Cchost/developer/Reverse Engineering - Revision history

Fourstones: /* A ccHost Quick Reverse Engineer */

2008-11-17T23:10:53Z

‎A ccHost Quick Reverse Engineer

Fourstones: /* A ccHost Quick Reverse Engineer */

2008-11-17T23:09:25Z

‎A ccHost Quick Reverse Engineer

Fourstones: New page: ==A ccHost Quick Reverse Engineer== by Victor When I sat down to write the auto 'feature this playlist' feature I knew I wanted to add a me...

2008-11-17T23:08:33Z

New page: ==A ccHost Quick Reverse Engineer== by Victor When I sat down to write the auto 'feature this playlist' feature I knew I wanted to add a me...

New page

==A ccHost Quick Reverse Engineer==
by Victor

When I sat down to write the [[Cchost/developer/tutorial/Featured_Playlist|auto 'feature this playlist']] feature I knew I wanted to add a menu item to the playlist's command window but I totally forgot how that menu was generated. It took less than a minute to figure it out but I thought it might be useful since I know this kind of 'view source/reverse engineer' is how most developers approach a codebase like ccHost.

Firefox has a 'Web Developer Toolbar' that I find invaluable.

*I [http://ccmixter.org/playlist/browse/10 browsed to a playlist].
*Selected 'View Style Information' from Firefox's Web Developer Toolbar which highlights the area under the cursor and gives you the CSS class selector name.
*For the menu that turned out to be 'cc_playlist_owner'
*I searched under '''ccskins''' for all occurances of that selector.
*I found the template that built the menu at '''ccskins/shared/playlist_2_head.tpl'''

<nowiki><ul class="cc_playlist_owner_menu </nowiki>
light_bg dark_border">
%loop(#R/menu,mi)%
<nowiki><li></nowiki>
<a target="_parent" href="%(#mi/url)%"
id="%(#mi/id)%"
class="%(#mi/class)%"><span>%text(#mi/text)%</span>
</a>
</li>
%end_loop%
</ul>

*From the code in this template I could deduce the following:
**the menu was just being displayed here. The menu was being built somewhere else.
**the menu itself is embedded in the 'R' record
**a few lines above is line '''%map(#R,records/0)%''' which means 'R' is result of the query ('records' is the array of a query result in a template)
**every query must have a dataview somewhere, sure enough at the top of the template
to display this playlist, '''dataview = playlist_detail'''
*I found '''ccdataviews/playlist_detail.php'''
*Since the 'menu' is a PHP array and not a normal SQL column, I deduced there must a dataview filter that is building the menu
*Filter events are returned in an array in a dataview and there was ''CC_EVENT_FILTER_CART_MENU'' (a playlist is actually a record in the ''cc_tbl_carts'' table)
*I searched '''cchost_lib/*''' for that event and found the declaration of a handler in '''cchost_lib/ccextras/cc-playlist.php'''
*That pointed to a method in '''cchost_lib/ccextras/cc-playlist-browse.inc''' called ''CCPlaylistBrowse::OnFilterCartMenu''

At this point I knew what event I had to handle ''CC_EVENT_FILTER_CART_MENU'' and I had an example of what the system was doing with that event in ''CCPlaylistBrowse::OnFilterCartMenu''.

@@ Line 26: / Line 26: @@
 **the menu itself is embedded in the 'R' record
 **a few lines above is line '''%map(#R,records/0)%''' which means 'R' is result of the query ('records' is the array of a query result in a template)
-**every query must have a dataview somewhere, sure enough at the top of the template
+**every query must have a dataview somewhere, at the top of the template is the meta declaration '''dataview = playlist_detail'''
 *I found '''ccdataviews/playlist_detail.php'''
-*Since the 'menu' is a PHP array and not a normal SQL column, I deduced there must a dataview filter that is building the menu
+*Since the 'menu' is a PHP array and not a normal SQL column, I deduced there must a dataview filter that is building the menu.
 *Filter events are returned in an array in a dataview and there was ''CC_EVENT_FILTER_CART_MENU'' (a playlist is actually a record in the ''cc_tbl_carts'' table)
 *I searched '''cchost_lib/*''' for that event and found the declaration of a handler in '''cchost_lib/ccextras/cc-playlist.php'''

@@ Line 3: / Line 3: @@
 When I sat down to write the [[Cchost/developer/tutorial/Featured_Playlist|auto 'feature this playlist']] feature I knew I wanted to add a menu item to the playlist's command window but I totally forgot how that menu was generated. It took less than a minute to figure it out but I thought it might be useful since I know this kind of 'view source/reverse engineer' is how most developers approach a codebase like ccHost.
 *I [http://ccmixter.org/playlist/browse/10 browsed to a playlist].
-*Selected 'View Style Information' from Firefox's Web Developer Toolbar which highlights the area under the cursor and gives you the CSS class selector name.
+*Selected 'View Style Information' from Firefox's Web Developer Toolbar which highlights the area under the cursor and gives you the CSS class selector name. (Of course view source also works, this is just faster.)
 *For the menu that turned out to be 'cc_playlist_owner'
 *I searched under '''ccskins''' for all occurances of that selector.