[rygel] renderer: Add play_speed_to_double() to MediaPlayer

[Jens Georg <jensgeorg src gnome org>]

commit d9e52441582026bc20e1e08a37a9186cf283e079
Author: Jussi Kukkonen <jussi kukkonen intel com>
Date:   Wed Oct 30 14:30:15 2013 +0200

    renderer: Add play_speed_to_double() to MediaPlayer
    
    This can be useful for all player implementations.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=710368

 src/librygel-renderer/rygel-media-player.vala |   19 ++++++++++++
 src/plugins/mpris/rygel-mpris-player.vala     |   38 ++++---------------------
 2 files changed, 25 insertions(+), 32 deletions(-)
---
diff --git a/src/librygel-renderer/rygel-media-player.vala b/src/librygel-renderer/rygel-media-player.vala
index 877780a..181ffeb 100644
--- a/src/librygel-renderer/rygel-media-player.vala
+++ b/src/librygel-renderer/rygel-media-player.vala
@@ -104,4 +104,23 @@ public interface Rygel.MediaPlayer : GLib.Object {
     /// Return the MIME types supported by this renderer.
     /// The mime types in this list should be all lowercase.
     public abstract string[] get_mime_types ();
+
+    /**
+     * Transform a fractional playspeed (e.g. "-1/4") to double.
+     * Input values are expected to be valid rational numbers.
+     */
+    protected double play_speed_to_double (string speed)
+    {
+         string[] rational = speed.split ("/", 2);
+
+         assert (rational[0] != "0");
+
+         if (rational[1] == null) {
+             return double.parse (rational[0]);
+         }
+
+         assert (rational[1] != "0");
+
+         return double.parse (rational[0]) / double.parse (rational[1]);
+    }
 }
diff --git a/src/plugins/mpris/rygel-mpris-player.vala b/src/plugins/mpris/rygel-mpris-player.vala
index ef1914e..ba7afaf 100644
--- a/src/plugins/mpris/rygel-mpris-player.vala
+++ b/src/plugins/mpris/rygel-mpris-player.vala
@@ -72,19 +72,21 @@ public class Rygel.MPRIS.Player : GLib.Object, Rygel.MediaPlayer {
         }
     }
 
+    private string _playback_speed;
     public string playback_speed {
         owned get {
-            return this.double_to_rational (this.actual_player.rate);
+            return this._playback_speed;
         }
 
         set {
-            this.actual_player.rate = this.rational_to_double (value);
+            this.actual_player.rate = this.play_speed_to_double (value);
+            this._playback_speed = value;
         }
     }
 
     public double minimum_rate {
         get {
-            return this.rational_to_double (_allowed_playback_speeds[0]);
+            return this.play_speed_to_double (_allowed_playback_speeds[0]);
         }
     }
 
@@ -94,7 +96,7 @@ public class Rygel.MPRIS.Player : GLib.Object, Rygel.MediaPlayer {
 
             assert (i > 0);
 
-            return this.rational_to_double (_allowed_playback_speeds[i-1]);
+            return this.play_speed_to_double (_allowed_playback_speeds[i-1]);
         }
     }
 
@@ -195,34 +197,6 @@ public class Rygel.MPRIS.Player : GLib.Object, Rygel.MediaPlayer {
         }
     }
 
-    private double rational_to_double (string r)
-    {
-         string[] rational;
-
-         rational = r.split("/", 2);
-
-         assert (rational[0] != "0");
-
-         if (rational[1] != null) {
-             assert (rational[1] != "0");
-         } else {
-             return double.parse (rational[0]);
-         }
-
-         return double.parse (rational[0]) / double.parse (rational[1]);
-    }
-
-    private string double_to_rational (double d)
-    {
-         foreach (var r in _allowed_playback_speeds) {
-             if (Math.fabs (rational_to_double (r) - d) < 0.1) {
-                 return r;
-             }
-         }
-
-         return "";
-    }
-
     private void on_properties_changed (DBusProxy actual_player,
                                         Variant   changed,
                                         string[]  invalidated) {