gif

commit f9bcb3eb69976b7eefa42da8438f659e502e2b37
parent 3a071e16f10fb7d922d361d14ac121659247f13e
Author: phoebos <ben@bvnf.space>
Date:   Wed,  1 Sep 2021 21:34:10 +0100

implement color table as a struct

Diffstat:
M
gif.c
 | 
32
+++++++++++++++++++-------------

1 file changed, 19 insertions(+), 13 deletions(-)
diff --git a/gif.c b/gif.c
@@ -18,6 +18,10 @@
 #define FAIL_SYS 2
 
 typedef unsigned char rgb[3];
+struct Color_table {
+    int len; /* 2- 256 */
+    rgb table[256];
+};
 struct Gif {
     char version[3]; /* 87a or 89a */
     uint16_t width;
@@ -30,20 +34,20 @@ struct Gif {
                          */
     unsigned char background; /* color index in GCT of screen background */
     unsigned char aspect_ratio; /* 89a+ only */
-    rgb colortable[256];
-    int colortable_len; /* 2 - 256 */
+    struct Color_table *gct;
     unsigned char *pixels; /* array of indices to colors */
 };
 struct Image {
-    int colortable_len; /* 2 - 256 */
-    /*  TODO: local color table */
+    struct Color_table *lct;
     unsigned char *pixels;
 };
 
 void
-print_colortable(struct Gif *g){
-    for (int i = 0; i < g->colortable_len; i++){
-        printf("%d: \033[48;2;%d;%d;%dm(%02x;%02x;%02x)\033[0m\n", i, g->colortable[i][0], g->colortable[i][1], g->colortable[i][2], g->colortable[i][0], g->colortable[i][1], g->colortable[i][2]);
+print_colortable(struct Color_table *c){
+    for (int i = 0; i < c->len; i++){
+        printf("%d: \033[48;2;%d;%d;%dm(%02x;%02x;%02x)\033[0m\n",
+                i, c->table[i][0], c->table[i][1], c->table[i][2],
+                c->table[i][0], c->table[i][1], c->table[i][2]);
     }
 }
 
@@ -57,6 +61,7 @@ gif_decode_image(struct Image *img, unsigned char *buf){
 int
 gif_decode(unsigned char *buf, size_t len){
     struct Gif g = {0 };
+    g.gct = malloc(sizeof(struct Color_table));
     struct Image *img;
     int cur_block;
     enum { HEAD = 1, SPEC = 2, IMGE = 4 };
@@ -87,19 +92,19 @@ gif_decode(unsigned char *buf, size_t len){
     g.background = *buf++;
     g.aspect_ratio = *buf++;
 
-    g.colortable_len = (int)pow(2.0, (double) (g.flags & 7U) + 1);
-    fprintf(stderr, "%d colors in GCT\n", g.colortable_len);
+    g.gct->len = (int)pow(2.0, (double) (g.flags & 7U) + 1);
+    fprintf(stderr, "%d colors in GCT\n", g.gct->len);
 
     /* if GCT... */
     if (g.flags & 0x80) {
         /* TODO: gif87a.txt L 336? */
-        for (int i = 0; i < g.colortable_len; i+=1) {
+        for (int i = 0; i < g.gct->len; i+=1) {
             rgb c = {*buf++, *buf++, *buf++};
-            memcpy(g.colortable[i], c, sizeof(rgb));
+            memcpy(g.gct->table[i], c, sizeof(rgb));
         }
     }
 
-    print_colortable(&g);
+    print_colortable(g.gct);
 
     /* END OF HEADER */
 
@@ -115,7 +120,8 @@ gif_decode(unsigned char *buf, size_t len){
                 if (cur_block != IMGE) {
                     cur_block = IMGE;
                     img = malloc(sizeof(struct Image));
-                    img->colortable_len = g.colortable_len;
+                    img->lct = malloc(sizeof(struct Color_table));
+                    img->lct->len = g.gct->len;
                     gif_decode_image(img, buf);
                 }
                 break;