Allow saving the screen to an output file

diff --git a/scrolling/sdl-scrolling.c b/scrolling/sdl-scrolling.c
index 4f49e25..4b9475f 100644 (file)
--- a/scrolling/sdl-scrolling.c
+++ b/scrolling/sdl-scrolling.c
@@ -17,6 +17,10 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
 #include <errno.h>
 #include <SDL.h>
 #include <SDL_image.h>
@@ -70,8 +74,10 @@ int main(int argc, char *argv[])
        Uint32 time_start;
        Uint32 time_end;
 
-       if (argc != 2) {
-               fprintf(stderr, "usage: %s <image>\n", argv[0]);
+       int output_fd = -1;
+
+       if (argc < 2) {
+               fprintf(stderr, "usage: %s <image> [<output file>]\n", argv[0]);
                return -EINVAL;
        }
 
@@ -90,6 +96,20 @@ int main(int argc, char *argv[])
                goto out;
        }
 
+       /* Set up the output file */
+       if (argc >= 3) {
+               if (strncmp(argv[2], "-", 1) == 0) {
+                       output_fd = STDOUT_FILENO;
+               } else {
+                       output_fd = open(argv[2], O_WRONLY | O_CREAT, S_IRUSR | S_IWUSR);
+                       if (output_fd < 0) {
+                               perror("open");
+                               ret = output_fd;
+                               goto out;
+                       }
+               }
+       }
+
        lastframe_limit = (map->h - HEIGHT);
 
        if (SDL_NumJoysticks() > 0)
@@ -148,6 +168,16 @@ int main(int argc, char *argv[])
                SDL_BlitSurface(map, &viewport, screen, NULL);
                SDL_Flip(screen);
 
+               if (output_fd >= 0) {
+                       int len = screen->w * screen->h * screen->format->BytesPerPixel;
+
+                       ret = write(output_fd, screen->pixels, len);
+                       if (ret != len) {
+                               fprintf(stderr, "invalid write\n");
+                               running = 0;
+                       }
+               }
+
                time_end = SDL_GetTicks();
                if (time_end - time_start < 1000 / FPS)
                        SDL_Delay((1000 / FPS) - (time_end - time_start));
@@ -155,6 +185,9 @@ int main(int argc, char *argv[])
 
        ret = 0;
 
+       if (output_fd >= 0)
+               close(output_fd);
+
        if (SDL_JoystickOpened(0))
                SDL_JoystickClose(joystick);