Flou is a PHP package integrating Glide (PHP) and vanilla-lazyload (JS). It's optimized to quickly implement lazy loading and responsive images from a local folder of source images.

Features:

• Transform local images on initial page load (does not expose Glide URLs)
• Can leverage custom Glide configurations (e.g. source images on S3)
• Generate responsive HTML for img and picture elements
• Useable with static site generators and in CLI scripts
• Framework agnostic (a set of plain PHP classes)

Requirements:

• PHP >= 8.0

Table of contents:

• Installing
• Getting Started
• Image Transformations
• Image Rendering
• Image Sets (Responsive Images)
• Remote Images
• Examples
• Development
• License

Demo project:

See the flou-jigsaw-demo repository for an example project integrating Flou with the Jigsaw PHP static site generator.

The package can be installed via Composer:

composer require pboivin/flou

This also installs Glide as a Composer dependency.

You can pull in the vanilla-lazyload library via a CDN:

<script src="https://cdn.jsdelivr.net/npm/vanilla-lazyload/dist/lazyload.min.js"></script>

or via NPM:

npm install --save vanilla-lazyload

Consult the vanilla-lazyload documentation for more installation options.

First, initialize the LazyLoad JS object. Add the following script to your page template:

<script>
    document.addEventListener("DOMContentLoaded", () => {
        new LazyLoad({
            elements_selector: ".lazyload",
        });
    });
</script>

Then, initialize the ImageFactory PHP object with your project-specific configuration:

use Pboivin\Flou\ImageFactory;

$flou = new ImageFactory([
    'sourcePath' => '/home/user/my-site.com/public/images/source',
    'cachePath' => '/home/user/my-site.com/public/images/cache',
    'sourceUrlBase' => '/images/source',
    'cacheUrlBase' => '/images/cache',
]);

The required options are:

Other options:

If you're using a framework with a Service Container, you can register the $flou instance as a singleton for your entire application. This will be your entry point to transform and render images.

Some examples below require additional JS and CSS. You'll find a more complete sample in the assets directory.

Use the image() method to transform a single image into a low-quality image placeholder (LQIP):

$image = $flou->image('01.jpg');

You can also provide custom Glide parameters for the image transformation:

$image = $flou->image('01.jpg', [
    'w' => 10,
    'h' => 10,
    'fit' => 'crop',
]);

You'll find all available parameters in the Glide documentation.

As you can see, the default parameters are used to generate LQIP from source images, but you are not restricted to that. You may generate as many transformations as you need from the source image:

$phone = $flou->image('01.jpg', ['w' => 500]);
$tablet = $flou->image('01.jpg', ['w' => 900]);
$desktop = $flou->image('01.jpg', ['w' => 1300]);

If you're working with responsive images and the srcset attribute, have a look at the next section (Image Sets).

You can customize the default Glide parameters in the ImageFactory configuration:

$flou = new ImageFactory([
    // ...
    'glideParams' => [
        'h' => 10,
        'fm' => 'gif',
    ],
]);

The image() method returns an Image object, from which you can conveniently access the source image file and the transformed (cached) image file:

$image = $flou->image('01.jpg');

# Source image data:
echo $image->source()->url();       # /images/source/01.jpg
echo $image->source()->path();      # /home/user/my-site.com/public/images/source/01.jpg
echo $image->source()->width();     # 3840 
echo $image->source()->height();    # 2160
echo $image->source()->ratio();     # 1.77777778

# Transformed image data:
echo $image->cached()->url();       # /images/cache/01.jpg/de828e8798017be816f79e131e41dcc9.jpg
...

Use the toArray() method to export the image to a plain array:

$data = $image->toArray();

# [
#     "source" => [
#         "url" => "/images/source/01.jpg",
#         "path" => "/home/user/my-site.com/public/images/source/01.jpg",
#         "width" => 3840,
#         "height" => 2160,
#         "ratio" => 1.77777778,
#     ],
#     "cached" => [
#         "url" => "/images/cache/01.jpg/de828e8798017be816f79e131e41dcc9.jpg",
#         ...
#     ],
# ]

Image resampling is a simple way to reuse a transformed image as the source of another transformation. Use the resample() method to begin:

$greyscale = $flou->resample('01.jpg', [
    'filt' => 'greyscale',
    'w' => 2000,
]);

This is the same as calling image(), but returns an instance of ResampledImage instead. The resampled image can then be used again as a source for image():

$image = $flou->image($greyscale, ['w' => 50]);

# Source image:
echo $image->source()->url();       # /images/cache/01.jpg/a50df0a8c8a84cfc6a77cf74b414d020.jpg
echo $image->source()->width();     # 2000
...

# Transformed image:
echo $image->cached()->url();       # /images/cache/_r/01.jpg/a50df0a8c8a84cfc6a77cf74b414d020.jpg/9a5bdd58bbc27a556121925569af7b0c.jpg
echo $image->cached()->width();     # 50
...

The render() method on the image returns an ImageRender object, which prepares HTML suitable for the vanilla-lazyload library. Then, img() is used to render an img element:

$image = $flou->image('01.jpg');

echo $image
        ->render()
        ->img(['class' => 'w-full', 'alt' => 'Lorem ipsum']);

<img 
  class="lazyload w-full" 
  alt="Lorem ipsum" 
  src="/images/cache/01.jpg/de828e8798017be816f79e131e41dcc9.gif" 
  data-src="/images/source/01.jpg" 
  width="3840" 
  height="2160"
>

Options passed into img() are included as HTML attributes on the element. Attribute values are not escaped by default.

Some attributes are automatically generated (e.g. src, width, height, etc.). You can override them with a ! prefix:

echo $image
        ->render()
        ->img([
            'class' => 'w-full',
            'alt' => 'Lorem ipsum',
            '!src' => false,
        ]);

<img 
  class="lazyload w-full" 
  alt="Lorem ipsum" 
  data-src="/images/source/01.jpg" 
  width="3840" 
  height="2160" 
>

The ImageRender object can be configured to optimize the HTML output:

• useAspectRatio(): Prevents content shifting when the LQIP is replaced with the source image:

  echo $image
          ->render()
          ->useAspectRatio()
          ->img(['class' => 'w-full', 'alt' => 'Lorem ipsum']);
  
  # or use a custom aspect-ratio:
  
  echo $image
          ->render()
          ->useAspectRatio(16 / 9)
          ->img(['class' => 'w-full', 'alt' => 'Lorem ipsum']);

  See HTML Output

  <img 
    class="lazyload w-full" 
    alt="Lorem ipsum" 
    style="aspect-ratio: 1.77777778; object-fit: cover; object-position: center;" 
    ...
  >

  
  

• usePaddingTop(): A workaround for older browsers not supporting the aspect-ratio CSS property:

  echo $image
          ->render()
          ->usePaddingTop()
          ->img(['class' => 'w-full', 'alt' => 'Lorem ipsum']);
  
  # or use a custom aspect-ratio:
  
  echo $image
          ->render()
          ->usePaddingTop(16 / 9)
          ->img(['class' => 'w-full', 'alt' => 'Lorem ipsum']);

  See HTML Output

  <div class="lazyload-padding" style="position: relative; padding-top: 56.25%;">
    <img
      class="lazyload w-full"
      alt="Lorem ipsum" 
      style="position: absolute; top: 0; left: 0; width: 100%; height: 100%; 
             object-fit: cover; object-position: center;"
      ...
    >
  </div>

  
  

• useWrapper(): Wraps the image with an extra div and separates the LQIP element from the main img element. This is used to add a fade-in effect when the image is loaded.

  (Requires additional JS and CSS. See fade-in example.)

  echo $image
          ->render()
          ->useWrapper()
          ->img(['class' => 'w-full', 'alt' => 'Lorem ipsum']);

  See HTML Output

  <div class="lazyload-wrapper">
    <img 
      class="lazyload w-full" 
      alt="Lorem ipsum" 
      ...
    >
    <img 
      class="lazyload-lqip" 
      src="/images/cache/01.jpg/de828e8798017be816f79e131e41dcc9.gif"
    >
  </div>

  
  

• useBase64Lqip(): Inlines a Base64 version of the LQIP in the src attribute of the img element. This reduces the number of HTTP requests needed to display a page, at the cost of making the HTML a bit heavier.

  echo $image
          ->render()
          ->useBase64Lqip()
          ->img(['class' => 'w-full', 'alt' => 'Lorem ipsum']);

  See HTML Output

  <img 
    class="lazyload w-full" 
    alt="Lorem ipsum" 
    src="data:image/gif;base64,R0lGODlhAQABAIABAAAAAP///yH+EUNyZWF0Z..."
    data-src="/images/source/01.jpg" 
    width="2932" 
    height="2000"
  >

  
  

You can set the default render options for all images in the ImageFactory configuration:

$flou = new ImageFactory([
    // ...
    'renderOptions' => [
        'aspectRatio' => true,
        'wrapper' => true,
        'base64Lqip' => true,
        // ...
    ],
]);

Use the noScript() method to render an img element without any lazy loading behavior:

echo $image
        ->render()
        ->noScript(['class' => 'w-full', 'alt' => 'Lorem ipsum']);

<img 
  class="lazyload-noscript w-full" 
  alt="Lorem ipsum" 
  src="/images/source/01.jpg" 
  width="2932" 
  height="2000"
>

This is used to add a noscript image fallback. (See Noscript image fallback example)

It can also be used creatively to work on the source image with CSS classes and HTML attributes. (See Browser native lazy loading example)

Use the imageSet() method to transform a source image into a set of responsive images:

$imageSet = $flou->imageSet([
    'image' => '01.jpg',
    'sizes' => '(max-width: 500px) 100vw, 50vw',
    'widths' => [500, 900, 1300, 1700],
]);

This returns an ImageSet object, which prepares all variations of the source image. The render() method on the image set returns an ImageSetRender instance, as seen before with single images:

echo $imageSet
        ->render()
        ->useAspectRatio()
        ->img(['class' => 'w-full', 'alt' => 'Lorem ipsum']);

<img 
  class="lazyload w-full" 
  alt="Lorem ipsum" 
  style="aspect-ratio: 1.77777778; object-fit: cover; object-position: center;" 
  src="/images/cache/01.jpg/de828e8798017be816f79e131e41dcc9.gif" 
  data-src="/images/cache/01.jpg/b8648e93b40b56d5c5a78acc7a23e3d9.jpg" 
  data-srcset="/images/cache/01.jpg/a50df0a8c8a84cfc6a77cf74b414d020.jpg 500w, 
               /images/cache/01.jpg/1422c06dea2257858f6437b9675fba1c.jpg 900w, 
               /images/cache/01.jpg/1eac615f1a50f20c434e5944225bdd4f.jpg 1300w, 
               /images/cache/01.jpg/b8648e93b40b56d5c5a78acc7a23e3d9.jpg 1700w" 
  data-sizes="(max-width: 500px) 100vw, 50vw"
  width="1700" 
  height="956" 
>

Like ImageRender, you can optimize ImageSetRender with the same methods:

• useAspectRatio()
• usePaddingTop()
• useWrapper()
• useBase64Lqip()
• noScript()

With a similar configuration, imageSet() also handles multiple source images:

$imageSet = $flou->imageSet([
    [
        'image' => 'portrait.jpg',
        'media' => '(max-width: 1023px)',
        'sizes' => '100vw',
        'widths' => [400, 800, 1200],
    ],
    [
        'image' => 'landscape.jpg',
        'media' => '(min-width: 1024px)',
        'sizes' => '66vw',
        'widths' => [800, 1200, 1600],
    ],
]);

Then, the picture() method is used to render a picture element:

echo $imageSet
        ->render()
        ->picture(['class' => 'my-image', 'alt' => 'Lorem ipsum']);

<picture>
  <source
    media="(max-width: 1023px)"
    data-sizes="100vw"
    data-srcset="/images/cache/portrait.jpg/a50df0a8c8a84cfc6a77cf74b414d020.jpg 400w,
                 /images/cache/portrait.jpg/1422c06dea2257858f6437b9675fba1c.jpg 800w,
                 /images/cache/portrait.jpg/de828e8798017be816f79e131e41dcc9.jpg 1200w"
  >
  <source 
    media="(min-width: 1024px)" 
    data-sizes="66vw" 
    data-srcset="/images/cache/landscape.jpg/c6f9c52bea237b64cc98fc9f5f3f15c6.jpg 800w,
                 /images/cache/landscape.jpg/fcc882305b523e823c7a24df05045c5a.jpg 1200w,
                 /images/cache/landscape.jpg/a50df0a8c8a84cfc6a77cf74b414d020.jpg 1600w"
  >
  <img
    class="lazyload my-image"
    alt="Lorem ipsum"
    src="/images/cache/landscape.jpg/66d1d4a938d99f2b0234e08008af09a8.gif"
    data-src="/images/cache/landscape.jpg/a50df0a8c8a84cfc6a77cf74b414d020.jpg"
    width="1600"
    height="900"
  >
</picture>

See also: Art-directed picture element example

The configuration allows multiple image formats for each source:

$imageSet = $flou->imageSet([
    'image' => '01.jpg',
    'sizes' => '100vw',
    'widths' => [400, 800, 1200, 1600],
    'formats' => ['webp', 'jpg'],
]);

echo $imageSet
        ->render()
        ->picture(['class' => 'my-image', 'alt' => 'Lorem ipsum']);

<picture>
  <source
    type="image/webp"
    data-srcset="/images/cache/01.jpg/7c7086baa60bb4b3876b14dd577fa9e8.webp 400w,
                 /images/cache/01.jpg/49ada5db20e72d539b611e5d17640d2f.webp 800w,
                 /images/cache/01.jpg/cb48c273b44bd0f00155d4932231fe28.webp 1200w,
                 /images/cache/01.jpg/a50df0a8c8a84cfc6a77cf74b414d020.webp 1600w"
    data-sizes="100vw"
  >
  <source
    type="image/jpeg"
    data-srcset="/images/cache/01.jpg/27e8a3f7fb4abe60654117a34f2007e1.jpg 400w,
                 /images/cache/01.jpg/f319ea155d0009a7e842f50fcc020fe3.jpg 800w,
                 /images/cache/01.jpg/cfdad3b69ae3a15ba479aa85868e75f3.jpg 1200w,
                 /images/cache/01.jpg/1422c06dea2257858f6437b9675fba1c.jpg 1600w"
    data-sizes="100vw"
  >
  <img
    class="lazyload w-full"
    alt="Lorem ipsum"
    src="/images/cache/01.jpg/bd0dc309cfc3b71731b2e2df3d6e130b.gif"
    data-src="/images/cache/01.jpg/1422c06dea2257858f6437b9675fba1c.jpg"
    width="1600"
    height="900"
  >
</picture>

You can provide an array of base Glide parameters as a second argument to imageSet():

$imageSet = $flou->imageSet([
    'image' => '01.jpg',
    'sizes' => '100vw',
    'widths' => [400, 800, 1200, 1600],
    'formats' => ['webp', 'jpg'],
], [
    'q' => 80,
]);

You'll find all available parameters in the Glide documentation.

Note: You may use all parameters except w and fm, which are automatically generated from the widths and formats configuration above.

The base ImageFactory class is optimized for cases where both source and cached images exist on the local filesystem. The RemoteImageFactory class was introduced to enable new use-cases:

• Working with remote Glide endpoints
• Integrating with existing Glide Server configurations

This adds support for images stored on remote filesystems, such as Amazon S3.

The options for RemoteImageFactory are:

If you already have a Glide instance setup and publicly accessible, you can hook into it with the following configuration:

$flou = new Pboivin\Flou\RemoteImageFactory([
    'glideUrlBase' => '/glide', // or use a full URL: https://cdn.my-site.com/glide
    'glideUrlSignKey' => 'secret',
]);

$image = $flou->image('test.jpg');

//...

Alternatively, you can pass in a fully configured Glide Server object:

// @see https://flysystem.thephpleague.com/docs/adapter/aws-s3-v3/

$sourceFilesystem = new League\Flysystem\Filesystem(
    new League\Flysystem\AwsS3V3\AwsS3V3Adapter(/* S3 adapter configuration */);
);

$server = League\Glide\ServerFactory::create([
    'source' => $sourceFilesystem,
    'cache' => '/home/my-site.com/storage/glide-cache',
    'base_url' => '/glide',
]);

$flou = new Pboivin\Flou\RemoteImageFactory([
    'glideServer' => $server,
    'glideUrlSignKey' => 'secret',
]);

$image = $flou->image('test.jpg');

//...

If you're using Laravel, you can access the filesystem driver from the Storage facade:

// @see https://laravel.com/docs/filesystem

$sourceFilesystem = Illuminate\Support\Facades\Storage::disk('s3')->getDriver(),

//...

When using RemoteImageFactory, it is too costly to fetch remote images to analyze their dimensions. Therefore, rendered images will not include width and height attributes. I recommend leveraging useAspectRatio() with a fixed aspect ratio value if possible.

Similarly, useBase64Lqip() will return a blank placeholder instead of a Base64 encoded LQIP.

Image resampling is not available for remote images.

Extra JS and CSS:

<script src="https://cdn.jsdelivr.net/npm/vanilla-lazyload/dist/lazyload.min.js"></script>
<script>
    /**
     * vanilla-lazyload API reference: 
     * https://github.com/verlok/vanilla-lazyload#options
     */

    document.addEventListener("DOMContentLoaded", () => {
        new LazyLoad({
            elements_selector: ".lazyload",

            callback_loaded: (el) => {
                const wrapper = el.closest(".lazyload-wrapper");
                if (wrapper) {
                    wrapper.classList.add("loaded");
                }
            }
        });
    });
</script>

<style>
    /* Example styles — adjust to taste */

    .lazyload-wrapper {
        position: relative;
        overflow: hidden;
    }

    .lazyload-wrapper .lazyload-lqip {
        filter: blur(10px);
        transform: scale(1.1);
        position: absolute;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
    }

    .lazyload-wrapper.loaded .lazyload-lqip {
        opacity: 0;
        transition: opacity 0.5s;
        transition-delay: 0.5s;
    }
</style>

Usage:

<?= $flou
        ->image('01.jpg')
        ->render()
        ->useAspectRatio()
        ->useWrapper()
        ->img(['class' => 'w-full', 'alt' => 'Lorem ipsum']);
?>

CSS:

<style>
    .my-image {
        width: 100%;
        height: auto;
        aspect-ratio: calc(3 / 4);
        object-fit: cover;
        object-position: center;
    }

    @media screen and (min-width: 1024px) {
        .my-image {
            max-width: 66vw;
            aspect-ratio: calc(16 / 9);
        }
    }
</style>

Usage:

<?= $flou->imageSet([
        [
            'image' => 'portrait.jpg',
            'media' => '(max-width: 1023px)',
            'sizes' => '100vw',
            'widths' => [400, 800, 1200],
        ],
        [
            'image' => 'landscape.jpg',
            'media' => '(min-width: 1024px)',
            'sizes' => '66vw',
            'widths' => [800, 1200, 1600],
        ],
    ])
    ->render()
    ->picture(['class' => 'my-image', 'alt' => 'Lorem ipsum']);
?>

CSS:

<noscript>
    <style>
        .lazyload {
            display: none;
        }
    </style>
</noscript>

Usage:

<div>
    <?= ($image = $flou->image('01.jpg'))
            ->render()
            ->img(['class' => 'w-full', 'alt' => 'Lorem ipsum'])
    ?>
    <noscript>
        <?= $image
                ->render()
                ->noScript(['class' => 'w-full', 'alt' => 'Lorem ipsum'])
        ?>
    </noscript>
</div>

Usage:

<?= ($image = $flou->image('01.jpg'))
        ->render()
        ->useAspectRatio()
        ->noScript([
            'class' => 'w-full', 
            'alt' => 'Lorem ipsum',
            'loading' => 'lazy',
            'decoding' => 'async',
            'style' => "background-image: url({$image->cached()->url()});
                        background-size: cover;"
        ]);
?>

Usage:

<?php $image = $flou->image('01.jpg'); ?>

<div class="lazyload"
     data-bg="<?= $image->source()->url() ?>"
     style="background-image: url( <?= $image->cached()->url() ?> );
            background-size: cover;"
>
    <!-- ... -->
</div>

Preprocess all images in a source directory and prepare a JSON inventory file:

<?php

require 'vendor/autoload.php';

$flou = new Pboivin\Flou\ImageFactory([
    'sourcePath' => './public/images/source',
    'cachePath' => './public/images/cache',
    'sourceUrlBase' => '/images/source',
    'cacheUrlBase' => '/images/cache',
]);

$data = [];

foreach (glob('./public/images/source/*.jpg') as $path) {
    $file = basename($path);

    echo "Processing image: $file\n";

    $data[$file] = [
        'source' => $flou->image($file)->source()->toArray(),
        'lqip' => $flou->image($file)->cached()->toArray(),
        'responsive' => array_map(
            fn ($width) => $flou->image($file, ['w' => $width])->cached()->toArray(),
            [500, 900, 1300, 1700]
        ),
    ];
}

file_put_contents('./data/images.json', json_encode($data, JSON_PRETTY_PRINT));

echo "Done!\n";

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Flou is open-sourced software licensed under the MIT license.