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How to Use Assetic for Image Optimization with Twig Functions
How to Use Assetic for Image Optimization with Twig Functions¶
Caution
Starting from Symfony 2.8, Assetic is no longer included by default in the Symfony Standard Edition. Refer to this article to learn how to install and enable Assetic in your Symfony application.
Among 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.
Using Jpegoptim¶
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:
- YAML
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# app/config/config.yml assetic: filters: jpegoptim: bin: path/to/jpegoptim
- XML
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<!-- app/config/config.xml --> <?xml version="1.0" encoding="UTF-8"?> <container xmlns="http://symfony.com/schema/dic/services" xmlns:assetic="http://symfony.com/schema/dic/assetic" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://symfony.com/schema/dic/services https://symfony.com/schema/dic/services/services-1.0.xsd http://symfony.com/schema/dic/assetic https://symfony.com/schema/dic/assetic/assetic-1.0.xsd"> <assetic:config> <assetic:filter name="jpegoptim" bin="path/to/jpegoptim"/> </assetic:config> </container>
- PHP
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// app/config/config.php $container->loadFromExtension('assetic', [ 'filters' => [ 'jpegoptim' => [ 'bin' => 'path/to/jpegoptim', ], ], ]);
It can now be used from a template:
1 2 3 4 | {% image '@AppBundle/Resources/public/images/example.jpg'
filter='jpegoptim' output='/images/example.jpg' %}
<img src="{{ asset_url }}" alt="Example"/>
{% endimage %}
|
Removing all EXIF Data¶
By default, the jpegoptim
filter removes some meta information stored
in the image. To remove all EXIF data and comments, set the strip_all
option
to true
:
- YAML
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# app/config/config.yml assetic: filters: jpegoptim: bin: path/to/jpegoptim strip_all: true
- XML
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<!-- app/config/config.xml --> <?xml version="1.0" encoding="UTF-8"?> <container xmlns="http://symfony.com/schema/dic/services" xmlns:assetic="http://symfony.com/schema/dic/assetic" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://symfony.com/schema/dic/services https://symfony.com/schema/dic/services/services-1.0.xsd http://symfony.com/schema/dic/assetic https://symfony.com/schema/dic/assetic/assetic-1.0.xsd"> <assetic:config> <assetic:filter name="jpegoptim" bin="path/to/jpegoptim" strip-all="true"/> </assetic:config> </container>
- PHP
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// app/config/config.php $container->loadFromExtension('assetic', [ 'filters' => [ 'jpegoptim' => [ 'bin' => 'path/to/jpegoptim', 'strip_all' => 'true', ], ], ]);
Lowering Maximum Quality¶
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
be at the expense of its quality:
- YAML
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# app/config/config.yml assetic: filters: jpegoptim: bin: path/to/jpegoptim max: 70
- XML
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<!-- app/config/config.xml --> <?xml version="1.0" encoding="UTF-8"?> <container xmlns="http://symfony.com/schema/dic/services" xmlns:assetic="http://symfony.com/schema/dic/assetic" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://symfony.com/schema/dic/services https://symfony.com/schema/dic/services/services-1.0.xsd http://symfony.com/schema/dic/assetic https://symfony.com/schema/dic/assetic/assetic-1.0.xsd"> <assetic:config> <assetic:filter name="jpegoptim" bin="path/to/jpegoptim" max="70"/> </assetic:config> </container>
- PHP
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// app/config/config.php $container->loadFromExtension('assetic', [ 'filters' => [ 'jpegoptim' => [ 'bin' => 'path/to/jpegoptim', 'max' => '70', ], ], ]);
Shorter Syntax: Twig Function¶
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:
- YAML
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# app/config/config.yml assetic: filters: jpegoptim: bin: path/to/jpegoptim twig: functions: jpegoptim: ~
- XML
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<!-- app/config/config.xml --> <?xml version="1.0" encoding="UTF-8"?> <container xmlns="http://symfony.com/schema/dic/services" xmlns:assetic="http://symfony.com/schema/dic/assetic" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://symfony.com/schema/dic/services https://symfony.com/schema/dic/services/services-1.0.xsd http://symfony.com/schema/dic/assetic https://symfony.com/schema/dic/assetic/assetic-1.0.xsd"> <assetic:config> <assetic:filter name="jpegoptim" bin="path/to/jpegoptim"/> <assetic:twig> <assetic:function name="jpegoptim"/> </assetic:twig> </assetic:config> </container>
- PHP
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// app/config/config.php $container->loadFromExtension('assetic', [ 'filters' => [ 'jpegoptim' => [ 'bin' => 'path/to/jpegoptim', ], ], 'twig' => [ 'functions' => ['jpegoptim'], ], ]);
The Twig template can now be changed to the following:
1 | <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:
- YAML
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# app/config/config.yml assetic: filters: jpegoptim: bin: path/to/jpegoptim twig: functions: jpegoptim: { output: images/*.jpg }
- XML
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<!-- app/config/config.xml --> <?xml version="1.0" encoding="UTF-8"?> <container xmlns="http://symfony.com/schema/dic/services" xmlns:assetic="http://symfony.com/schema/dic/assetic" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://symfony.com/schema/dic/services https://symfony.com/schema/dic/services/services-1.0.xsd http://symfony.com/schema/dic/assetic https://symfony.com/schema/dic/assetic/assetic-1.0.xsd"> <assetic:config> <assetic:filter name="jpegoptim" bin="path/to/jpegoptim"/> <assetic:twig> <assetic:function name="jpegoptim" output="images/*.jpg"/> </assetic:twig> </assetic:config> </container>
- PHP
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// app/config/config.php $container->loadFromExtension('assetic', [ 'filters' => [ 'jpegoptim' => [ 'bin' => 'path/to/jpegoptim', ], ], 'twig' => [ 'functions' => [ 'jpegoptim' => [ 'output' => 'images/*.jpg', ], ], ], ]);
Tip
For uploaded images, you can compress and manipulate them using the LiipImagineBundle community bundle.
This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.