SDL_slideshow.c

#include <stdlib.h>
#include <stdio.h>

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

void displayImage(const char *, SDL_Surface *);

int main(int argc, char **argv) {
    if (argc <= 1) {
        printf("At least one argument is required.\n");
        exit(1);
    }
    //Set up screen
    //putenv("SDL_NOMOUSE=1");  //Don't even try to grab the mouse when using fbcon
    if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER) != 0) {
        printf("SDL_Init: %s\n", SDL_GetError());
        exit(1);
    }
    atexit(SDL_Quit);
    SDL_Surface *screen = SDL_SetVideoMode(1024, 768, 32, SDL_DOUBLEBUF | SDL_FULLSCREEN);
    if (screen == NULL) {
        printf("SDL_SetVideoMode: %s\n", SDL_GetError());
        exit(1);
    }
    char driver[16];
    SDL_VideoDriverName((char *)&driver, sizeof(driver));
    printf("Got screen: %ix%i-%i via %s\n", screen->w, screen->h, screen->format->BitsPerPixel, driver);
    SDL_ShowCursor(SDL_DISABLE);

    //Set up image library
    IMG_Init(IMG_INIT_JPG | IMG_INIT_PNG | IMG_INIT_TIF);
    atexit(IMG_Quit);


    //Wait for kill or mouse click
#define EVTLOOP_WAIT 200
#define IMAGE_INTERVAL 30000
    SDL_Event event;
    unsigned long ticks = IMAGE_INTERVAL;   //Force immediate render
    unsigned int imgindex = 1;
    do {
        ticks += EVTLOOP_WAIT;
        if (ticks >= IMAGE_INTERVAL) {
            ticks = 0;
            if (++imgindex >= argc)
                imgindex = 1;
            displayImage(argv[imgindex], screen);
        }

        SDL_Delay(EVTLOOP_WAIT);
        SDL_PollEvent(&event);
    } while (event.type != SDL_QUIT && event.type != SDL_MOUSEBUTTONUP);
}

void displayImage(const char *file, SDL_Surface *screen) {
    SDL_Surface *img = IMG_Load(file);
    if (img == NULL) {
        printf("IMG_Load: %s\n", IMG_GetError());
        exit(1);
    }
    printf("%s: %ix%i", file, img->w, img->h);
    //Scale to fullscreen, preserve aspect
    double s_aspect = (double)screen->w / screen->h;
    double i_aspect = (double)img->w / img->h;
    double scale;
    if (i_aspect > s_aspect) {
        //Scale to screen width
        scale = (double)screen->w / img->w;
    } else {
        // " " height
        scale = (double)screen->h / img->h;
    }
    SDL_Surface *scaled = zoomSurface(img, scale, scale, SMOOTHING_ON);
    printf(" scaled to %ix%i\n", scaled->w, scaled->h);
    SDL_FreeSurface(img);

    //Display
    SDL_FillRect(screen, NULL, 0x000000);
    SDL_Rect destrect = {(screen->w - scaled->w) / 2, (screen->h - scaled->h) / 2};
    if (SDL_BlitSurface(scaled, NULL, screen, &destrect) != 0) {
        printf("SDL_BlitSurface: %s\n", SDL_GetError());
        exit(1);
    }
    SDL_FreeSurface(scaled);
    SDL_Flip(screen);
}