--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/lib/cache.h	Sun Dec 27 22:01:17 2009 +0200
@@ -0,0 +1,47 @@
+#ifndef PNGTILE_CACHE_H
+#define PNGTILE_CACHE_H
+
+/**
+ * @file
+ *
+ * Internal image cache implementation
+ */
+#include "image.h"
+
+/**
+ * State for cache access
+ */
+struct pt_cache {
+
+};
+
+/**
+ * On-disk header
+ */
+struct pt_cache_header {
+    /** Pixel dimensions of image */
+    uint32_t width, height;
+    
+    /** Pixel format */
+    uint8_t bit_depth, color_type;
+
+    /** Convenience field for number of bytes per row */
+    uint32_t row_bytes;
+};
+
+/**
+ * Construct the image cache info object associated with the given image.
+ */
+int pt_cache_open (struct pt_cache **cache_ptr, struct pt_image *img, int mode);
+
+/**
+ * Verify if the cached data is still fresh compared to the original.
+ */
+bool pt_cache_fresh (struct pt_cache *cache);
+
+/**
+ * Update the cache data from the given PNG image.
+ */
+int pt_cache_update_png (struct pt_cache *cache, png_structp png, png_infop info);
+
+#endif