SDL_test_compare.c File Reference

#include "SDL_config.h"
#include "SDL_test.h"

Include dependency graph for SDL_test_compare.c:

Go to the source code of this file.

Functions
int	SDLTest_CompareSurfaces (SDL_Surface *surface, SDL_Surface *referenceSurface, int allowable_error)
	Compares a surface and with reference image data for equality.

Variables
static int	_CompareSurfaceCount = 0

Function Documentation

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

Compares a surface and with reference image data for equality.

Parameters

surface	Surface used in comparison
referenceSurface	Test Surface used in comparison
allowable_error	Allowable difference (=sum of squared difference for each RGB component) in blending accuracy.

Returns

0 if comparison succeeded, >0 (=number of pixels for which the comparison failed) if comparison failed, -1 if any of the surfaces were NULL, -2 if the surface sizes differ.

Definition at line 39 of file SDL_test_compare.c.

References _CompareSurfaceCount, SDL_PixelFormat::BytesPerPixel, SDL_Surface::format, G, SDL_Surface::h, i, j, NULL, SDL_Surface::pitch, SDL_Surface::pixels, SDL_GetRGBA, SDL_LockSurface, SDL_SaveBMP, SDL_snprintf, SDL_UnlockSurface, SDLTest_LogError(), and SDL_Surface::w.

Referenced by _compare(), surface_testBlit(), surface_testBlitAlphaMod(), surface_testBlitBlendAdd(), surface_testBlitBlendBlend(), surface_testBlitBlendLoop(), surface_testBlitBlendMod(), surface_testBlitBlendNone(), surface_testBlitColorMod(), surface_testCompleteSurfaceConversion(), and surface_testSurfaceConversion().

{
   int ret;
   int i,j;
   int bpp, bpp_reference;
   Uint8 *p, *p_reference;
   int dist;
   int sampleErrorX = 0, sampleErrorY = 0, sampleDist = 0;
   Uint8 R, G, B, A;
   Uint8 Rd, Gd, Bd, Ad;
   char imageFilename[128];
   char referenceFilename[128];

   /* Validate input surfaces */
   if (surface == NULL || referenceSurface == NULL) {
      return -1;
   }

   /* Make sure surface size is the same. */
   if ((surface->w != referenceSurface->w) || (surface->h != referenceSurface->h)) {
      return -2;
   }

   /* Sanitize input value */
   if (allowable_error<0) {
      allowable_error = 0;
   }

   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;

         SDL_GetRGBA(*(Uint32*)p, surface->format, &R, &G, &B, &A);
         SDL_GetRGBA(*(Uint32*)p_reference, referenceSurface->format, &Rd, &Gd, &Bd, &Ad);

         dist = 0;
         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++;
            if (ret == 1) {
               sampleErrorX = i;
               sampleErrorY = j;
               sampleDist = dist;
            }
         }
      }
   }

   SDL_UnlockSurface( surface );
   SDL_UnlockSurface( referenceSurface );

   /* Save test image and reference for analysis on failures */
   _CompareSurfaceCount++;
   if (ret != 0) {
      SDLTest_LogError("Comparison of pixels with allowable error of %i failed %i times.", allowable_error, ret);
      SDLTest_LogError("First detected occurrence at position %i,%i with a squared RGB-difference of %i.", sampleErrorX, sampleErrorY, sampleDist); 
      SDL_snprintf(imageFilename, 127, "CompareSurfaces%04d_TestOutput.bmp", _CompareSurfaceCount);
      SDL_SaveBMP(surface, imageFilename);
      SDL_snprintf(referenceFilename, 127, "CompareSurfaces%04d_Reference.bmp", _CompareSurfaceCount);
      SDL_SaveBMP(referenceSurface, referenceFilename);
      SDLTest_LogError("Surfaces from failed comparison saved as '%s' and '%s'", imageFilename, referenceFilename);
   }

   return ret;
}

Variable Documentation

int _CompareSurfaceCount = 0

static

Definition at line 36 of file SDL_test_compare.c.

Referenced by SDLTest_CompareSurfaces().