More binding friendly API for SugarPreview.

Fix a leak.

NEWS

@@ -1,3 +1,5 @@
+* #4768 Fix memory leak when switching between activities. (marco)
+
 Snapshot 9d28557bbd
 
 * Fix randr. (marco)

lib/sugar/sugar-preview.c

@@ -39,16 +39,22 @@ sugar_preview_get_pixbuf(SugarPreview *preview)
 {
     GdkPixbuf *pixbuf;
 
+    if (preview->pixbuf != NULL) {
+        return preview->pixbuf;
+    }
+
     if (preview->image == NULL) {
         return NULL;
     }
 
-    pixbuf = gdk_pixbuf_get_from_image(NULL, preview->image, NULL,
-                                       0, 0, 0, 0,
-                                       preview->image->width,
-                                       preview->image->height);
+    preview->pixbuf = gdk_pixbuf_get_from_image(NULL, preview->image, NULL,
+                                                0, 0, 0, 0,
+                                                preview->image->width,
+                                                preview->image->height);
+    g_object_unref(G_OBJECT(preview->image));
+    preview->image = NULL;
 
-    return pixbuf;
+    return preview->pixbuf;
 }
 
 void
@@ -58,6 +64,10 @@ sugar_preview_clear(SugarPreview *preview)
         g_object_unref(G_OBJECT(preview->image));
         preview->image = NULL;
     }
+    if (preview->pixbuf != NULL) {
+        g_object_unref(G_OBJECT(preview->pixbuf));
+        preview->pixbuf = NULL;
+    }
 }
 
 void
@@ -104,4 +114,5 @@ static void
 sugar_preview_init(SugarPreview *preview)
 {
     preview->image = NULL;
+    preview->pixbuf = NULL;
 }

lib/sugar/sugar-preview.h

@@ -38,6 +38,8 @@ struct _SugarPreview {
     GObject base_instance;
 
     GdkImage *image;
+    GdkPixbuf *pixbuf;
+
     int width;
     int height;
 };