//#include "trop.h"

#include "tpalette.h"

#include "tropcm.h"

//------------------------------------------------------------------------------

namespace

{

inline double gauss(double x, double y, double x0, double y0, double s)

{

	return exp(-((x - x0) * (x - x0) + (y - y0) * (y - y0)) / s) / (s * TConsts::pi);

}

//------------------------------------------------------------------------------

double integ_gauss(double xmin, double ymin, double xmax, double ymax,

				   double x0, double y0, double s)

{

	int i, j, n;

	double x1, y1, x2, y2, xstep, ystep, area;

	double sum;

	n = 50;

	sum = 0;

	xstep = (xmax - xmin) / n;

	ystep = (ymax - ymin) / n;

	area = xstep * ystep;

	for (i = 0; i < n; i++)

		for (j = 0; j < n; j++) {

			x1 = xmin + xstep * i;

			y1 = ymin + ystep * i;

			x2 = x1 + xstep;

			y2 = y1 + ystep;

			sum += area * (gauss(x1, y1, x0, y0, s) +

						   gauss(x1, y2, x0, y0, s) +

						   gauss(x2, y2, x0, y0, s) +

						   gauss(x2, y1, x0, y0, s)) /

				   4;

		}

	return sum;

}

//------------------------------------------------------------------------------

void build_filter(double h[], double x0, double y0, double s)

{

	double sum, vv;

	int i, j, k;

	double x1, y1, x2, y2;

	k = 0;

	sum = 0.0;

	for (i = 0; i < 3; i++)

		for (j = 0; j < 3; j++) {

			x1 = -1.5 + j;

			y1 = -1.5 + i;

			x2 = x1 + 1.0;

			y2 = y1 + 1.0;

			h[k++] = vv = integ_gauss(x1, y1, x2, y2, x0, y0, s);

			sum += vv;

		}

	if (sum > 0.0) {

		sum = 1.0 / sum;

		for (k = 0; k < 9; k++)

			h[k] *= sum;

	}

}

} // anonymous namespace

//------------------------------------------------------------------------------

void TRop::fracmove(TRasterP rout, TRasterP rin, double dx, double dy)

{

	//Using a bilinear filter is best - consider that only 4 pixels should contribute

	//to a fractionarily shifted one, with weights proportional to the intersection areas.

	double w[4] = {1, 0, 0, 0};

	double sum = 0;

	int idx = tfloor(dx);

	int idy = tfloor(dy);

	double fracX = dx - idx;

	double fracY = dy - idy;

	int i, j;

	for (i = 0; i < 2; ++i)

		for (j = 0; j < 2; ++j)

			sum += w[j + 2 * i] = fabs(fracX - j) * fabs(fracY - i);

	for (i = 0; i < 4; ++i)

		w[i] /= sum;

	TRop::convolve_i(rout, rin, idx, idy, w, 2);

}

//------------------------------------------------------------------------------

void TRop::fracmove(TRasterP rout, TRasterCM32P rin, const TPaletteP &palette, double dx, double dy)

{

	double w[4] = {1, 0, 0, 0};

	double sum = 0;

	int idx = tfloor(dx);

	int idy = tfloor(dy);

	double fracX = dx - idx;

	double fracY = dy - idy;

	int i, j;

	for (i = 0; i < 2; ++i)

		for (j = 0; j < 2; ++j)

			sum += w[j + 2 * i] = fabs(fracX - j) * fabs(fracY - i);

	for (i = 0; i < 4; ++i)

		w[i] /= sum;

	TRop::convolve_i(rout, rin, idx, idy, w, 2);

}