[gthumb: 93/129] fixed crash when the image is smaller than the preview area

[Paolo Bacchilega <paobac src gnome org>]

commit a54d2b6d1529b4e65252cac19f4304f748b7196c
Author: Paolo Bacchilega <paobac src gnome org>
Date:   Tue Apr 26 20:05:01 2011 +0200

    fixed crash when the image is smaller than the preview area

 extensions/file_tools/gth-file-tool-sharpen.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/extensions/file_tools/gth-file-tool-sharpen.c b/extensions/file_tools/gth-file-tool-sharpen.c
index 0024274..a4a803f 100644
--- a/extensions/file_tools/gth-file-tool-sharpen.c
+++ b/extensions/file_tools/gth-file-tool-sharpen.c
@@ -228,10 +228,10 @@ apply_cb (gpointer user_data)
 		cairo_t         *cr;
 
 		sharpen_data = sharpen_data_new (self);
-		x = gtk_adjustment_get_value (preview->hadj);
-		y = gtk_adjustment_get_value (preview->vadj);
-		w = gtk_adjustment_get_page_size (preview->hadj);
-		h = gtk_adjustment_get_page_size (preview->vadj);
+		x = MAX (gtk_adjustment_get_value (preview->hadj), 0);
+		y = MAX (gtk_adjustment_get_value (preview->vadj), 0);
+		w = MIN (gtk_adjustment_get_page_size (preview->hadj), cairo_image_surface_get_width (self->priv->source));
+		h = MIN (gtk_adjustment_get_page_size (preview->vadj), cairo_image_surface_get_height (self->priv->source));
 
 		cairo_surface_destroy (self->priv->destination);
 		self->priv->destination = _cairo_image_surface_copy (self->priv->source);