UmanIT - Twig Image Extension

This Twig extension facilitates the integration of responsive images markup in Twig templates.

It uses LiipImagineBundle and its filters to generate HTML markup with all you need to handle responsive images.

Lazy loading relies on the browser-native loading="lazy" attribute, so no JavaScript library is required. An optional blur-up effect (a small, dependency-free JavaScript module and CSS file) is provided if you want it.

Installation

Use the package manager composer to install the extension.

composer require umanit/twig-image-extension

Load the bundle into your Symfony project.

<?php

# config/bundles.php
return [
    // ...
    Umanit\TwigImage\UmanitTwigImageBundle::class => ['all' => true],
];

(Optional) Install bundle assets if you want to use the blur-up effect (JavaScript module and CSS file):

bin/console assets:install --symlink

Configuration

umanit_twig_image:
    allow_fallback: false
    use_liip_default_image: false
    lazy_load:
        blur: false
        blur_class_selector: lazy-blur

The *_lazy_load functions render images using the native loading="lazy" attribute.

Set lazy_load.blur to true to enable the optional blur-up effect: the placeholder (generated with the placeholderFilter filter) is exposed as a background-image and the real image fades in once loaded. This requires importing the provided JavaScript module and CSS file. The class added on the img can be customized with lazy_load.blur_class_selector.

⚠	If you customize blur_class_selector, you cannot use the provided JavaScript module and CSS that rely on the default lazy-blur class anymore

Fallback images

By default, if the image path given in functions calls is null, empty or points to a missing file on the server, an exception is thrown. You have two options to avoid this:

• setting twig_image_extension.allow_fallback to true
• setting twig_image_extension.use_liip_default_image to true

twig_image_extension.allow_fallback

If the path given points to a missing file, a default image will be rendered instead. The default images are available in four sizes:

• small: 320px wide
• medium: 640 wide
• large: 1280px wide
• extra large: 2560px wide (for Retina screens mostly)

If a default image needs to be rendered, the size will be guessed using the given Liip filter:

• a filter ending with 2x will give you an extra large default image
• a filter ending with xl or xxl will give you a large default image
• a filter ending with xs or xxs will give you a small default image
• any other filter name will default to the medium size

twig_image_extension.use_liip_default_image

This parameter will only be used as a backup if allow_fallback is set to false and requires you to use the default image mecanism of Liip ( see Liip configuration)

⚠	If neither twig_image_extension.allow_fallback nor twig_image_extension.use_liip_default_image are set to true and the image isn't found on the server, an exception will be thrown!

Usage

The following Twig functions are available in your templates.

1. umanit_image_figure_lazy_load
2. umanit_image_figure
3. umanit_image_picture_lazy_load
4. umanit_image_picture
5. umanit_image_img
6. umanit_image_srcset
7. (Optional) Blur-up effect

When a LiipImagine filter is used, the extension will read its configuration and automatically guess the right width or height to apply in the markup. If it's not possible, the extension will try to get the original image dimensions instead. In both case, the result is saved in cache to avoid multiple process for the same image.

When the used function is for lazy load, the loading="lazy" attribute is added on the img. If the blur option is enabled, the lazy-blur class (customizable, see the Configuration part) is added as well.

width and height attributes are added in the <img /> tag, based on the size calculated by the src filter (except for downscale and upscale filters, which fallback to the original image size). By doing this, sudden layout shifts are avoided for a better user experience.

To use htmlAlt, the css file umanit-alt-text.css must be loaded. It hides the div used to display the html alt content.

umanit_image_figure_lazy_load

Generates a figure tag with a natively lazy loaded img inside (loading="lazy"). If the blur option is enabled, the lazy-blur class and the placeholder background-image are added for the blur-up effect.

Parameters

Name	Explanation
path	Path to the image, used to generated the browser path with LiipImagine
srcFilter	Name of the LiipImagine filter used to generate the path for src
placeholderFilter	Name of the LiipImagine filter used to generate the blur-up placeholder background-image (only when blur is enabled)
srcsetFilters	A list of LiipImagine filters used to generate the srcset
alt	The text to put in the alt attribute of the img
imgClass	Classes to add on the img
sizes	Value of the sizes attribute (100vw if not defined)
figureClass	Classes to add on the figure
figcaptionText	Text of the figcaption (if nothing is passed, no figcaption will be rendered)
figcaptionClass	Classes to add on the figcaption
imgImportance	Importance of the image (see this link for more information)
figureDataAttributes	Raw string passed to add data-attributes on the figure
imgDataAttributes	Raw string passed to add data-attributes on the img
htmlAlt	The html to put in a div referenced by the aria-describedby of the img. If given a non-empty value, the alt attribute vill be empty.

Example

Click to show

Without htmlAlt

    umanit_image_figure_lazy_load(
      image.path,
      'small_thumbnail',
      'tiny_thumbnail',
      ['thumbnail', 'large_thumbnail'],
      'image alt',
      'img img--cover img--zoom',
      '(min-width: 768px) 33.3vw, 100vw',
      'class-figure',
      'Figcaption text',
      'class-figcaption',
      'high',
      'data-container="a"',
      'data-image="b" data-test'
    )

HTML generated:

<figure class="class-figure" data-container="a">
<img
    alt="image alt"
    class="lazy-blur img img--cover img--zoom"
    src="https://domain.tld/media/cache/resolve/small_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg"
    srcset="https://domain.tld/media/cache/resolve/thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 260w, https://domain.tld/media/cache/resolve/large_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 2880w"
    loading="lazy"
    style="background-image:url(https://domain.tld/media/cache/tiny_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg)"
    sizes="(min-width: 768px) 33.3vw, 100vw"
    width="600" height="400"
    importance="high"
    data-image="b" data-test
>
<figcaption class="class-figcaption">Figcaption text</figcaption>
</figure>

With htmlAlt

    umanit_image_figure_lazy_load(
      image.path,
      'small_thumbnail',
      'tiny_thumbnail',
      ['thumbnail', 'large_thumbnail'],
      'image alt',
      'img img--cover img--zoom',
      '(min-width: 768px) 33.3vw, 100vw',
      'class-figure',
      'Figcaption text',
      'class-figcaption',
      '<p>Html to describe content</p>'
    )

HTML generated

<figure class="class-figure">
<img
    alt=""
    aria-describedby="1234567890"
    class="lazy-blur img img--cover img--zoom"
    src="https://domain.tld/media/cache/resolve/small_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg"
    srcset="https://domain.tld/media/cache/resolve/thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 260w, https://domain.tld/media/cache/resolve/large_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 2880w"
    loading="lazy"
    style="background-image:url(https://domain.tld/media/cache/tiny_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg)"
    sizes="(min-width: 768px) 33.3vw, 100vw"
    width="600" height="400"
>
<figcaption class="class-figcaption">Figcaption text</figcaption>
</figure>
<div id="1234567890"><p>Html to describe content</p></div>

The id used for aria-describedby is a random dynamically generated value.

umanit_image_figure

Generates a figure tag with an img inside.

Parameters

Name	Explanation
path	Path to the image, used to generated the browser path with LiipImagine
srcFilter	Name of the LiipImagine filter used to generate the path for src
srcsetFilters	A list of LiipImagine filters used to generate the srcset
alt	The text to put in the alt attribute of the img
imgClass	Classes to add on the img
sizes	Value of the sizes attribute (100vw if not defined)
figureClass	Classes to add on the figure
figcaptionText	Text of the figcaption (if nothing is passed, no figcaption will be rendered
figcaptionClass	Classes to add on the figcaption
imgImportance	Importance of the image (see this link for more information)
figureDataAttributes	Raw string passed to add data-attributes on the figure
imgDataAttributes	Raw string passed to add data-attributes on the img
htmlAlt	The html to put in a div referenced by the aria-describedby of the img. If given a non-empty value, the alt attribute vill be empty.

Example

Click to show

Without htmlAlt

    umanit_image_figure(
      image.path,
      'small_thumbnail',
      ['thumbnail', 'large_thumbnail'],
      'image alt',
      'img img--cover img--zoom',
      '(min-width: 768px) 33.3vw, 100vw',
      'class-figure',
      'Figcaption text',
      'class-figcaption',
      'low',
      'data-container="a"',
      'data-image="b" data-test'
    )

HTML generated:

<figure class="class-figure" data-container="a">
<img
    alt="image alt"
    class="img img--cover img--zoom"
    src="https://domain.tld/media/cache/resolve/small_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg"
    sizes="(min-width: 768px) 33.3vw, 100vw"
    srcset="https://domain.tld/media/cache/resolve/thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 260w, https://domain.tld/media/cache/resolve/large_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 2880w"
    width="600" height="400"
    importance="low"
    importance="high"
    data-image="b" data-test
>
<figcaption class="class-figcaption">Figcaption text</figcaption>
</figure>

With htmlAlt

     umanit_image_figure(
       image.path,
       'small_thumbnail',
       ['thumbnail', 'large_thumbnail'],
       'image alt',
       'img img--cover img--zoom',
       '(min-width: 768px) 33.3vw, 100vw',
       'class-figure',
       'Figcaption text',
       'class-figcaption',
       '<p>Html to describe content</p>'
     )

HTML generated

<figure class="class-figure">
<img
    alt=""
    aria-describedby="1234567890"
    class="img img--cover img--zoom"
    src="https://domain.tld/media/cache/resolve/small_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg"
    sizes="(min-width: 768px) 33.3vw, 100vw"
    srcset="https://domain.tld/media/cache/resolve/thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 260w, https://domain.tld/media/cache/resolve/large_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 2880w"
    width="600" height="400"
>
<figcaption class="class-figcaption">Figcaption text</figcaption>
</figure>
<div id="1234567890"><p>Html to describe content</p></div>

The id used for aria-describedby is a random dynamically generated value.

umanit_image_picture_lazy_load

Generates a picture tag with an img inside and X source. Each source can have a media and sizes attribute if needed. The img uses the native loading="lazy" attribute. If the blur option is enabled, the lazy-blur class and the placeholder background-image are added for the blur-up effect.

Parameters

Name	Explanation
path	Path to the image, used to generate the browser path with LiipImagine
srcFilter	Name of the LiipImagine filter used to generate the path for src
placeholderFilter	Name of the LiipImagine filter used to generate the blur-up placeholder background-image (only when blur is enabled)
srcsetFilters	A list of LiipImagine filters used to generate the srcset
sources	A list of LiipImagine filters used to generate the sources tags. The key of the array is the path to the image and the value can be a list of filters name or, if you need to define a media or sizes attribute on the source, an array with filters and media and/or sizes key.
alt	The text to put in the alt attribute of the img
imgClass	Classes to add on the img
pictureClass	Classes to add on the picture
imgImportance	Importance of the image (see this link for more information)
pictureDataAttributes	Raw string passed to add data-attributes on the picture
imgDataAttributes	Raw string passed to add data-attributes on the img
htmlAlt	The html to put in a div referenced by the aria-describedby of the img. If given a non-empty value, the alt attribute vill be empty.

Example

Click to show

Without htmlAlt

  umanit_image_picture_lazy_load(
    image.path,
    'small_thumbnail',
    'tiny_thumbnail',
    ['thumbnail', 'large_thumbnail'],
    {
      (image.path): {
        'media': '(min-width: 768px)',
        'sizes': '(min-width: 1400px) 25vw, 50vw',
        'filters': ['thumbnail', 'large_thumbnail']
      },
      (image2.path): ['thumbnail', 'large_thumbnail']
    },
    'alt img',
    'img img-fluid',
    'class-picture',
    'high',
    'data-picture data-markup="c"',
    'data-image="d"
  )

HTML generated

<picture class="class-picture" data-picture data-markup="c">
<source media="(min-width: 768px)" sizes="(min-width: 1400px) 25vw, 50vw" srcset="https://domain.tld/media/cache/resolve/thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 260w, https://domain.tld/media/cache/resolve/large_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 2880w" width="600" height="400">
<source srcset="https://domain.tld/media/cache/resolve/thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 260w, https://domain.tld/media/cache/resolve/large_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 2880w" width="300" height="200">
<img
    alt="alt img"
    class="lazy-blur img img-fluid"
    src="https://domain.tld/media/cache/resolve/small_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg"
    srcset="https://domain.tld/media/cache/resolve/thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 260w, https://domain.tld/media/cache/resolve/large_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 2880w"
    loading="lazy"
    style="background-image:url(https://domain.tld/media/cache/tiny_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg)"
    width="600" height="400"
    importance="high"
    data-image="d"
>
</picture>

With htmlAlt

  umanit_image_picture_lazy_load(
    image.path,
    'small_thumbnail',
    'tiny_thumbnail',
    ['thumbnail', 'large_thumbnail'],
    {
      (image.path): {
        'media': '(min-width: 768px)',
        'sizes': '(min-width: 1400px) 25vw, 50vw',
        'filters': ['thumbnail', 'large_thumbnail']
      },
      (image2.path): ['thumbnail', 'large_thumbnail']
    },
    'alt img',
    'img img-fluid',
    'class-picture',
    '<p>Html to describe content</p>'
  )

HTML generated

<picture class="class-picture">
<source media="(min-width: 768px)" sizes="(min-width: 1400px) 25vw, 50vw" srcset="https://domain.tld/media/cache/resolve/thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 260w, https://domain.tld/media/cache/resolve/large_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 2880w" width="600" height="400">
<source srcset="https://domain.tld/media/cache/resolve/thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg2 260w, https://domain.tld/media/cache/resolve/large_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg2 2880w" width="300" height="200">
<img
    alt=""
    aria-describedby="1234567890"
    class="lazy-blur img img-fluid"
    src="https://domain.tld/media/cache/resolve/small_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg"
    srcset="https://domain.tld/media/cache/resolve/thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 260w, https://domain.tld/media/cache/resolve/large_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 2880w"
    loading="lazy"
    style="background-image:url(https://domain.tld/media/cache/tiny_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg)"
    width="600" height="400"
>
</picture>
<div id="1234567890"><p>Html to describe content</p></div>

The id used for aria-describedby is a random dynamically generated value.

umanit_image_picture

Generates a picture tag with an img inside and X source. Each source can have a media and sizes attribute if needed.

Parameters

Name	Explanation
path	Path to the image, used to generate the browser path with LiipImagine
srcFilter	Name of the LiipImagine filter used to generate the path for src
srcsetFilters	A list of LiipImagine filters used to generate the srcset
sources	A list of LiipImagine filters used to generate the sources tags. The key of the array is the path to the image and the value can be a list of filters name or, if you need to define a media or sizes attribute on the source, an array with filters and media and/or sizes key.
imgClass	Classes to add on the img
pictureClass	Classes to add on the picture
imgImportance	Importance of the image (see this link for more information)
pictureDataAttributes	Raw string passed to add data-attributes on the picture
imgDataAttributes	Raw string passed to add data-attributes on the img
htmlAlt	The html to put in a div referenced by the aria-describedby of the img. If given a non-empty value, the alt attribute vill be empty.

Example

Click to show

Without htmlAlt

  umanit_image_picture(
    image.path,
    'small_thumbnail',
    ['thumbnail', 'large_thumbnail'],
    {
      (image.path): {
        'media': '(min-width: 768px)',
        'sizes': '(min-width: 1400px) 25vw, 50vw',
        'filters': ['thumbnail', 'large_thumbnail']
      },
      (image2.path): ['thumbnail', 'large_thumbnail']
    },
    'alt img',
    'img img-fluid',
    'class-picture',
    'low',
    'data-picture data-markup="c"',
    'data-image="d"
  )

HTML generated

<picture class="class-picture" data-picture data-markup="c">
<source media="(min-width: 768px)" sizes="(min-width: 1400px) 25vw, 50vw" srcset="https://domain.tld/media/cache/resolve/thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 260w, https://domain.tld/media/cache/resolve/large_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 2880w" width="600" height="400">
<source srcset="https://domain.tld/media/cache/resolve/thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 260w, https://domain.tld/media/cache/resolve/large_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 2880w" width="300" height="200">
<img
    class="img img-fluid"
    alt="alt img"
    src="https://domain.tld/media/cache/resolve/small_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg"
    srcset="https://domain.tld/media/cache/resolve/thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 260w, https://domain.tld/media/cache/resolve/large_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 2880w"
    width="600" height="400"
    importance="low"
    data-image="d"
>
</picture>

With htmlAlt

  umanit_image_picture(
    image.path,
    'small_thumbnail',
    ['thumbnail', 'large_thumbnail'],
    {
      (image.path): {
        'media': '(min-width: 768px)',
        'sizes': '(min-width: 1400px) 25vw, 50vw',
        'filters': ['thumbnail', 'large_thumbnail']
      },
      (image2.path): ['thumbnail', 'large_thumbnail']
    },
    'alt img',
    'img img-fluid',
    'class-picture',
    '<p>Html to describe content</p>'
  )

HTML generated

<picture class="class-picture">
<source media="(min-width: 768px)" sizes="(min-width: 1400px) 25vw, 50vw" srcset="https://domain.tld/media/cache/resolve/thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 260w, https://domain.tld/media/cache/resolve/large_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 2880w" width="600" height="400">
<source srcset="https://domain.tld/media/cache/resolve/thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg2 260w, https://domain.tld/media/cache/resolve/large_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg2 2880w" width="300" height="200">
<img
    class="img img-fluid"
    alt=""
    aria-describedby="1234567890"
    src="https://domain.tld/media/cache/resolve/small_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg"
    srcset="https://domain.tld/media/cache/resolve/thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 260w, https://domain.tld/media/cache/resolve/large_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 2880w"
    width="600" height="400"
>
</picture>
<div id="1234567890"><p>Html to describe content</p></div>

umanit_image_img

Generates an img tag.

Parameters

Name	Explanation
path	Path to the image, used to generate the browser path with LiipImagine
srcFilter	Name of the LiipImagine filter used to generate the path for src
srcsetFilters	A list of LiipImagine filters used to generate the srcset
alt	The text to put in the alt attribute of the img
imgClass	Classes to add on the img
sizes	Value of the sizes attribute (100vw if not defined)
importance	Importance of the image (see this link for more information)
imgDataAttributes	Raw string passed to add data-attributes on the img

Example

Click to show

    umanit_image_img(
      image.path,
      'small_thumbnail',
      ['thumbnail', 'large_thumbnail'],
      'image alt',
      'img img--cover img--zoom',
      '(min-width: 768px) 33.3vw, 100vw',
      'low',
      'data-image="b" data-test'
    )

HTML generated:

<img
  alt="image alt"
  class="img img--cover img--zoom"
  src="https://domain.tld/media/cache/resolve/small_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg"
  sizes="(min-width: 768px) 33.3vw, 100vw"
  srcset="https://domain.tld/media/cache/resolve/thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 260w, https://domain.tld/media/cache/resolve/large_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 2880w"
  width="600" height="400"
  importance="low"
  data-image="b" data-test
>

umanit_image_srcset

Generates the content of a srcset attribute if you wan to use it in your own markup.

Parameters

Name	Explanation
path	Path to the image, used to generate the browser path with LiipImagine
filters	A list of LiipImagine filters used to generate the srcset

Example

Click to show

umanit_image_srcset(image.path, ['thumbnail', 'large_thumbnail'])

HTML generated

https://domain.tld/media/cache/resolve/thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 260w, https://domain.tld/media/cache/resolve/large_thumbnail/99/30/c1f268bbf1487fb88734f2ba826b.jpeg 2880w

(Optional) Blur-up effect

Lazy loading works out of the box with the native loading="lazy" attribute, no JavaScript required.

If you enabled lazy_load.blur in the Configuration, import the provided (dependency-free) JavaScript module and CSS file to power the blur-up effect. The module registers a single load listener that removes the blur once the real image has loaded. An optional loadEventCallback argument is called for each loaded image.

import umanitImageLazyLoad from '../../public/bundles/umanittwigimage/js/umanit-image-lazy-loading';
import '../../public/bundles/umanittwigimage/css/umanit-image-lazy-loading.css';

umanitImageLazyLoad();

Or import the CSS through Twig:

<link rel="stylesheet" href="{{ asset('css/umanit-image-lazy-loading.css', 'twig_image_bundle') }}">

Contributing

Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.

License

MIT