Basic image comparison tool. http://www.flibitijibibo.com/adobesucks.zip

adobesucks.c

/* Adobe Sucks - Image Comparison Program for Checking Creative Suite Fuckups
 * Written by Ethan "flibitijibibo" Lee
 * http://www.flibitijibibo.com/
 *
 * Released under public domain.
 * No warranty implied; use at your own risk.
 *
 * How to Build:
 * cc adobesucks.c `sdl2-config --cflags --libs` -lSDL2_image
 */

#include <SDL.h>
#include <SDL_image.h>

#define SOLID_COLOR 0

static SDL_Surface* LoadImage(
	SDL_Renderer *renderer,
	SDL_Texture *texture,
	char *imgPath
) {
	SDL_Surface *surface;
	SDL_Event evt;
	Uint8 free = 0;
	while (imgPath == NULL)
	{
		while (SDL_PollEvent(&evt) > 0)
		{
			if (evt.type == SDL_QUIT)
			{
				return NULL;
			}
			if (evt.type == SDL_DROPFILE)
			{
				imgPath = evt.drop.file;
				free = 1;
			}
		}
		SDL_RenderClear(renderer);
		if (texture != NULL)
		{
			SDL_RenderCopy(
				renderer,
				texture,
				NULL,
				NULL
			);
		}
		SDL_RenderPresent(renderer);
	}
	surface = IMG_Load(imgPath);
	if (free)
	{
		SDL_free(imgPath);
	}
	if (!surface)
	{
		SDL_ShowSimpleMessageBox(
			SDL_MESSAGEBOX_ERROR,
			"Image load failed!",
			IMG_GetError(),
			NULL
		);
	}
	return surface;
}

int main(int argc, char **argv)
{
	SDL_Window *window;
	SDL_Renderer *renderer;
	SDL_Texture *texture;
	SDL_Surface *src, *dst, *tmp;
	char *imgPath;
	char *diff, *srcpx, *dstpx;
	int pitch, wi, hi;
	SDL_Event evt;
	Uint8 run = 1;

	SDL_Init(SDL_INIT_VIDEO);
	SDL_CreateWindowAndRenderer(
		256,
		256,
		SDL_WINDOW_SHOWN,
		&window,
		&renderer
	);
	SDL_SetWindowTitle(window, "Drag original image here...");

	/* Source image is either first arg or the first dragged image */
	imgPath = (argc > 1) ? argv[1] : NULL;
	src = LoadImage(renderer, NULL, imgPath);
	if (!src)
	{
		return 0;
	}

	/* Create the texture, show it as the source because we can */
	texture = SDL_CreateTexture(
		renderer,
		src->format->format,
		SDL_TEXTUREACCESS_STREAMING,
		src->w,
		src->h
	);
	SDL_UpdateTexture(texture, NULL, src->pixels, src->pitch);
	SDL_SetWindowSize(window, src->w, src->h);
	SDL_SetWindowTitle(window, "Drag new image here...");

	/* Comparison image is either second arg or the second dragged image */
	imgPath = (argc > 2) ? argv[2] : NULL;
	dst = LoadImage(renderer, texture, imgPath);
	if (!dst)
	{
		SDL_FreeSurface(src);
		return 0;
	}
	SDL_SetWindowTitle(window, NULL);

	while (run)
	{
		while (SDL_PollEvent(&evt) > 0)
		{
			if (evt.type == SDL_QUIT)
			{
				run = 0;
			}
			if (evt.type == SDL_DROPFILE)
			{
				/* Dragged files replace the comparison image */
				tmp = IMG_Load(evt.drop.file);
				if (!tmp)
				{
					SDL_ShowSimpleMessageBox(
						SDL_MESSAGEBOX_ERROR,
						"New image load failed!",
						IMG_GetError(),
						NULL
					);
				}
				SDL_FreeSurface(dst);
				dst = tmp;
			}
		}

		/* Images aren't related? Bail. */
		if (	(src->w != dst->w) ||
			(src->h != dst->h) ||
			(src->format->format != dst->format->format)	)
		{
			SDL_ShowSimpleMessageBox(
				SDL_MESSAGEBOX_ERROR,
				"Image mismatch!",
				"Source and Destination must be the same size/format!",
				NULL
			);
			break;
		}

		/* Compare each pixel, write unique pixels to texture */
		SDL_LockTexture(
			texture,
			NULL,
			(void**) &diff,
			&pitch
		);
		srcpx = (char*) src->pixels;
		dstpx = (char*) dst->pixels;
		for (hi = 0; hi < src->h; hi += 1)
		for (wi = 0; wi < src->w; wi += 1)
		{
			const int offset = (
				(hi * pitch) +
				(wi * src->format->BytesPerPixel)
			);
			if (SDL_memcmp(
				&srcpx[offset],
				&dstpx[offset],
				src->format->BytesPerPixel
			) != 0) {
#if SOLID_COLOR
				SDL_memset(
					&diff[offset],
					'\0',
					src->format->BytesPerPixel
				);
				diff[offset] = 0xFF;
				if (src->format->BytesPerPixel == 4)
				{
					diff[offset + 3] = 0xFF;
				}
#else
				SDL_memcpy(
					&diff[offset],
					&dstpx[offset],
					src->format->BytesPerPixel
				);
#endif
			}
			else
			{
				SDL_memset(
					&diff[offset],
					'\0',
					src->format->BytesPerPixel
				);
			}
		}
		SDL_UnlockTexture(texture);

		/* Draw the result! */
		SDL_RenderClear(renderer);
		SDL_RenderCopy(
			renderer,
			texture,
			NULL,
			NULL
		);
		SDL_RenderPresent(renderer);
	}

	SDL_FreeSurface(src);
	SDL_FreeSurface(dst);
	SDL_DestroyTexture(texture);
	SDL_DestroyRenderer(renderer);
	SDL_DestroyWindow(window);
	SDL_Quit();
	return 0;
}