drag/drop

playlist.rkt

@@ -2,10 +2,11 @@
 
 (require racket/class
          "music-library.rkt"
-         racket-sound
+         racket-audio
          "utils.rkt"
          racket-sprintf
          keystore/class
+         racket/list
          )
 
 (provide track%
@@ -331,6 +332,42 @@
         (send this save-tab!))
       )
 
+    (define/public (move-track from-idx to-idx)
+      (let ((tr (list-ref tracks from-idx))
+            (idx 0))
+        (if (= from-idx to-idx)
+            #t
+            (begin
+              (when (< from-idx to-idx)
+                (set! to-idx (- to-idx 1)))
+              (let* ((l1 (if (= from-idx 0)
+                             '()
+                             (take tracks from-idx)))
+                     (l2 (drop tracks (+ from-idx 1)))
+                     (l (append l1 l2))
+                     )
+                (set! tracks (append
+                              (if (= to-idx 0) '() (take l to-idx))
+                              (list tr)
+                              (drop l to-idx)))
+                )
+              (send this save-tab!)
+              )
+            )
+        )
+      )
+
+    (define/public (drop-id track-id)
+      (let ((idx (send this index track-id)))
+        (let* ((l1 (if (= idx 0) '() (take tracks idx)))
+               (l2 (drop tracks (+ idx 1)))
+               (l (append l1 l2)))
+          (set! tracks l)
+          (send this save-tab!)
+          )
+        )
+      )
+
     (define/public (track i)
       (list-ref tracks i))