[gthumb] slideshow: use a sinusoidal increment and decrement on the animations

[Paolo Bacchilega <paobac src gnome org>]

commit 618654671c402c3eaf68c686a8db5d1df97bd6c5
Author: Paolo Bacchilega <paobac src gnome org>
Date:   Fri Apr 29 22:56:00 2011 +0200

    slideshow: use a sinusoidal increment and decrement on the animations

 extensions/slideshow/gth-slideshow.c |    9 ++++++++-
 1 files changed, 8 insertions(+), 1 deletions(-)
---
diff --git a/extensions/slideshow/gth-slideshow.c b/extensions/slideshow/gth-slideshow.c
index b875127..283434d 100644
--- a/extensions/slideshow/gth-slideshow.c
+++ b/extensions/slideshow/gth-slideshow.c
@@ -58,6 +58,7 @@ struct _GthSlideshowPrivate {
 	GthSlideshowDirection  direction;
 #if HAVE_CLUTTER
 	ClutterTimeline       *timeline;
+	ClutterAlpha          *alpha;
 	ClutterActor          *image1;
 	ClutterActor          *image2;
 	ClutterActor          *paused_actor;
@@ -875,7 +876,10 @@ animation_frame_cb (ClutterTimeline *timeline,
 		    GthSlideshow    *self)
 {
 	if (self->priv->transition != NULL)
-		gth_transition_frame (self->priv->transition, self, msecs);
+		gth_transition_frame (self->priv->transition,
+				      self,
+				      clutter_alpha_get_alpha (self->priv->alpha));
+
 	if (self->first_frame)
 		self->first_frame = FALSE;
 }
@@ -972,6 +976,7 @@ static void
 clutter_projector_finalize (GthSlideshow *self)
 {
 	_g_object_unref (self->priv->timeline);
+	_g_object_unref (self->priv->alpha);
 }
 
 
@@ -1172,6 +1177,8 @@ clutter_projector_construct (GthSlideshow *self)
 	g_signal_connect (self->priv->timeline, "new-frame", G_CALLBACK (animation_frame_cb), self);
 	g_signal_connect (self->priv->timeline, "started", G_CALLBACK (animation_started_cb), self);
 
+	self->priv->alpha = clutter_alpha_new_full (self->priv->timeline, CLUTTER_EASE_IN_OUT_SINE);
+
 	if (self->priv->pause_pixbuf != NULL)
 		self->priv->paused_actor = gtk_clutter_texture_new_from_pixbuf (self->priv->pause_pixbuf);
 	else