d = gd_mulfx(f_fm1,gd_mulfx(f_fm1,f_fm1));

					f_RX = gd_divfx((f_a-gd_mulfx(f_4,f_b)+gd_mulfx(f_6,f_c)-gd_mulfx(f_4,f_d)),f_6);
					f_R = gd_mulfx(f_RY,f_RX);

					c = src->tpixels[*(src_offset_y + _k)][*(src_offset_x + _k)];
					f_rs = gd_itofx(gdTrueColorGetRed(c));
					f_gs = gd_itofx(gdTrueColorGetGreen(c));
					f_bs = gd_itofx(gdTrueColorGetBlue(c));
					f_ba = gd_itofx(gdTrueColorGetAlpha(c));

					f_red += gd_mulfx(f_rs,f_R);
					f_green += gd_mulfx(f_gs,f_R);
					f_blue += gd_mulfx(f_bs,f_R);
					f_alpha += gd_mulfx(f_ba,f_R);
				}
			}

			red    = (unsigned char) CLAMP(gd_fxtoi(gd_mulfx(f_red,   f_gamma)),  0, 255);
			green  = (unsigned char) CLAMP(gd_fxtoi(gd_mulfx(f_green, f_gamma)),  0, 255);
			blue   = (unsigned char) CLAMP(gd_fxtoi(gd_mulfx(f_blue,  f_gamma)),  0, 255);
			alpha  = (unsigned char) CLAMP(gd_fxtoi(gd_mulfx(f_alpha,  f_gamma)), 0, 127);

			*(dst_row + dst_offset_x) = gdTrueColorAlpha(red, green, blue, alpha);

			dst_offset_x++;
		}
		dst_offset_y++;
	}
	return dst;
}

gdImagePtr gdImageScale(const gdImagePtr src, const unsigned int new_width, const unsigned int new_height)
{
	gdImagePtr im_scaled = NULL;

	if (src == NULL || src->interpolation_id < 0 || src->interpolation_id > GD_METHOD_COUNT) {
		return 0;
	}

	switch (src->interpolation_id) {
		/*Special cases, optimized implementations */
		case GD_NEAREST_NEIGHBOUR:
			im_scaled = gdImageScaleNearestNeighbour(src, new_width, new_height);
			break;

		case GD_BILINEAR_FIXED:
			im_scaled = gdImageScaleBilinear(src, new_width, new_height);
			break;

		case GD_BICUBIC_FIXED:
			im_scaled = gdImageScaleBicubicFixed(src, new_width, new_height);
			break;

		/* generic */
		default:
			if (src->interpolation == NULL) {
				return NULL;
			}
			im_scaled = gdImageScaleTwoPass(src, src->sx, src->sy, new_width, new_height);
			break;
	}
	return im_scaled;
}

gdImagePtr gdImageRotateNearestNeighbour(gdImagePtr src, const float degrees, const int bgColor)
{
	float _angle = ((float) (-degrees / 180.0f) * (float)M_PI);
	const int src_w  = gdImageSX(src);
	const int src_h = gdImageSY(src);
	const unsigned int new_width = (unsigned int)(abs((int)(src_w * cos(_angle))) + abs((int)(src_h * sin(_angle))) + 0.5f);
	const unsigned int new_height = (unsigned int)(abs((int)(src_w * sin(_angle))) + abs((int)(src_h * cos(_angle))) + 0.5f);
	const gdFixed f_0_5 = gd_ftofx(0.5f);
	const gdFixed f_H = gd_itofx(src_h/2);
	const gdFixed f_W = gd_itofx(src_w/2);
	const gdFixed f_cos = gd_ftofx(cos(-_angle));
	const gdFixed f_sin = gd_ftofx(sin(-_angle));

	unsigned int dst_offset_x;
	unsigned int dst_offset_y = 0;
	unsigned int i;
	gdImagePtr dst;

	dst = gdImageCreateTrueColor(new_width, new_height);
	if (!dst) {
		return NULL;
	}
	dst->saveAlphaFlag = 1;
	for (i = 0; i < new_height; i++) {
		unsigned int j;
		dst_offset_x = 0;
		for (j = 0; j < new_width; j++) {
			gdFixed f_i = gd_itofx((int)i - (int)new_height/2);
			gdFixed f_j = gd_itofx((int)j - (int)new_width/2);
			gdFixed f_m = gd_mulfx(f_j,f_sin) + gd_mulfx(f_i,f_cos) + f_0_5 + f_H;
			gdFixed f_n = gd_mulfx(f_j,f_cos) - gd_mulfx(f_i,f_sin) + f_0_5 + f_W;
			long m = gd_fxtoi(f_m);
			long n = gd_fxtoi(f_n);

			if ((m > 0) && (m < src_h-1) && (n > 0) && (n < src_w-1)) {
				if (dst_offset_y < new_height) {
					dst->tpixels[dst_offset_y][dst_offset_x++] = src->tpixels[m][n];
				}
			} else {
				if (dst_offset_y < new_height) {
					dst->tpixels[dst_offset_y][dst_offset_x++] = bgColor;
				}
			}
		}
		dst_offset_y++;
	}
	return dst;
}

gdImagePtr gdImageRotateGeneric(gdImagePtr src, const float degrees, const int bgColor)
{
	float _angle = ((float) (-degrees / 180.0f) * (float)M_PI);
	const int angle_rounded = (int)floor(degrees * 100);
	const int src_w  = gdImageSX(src);
	const int src_h = gdImageSY(src);
	const unsigned int new_width = (unsigned int)(abs((int)(src_w * cos(_angle))) + abs((int)(src_h * sin(_angle))) + 0.5f);
	const unsigned int new_height = (unsigned int)(abs((int)(src_w * sin(_angle))) + abs((int)(src_h * cos(_angle))) + 0.5f);
	const gdFixed f_0_5 = gd_ftofx(0.5f);
	const gdFixed f_H = gd_itofx(src_h/2);
	const gdFixed f_W = gd_itofx(src_w/2);
	const gdFixed f_cos = gd_ftofx(cos(-_angle));
	const gdFixed f_sin = gd_ftofx(sin(-_angle));

	unsigned int dst_offset_x;
	unsigned int dst_offset_y = 0;
	unsigned int i;
	gdImagePtr dst;

	const gdFixed f_slop_y = f_sin;
	const gdFixed f_slop_x = f_cos;
	const gdFixed f_slop = f_slop_x > 0 && f_slop_x > 0 ?
							f_slop_x > f_slop_y ? gd_divfx(f_slop_y, f_slop_x) : gd_divfx(f_slop_x, f_slop_y)
						: 0;


	if (bgColor < 0) {
		return NULL;
	}

	dst = gdImageCreateTrueColor(new_width, new_height);
	if (!dst) {
		return NULL;
	}
	dst->saveAlphaFlag = 1;

	for (i = 0; i < new_height; i++) {
		unsigned int j;
		dst_offset_x = 0;
		for (j = 0; j < new_width; j++) {
			gdFixed f_i = gd_itofx((int)i - (int)new_height/ 2);
			gdFixed f_j = gd_itofx((int)j - (int)new_width / 2);
			gdFixed f_m = gd_mulfx(f_j,f_sin) + gd_mulfx(f_i,f_cos) + f_0_5 + f_H;
			gdFixed f_n = gd_mulfx(f_j,f_cos) - gd_mulfx(f_i,f_sin) + f_0_5 + f_W;
			long m = gd_fxtoi(f_m);
			long n = gd_fxtoi(f_n);

			if ((n <= 0) || (m <= 0) || (m >= src_h) || (n >= src_w)) {
				dst->tpixels[dst_offset_y][dst_offset_x++] = bgColor;
			} else if ((n <= 1) || (m <= 1) || (m >= src_h - 1) || (n >= src_w - 1)) {
				gdFixed f_127 = gd_itofx(127);
				register int c = getPixelInterpolated(src, n, m, bgColor);
				c = c | (( gdTrueColorGetAlpha(c) + ((int)(127* gd_fxtof(f_slop)))) << 24);

				dst->tpixels[dst_offset_y][dst_offset_x++] = _color_blend(bgColor, c);
			} else {
				dst->tpixels[dst_offset_y][dst_offset_x++] = getPixelInterpolated(src, n, m, bgColor);
			}
		}
		dst_offset_y++;
	}
	return dst;
}

gdImagePtr gdImageRotateBilinear(gdImagePtr src, const float degrees, const int bgColor)
{
	float _angle = (float)((- degrees / 180.0f) * M_PI);
	const unsigned int src_w = gdImageSX(src);
	const unsigned int src_h = gdImageSY(src);
	unsigned int new_width = abs((int)(src_w*cos(_angle))) + abs((int)(src_h*sin(_angle) + 0.5f));
	unsigned int new_height = abs((int)(src_w*sin(_angle))) + abs((int)(src_h*cos(_angle) + 0.5f));
	const gdFixed f_0_5 = gd_ftofx(0.5f);
	const gdFixed f_H = gd_itofx(src_h/2);
	const gdFixed f_W = gd_itofx(src_w/2);
	const gdFixed f_cos = gd_ftofx(cos(-_angle));
	const gdFixed f_sin = gd_ftofx(sin(-_angle));
	const gdFixed f_1 = gd_itofx(1);
	unsigned int i;
	unsigned int dst_offset_x;
	unsigned int dst_offset_y = 0;
	unsigned int src_offset_x, src_offset_y;
	gdImagePtr dst;

	dst = gdImageCreateTrueColor(new_width, new_height);
	if (dst == NULL) {
		return NULL;
	}
	dst->saveAlphaFlag = 1;

	for (i = 0; i < new_height; i++) {
		unsigned int j;
		dst_offset_x = 0;

		for (j=0; j < new_width; j++) {
			const gdFixed f_i = gd_itofx((int)i - (int)new_height/2);
			const gdFixed f_j = gd_itofx((int)j - (int)new_width/2);
			const gdFixed f_m = gd_mulfx(f_j,f_sin) + gd_mulfx(f_i,f_cos) + f_0_5 + f_H;
			const gdFixed f_n = gd_mulfx(f_j,f_cos) - gd_mulfx(f_i,f_sin) + f_0_5 + f_W;
			const unsigned int m = gd_fxtoi(f_m);
			const unsigned int n = gd_fxtoi(f_n);

			if ((m > 0) && (m < src_h - 1) && (n > 0) && (n < src_w - 1)) {
				const gdFixed f_f = f_m - gd_itofx(m);
				const gdFixed f_g = f_n - gd_itofx(n);
				const gdFixed f_w1 = gd_mulfx(f_1-f_f, f_1-f_g);
				const gdFixed f_w2 = gd_mulfx(f_1-f_f, f_g);
				const gdFixed f_w3 = gd_mulfx(f_f, f_1-f_g);
				const gdFixed f_w4 = gd_mulfx(f_f, f_g);

				if (n < src_w - 1) {
					src_offset_x = n + 1;
					src_offset_y = m;
				}

				if (m < src_h-1) {
					src_offset_x = n;
					src_offset_y = m + 1;
				}

				if (!((n >= src_w-1) || (m >= src_h-1))) {
					src_offset_x = n + 1;
					src_offset_y = m + 1;
				}
				{
					const int pixel1 = src->tpixels[src_offset_y][src_offset_x];
					register int pixel2, pixel3, pixel4;

					if (src_offset_y + 1 >= src_h) {
						pixel2 = bgColor;
						pixel3 = bgColor;
						pixel4 = bgColor;
					} else if (src_offset_x + 1 >= src_w) {
						pixel2 = bgColor;
						pixel3 = bgColor;
						pixel4 = bgColor;
					} else {
					    pixel2 = src->tpixels[src_offset_y][src_offset_x + 1];
						pixel3 = src->tpixels[src_offset_y + 1][src_offset_x];
						pixel4 = src->tpixels[src_offset_y + 1][src_offset_x + 1];
					}
					{
						const gdFixed f_r1 = gd_itofx(gdTrueColorGetRed(pixel1));
						const gdFixed f_r2 = gd_itofx(gdTrueColorGetRed(pixel2));
						const gdFixed f_r3 = gd_itofx(gdTrueColorGetRed(pixel3));
						const gdFixed f_r4 = gd_itofx(gdTrueColorGetRed(pixel4));
						const gdFixed f_g1 = gd_itofx(gdTrueColorGetGreen(pixel1));
						const gdFixed f_g2 = gd_itofx(gdTrueColorGetGreen(pixel2));
						const gdFixed f_g3 = gd_itofx(gdTrueColorGetGreen(pixel3));
						const gdFixed f_g4 = gd_itofx(gdTrueColorGetGreen(pixel4));
						const gdFixed f_b1 = gd_itofx(gdTrueColorGetBlue(pixel1));
						const gdFixed f_b2 = gd_itofx(gdTrueColorGetBlue(pixel2));
						const gdFixed f_b3 = gd_itofx(gdTrueColorGetBlue(pixel3));
						const gdFixed f_b4 = gd_itofx(gdTrueColorGetBlue(pixel4));
						const gdFixed f_a1 = gd_itofx(gdTrueColorGetAlpha(pixel1));
						const gdFixed f_a2 = gd_itofx(gdTrueColorGetAlpha(pixel2));
						const gdFixed f_a3 = gd_itofx(gdTrueColorGetAlpha(pixel3));
						const gdFixed f_a4 = gd_itofx(gdTrueColorGetAlpha(pixel4));
						const gdFixed f_red = gd_mulfx(f_w1, f_r1) + gd_mulfx(f_w2, f_r2) + gd_mulfx(f_w3, f_r3) + gd_mulfx(f_w4, f_r4);
						const gdFixed f_green = gd_mulfx(f_w1, f_g1) + gd_mulfx(f_w2, f_g2) + gd_mulfx(f_w3, f_g3) + gd_mulfx(f_w4, f_g4);
						const gdFixed f_blue = gd_mulfx(f_w1, f_b1) + gd_mulfx(f_w2, f_b2) + gd_mulfx(f_w3, f_b3) + gd_mulfx(f_w4, f_b4);
						const gdFixed f_alpha = gd_mulfx(f_w1, f_a1) + gd_mulfx(f_w2, f_a2) + gd_mulfx(f_w3, f_a3) + gd_mulfx(f_w4, f_a4);

						const unsigned char red   = (unsigned char) CLAMP(gd_fxtoi(f_red),   0, 255);
						const unsigned char green = (unsigned char) CLAMP(gd_fxtoi(f_green), 0, 255);
						const unsigned char blue  = (unsigned char) CLAMP(gd_fxtoi(f_blue),  0, 255);
						const unsigned char alpha = (unsigned char) CLAMP(gd_fxtoi(f_alpha), 0, 127);

						dst->tpixels[dst_offset_y][dst_offset_x++] = gdTrueColorAlpha(red, green, blue, alpha);
					}
				}
			} else {
				dst->tpixels[dst_offset_y][dst_offset_x++] = bgColor;
			}
		}
		dst_offset_y++;
	}
	return dst;
}

gdImagePtr gdImageRotateBicubicFixed(gdImagePtr src, const float degrees, const int bgColor)
{
	const float _angle = (float)((- degrees / 180.0f) * M_PI);
	const int src_w = gdImageSX(src);
	const int src_h = gdImageSY(src);
	const unsigned int new_width = abs((int)(src_w*cos(_angle))) + abs((int)(src_h*sin(_angle) + 0.5f));
	const unsigned int new_height = abs((int)(src_w*sin(_angle))) + abs((int)(src_h*cos(_angle) + 0.5f));
	const gdFixed f_0_5 = gd_ftofx(0.5f);
	const gdFixed f_H = gd_itofx(src_h/2);
	const gdFixed f_W = gd_itofx(src_w/2);
	const gdFixed f_cos = gd_ftofx(cos(-_angle));
	const gdFixed f_sin = gd_ftofx(sin(-_angle));
	const gdFixed f_1 = gd_itofx(1);
	const gdFixed f_2 = gd_itofx(2);
	const gdFixed f_4 = gd_itofx(4);
	const gdFixed f_6 = gd_itofx(6);
	const gdFixed f_gama = gd_ftofx(1.04f);

	unsigned int dst_offset_x;
	unsigned int dst_offset_y = 0;
	unsigned int i;
	gdImagePtr dst;

	dst = gdImageCreateTrueColor(new_width, new_height);

	if (dst == NULL) {
		return NULL;
	}
	dst->saveAlphaFlag = 1;

	for (i=0; i < new_height; i++) {
		unsigned int j;
		dst_offset_x = 0;

		for (j=0; j < new_width; j++) {
			const gdFixed f_i = gd_itofx((int)i - (int)new_height/2);
			const gdFixed f_j = gd_itofx((int)j - (int)new_width/2);
			const gdFixed f_m = gd_mulfx(f_j,f_sin) + gd_mulfx(f_i,f_cos) + f_0_5 + f_H;
			const gdFixed f_n = gd_mulfx(f_j,f_cos) - gd_mulfx(f_i,f_sin) + f_0_5 + f_W;
			const int m = gd_fxtoi(f_m);
			const int n = gd_fxtoi(f_n);

			if ((m > 0) && (m < src_h - 1) && (n > 0) && (n < src_w-1)) {
				const gdFixed f_f = f_m - gd_itofx(m);
				const gdFixed f_g = f_n - gd_itofx(n);
				unsigned int src_offset_x[16], src_offset_y[16];
				unsigned char red, green, blue, alpha;
				gdFixed f_red=0, f_green=0, f_blue=0, f_alpha=0;
				int k;

				if ((m < 1) || (n < 1)) {
					src_offset_x[0] = n;
					src_offset_y[0] = m;
				} else {
					src_offset_x[0] = n - 1;
					src_offset_y[0] = m;
				}

				if (m < 1) {
					src_offset_x[1] = n;
					src_offset_y[1] = m;
				} else {
					src_offset_x[1] = n;
					src_offset_y[1] = m ;
				}

				if ((m < 1) || (n >= src_w-1)) {
					src_offset_x[2] = - 1;
					src_offset_y[2] = - 1;
				} else {
					src_offset_x[2] = n + 1;
					src_offset_y[2] = m ;
				}

				if ((m < 1) || (n >= src_w-2)) {
					src_offset_x[3] = - 1;
					src_offset_y[3] = - 1;
				} else {
					src_offset_x[3] = n + 1 + 1;
					src_offset_y[3] = m ;
				}

				if (n < 1) {
					src_offset_x[4] = - 1;
					src_offset_y[4] = - 1;
				} else {
					src_offset_x[4] = n - 1;
					src_offset_y[4] = m;
				}

				src_offset_x[5] = n;
				src_offset_y[5] = m;
				if (n >= src_w-1) {
					src_offset_x[6] = - 1;
					src_offset_y[6] = - 1;
				} else {
					src_offset_x[6] = n + 1;
					src_offset_y[6] = m;
				}

				if (n >= src_w-2) {
					src_offset_x[7] = - 1;
					src_offset_y[7] = - 1;
				} else {
					src_offset_x[7] = n + 1 + 1;
					src_offset_y[7] = m;
				}

				if ((m >= src_h-1) || (n < 1)) {
					src_offset_x[8] = - 1;
					src_offset_y[8] = - 1;
				} else {
					src_offset_x[8] = n - 1;
					src_offset_y[8] = m;
				}

				if (m >= src_h-1) {
					src_offset_x[8] = - 1;
					src_offset_y[8] = - 1;
				} else {
					src_offset_x[9] = n;
					src_offset_y[9] = m;
				}

				if ((m >= src_h-1) || (n >= src_w-1)) {
					src_offset_x[10] = - 1;
					src_offset_y[10] = - 1;
				} else {
					src_offset_x[10] = n + 1;
					src_offset_y[10] = m;
				}

				if ((m >= src_h-1) || (n >= src_w-2)) {
					src_offset_x[11] = - 1;
					src_offset_y[11] = - 1;
				} else {
					src_offset_x[11] = n + 1 + 1;
					src_offset_y[11] = m;
				}

				if ((m >= src_h-2) || (n < 1)) {
					src_offset_x[12] = - 1;
					src_offset_y[12] = - 1;
				} else {
					src_offset_x[12] = n - 1;
					src_offset_y[12] = m;
				}

				if (m >= src_h-2) {
					src_offset_x[13] = - 1;
					src_offset_y[13] = - 1;
				} else {
					src_offset_x[13] = n;
					src_offset_y[13] = m;
				}

				if ((m >= src_h-2) || (n >= src_w - 1)) {
					src_offset_x[14] = - 1;
					src_offset_y[14] = - 1;
				} else {
					src_offset_x[14] = n + 1;
					src_offset_y[14] = m;
				}

				if ((m >= src_h-2) || (n >= src_w-2)) {
					src_offset_x[15] = - 1;
					src_offset_y[15] = - 1;
				} else {
					src_offset_x[15] = n  + 1 + 1;
					src_offset_y[15] = m;
				}

				for (k=-1; k<3; k++) {
					const gdFixed f = gd_itofx(k)-f_f;
					const gdFixed f_fm1 = f - f_1;
					const gdFixed f_fp1 = f + f_1;
					const gdFixed f_fp2 = f + f_2;
					gdFixed f_a = 0, f_b = 0,f_c = 0, f_d = 0;
					gdFixed f_RY;
					int l;

					if (f_fp2 > 0) {
						f_a = gd_mulfx(f_fp2,gd_mulfx(f_fp2,f_fp2));
					}

					if (f_fp1 > 0) {
						f_b = gd_mulfx(f_fp1,gd_mulfx(f_fp1,f_fp1));
					}

					if (f > 0) {
						f_c = gd_mulfx(f,gd_mulfx(f,f));
					}

					if (f_fm1 > 0) {
						f_d = gd_mulfx(f_fm1,gd_mulfx(f_fm1,f_fm1));
					}
					f_RY = gd_divfx((f_a-gd_mulfx(f_4,f_b)+gd_mulfx(f_6,f_c)-gd_mulfx(f_4,f_d)),f_6);

					for (l=-1;  l< 3; l++) {
						const gdFixed f = gd_itofx(l) - f_g;
						const gdFixed f_fm1 = f - f_1;
						const gdFixed f_fp1 = f + f_1;
						const gdFixed f_fp2 = f + f_2;
						gdFixed f_a = 0, f_b = 0, f_c = 0, f_d = 0;
						gdFixed f_RX, f_R;
						const int _k = ((k + 1) * 4) + (l + 1);
						register gdFixed f_rs, f_gs, f_bs, f_as;
						register int c;

						if (f_fp2 > 0) {
							f_a = gd_mulfx(f_fp2,gd_mulfx(f_fp2,f_fp2));
						}

						if (f_fp1 > 0) {
							f_b = gd_mulfx(f_fp1,gd_mulfx(f_fp1,f_fp1));
						}

						if (f > 0) {
							f_c = gd_mulfx(f,gd_mulfx(f,f));
						}

						if (f_fm1 > 0) {
							f_d = gd_mulfx(f_fm1,gd_mulfx(f_fm1,f_fm1));
						}

						f_RX = gd_divfx((f_a - gd_mulfx(f_4, f_b) + gd_mulfx(f_6, f_c) - gd_mulfx(f_4, f_d)), f_6);
						f_R = gd_mulfx(f_RY, f_RX);

						if ((src_offset_x[_k] <= 0) || (src_offset_y[_k] <= 0) || (src_offset_y[_k] >= src_h) || (src_offset_x[_k] >= src_w)) {
							c = bgColor;
						} else if ((src_offset_x[_k] <= 1) || (src_offset_y[_k] <= 1) || (src_offset_y[_k] >= (int)src_h - 1) || (src_offset_x[_k] >= (int)src_w - 1)) {
							gdFixed f_127 = gd_itofx(127);
							c = src->tpixels[src_offset_y[_k]][src_offset_x[_k]];
							c = c | (( (int) (gd_fxtof(gd_mulfx(f_R, f_127)) + 50.5f)) << 24);
							c = _color_blend(bgColor, c);
						} else {
							c = src->tpixels[src_offset_y[_k]][src_offset_x[_k]];
						}

						f_rs = gd_itofx(gdTrueColorGetRed(c));
						f_gs = gd_itofx(gdTrueColorGetGreen(c));
						f_bs = gd_itofx(gdTrueColorGetBlue(c));
						f_as = gd_itofx(gdTrueColorGetAlpha(c));

						f_red   += gd_mulfx(f_rs, f_R);
						f_green += gd_mulfx(f_gs, f_R);
						f_blue  += gd_mulfx(f_bs, f_R);
						f_alpha += gd_mulfx(f_as, f_R);
					}
				}

				red   = (unsigned char) CLAMP(gd_fxtoi(gd_mulfx(f_red, f_gama)),   0, 255);
				green = (unsigned char) CLAMP(gd_fxtoi(gd_mulfx(f_green, f_gama)), 0, 255);
				blue  = (unsigned char) CLAMP(gd_fxtoi(gd_mulfx(f_blue, f_gama)),  0, 255);
				alpha = (unsigned char) CLAMP(gd_fxtoi(gd_mulfx(f_alpha, f_gama)), 0, 127);

				dst->tpixels[dst_offset_y][dst_offset_x] =  gdTrueColorAlpha(red, green, blue, alpha);
			} else {
				dst->tpixels[dst_offset_y][dst_offset_x] =  bgColor;
			}
			dst_offset_x++;
		}

		dst_offset_y++;
	}
	return dst;
}

gdImagePtr gdImageRotateInterpolated(const gdImagePtr src, const float angle, int bgcolor)
{
	const int angle_rounded = (int)floor(angle * 100);

	if (bgcolor < 0) {
		return NULL;
	}

	/* impact perf a bit, but not that much. Implementation for palette
	   images can be done at a later point.
	*/
	if (src->trueColor == 0) {
		if (bgcolor >= 0) {
			bgcolor =  gdTrueColorAlpha(src->red[bgcolor], src->green[bgcolor], src->blue[bgcolor], src->alpha[bgcolor]);
		}
		gdImagePaletteToTrueColor(src);
	}

	/* no interpolation needed here */
	switch (angle_rounded) {
		case -27000:
		case   9000:
			return gdImageRotate90(src, 0);
		case -18000:
		case  18000:
			return gdImageRotate180(src, 0);
		case -9000:
		case 27000:
			return gdImageRotate270(src, 0);
	}

	if (src == NULL || src->interpolation_id < 1 || src->interpolation_id > GD_METHOD_COUNT) {
		return NULL;
	}

	switch (src->interpolation_id) {
		case GD_NEAREST_NEIGHBOUR:
			return gdImageRotateNearestNeighbour(src, angle, bgcolor);
			break;

		case GD_BILINEAR_FIXED:
			return gdImageRotateBilinear(src, angle, bgcolor);
			break;

		case GD_BICUBIC_FIXED:
			return gdImageRotateBicubicFixed(src, angle, bgcolor);
			break;

		default:
			return gdImageRotateGeneric(src, angle, bgcolor);
	}
	return NULL;
}

/**
 * Title: Affine transformation
 **/

/**
 * Group: Transform
 **/

 static void gdImageClipRectangle(gdImagePtr im, gdRectPtr r)
{
	int c1x, c1y, c2x, c2y;
	int x1,y1;

	gdImageGetClip(im, &c1x, &c1y, &c2x, &c2y);
	x1 = r->x + r->width - 1;
	y1 = r->y + r->height - 1;
	r->x = CLAMP(r->x, c1x, c2x);
	r->y = CLAMP(r->y, c1y, c2y);
	r->width = CLAMP(x1, c1x, c2x) - r->x + 1;
	r->height = CLAMP(y1, c1y, c2y) - r->y + 1;
}

void gdDumpRect(const char *msg, gdRectPtr r)
{
	printf("%s (%i, %i) (%i, %i)\n", msg, r->x, r->y, r->width, r->height);
}

/**
 * Function: gdTransformAffineGetImage
 *  Applies an affine transformation to a region and return an image
 *  containing the complete transformation.
 *
 * Parameters:
 * 	dst - Pointer to a gdImagePtr to store the created image, NULL when
 *        the creation or the transformation failed
 *  src - Source image
 *  src_area - rectangle defining the source region to transform
 *  dstY - Y position in the destination image
 *  affine - The desired affine transformation
 *
 * Returns:
 *  GD_TRUE if the affine is rectilinear or GD_FALSE
 */
int gdTransformAffineGetImage(gdImagePtr *dst,
		  const gdImagePtr src,
		  gdRectPtr src_area,
		  const double affine[6])
{
	int res;
	double m[6];
	gdRect bbox;
	gdRect area_full;

	if (src_area == NULL) {
		area_full.x = 0;
		area_full.y = 0;
		area_full.width  = gdImageSX(src);
		area_full.height = gdImageSY(src);
		src_area = &area_full;
	}

	gdTransformAffineBoundingBox(src_area, affine, &bbox);

	*dst = gdImageCreateTrueColor(bbox.width, bbox.height);
	if (*dst == NULL) {
		return GD_FALSE;
	}
	(*dst)->saveAlphaFlag = 1;

	if (!src->trueColor) {
		gdImagePaletteToTrueColor(src);
	}

	/* Translate to dst origin (0,0) */
	gdAffineTranslate(m, -bbox.x, -bbox.y);
	gdAffineConcat(m, affine, m);

	gdImageAlphaBlending(*dst, 0);

	res = gdTransformAffineCopy(*dst,
		  0,0,
		  src,
		  src_area,
		  m);

	if (res != GD_TRUE) {
		gdImageDestroy(*dst);
		dst = NULL;
		return GD_FALSE;
	} else {
		return GD_TRUE;
	}
}

/**
 * Function: gdTransformAffineCopy
 *  Applies an affine transformation to a region and copy the result
 *  in a destination to the given position.
 *
 * Parameters:
 * 	dst - Image to draw the transformed image
 *  src - Source image
 *  dstX - X position in the destination image
 *  dstY - Y position in the destination image
 *  src_area - Rectangular region to rotate in the src image
 *
 * Returns:
 *  GD_TRUE if the affine is rectilinear or GD_FALSE
 */
int gdTransformAffineCopy(gdImagePtr dst,
		  int dst_x, int dst_y,
		  const gdImagePtr src,
		  gdRectPtr src_region,
		  const double affine[6])
{
	int c1x,c1y,c2x,c2y;
	int backclip = 0;
	int backup_clipx1, backup_clipy1, backup_clipx2, backup_clipy2;
	register int x, y, src_offset_x, src_offset_y;
	double inv[6];
	int *dst_p;
	gdPointF pt, src_pt;
	gdRect bbox;
	int end_x, end_y;
	gdInterpolationMethod interpolation_id_bak = GD_DEFAULT;
	interpolation_method interpolation_bak;

	/* These methods use special implementations */
	if (src->interpolation_id == GD_BILINEAR_FIXED || src->interpolation_id == GD_BICUBIC_FIXED || src->interpolation_id == GD_NEAREST_NEIGHBOUR) {
		interpolation_id_bak = src->interpolation_id;
		interpolation_bak = src->interpolation;

		gdImageSetInterpolationMethod(src, GD_BICUBIC);
	}


	gdImageClipRectangle(src, src_region);

	if (src_region->x > 0 || src_region->y > 0
		|| src_region->width < gdImageSX(src)
		|| src_region->height < gdImageSY(src)) {
		backclip = 1;

		gdImageGetClip(src, &backup_clipx1, &backup_clipy1,
		&backup_clipx2, &backup_clipy2);

		gdImageSetClip(src, src_region->x, src_region->y,
			src_region->x + src_region->width - 1,
			src_region->y + src_region->height - 1);
	}

	if (!gdTransformAffineBoundingBox(src_region, affine, &bbox)) {
		if (backclip) {
			gdImageSetClip(src, backup_clipx1, backup_clipy1,
					backup_clipx2, backup_clipy2);
		}
		gdImageSetInterpolationMethod(src, interpolation_id_bak);
		return GD_FALSE;
	}

	gdImageGetClip(dst, &c1x, &c1y, &c2x, &c2y);

	end_x = bbox.width  + (int) fabs(bbox.x);
	end_y = bbox.height + (int) fabs(bbox.y);

	/* Get inverse affine to let us work with destination -> source */
	gdAffineInvert(inv, affine);

	src_offset_x =  src_region->x;
	src_offset_y =  src_region->y;

	if (dst->alphaBlendingFlag) {
		for (y = bbox.y; y <= end_y; y++) {
			pt.y = y + 0.5;
			for (x = 0; x <= end_x; x++) {
				pt.x = x + 0.5;
				gdAffineApplyToPointF(&src_pt, &pt, inv);
				gdImageSetPixel(dst, dst_x + x, dst_y + y, getPixelInterpolated(src, src_offset_x + src_pt.x, src_offset_y + src_pt.y, 0));
			}
		}
	} else {
		for (y = 0; y <= end_y; y++) {
			pt.y = y + 0.5 + bbox.y;
			if ((dst_y + y) < 0 || ((dst_y + y) > gdImageSY(dst) -1)) {
				continue;
			}
			dst_p = dst->tpixels[dst_y + y] + dst_x;

			for (x = 0; x <= end_x; x++) {
				pt.x = x + 0.5 + bbox.x;
				gdAffineApplyToPointF(&src_pt, &pt, inv);

				if ((dst_x + x) < 0 || (dst_x + x) > (gdImageSX(dst) - 1)) {
					break;
				}
				*(dst_p++) = getPixelInterpolated(src, src_offset_x + src_pt.x, src_offset_y + src_pt.y, -1);
			}
		}
	}

	/* Restore clip if required */
	if (backclip) {
		gdImageSetClip(src, backup_clipx1, backup_clipy1,
				backup_clipx2, backup_clipy2);
	}

	gdImageSetInterpolationMethod(src, interpolation_id_bak);
	return GD_TRUE;
}

/**
 * Function: gdTransformAffineBoundingBox
 *  Returns the bounding box of an affine transformation applied to a
 *  rectangular area <gdRect>
 *
 * Parameters:
 * 	src - Rectangular source area for the affine transformation
 *  affine - the affine transformation
 *  bbox - the resulting bounding box
 *
 * Returns:
 *  GD_TRUE if the affine is rectilinear or GD_FALSE
 */
int gdTransformAffineBoundingBox(gdRectPtr src, const double affine[6], gdRectPtr bbox)
{
	gdPointF extent[4], min, max, point;
	int i;

	extent[0].x=0.0;
	extent[0].y=0.0;
	extent[1].x=(double) src->width;
	extent[1].y=0.0;
	extent[2].x=(double) src->width;
	extent[2].y=(double) src->height;
	extent[3].x=0.0;
	extent[3].y=(double) src->height;

	for (i=0; i < 4; i++) {
		point=extent[i];
		if (gdAffineApplyToPointF(&extent[i], &point, affine) != GD_TRUE) {
			return GD_FALSE;
		}
	}
	min=extent[0];
	max=extent[0];

	for (i=1; i < 4; i++) {
		if (min.x > extent[i].x)
			min.x=extent[i].x;
		if (min.y > extent[i].y)
			min.y=extent[i].y;
		if (max.x < extent[i].x)
			max.x=extent[i].x;
		if (max.y < extent[i].y)
			max.y=extent[i].y;
	}
	bbox->x = (int) min.x;
	bbox->y = (int) min.y;
	bbox->width  = (int) floor(max.x - min.x) - 1;
	bbox->height = (int) floor(max.y - min.y);
	return GD_TRUE;
}

int gdImageSetInterpolationMethod(gdImagePtr im, gdInterpolationMethod id)
{
	if (im == NULL || id < 0 || id > GD_METHOD_COUNT) {
		return 0;
	}

	switch (id) {
		case GD_DEFAULT:
			id = GD_BILINEAR_FIXED;
		/* Optimized versions */
		case GD_BILINEAR_FIXED:
		case GD_BICUBIC_FIXED:
		case GD_NEAREST_NEIGHBOUR:
		case GD_WEIGHTED4:
			im->interpolation = NULL;
			break;

		/* generic versions*/
		case GD_BELL:
			im->interpolation = filter_bell;
			break;
		case GD_BESSEL:
			im->interpolation = filter_bessel;
			break;
		case GD_BICUBIC:
			im->interpolation = filter_bicubic;
			break;
		case GD_BLACKMAN:
			im->interpolation = filter_blackman;
			break;
		case GD_BOX:
			im->interpolation = filter_box;
			break;
		case GD_BSPLINE:
			im->interpolation = filter_bspline;
			break;
		case GD_CATMULLROM:
			im->interpolation = filter_catmullrom;
			break;
		case GD_GAUSSIAN:
			im->interpolation = filter_gaussian;
			break;
		case GD_GENERALIZED_CUBIC:
			im->interpolation = filter_generalized_cubic;
			break;
		case GD_HERMITE:
			im->interpolation = filter_hermite;
			break;
		case GD_HAMMING:
			im->interpolation = filter_hamming;
			break;
		case GD_HANNING:
			im->interpolation = filter_hanning;
			break;
		case GD_MITCHELL:
			im->interpolation = filter_mitchell;
			break;
		case GD_POWER:
			im->interpolation = filter_power;
			break;
		case GD_QUADRATIC:
			im->interpolation = filter_quadratic;
			break;
		case GD_SINC:
			im->interpolation = filter_sinc;
			break;
		case GD_TRIANGLE:
			im->interpolation = filter_triangle;
			break;

		default:
			return 0;
			break;
	}
	im->interpolation_id = id;
	return 1;
}

#ifdef _MSC_VER
# pragma optimize("", on)
#endif