[emms-help] [patch] move tracks in playlist

[Rasmus]

Hi,

This patch adds support for moving tracks in the playlist.

Since I change other playlist functions (not user-visible, I think), I'll
wait a couple of days before merging to see if anybody is opposed to any
changes.

A small rant:

The playlist is a mess.  Faces differ depending on how they were inserted
into the buffer.  The displayed string depends on how it was inserted.
The indentation is also a function of insertion method.

One thing I would be cool would be use tabulated list (like packaged mode)
and have /one/ format-string that controls how items look and are aligned.
I'd have to check if cover art can work with this.

Rasmus

-- 
Together we will make the possible totalllly impossible!

>From 4c0be3c9ecf66d7fb2dfeac56158fcf89aecf8eb Mon Sep 17 00:00:00 2001
From: Rasmus <address@hidden>
Date: Sun, 24 May 2015 14:30:03 +0200
Subject: [PATCH] Add move functions to the playlist view

This allows moving track with M-up and M-down (like Org headings).

To facilitate a consistent behavior (e.g. not changing fonts or
strings), a number of functions were changed:
 - Kill functions take an optional no-stop argument
 - emms-playlist-mode-insert-track takes a new optional
   track-string argument that is used as string if non-nil.
   Further, it tries to use the same face as track-string if present.
---
 NEWS                       |  1 +
 doc/emms.texinfo           | 10 ++++++
 lisp/emms-playlist-mode.el | 85 +++++++++++++++++++++++++++++++++++-----------
 3 files changed, 77 insertions(+), 19 deletions(-)

diff --git a/NEWS b/NEWS
index 65c439b..40b45bd 100644
--- a/NEWS
+++ b/NEWS
@@ -9,6 +9,7 @@ News since version 4.0:
   - emms-lyrics.el now uses eww if present.  Also EMMS tries to fetch
     non-Chinese lyrics from lyricwiki.org.
   - Add HTTPS support where possible.
+  - Tracks can be moved in the emms playlist using M-up and M-down.
 
 News since version 3.0:
 
diff --git a/doc/emms.texinfo b/doc/emms.texinfo
index 26bb10f..c0db3cd 100644
--- a/doc/emms.texinfo
+++ b/doc/emms.texinfo
@@ -681,6 +681,10 @@ Move to the previous track in the current buffer.
 @defun emms-playlist-previous
 Move to the previous track in the current buffer.
 @end defun
address@hidden emms-playlist-move-track-up
+Move the current track up in the playlist.
address@hidden emms-playlist-move-track-down
+Move the current track down in the playlist.
 @defun emms-random
 Jump to a random track.
 @end defun
@@ -1042,9 +1046,15 @@ Set the current playlist buffer.
 @item n
 @findex emms-next
 Start playing the next track in the playlist.
address@hidden M-down
address@hidden emms-playlist-move-track-down
+Move the current track down in the playlist.
 @item p
 @findex emms-next
 Start playing the previous track in the playlist.
address@hidden M-up
address@hidden emms-playlist-move-track-up
+Move the current track up in the playlist.
 @item s
 @findex emms-stop
 Stop playing.
diff --git a/lisp/emms-playlist-mode.el b/lisp/emms-playlist-mode.el
index e8972c0..ee175a4 100644
--- a/lisp/emms-playlist-mode.el
+++ b/lisp/emms-playlist-mode.el
@@ -130,6 +130,8 @@ This is true for every invocation of 
`emms-playlist-mode-go'."
     (define-key map (kbd "M->") 'emms-playlist-mode-last)
     (define-key map (kbd "M-n") 'emms-playlist-mode-next)
     (define-key map (kbd "M-p") 'emms-playlist-mode-previous)
+    (define-key map [(meta up)] 'emms-playlist-move-track-up)
+    (define-key map [(meta down)] 'emms-playlist-move-track-down)
     (define-key map (kbd "a") 'emms-playlist-mode-add-contents)
     (define-key map (kbd "b") 'emms-playlist-set-playlist-buffer)
     (define-key map (kbd "D") 'emms-playlist-mode-kill-track)
@@ -341,6 +343,38 @@ set it as current."
       (error "No track at point"))))
 
 ;;; --------------------------------------------------------
+;;; Move track
+;;; --------------------------------------------------------
+
+(defun emms-playlist-move-track-up (&optional n)
+  "Move track at point upwards in the playlist.
+Optional argument n is the number of spaces "
+  (interactive "p")
+  (let ((track (emms-playlist-track-at))
+        (playing-track (and emms-player-playing-p
+                            (emms-playlist-selected-track-at-p)))
+        (string (buffer-substring (line-beginning-position)
+                                  (line-end-position)))
+        (n (- (or n 1))))
+    (emms-playlist-mode-kill-entire-track t)
+    (forward-line n)
+    (save-excursion
+      (emms-with-inhibit-read-only-t
+       (emms-playlist-mode-insert-track track nil string)
+       (emms-playlist-mode-correct-previous-yank)))
+    (and playing-track
+         (emms-with-inhibit-read-only-t
+          (emms-playlist-select (point))))))
+
+(defun emms-playlist-move-track-down (&optional n)
+  "Drag track at point downwards in the playlist.
+Optional argument n is the number of spaces "
+  (interactive "p")
+  (let ((n (- (or n 1))))
+    (emms-playlist-move-track-up n)))
+
+
+;;; --------------------------------------------------------
 ;;; Killing and yanking
 ;;; --------------------------------------------------------
 
@@ -350,15 +384,17 @@ set it as current."
        (<= p b)))
 
 ;; D
-(defun emms-playlist-mode-kill-entire-track ()
+(defun emms-playlist-mode-kill-entire-track (&optional no-stop)
   "Kill track at point, including newline."
   (interactive)
   (let ((kill-whole-line t))
-    (emms-playlist-mode-kill-track)))
+    (emms-playlist-mode-kill-track no-stop)))
 
 ;; C-k
-(defun emms-playlist-mode-kill-track ()
-  "Kill track at point."
+(defun emms-playlist-mode-kill-track (&optional no-stop)
+  "Kill track at point.
+Optional no-stop allows the track to continue playing.
+"
   (interactive)
   (emms-with-inhibit-read-only-t
    (let ((track (emms-playlist-track-at)))
@@ -366,8 +402,8 @@ set it as current."
        (let ((track-region (emms-property-region (point)
                                                 'emms-track)))
         (when (and emms-player-playing-p
-                   (emms-playlist-selected-track-at-p))
-          (emms-stop)
+                    (emms-playlist-selected-track-at-p))
+          (unless no-stop (emms-stop))
           (delete-overlay emms-playlist-mode-selected-overlay)
           (setq emms-playlist-mode-selected-overlay nil))))
      (let ((kill-whole-line emms-playlist-mode-kill-whole-line-p))
@@ -375,7 +411,7 @@ set it as current."
        (kill-line)))))
 
 ;; C-w
-(defun emms-playlist-mode-kill ()
+(defun emms-playlist-mode-kill (&optional no-stop)
   "Kill from mark to point."
   (interactive)
   (emms-with-inhibit-read-only-t
@@ -385,7 +421,7 @@ set it as current."
                (marker-position emms-playlist-selected-marker)
                (region-beginning)
                (region-end)))
-     (emms-stop)
+     (unless no-stop (emms-stop))
      (delete-overlay emms-playlist-mode-selected-overlay)
      (setq emms-playlist-mode-selected-overlay nil))
    (kill-region (region-beginning)
@@ -481,18 +517,29 @@ This preserves the current EMMS buffer."
 ;;; Local functions
 ;;; --------------------------------------------------------
 
-(defun emms-playlist-mode-insert-track (track &optional no-newline)
+(defun emms-playlist-mode-insert-track (track &optional no-newline 
track-string)
   "Insert the description of TRACK at point.
-When NO-NEWLINE is non-nil, do not insert a newline after the track."
+When NO-NEWLINE is non-nil, do not insert a newline after the track.
+When TRACK-STRING is non-nil it will be used as the playlist text.
+Otherwise `emms-track-force-description' is used."
   (emms-playlist-ensure-playlist-buffer)
-  (emms-with-inhibit-read-only-t
-   (insert (emms-propertize (emms-track-force-description track)
-                            'emms-track track
-                            'face 'emms-playlist-track-face))
-   (when (emms-playlist-selected-track-at-p)
-     (emms-playlist-mode-overlay-selected))
-   (unless no-newline
-     (insert "\n"))))
+  (let ((face (and track-string
+                   (or (get-text-property 0 'face track-string)
+                       (get-text-property
+                        (next-single-property-change 0 'face track-string)
+                        'face track-string)))))
+    (and track-string
+         (set-text-properties 0 (length track-string) nil track-string))
+    (emms-with-inhibit-read-only-t
+     (insert (emms-propertize (or track-string
+                                  (emms-track-force-description track))
+                              'emms-track track
+                              'face (or face 'emms-playlist-track-face)))
+     (when (save-excursion (beginning-of-line)
+                           (emms-playlist-selected-track-at-p))
+       (emms-playlist-mode-overlay-selected))
+     (unless no-newline
+       (insert "\n")))))
 
 (defun emms-playlist-mode-update-track-function ()
   "Update the track display at point."
@@ -509,7 +556,7 @@ When NO-NEWLINE is non-nil, do not insert a newline after 
the track."
        (when selectedp
         (delete-overlay emms-playlist-mode-selected-overlay)
         (setq emms-playlist-mode-selected-overlay nil))
-       (emms-playlist-mode-insert-track track t))
+       (emms-playlist-mode-insert-trac track t))
      (when selectedp
        (emms-playlist-select (point))))))
 
-- 
2.4.1