add thumb/preview decoding

src/add/class.js

@@ -106,6 +106,12 @@ self.DataReader = class DataReader {
         return p;
     }
 
+    readBytes(len) {
+        let buf = this.view.buffer.slice(this.pos, this.pos + len);
+        this.pos += len;
+        return buf;
+    }
+
     readU8() {
         return this.view.getUint8(this.pos++);
     }

src/mode/sla/x_cxdlp.js

@@ -64,9 +64,12 @@
                 res_y: read.readU16(),
                 height: read.readU32(),
                 skip: read.skip(60),
-                thumb: read.skip(26914),
-                preview1: read.skip(168202),
-                preview2: read.skip(168202),
+                thumb: read.readBytes(26912),
+                skip: read.skip(2), // 0xd0a term
+                preview1: read.readBytes(168200),
+                skip: read.skip(2), // 0xd0a term
+                preview2: read.readBytes(168200),
+                skip: read.skip(2), // 0xd0a term
                 dim_x: read_string(true),
                 dim_y: read_string(true),
                 layer: read_string(true),