/*

Simple DirectMedia Layer

Copyright (C) 1997-2012 Sam Lantinga <slouken@libsdl.org>

This software is provided 'as-is', without any express or implied

warranty. In no event will the authors be held liable for any damages

arising from the use of this software.

Permission is granted to anyone to use this software for any purpose,

including commercial applications, and to alter it and redistribute it

freely, subject to the following restrictions:

1. The origin of this software must not be misrepresented; you must not

claim that you wrote the original software. If you use this software

in a product, an acknowledgment in the product documentation would be

appreciated but is not required.

2. Altered source versions must be plainly marked as such, and must not be

misrepresented as being the original software.

3. This notice may not be removed or altered from any source distribution.

*/

/*

Based on automated SDL_Surface tests originally written by Edgar Simo 'bobbens'.

Rewritten for test lib by Andreas Schiffler.

*/

#include "SDL_config.h"

#include "SDL_test.h"

int SDLTest_CompareSurfaces( SDL_Surface *surface, SDL_Surface *referenceSurface, int allowable_error )

{

int ret;

int i,j;

int bpp, bpp_reference;

Uint8 *p, *p_reference;

int dist;

Uint8 R, G, B, A;

Uint8 Rd, Gd, Bd, Ad;

/* Make surfacee size is the same. */

if ((surface->w != referenceSurface->w) || (surface->h != referenceSurface->h))

{

return -1;

}

SDL_LockSurface( surface );

SDL_LockSurface( referenceSurface );

ret = 0;

bpp = surface->format->BytesPerPixel;

bpp_reference = referenceSurface->format->BytesPerPixel;

/* Compare image - should be same format. */

for (j=0; j<surface->h; j++) {

for (i=0; i<surface->w; i++) {

p = (Uint8 *)surface->pixels + j * surface->pitch + i * bpp;

p_reference = (Uint8 *)referenceSurface->pixels + j * referenceSurface->pitch + i * bpp_reference;

dist = 0;

SDL_GetRGBA(*(Uint32*)p, surface->format, &R, &G, &B, &A);

SDL_GetRGBA(*(Uint32*)p_reference, referenceSurface->format, &Rd, &Gd, &Bd, &Ad);

dist += (R-Rd)*(R-Rd);

dist += (G-Gd)*(G-Gd);

dist += (B-Bd)*(B-Bd);

/* Allow some difference in blending accuracy */

if (dist > allowable_error) {

ret++;

}

}

}

SDL_UnlockSurface( surface );

SDL_UnlockSurface( referenceSurface );

return ret;

}