[shotwell] Don't uncessarily do a raw processing for thumbs

[Jens Georg <jensgeorg src gnome org>]

commit 50cce33b66a3bd40f9edc347e56c9b8a19b1b234
Author: Jens Georg <mail jensge org>
Date:   Sun Oct 9 18:26:00 2016 +0200

    Don't uncessarily do a raw processing for thumbs
    
    Try to use the embedded preview instead.
    
    Signed-off-by: Jens Georg <mail jensge org>
    
    https://bugzilla.gnome.org/show_bug.cgi?id=718248

 src/photos/RawSupport.vala |   13 +++++++++++++
 1 files changed, 13 insertions(+), 0 deletions(-)
---
diff --git a/src/photos/RawSupport.vala b/src/photos/RawSupport.vala
index 441b899..05f652c 100644
--- a/src/photos/RawSupport.vala
+++ b/src/photos/RawSupport.vala
@@ -240,6 +240,7 @@ public class RawReader : PhotoFileReader {
     }
     
     public override Gdk.Pixbuf scaled_read(Dimensions full, Dimensions scaled) throws Error {
+        // Try to get the embedded thumbnail first
         double width_proportion = (double) scaled.width / (double) full.width;
         double height_proportion = (double) scaled.height / (double) full.height;
         bool half_size = width_proportion < 0.5 && height_proportion < 0.5;
@@ -249,6 +250,18 @@ public class RawReader : PhotoFileReader {
         processor.output_params->user_flip = GRaw.Flip.NONE;
         
         processor.open_file(get_filepath());
+        try {
+            if (this.get_role () == Role.THUMBNAIL) {
+                processor.unpack_thumb();
+                var image = processor.make_thumb_image ();
+                return resize_pixbuf (image.get_pixbuf_copy (),
+                                      scaled,
+                                      Gdk.InterpType.BILINEAR);
+            }
+        } catch (Error error) {
+            // Nothing to do, continue with raw developer
+        }
+
         processor.unpack();
         processor.process();