Theming

Theming is a systematic way of customizing the outlook of pages in a Web application. By applying a new theme, the overall appearance of a Web application can be changed instantly and dramatically.

In Yii, each theme is represented as a directory consisting of view files, layout files, and relevant resource files such as images, CSS files, JavaScript files, etc. The name of a theme is its directory name. All themes reside under the same directory WebRoot/themes. At any time, only one theme can be active.

Tip: The default theme root directory WebRoot/themes can be configured to be a different one. Simply configure the basePath and the baseUrl properties of the themeManager application component to be the desired ones.

1. Using a Theme ¶

To activate a theme, set the theme property of the Web application to be the name of the desired theme. This can be done either in the application configuration or during runtime in controller actions.

Note: Theme name is case-sensitive. If you attempt to activate a theme that does not exist, Yii::app()->theme will return null.

2. Creating a Theme ¶

Contents under a theme directory should be organized in the same way as those under the application base path. For example, all view files must be located under views, layout view files under views/layouts, and system view files under views/system. For example, if we want to replace the create view of PostController with a view in the classic theme, we should save the new view file as WebRoot/themes/classic/views/post/create.php.

For views belonging to controllers in a module, the corresponding themed view files should also be placed under the views directory. For example, if the aforementioned PostController is in a module named forum, we should save the create view file as WebRoot/themes/classic/views/forum/post/create.php. If the forum module is nested in another module named support, then the view file should be WebRoot/themes/classic/views/support/forum/post/create.php.

Note: Because the views directory may contain security-sensitive data, it should be configured to prevent from being accessed by Web users.

When we call render or renderPartial to display a view, the corresponding view file as well as the layout file will be looked for in the currently active theme. And if found, those files will be rendered. Otherwise, it falls back to the default location as specified by viewPath and layoutPath.

Tip: Inside a theme view, we often need to link other theme resource files. For example, we may want to show an image file under the theme's images directory. Using the baseUrl property of the currently active theme, we can generate the URL for the image as follows,

Yii::app()->theme->baseUrl . '/images/FileName.gif'

Below is an example of directory organization for an application with two themes basic and fancy.

WebRoot/
    assets
    protected/
        .htaccess
        components/
        controllers/
        models/
        views/
            layouts/
                main.php
            site/
                index.php
    themes/
        basic/
            views/
                .htaccess
                layouts/
                    main.php
                site/
                    index.php
        fancy/
            views/
                .htaccess
                layouts/
                    main.php
                site/
                    index.php

In the application configuration, if we configure

return array(
    'theme'=>'basic',
    ......
);

then the basic theme will be in effect, which means the application's layout will use the one under the directory themes/basic/views/layouts, and the site's index view will use the one under themes/basic/views/site. In case a view file is not found in the theme, it will fall back to the one under the protected/views directory.

3. Theming Widgets ¶

Starting from version 1.1.5, views used by a widget can also be themed. In particular, when we call CWidget::render() to render a widget view, Yii will attempt to search under the theme folder as well as the widget view folder for the desired view file.

To theme the view xyz for a widget whose class name is Foo, we should first create a folder named Foo (same as the widget class name) under the currently active theme's view folder. If the widget class is namespaced (available in PHP 5.3.0 or above), such as \app\widgets\Foo, we should create a folder named app_widgets_Foo. That is, we replace the namespace separators with the underscore characters.

We then create a view file named xyz.php under the newly created folder. To this end, we should have a file themes/basic/views/Foo/xyz.php, which will be used by the widget to replace its original view, if the currently active theme is basic.

4. Customizing Widgets Globally ¶

Note: this feature has been available since version 1.1.3.

When using a widget provided by third party or Yii, we often need to customize it for specific needs. For example, we may want to change the value of CLinkPager::maxButtonCount from 10 (default) to 5. We can accomplish this by passing the initial property values when calling CBaseController::widget to create a widget. However, it becomes troublesome to do so if we have to repeat the same customization in every place we use CLinkPager.

$this->widget('CLinkPager', array(
    'pages'=>$pagination,
    'maxButtonCount'=>5,
    'cssFile'=>false,
));

Using the global widget customization feature, we only need to specify these initial values in a single place, i.e., the application configuration. This makes the customization of widgets more manageable.

To use the global widget customization feature, we need to configure the widgetFactory as follows:

return array(
    'components'=>array(
        'widgetFactory'=>array(
            'widgets'=>array(
                'CLinkPager'=>array(
                    'maxButtonCount'=>5,
                    'cssFile'=>false,
                ),
                'CJuiDatePicker'=>array(
                    'language'=>'ru',
                ),
            ),
        ),
    ),
);

In the above, we specify the global widget customization for both CLinkPager and CJuiDatePicker widgets by configuring the CWidgetFactory::widgets property. Note that the global customization for each widget is represented as a key-value pair in the array, where the key refers to the wiget class name while the value specifies the initial property value array.

Now, whenever we create a CLinkPager widget in a view, the above property values will be assigned to the widget, and we only need to write the following code in the view to create the widget:

$this->widget('CLinkPager', array(
    'pages'=>$pagination,
));

We can still override the initial property values when necessary. For example, if in some view we want to set maxButtonCount to be 2, we can do the following:

$this->widget('CLinkPager', array(
    'pages'=>$pagination,
    'maxButtonCount'=>2,
));

5. Skin ¶

While using a theme we can quickly change the outlook of views, we can use skins to systematically customize the outlook of the widgets used in the views.

A skin is an array of name-value pairs that can be used to initialize the properties of a widget. A skin belongs to a widget class, and a widget class can have multiple skins identified by their names. For example, we can have a skin for the CLinkPager widget and the skin is named as classic.

In order to use the skin feature, we first need to modify the application configuration by configuring the CWidgetFactory::enableSkin property to be true for the widgetFactory application component:

return array(
    'components'=>array(
        'widgetFactory'=>array(
            'enableSkin'=>true,
        ),
    ),
);

Please note that in versions prior to 1.1.3, you need to use the following configuration to enable widget skinning:

return array(
    'components'=>array(
        'widgetFactory'=>array(
            'class'=>'CWidgetFactory',
        ),
    ),
);

We then create the needed skins. Skins belonging to the same widget class are stored in a single PHP script file whose name is the widget class name. All these skin files are stored under protected/views/skins, by default. If you want to change this to be a different directory, you may configure the skinPath property of the widgetFactory component. As an example, we may create under protected/views/skins a file named CLinkPager.php whose content is as follows,

<?php
return array(
    'default'=>array(
        'nextPageLabel'=>'next',
        'prevPageLabel'=>'prev',
    ),
    'classic'=>array(
        'header'=>'',
        'maxButtonCount'=>5,
    ),
);

In the above, we create two skins for the CLinkPager widget: default and classic. The former is the skin that will be applied to any CLinkPager widget that we do not explicitly specify its skin property, while the latter is the skin to be applied to a CLinkPager widget whose skin property is specified as classic. For example, in the following view code, the first pager will use the default skin while the second the classic skin:

<?php $this->widget('CLinkPager'); ?>
 
<?php $this->widget('CLinkPager', array('skin'=>'classic')); ?>

If we create a widget with a set of initial property values, they will take precedence and be merged with any applicable skin. For example, the following view code will create a pager whose initial values will be array('header'=>'', 'maxButtonCount'=>6, 'cssFile'=>false), which is the result of merging the initial property values specified in the view and the classic skin.

<?php $this->widget('CLinkPager', array(
    'skin'=>'classic',
    'maxButtonCount'=>6,
    'cssFile'=>false,
)); ?>

Note that the skin feature does NOT require using themes. However, when a theme is active, Yii will also look for skins under the skins directory of the theme's view directory (e.g. WebRoot/themes/classic/views/skins). In case a skin with the same name exists in both the theme and the main application view directories, the theme skin will take precedence.

If a widget is using a skin that does not exist, Yii will still create the widget as usual without any error.

Info: Using skin may degrade the performance because Yii needs to look for the skin file the first time a widget is being created.

Skin is very similar to the global widget customization feature. The main differences are as follows.

• Skin is more related with the customization of presentational property values;
• A widget can have multiple skins;
• Skin is themeable;
• Using skin is more expensive than using global widget customization.