Framing out level loading and specify KBLE file format

kbleformat.md

@@ -0,0 +1,12 @@
+# .kble file format
+Recommanded extension: `.kble`
+
+Data stored: level size, level content.
+
+Encoding:
+* first byte indicates how big is a chunk of data (in bytes)
+* second and third bytes indicates level width
+* fourth and fifth bytes indicates level height
+* 7th => (7 + data_size * width * height) contains level data
+
+If the encoding is incorrect, return an error or crash the program.

src/level.zig

@@ -48,6 +48,19 @@ pub fn init(allocator: *std.mem.Allocator, width: u16, height: u16) !Self {
     return self;
 }
 
+/// Load level content from given absolute path. Expect the KBLE file format (see
+/// `kbleformat.md` for more details.
+pub fn init_load(allocator: *std.mem.Allocator, kble_file_path: []const u8) !Self {
+    var self = Self{
+        .width = undefined,
+        .height = undefined,
+        .content = undefined,
+        .selection = undefined,
+    };
+
+    return self;
+}
+
 /// Free the level content.
 pub fn deinit(self: *Self, allocator: *std.mem.Allocator) void {
     allocator.free(self.selection);