Using the skin

Freevo Plugin Writing HOWTO: Writing your own plugins for Freevo
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# 2.5. Using the skin

Some plugins may want to draw something on the screen. One example is the weather plugin (external plugin, download it from `http://freevo.sf.net/addons/`). Since this has nothing to do with the normal menu system, such plugins also need an eventhandler to react on buttons.

Since Freevo knows nothing about which elements should be displayed and were to put them, the plugin needs to define a fxd file in `share/skins/plugins` with the needed information.

    <?xml version="1.0" ?>
    <freevo>
      <skin geometry="800x600">
        <foo>
          <screen layout="screen" x="0" y="0" width="800" height="600"/>
          <title .../>
          <view  .../>
        </foo>
      </skin>
    </freevo>

Now the freevo skin has fxd information about the type `foo`, but doesn't know which areas are allowed (ok, the skin could guess it). So the plugin needs to call

    skin.register('foo', ('screen', 'title', 'view', 'plugin'))

once. Now the plugin can call

    skin.draw('foo', item)

to draw `item` with the settings of `foo`.

So far so good, but it may happen that the plugin needs an area which isn't defined right now. The default areas for Freevo are `screen`, `title`, `subtitle`, `listing`, `info`, `view` and `plugin`. The plugin area is used for smaller plugins to draw on the screen, e.g. the idlebar.

To create an area of your own, you first need to define it in the fxd file:

    <?xml version="1.0" ?>
    <freevo>
      <skin geometry="800x600">
        <foo>
          <screen layout="screen" x="0" y="0" width="800" height="600"/>
          <foo_area layout="foo" x="10" y="100" width="300" height="200"/>
        </foo>
      </skin>

      <layout label="foo">
        <background>
          ...
        </background>
        <content ...>
          ...
        </content>
      </layout>
    </freevo>

Now the skin has fxd information about an area `foo`. The skin knows were it is and can also draw the background of the layout. But it needs an object to draw the real content. The following example defines a class which inherits from `skin.Area`. It defines itself as class to draw `foo_area`. The skin now calls the function `update_content_needed` to check if the area needs an update (return `True` or `False`). When Freevo knows that an update is needed, this function may not be called after all. The real work is done is `update_content`.

(add more doc here)

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