#include <stdio.h>

#include "gd.h"
#include "gdtest.h"

/* Test gdImageScale() with bicubic interpolation on a simple
 * all-white image. */

gdImagePtr mkwhite(int x, int y)
{
	gdImagePtr im;

	im = gdImageCreateTrueColor(x, y);
	gdImageFilledRectangle(im, 0, 0, x-1, y-1,
						   gdImageColorExactAlpha(im, 255, 255, 255, 0));

	gdTestAssert(im != NULL);

	gdImageSetInterpolationMethod(im, GD_BILINEAR_FIXED);    // FP interp'n

	return im;
}/* mkwhite*/


/* Fill with almost-black. */
void mkblack(gdImagePtr ptr)
{
	gdImageFilledRectangle(ptr, 0, 0, ptr->sx - 1, ptr->sy - 1,
						   gdImageColorExactAlpha(ptr, 2, 2, 2, 0));
}/* mkblack*/


#define CLOSE_ENOUGH 15

void scaletest(int x, int y, int nx, int ny)
{
	gdImagePtr im, imref, tmp, same;

	imref = mkwhite(x, y);
	im = mkwhite(x, y);
	tmp = gdImageScale(im, nx, ny);
	same = gdImageScale(tmp, x, y);

	/* Test the result to insure that it's close enough to the
	 * original. */
	gdTestAssert(gdMaxPixelDiff(im, same) < CLOSE_ENOUGH);

	/* Modify the original and test for a change again.  (I.e. test
	 * for accidentally shared memory.) */
	mkblack(tmp);
	gdTestAssert(gdMaxPixelDiff(imref, same) < CLOSE_ENOUGH);

	gdImageDestroy(im);
	gdImageDestroy(imref);
	gdImageDestroy(tmp);
	gdImageDestroy(same);
}/* scaletest*/

void do_test(int x, int y, int nx, int ny)
{
	gdImagePtr im, imref, same;
	im = mkwhite(x, y);
	imref = mkwhite(x, y);

	same = gdImageScale(im, x, y);

	/* Trivial resize should be a straight copy. */
	gdTestAssert(im != same);
	gdTestAssert(gdMaxPixelDiff(im, same) == 0);
	gdTestAssert(gdMaxPixelDiff(imref, same) == 0);

	/* Ensure that modifying im doesn't modify same (i.e. see if we
	 * can catch them accidentally sharing the same pixel buffer.) */
	mkblack(im);
	gdTestAssert(gdMaxPixelDiff(imref, same) == 0);

	gdImageDestroy(same);
	gdImageDestroy(im);
	gdImageDestroy(imref);

	/* Scale horizontally, vertically and both. */
	scaletest(x, y, nx, y);
	scaletest(x, y, x, ny);
	scaletest(x, y, nx, ny);
}

int main()
{
	do_test(300, 300, 600, 600);
	do_test(1500, 1000, 600, 400);

	return gdNumFailures();
}