Further refinements on interfaces

common/image.c

@@ -1,9 +1,4 @@
 #include "image.h"
 #include <stdlib.h>
 
-void free_image(Image* img) {
-  if (img && img->data) {
-    free(img->data);
-    img->data = NULL;
-  }
-}
+

common/image_loader.h

@@ -6,8 +6,8 @@
 
 typedef struct image_decoder {
   const char *name;
-  int (*can_decode)(const uint8_t data, size_t size);
-  image_t* (*decode)(const uint8_t data, size_t size);
+  int (*can_decode)(const uint8_t *data, size_t size);
+  image_t* (*decode)(const uint8_t *data, size_t size);
   void (*destroy)(struct image_decoder *self);
 } image_decoder_t;
 

formats/img_png.c

@@ -3,14 +3,19 @@
 #include <stdlib.h>
 #include <string.h>
 #include "img_png.h"
-#include "common.h"
+#include "../common/utils.h"
 
 #define BUFSIZE 1024
 
 const unsigned char img_png_signature[] = {0x89, 'P', 'N', 'G', '\r', '\n', 0x1a, '\n'};
 
+// Reads magic number and determines if data is PNG
+int png_can_decode(const uint8_t *data, size_t size) {
+  if (size < 8) return 0;
+  return memcmp(data, img_png_signature, 8) == 0;
+}
 
-int read_chunk(FILE *fp) {
+struct img_png_chunk read_chunk(FILE *fp) {
   struct img_png_chunk cur_chunk;
 
   // Read chunk length
@@ -49,37 +54,26 @@ int read_chunk(FILE *fp) {
     exit(EXIT_FAILURE);
   }
 
-  return feof(fp);
+  return cur_chunk;
 }
 
-uint8_t* img_png_decode(FILE *fp) {
-  unsigned char magic[8];
-
-  // Check PNG Magic
-  if(fread(magic, sizeof(*magic), 8, fp) < 8) {
-    fprintf(stderr, "Couldn\'t read PNG magic.");
-    exit(EXIT_FAILURE);
-  }
-
-  if(memcmp(magic, img_png_signature, 8) != 0) {
-    fprintf(stderr, "Invalid PNG magic\n");
-    exit(EXIT_FAILURE);
-  }
-  
-  printf("PNG Magic: %#04x%02x%02x%02x%02x%02x%02x%02x\n", magic[0], magic[1], magic[2],
-         magic[3], magic[4], magic[5], magic[6], magic[7]);
-
-  struct img_png_chunk cur_chunk;  
-
-  // Read chunk   
-  
-  while (read_chunk(fp) == 0);
-  
-  if(!feof(fp)) {
-    perror("fread() failed!");
-    exit(EXIT_FAILURE);
-  }
-  
-
+image_t* png_decode (const uint8_t *data, size_t size) {
   return NULL;
 }
+
+void png_destroy(struct image_decoder *self) {
+  if (self) {
+    free(self);
+    self = NULL;
+  } else self = NULL;
+}
+
+image_decoder_t* png_decoder_create () {
+  image_decoder_t* decoder = malloc(sizeof(image_decoder_t));
+  decoder->name = "PNG";
+  decoder->can_decode = png_can_decode;
+  decoder->decode = png_decode;
+  decoder->destroy = png_destroy;
+
+  return decoder;
+}

formats/img_png.h

@@ -3,6 +3,8 @@
 
 #include <stdint.h>
 #include <stdio.h>
+#include "../common/image.h"
+#include "../common/image_loader.h"
 
 struct img_png_chunk {
   unsigned char* chunk_data;
@@ -10,7 +12,9 @@ struct img_png_chunk {
   uint32_t crc;
   char chunk_type[4];
 };
-
-uint8_t* img_png_decode (FILE* fp);
+image_decoder_t* png_decoder_create (void);
+int png_can_decode (const uint8_t *data, size_t size);
+image_t* png_decode (const uint8_t *data, size_t size);
+void png_destroy (struct image_decoder *self);
 
 #endif