发布于 2015-08-27 16:48:53 | 299 次阅读 | 评论: 0 | 来源: 网络整理
Amongst its many filters, Assetic has four filters which can be used for on-the-fly image optimization. This allows you to get the benefits of smaller file sizes without having to use an image editor to process each image. The results are cached and can be dumped for production so there is no performance hit for your end users.
Jpegoptim is a utility for optimizing JPEG files. To use it with Assetic, make
sure to have it already installed on your system and then, configure its location
using the bin option of the jpegoptim filter:
# app/config/config.yml
assetic:
filters:
jpegoptim:
bin: path/to/jpegoptim
<!-- app/config/config.xml -->
<assetic:config>
<assetic:filter
name="jpegoptim"
bin="path/to/jpegoptim" />
</assetic:config>
// app/config/config.php
$container->loadFromExtension('assetic', array(
'filters' => array(
'jpegoptim' => array(
'bin' => 'path/to/jpegoptim',
),
),
));
It can now be used from a template:
{% image '@AppBundle/Resources/public/images/example.jpg'
filter='jpegoptim' output='/images/example.jpg' %}
<img src="{{ asset_url }}" alt="Example"/>
{% endimage %}
<?php foreach ($view['assetic']->image(
array('@AppBundle/Resources/public/images/example.jpg'),
array('jpegoptim')
) as $url): ?>
<img src="<?php echo $view->escape($url) ?>" alt="Example"/>
<?php endforeach ?>
By default, the jpegoptim filter removes some of the meta information stored
in the image. To remove all EXIF data and comments, set the strip_all option
to true:
# app/config/config.yml
assetic:
filters:
jpegoptim:
bin: path/to/jpegoptim
strip_all: true
<!-- app/config/config.xml -->
<assetic:config>
<assetic:filter
name="jpegoptim"
bin="path/to/jpegoptim"
strip_all="true" />
</assetic:config>
// app/config/config.php
$container->loadFromExtension('assetic', array(
'filters' => array(
'jpegoptim' => array(
'bin' => 'path/to/jpegoptim',
'strip_all' => 'true',
),
),
));
By default, the jpegoptim filter doesn’t alter the quality level of the JPEG
image. Use the max option to configure the maximum quality setting (in a
scale of 0 to 100). The reduction in the image file size will of course
be at the expense of its quality:
# app/config/config.yml
assetic:
filters:
jpegoptim:
bin: path/to/jpegoptim
max: 70
<!-- app/config/config.xml -->
<assetic:config>
<assetic:filter
name="jpegoptim"
bin="path/to/jpegoptim"
max="70" />
</assetic:config>
// app/config/config.php
$container->loadFromExtension('assetic', array(
'filters' => array(
'jpegoptim' => array(
'bin' => 'path/to/jpegoptim',
'max' => '70',
),
),
));
If you’re using Twig, it’s possible to achieve all of this with a shorter syntax by enabling and using a special Twig function. Start by adding the following configuration:
# app/config/config.yml
assetic:
filters:
jpegoptim:
bin: path/to/jpegoptim
twig:
functions:
jpegoptim: ~
<!-- app/config/config.xml -->
<assetic:config>
<assetic:filter
name="jpegoptim"
bin="path/to/jpegoptim" />
<assetic:twig>
<assetic:twig_function
name="jpegoptim" />
</assetic:twig>
</assetic:config>
// app/config/config.php
$container->loadFromExtension('assetic', array(
'filters' => array(
'jpegoptim' => array(
'bin' => 'path/to/jpegoptim',
),
),
'twig' => array(
'functions' => array('jpegoptim'),
),
),
));
The Twig template can now be changed to the following:
<img src="{{ jpegoptim('@AppBundle/Resources/public/images/example.jpg') }}" alt="Example"/>
You can also specify the output directory for images in the Assetic configuration file:
# app/config/config.yml
assetic:
filters:
jpegoptim:
bin: path/to/jpegoptim
twig:
functions:
jpegoptim: { output: images/*.jpg }
<!-- app/config/config.xml -->
<assetic:config>
<assetic:filter
name="jpegoptim"
bin="path/to/jpegoptim" />
<assetic:twig>
<assetic:twig_function
name="jpegoptim"
output="images/*.jpg" />
</assetic:twig>
</assetic:config>
// app/config/config.php
$container->loadFromExtension('assetic', array(
'filters' => array(
'jpegoptim' => array(
'bin' => 'path/to/jpegoptim',
),
),
'twig' => array(
'functions' => array(
'jpegoptim' => array(
output => 'images/*.jpg'
),
),
),
));