This function does the "heavy" lifting of updating an unread
count. (It's not exactly heavy lifting, but it makes it so
the parent just needs to find the outer element of the unread
div, using whatever method makes sense for the parent.)
The widget that gets built in topic_list.build_widget()
now knows how to add itself to its parent element and expose
an interface to retrieve the parent.
For cases where we are zoomed in to a stream and then go
to a different narrow (Home, PMs, etc.), we now let
topic_list.zoom_out orchestrate the removal of the topic list
instead of stream_list.zoom_out.
This will help us when we move to a world where topic_list
redraws topic lists on zoom-in/zoom-out, because we won't
waste effort rebuilding lists that are about to be removed.
The flow for topic list zooming is kind of complicated now, but
it's mostly a consequence of the way the UI works.
* stream_list tells topic_list to set up the topic list
click handlers to have callbacks to stream_list
* topic_list click handlers call to stream_list zoom methods
to hide/show all the other streams
* stream_list zoom methods call back to topic_list methods to
redraw topics as needed (this isn't happening yet, but allowing
topic_list.js to know that it's zoomed will set the stage for
this to happen in a more controlled manner)
This change makes most of the logic on set_count() live
on our per-stream topic list widget. We can find the
jQuery object directly now rather than using the
complicated iterate_to_find() method.
This also brought along:
iterate_to_find (copied, see large comment explaining why)
activate_topic (extracted from a one-liner)
set_count (formerly stream_list.set_subject_count)
For get_topic_filter_li, we now pass in stream_li instead of
stream to decouple parent/child responsibilities between the
components.
Also, I made some s/subject/topic/ fixes.
This creates the new topic_list.js module, and the first
function that we extract is topic_list.update_count_in_dom().
This function needed to be decoupled from some non-topic-list
stuff which was overly complicated.
Steve Howell