From: Bluezery <ohpowel@gmail.com>

From: Bluezery <ohpowel@gmail.com>
Subject: Re: [E-devel] [Patch][elm_map] Change grid management

(1) Grid Management
There are no caching mechanism in current elm_map.
So, too many network resources are wasted because elm_map keeps only
two grids and already downloaded images are downloaded again and
again. (This also slows the map loading speed)
I have changed this grid management policy.

I have done followings.
1. Create all grids (all zoom levels) when elm_map_add() is called (No
memory overhead because of sparse matrix)
2. Clear all grids when map object is deleted.
3. Loads necessary grids and unloads unused grids when zoom level is
changed.

Changed grid management have one weakness that memory and tmp size can
grow bigger while map object is live.
I think it may need API such as elm_map_cache_size_set().

git-svn-id: svn+ssh://svn.enlightenment.org/var/svn/e/trunk/elementary@66140 7cbeb6ba-43b4-40fd-8cce-4c39aea84d33