Tag bug?

[Russell Cloran <russell rucus net>]

Hi all,

My apologies if this is not the correct place to report bugs, please direct
me at the right place if I've found the wrong one.

I'm not entirely sure how I created this problem, but I'll describe the
problem nevertheless.

As soon as I open up f-spot I get the following traceback (snipped a
little):

Unhandled Exception: System.NullReferenceException: Object reference not set
to an instance of an object
in [0x005ce] (at .../IconView.cs:727) IconView:DrawCell (Int32
thumbnail_num, Rectangle area)
in [0x000d6] (at .../IconView.cs:792) IconView:DrawAllCells (Rectangle area)
in [0x0002a] (at .../IconView.cs:1089) IconView:OnExposeEvent
(Gdk.EventExpose args)
... etc ...


I managed to track this down to a null Tag object somehow being passed up to
the DrawCell function. I hacked around this with the following patchlet:



--- IconView.cs~        2005-06-09 00:19:12.000000000 +0200
+++ IconView.cs 2005-06-09 00:19:12.000000000 +0200
@@ -722,6 +722,7 @@
                        tag_bounds.Height = tag_icon_size;
 
                        foreach (Tag t in tags) {
+                               if (t == null) continue;
                                Pixbuf icon = null;
                                if (t.Category.Icon == null) {
                                        if (t.Icon == null)




I noticed a similar problem occurring when trying to remove a tag, the
following hack solved that:


--- PhotoTagMenu.cs~    2005-06-09 00:20:24.000000000 +0200
+++ PhotoTagMenu.cs     2005-06-09 00:20:24.000000000 +0200
@@ -55,7 +55,7 @@
                if (photos != null) {
                        foreach (Photo p in photos) {
                                foreach (Tag t in p.Tags) {
-                                       if (tag != null && !hash.Contains (t.Id)) {
+                                       if (t != null && !hash.Contains (t.Id)) {
                                                hash.Add (t.Id, t);
                                        }
                                }



Now I'm sure that this is probably just putting a bandage over the real
problem, but unfortunately I don't have the C# acumen (nor the time, really)
to delve too much deeper :) There is at least one problem with the first
patchlet -- tag icons are not properly centered on the photo :)

Out of interest I put together some code to inspect the tables in the
photos.db, and I noticed that my photo_tags table contained entries which
had a valid photo, but referenced non-existant tags. I did create a few tags
and delete them soon before F-Spot first crashed with the problem, and the
ID's referenced in photo_tags would be in the sort of range of ID's that
those tags would've had.

If it would help I can try to recreate this bug, or supply my photos.db or
any other information needed for debugging.

Russell
-- 
echo http://russell.rucus.net/spam/ | sed 's,t/.*,t,;P;s,.*//,,;s,\.,@,;'