refactor(imagor): fan-out reader sequence

blob.go

@@ -190,14 +190,6 @@ func (b *Blob) init() {
 			return
 		}
 		b.size = size
-		if _, ok := reader.(io.ReadSeekCloser); ok {
-			// construct seeker factory if source supports seek
-			newReader := b.newReader
-			b.newReadSeeker = func() (io.ReadSeekCloser, int64, error) {
-				r, size, err := newReader()
-				return r.(io.ReadSeekCloser), size, err
-			}
-		}
 		if b.fanout && size > 0 && size < maxMemorySize && err == nil {
 			// use fan-out reader if buf size known and within memory size
 			// otherwise create new readers
@@ -208,6 +200,14 @@ func (b *Blob) init() {
 			reader = fanout.NewReader()
 		} else {
 			b.fanout = false
+			if _, ok := reader.(io.ReadSeekCloser); ok {
+				// construct seeker factory if source supports seek
+				newReader := b.newReader
+				b.newReadSeeker = func() (io.ReadSeekCloser, int64, error) {
+					r, size, err := newReader()
+					return r.(io.ReadSeekCloser), size, err
+				}
+			}
 		}
 		// sniff first 512 bytes for type sniffing
 		b.sniffBuf = make([]byte, 512)