robinkrens.nl - git repository - swan-dev/blob - tools/bmp2tiles/bmp2tiles.c

   1 /**
   2  * File              : bmp2tiles.c
   3  * Author            : Robin Krens <robin@robinkrens.nl>
   4  * Date              : 04.06.2022
   5  * Last Modified Date: 12.06.2022
   6  * Last Modified By  : Robin Krens <robin@robinkrens.nl>
   7  */
   8
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #include <stdint.h>
  12 #include <stdbool.h>
  13 #include <string.h>
  14 #include <SDL2/SDL_image.h>
  15
  16 #define TILE_SZ         32
  17 #define FOURBBP_ROW     8
  18 #define FOURBPP_COL     8
  19
  20 typedef struct {
  21         unsigned width;
  22         unsigned height;
  23         unsigned bpp;
  24 } swan_gfx_t;
  25
  26 void set_info(swan_gfx_t * gfx, SDL_Surface * img)
  27 {
  28         gfx->width = img->w;
  29         gfx->height = img->h;
  30         gfx->bpp = img->format->BitsPerPixel;
  31
  32         /* set userdata to iterate */
  33         SDL_LockSurface(img);
  34         img->userdata = img->pixels;
  35         SDL_UnlockSurface(img);
  36 }
  37
  38 void generate_4bpp_tile(unsigned char *buf, void * userdata,
  39                 bool packed)
  40 {
  41         unsigned char * ptr = (unsigned char *) userdata;
  42         for (int i = 0; i < TILE_SZ; i+=4) {
  43                 for (int j = 0; j < 4; ++j) {
  44                         if (packed) { /* packed format */
  45                                 buf[i+j] = ptr[0] << 4;
  46                                 buf[i+j] |= ptr[1];
  47                                 ptr += 2;
  48                         } else { /* planar format */
  49                                 for (int x = 0; x < 8; ++x) {
  50                                         buf[i + j] = ptr[x] << j;
  51                                 }
  52                         }
  53                 }
  54                 if (!packed)
  55                         ptr += 8;
  56         }
  57 }
  58
  59 int main(void)
  60 {
  61         SDL_Surface * rawbmp;
  62         FILE * ostream;
  63         char filename[] = "test.bmp";
  64         char outname[] = "test.gfx";
  65         rawbmp = SDL_LoadBMP(filename);
  66
  67         if (!rawbmp) {
  68                 fprintf(stderr, "can not load .bmp file\n");
  69                 exit(EXIT_FAILURE);
  70         }
  71
  72         swan_gfx_t * gfx = malloc(sizeof(swan_gfx_t));
  73         set_info(gfx, rawbmp);
  74
  75         unsigned char *tile_buf = malloc(sizeof(unsigned char) * TILE_SZ);
  76
  77         if (gfx->bpp != 8) {
  78                 fprintf(stderr, "warning: %d bpp format detected\n", rawbmp->format->BitsPerPixel);
  79                 fprintf(stderr, "use --force in command to run\n");
  80                 exit(EXIT_FAILURE);
  81         }
  82
  83         ostream = fopen(outname, "w");
  84         if (!ostream) {
  85                 fprintf(stderr, "can not open file for writing!\n");
  86                 exit(EXIT_FAILURE);
  87         }
  88
  89         unsigned nr_tiles = 1;
  90
  91         for (int i = 0; i < nr_tiles; ++i) {
  92                 generate_4bpp_tile(tile_buf, rawbmp->userdata, true);
  93                 int ret = fwrite(tile_buf, sizeof(unsigned char), TILE_SZ, ostream);
  94                 if (ret != TILE_SZ) {
  95                         fprintf(stderr, "failed to convert, only write %d instead of %d\n", ret, TILE_SZ);
  96                         goto cleanup;
  97                 }
  98         }
  99
 100 cleanup:
 101         free(gfx);
 102         SDL_FreeSurface(rawbmp);
 103         fclose(ostream);
 104 }