Nigel McNie

One of the things we're doing for the upcoming 1.2 release of Mahara is doing a big tidyup of the theming. There are some code level changes, but the most important changes are to do with the themes themselves.

Note that I said "themes". This is because 1.2 won't have just one theme - it'll have six. One is a brushed up version of the default, one is "special" (more on that in a minute), and the other four are all-new themes that will give Mahara users a chance to immediately personalise their installation "out of the box". The new themes are mainly just colour changes, but they're pretty damn good looking colour changes all the same. They'll also give people good examples to work from when creating their own themes.

Now, the special theme. Mahara will now have a theme called 'raw', which is a very stripped down theme. There's very few colours or styles, and most of the theme's job is to position everything correctly and set sensible defaults. All other themes extend from this theme. Mahara has a theme inheritance system, where by you can specify another theme as the 'parent' of your theme, and thus rely on it to provide the templates and most of the CSS. From now, every theme will ultimately extend from the 'raw' theme - including the default theme.

The inheritance can have any number of levels, so for example a theme someone did for Mahara 1.1 might have a parent of the default theme which might be parented by the raw theme. Sadly, because we haven't documented the theme inheritance well, some of the themes out there have copied the entire default/ directory to create their new theme. These people will probably have noticed that when new versions of Mahara come out, sometimes bugs they are supposed to fix are not fixed - this is because the fix was made in a 'default' theme template, which is overridden by their theme's copy. When they upgrade to 1.2, it's highly likely their theme will totally break.

Elsewhere on the backward compatibility front, it should be easier though. If your theme uses theme inheritance, then it will continue to inherit from the (slightly changed) default theme. You may also have to change some CSS selectors in your stylesheet to match the new HTML structure.

Speaking of which, we've cleaned up the HTML immensely, and the CSS along with it. I think the default stylesheet was over 50KB in previous versions of Mahara, at the moment I have the raw theme down to much less than half that, and I don't think it will end up much bigger than 25KB. The default theme's stylesheet will be negligible in size. We're also going to cut the print stylesheet down to size, and if we get the chance we'll add in RTL and browser-specific stylesheets too.

The net result of all of this is a bit of short-term pain while people migrate their themes, but a lot of long-term gain, as the HTML will be cleaner, the CSS smaller and every Mahara faster because of it. Theme development will be much easier from 1.2 onwards, I'll make sure we write documentation so people don't get caught out by the theme inheritance issue again.

Maybe at some point after 1.2 we can look at some fine-tuning and performance of the theming system. I'd love to crank out some CSS sprites and javascript minification, but right now I don't think there's going to be much time other than for 'easy wins', such as expires headers and configuring mod_deflate (which Mahara does already).

Anyway, that's enough from me for now. We have this theming work and finishing off import/export to do, followed by a lot of bug fixing before 1.2 can be released. Look out for another alpha soon, at least.

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