This is the standalone PHP implementation of "3-layer technique" for Adaptive Images generation. See https://openweb.eu.org/277 for technical explanations and justifications (french version available : <openweb.eu.org/280>)
PHP>=5.1 with GD library
(if PHP<5.3.0 extending AdaptiveImages
also needs to override method getInstance()
)
Call adaptHTMLPage
method on your HTML page with optional maximum display width of images in your HTML page.
require_once "AdaptiveImages.php" $AdaptiveImages = AdaptiveImages::getInstance(); $html = $AdaptiveImages->adaptHTMLPage($html,780);
First view of page with adaptive Images can timeout due to all the images to generate. Reload the page to complete image generation.
If your CMS/application allow caching of HTML part of pages, apply adaptHTMLPart
method on this part in order to cache Adaptive Images
require_once "AdaptiveImages.php" $AdaptiveImages = AdaptiveImages::getInstance(); return $AdaptiveImages->adaptHTMLPart($texte, 780);
then recall adaptHTMLPage
method on full HTML page to finish the job
$AdaptiveImages = AdaptiveImages::getInstance(); $html = $AdaptiveImages->adaptHTMLPage($html,780);
By default AdaptiveImages considers that relative URLs are also relative file system path.
If this is not the case in your URL scheme, you can override the 2 methods URL2filepath
and filepath2URL
that are used to make transpositions.
In the following example we transpose absolutes URLs to relative file system path and, if defined we add special domain _ADAPTIVE_IMAGES_DOMAIN
to file path in the final URL (domain sharding)
class MyAdaptiveImages extends AdaptiveImages { protected function URL2filepath($url){ $url = parent::URL2filepath($url); // absolute URL to relative file path if (preg_match(",^https?://,",$url)){ $base = url_de_base(); if (strncmp($url,$base,strlen($base))==0) $url = _DIR_RACINE . substr($url,strlen($base)); elseif (defined('_ADAPTIVE_IMAGES_DOMAIN') AND strncmp($url,_ADAPTIVE_IMAGES_DOMAIN,strlen(_ADAPTIVE_IMAGES_DOMAIN))==0){ $url = _DIR_RACINE . substr($url,strlen(_ADAPTIVE_IMAGES_DOMAIN)); } } return $url; } protected function filepath2URL($filepath){ $filepath = parent::filepath2URL($filepath); if (defined('_ADAPTIVE_IMAGES_DOMAIN')){ $filepath = rtrim(_ADAPTIVE_IMAGES_DOMAIN,"/")."/".$filepath; } return $filepath; } } $AdaptiveImages = MyAdaptiveImages::getInstance();
If source <img/>
has some inline styles, it can be needed to add some wrapper and put the style on it on order to keep initial visual result.
This can be done in overriding the method imgMarkupHook(&$markup,$originalClass,$originalStyle)
.
It is call with following arguments
<span>
wrapper with the fallback <img/>
inside)<img/>
<img/>
The method must return the partial markup, with your modifications.
To avoid timeout on first view of HTML page you can activate OnDemand images generation. In this case, only URL of adapted images will be computed, and you need to use a Rewrite Rules and a router to call AdaptiveImages::deliverBkptImage
.
For instance with SPIP CMS :
### # If file or directory exists deliver it and ignore others rewrite rules RewriteCond %{REQUEST_FILENAME} -f RewriteRule "." - [skip=100] RewriteCond %{REQUEST_FILENAME} -d RewriteRule "." - [skip=100] # ### ### # Adaptive Images : call action_adapt_img_dist() function if image not available RewriteRule \badapt-img/(\d+/\d\dx/.*)$ spip.php?action=adapt_img&arg=$1 [QSA,L] # Fin des Adaptive Images ###
function action_adapt_img_dist(){ $AdaptiveImages = AdaptiveImages::getInstance(); try { $AdaptiveImages->deliverBkptImage(_request('arg')); } catch (Exception $e){ http_status(404); die('Error : '.$e->getMessage()); } exit; }
$AdaptiveImages->destDirectory = "local/adapt-img/";
$AdaptiveImages->maxWidth1x = 640;
$AdaptiveImages->minWidth1x = 320;
$AdaptiveImages->maxWidthMobileVersion = 320;
$AdaptiveImages->onDemandImages = true;
$AdaptiveImages->lowsrcJpgBgColor = '#eeeeee';
$AdaptiveImages->defaultBkpts = array(160,320,480,640,960,1440);
$AdaptiveImages->nojsPngGifProgressiveRendering = true;
$AdaptiveImages->maxWidthFallbackVersion = 160;
$AdaptiveImages->lowsrcJpgQuality = 40;
$AdaptiveImages->x10JpgQuality = 75;
$AdaptiveImages->x15JpgQuality = 65;
$AdaptiveImages->x15JpgQuality = 45;
$AdaptiveImages->maxImagePxGDMemoryLimit = 2000*2000;
This library is already available through plugins in: