[gthumb/gthumb-2-14] do not set the image if it's NULL or equal to the current image

[Paolo Bacchilega <paobac src gnome org>]

commit b323772867ae2cea9cfd252a1553256a56565c60
Author: Paolo Bacchilega <paobac src gnome org>
Date:   Fri Nov 4 09:34:47 2011 +0100

    do not set the image if it's NULL or equal to the current image

 extensions/image_viewer/gth-image-viewer-page.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)
---
diff --git a/extensions/image_viewer/gth-image-viewer-page.c b/extensions/image_viewer/gth-image-viewer-page.c
index 2c75eeb..bcaaeca 100644
--- a/extensions/image_viewer/gth-image-viewer-page.c
+++ b/extensions/image_viewer/gth-image-viewer-page.c
@@ -1304,6 +1304,9 @@ _gth_image_viewer_page_set_image (GthImageViewerPage *self,
 	int          height;
 	char        *size;
 
+	if (image == NULL)
+		return;
+
 	gth_image_viewer_set_surface (GTH_IMAGE_VIEWER (self->priv->viewer), image, -1, -1);
 
 	file_data = gth_browser_get_current_file (GTH_BROWSER (self->priv->browser));
@@ -1499,10 +1502,15 @@ gth_image_viewer_page_set_image (GthImageViewerPage *self,
 			 	 cairo_surface_t    *image,
 			 	 gboolean            add_to_history)
 {
+	if (gth_image_viewer_page_get_image (self) == image)
+		return;
+
 	if (add_to_history)
 		gth_image_history_add_image (self->priv->history, image, TRUE);
+
 	_gth_image_viewer_page_set_image (self, image, TRUE);
 	self->priv->image_changed = TRUE;
+
 	if (add_to_history)
 		gth_viewer_page_focus (GTH_VIEWER_PAGE (self));
 }