[banshee] Dap.Mtp: Main thread for pixbuf handling (bgo#733659)

[Andrés Aragoneses <aaragoneses src gnome org>]

commit 3e748631a9437d3f1e74f890d0e9af31a9680481
Author: Nicholas Little <arealityfarbetween googlemail com>
Date:   Wed Jul 30 21:09:46 2014 +0200

    Dap.Mtp: Main thread for pixbuf handling (bgo#733659)
    
    It looks like Gdk.Pixbuf gets very unhappy if you don't work with it on
    the main thread, even property access generates a gui-thread-check
    warning.
    
    In this patch, we block while retrieving the artwork, converting it to a
    byte array and recording the geometry.
    
    Signed-off-by: Andrés G. Aragoneses <knocte gmail com>

 .../Banshee.Dap.Mtp/Banshee.Dap.Mtp/MtpSource.cs   |   34 +++++++++++++++-----
 1 files changed, 26 insertions(+), 8 deletions(-)
---
diff --git a/src/Dap/Banshee.Dap.Mtp/Banshee.Dap.Mtp/MtpSource.cs 
b/src/Dap/Banshee.Dap.Mtp/Banshee.Dap.Mtp/MtpSource.cs
index 3ef48ff..bf3eb6a 100644
--- a/src/Dap/Banshee.Dap.Mtp/Banshee.Dap.Mtp/MtpSource.cs
+++ b/src/Dap/Banshee.Dap.Mtp/Banshee.Dap.Mtp/MtpSource.cs
@@ -36,6 +36,7 @@ using Mtp;
 using MTP = Mtp;
 
 using Banshee.Dap;
+using Banshee.Collection.Gui;
 using Banshee.ServiceStack;
 using Banshee.Sources;
 using Banshee.Playlist;
@@ -353,16 +354,33 @@ namespace Banshee.Dap.Mtp
                         album.AddTrack (mtp_track);
 
                         if (supports_jpegs && can_sync_albumart) {
+                            ArtworkManager art = ServiceManager.Get<ArtworkManager> ();
+                            Exception ex = null;
+                            Gdk.Pixbuf pic = null;
+                            byte[] bytes = null;
+                            uint width = 0, height = 0;
+                            ThreadAssist.BlockingProxyToMain (() => {
+                                try {
+                                    pic = art.LookupScalePixbuf (track.ArtworkId, thumb_width);
+                                    if (pic != null) {
+                                        bytes = pic.SaveToBuffer ("jpeg");
+                                        width = (uint) pic.Width;
+                                        height = (uint) pic.Height;
+                                    }
+                                } catch (Exception e) {
+                                    ex = e;
+                                }
+                            });
+
                             try {
-                                Gdk.Pixbuf pic = ServiceManager.Get<Banshee.Collection.Gui.ArtworkManager> 
().LookupScalePixbuf (
-                                    track.ArtworkId, thumb_width
-                                );
-                                if (pic != null) {
-                                    byte [] bytes = pic.SaveToBuffer ("jpeg");
-                                    album.Save (bytes, (uint)pic.Width, (uint)pic.Height);
-                                    Banshee.Collection.Gui.ArtworkManager.DisposePixbuf (pic);
+                                if (ex != null) {
+                                    throw ex;
+                                }
+                                if (bytes != null) {
+                                    ArtworkManager.DisposePixbuf (pic);
+                                    album.Save (bytes, width, height);
+                                    album_cache [key] = album;
                                 }
-                                album_cache[key] = album;
                             } catch (Exception e) {
                                 Log.Debug ("Failed to create MTP Album", e.Message);
                             }