[Summary view] [Print] [Text view]

   1  A gallery's cover image is a single image from that gallery, selected according to a particular criterion. For example, the cover for each gallery might be the most recent image in that gallery.
   2  
   3  If a gallery has no descendant galleries, this is a simple procedure. However, what to do when the gallery itself contains galleries is a more complicated matter.
   4  
   5  There are three ways to handle descendant galleries when getting a cover image for a gallery.
   6  
   7  <dl>
   8    <dt>Plain</dt>
   9    <dd>Do not go into any descendant galleries: only consider images in the gallery itself. If the gallery itself has no images, then there will be no cover node.
  10    </dd>
  11  
  12    <dt>Flat</dt>
  13    <dd>Consider the gallery itself and its descendants to a given depth as one single pool of images from which to select the cover.
  14    </dd>
  15  
  16    <dt>Recursion</dt>
  17    <dd>Consider first the gallery itself, and if it is empty, consider each child gallery one at a time (in weight order). The recusion depth sets how far to go into a child gallery's own children before giving up and moving to the next child gallery. Be warned that this is potentially a time-consuming procedure!</dd>
  18  
  19  </dl>
  20  
  21  These methods are illustrated in this example.
  22  
  23  Consider the following tree of galleries: the numbers are the term IDs that make the galleries and the letters are the titles of the image nodes.
  24  
  25  <pre>
  26    - 1: empty
  27      - 2: empty
  28        - 6: nodes G, H
  29      - 3: nodes M, N
  30      - 4: nodes D, E, F
  31      - 5: nodes X, Y, Z
  32        - 7: nodes A, B
  33  </pre>
  34  
  35  Suppose our sort criterion for the cover is the image node title in alphabetical order. What cover image will gallery 1 have?
  36  
  37  <dl>
  38    <dt>Plain</dt>
  39    <dd>Term 1 has no nodes: there is no cover image.
  40    </dd>
  41  
  42    <dt>Flat depth 0; Recursion depth 0</dt>
  43    <dd>Depth 0 means we don't go into child galleries: so this is the same as plain and there is no cover image.
  44    </dd>
  45  
  46    <dt>Flat depth 1</dt>
  47    <dd>We consider all nodes in the galleries 1, 2, 3, 4, 5.
  48    The first node by name is D.
  49    </dd>
  50  
  51    <dt>Flat depth 2</dt>
  52    <dd>We consider all nodes in the galleries 1, 2, 3, 4, 5, 6, 7.
  53    The first node by name is A.
  54    </dd>
  55  
  56    <dt>Recursion depth 1</dt>
  57    <dd>We find the gallery itself empty, so look in gallery 2.
  58    That's empty too, so we look in gallery 3.
  59    Here we find nodes, and M is the first by name: so the cover is M.</dd>
  60  
  61    <dt>Recursion depth 2</dt>
  62    <dd>We find the gallery itself empty, so look in gallery 2.
  63    That's empty too, and so we go one level deeper to gallery 6.
  64    Here we find nodes, and G is the first by name: so the cover is G.
  65    Node A is a better fit at this depth, but we consider child galleries one by one, by weight, and we found something in gallery 6.</dd>
  66  </dl>