Information about Categories
----------------------------

Last Updated: 17-May-2000

I added the category feature because I found (from a question in the survey)
that some of my friends and family preferred to see the friends photos and 
family photos separated, while others wanted all the photos together.  The 
major category can be any combination of 'Friend', 'Family', or 
'Miscellaneous'.  The idea of the minor category was for things like: camping,
wedding, birthday, holiday, party, etc.  The minor category stuff is not
implemented so you can probably just ignore it for now (or implement it 
yourself if you code).  The major categories have been further extended to 
handle 'movies' and the custom choice options.

To efficiently store these major category choices, I use a bit map.  The
major field in the database can hold up to 32 bits (a bit is either 0 or 1,
true or false).  Bits 0 to 15 are used for category types, bit 16 marks
movies, and bit 20 marks custom choice.  Consider bits 16 and up to be 
reserved.  If you want to rename my categories, go ahead.  If you want to add
some, add lines to constants.php3 like:

  $major_categories[] = new category("Long Name","short_name",bitnumber);

where bitnumber is some number between 0 and 15 that is not already used.
You will find in the admin section a means to set the category bits for all
your photo collections.  It is best that you decide on these categories before
you start adding a bunch of pictures to the album.

Below are my notes to myself about categories:

Major Categories
----------------

  bit 20 - Custom choice (set by user, not by admin)
  bit 16 - Movie (animated gif)
  bit 11 - Family
  bit 10 - Friend
  bit 0  - Miscellaneous

Minor Categories (proposed)
---------------------------

  bit 15 - Wedding
  bit 14 - Party (General)
  bit 13 - Skiing
  bit 12 - Camping
  bit 11 - Football
  bit 10 - Dinner
  bit 9  - Party (Birthday)
  bit 0  - Miscellaneous
