Using Responsive Image library

To add Responsive Image library to a web page and manage existing images with the library, complete the following steps.

To use Responsive Image library

In Dynamic Media Classic, create an Image Preset in case you plan to use Responsive Image library with presets.

When you define Image Presets that are used with Responsive Image Library, do not use any settings that affect image size, such as wid=, hei=, or scl=. Do not specify any size fields in the Image Preset. Instead, leave them as blank values.
Add the library JavaScript file to your web page.

Before you can use library API, be sure that you include responsive_image.js. This JavaScript file is located in the libs/ subfolder of your standard IS-Viewers deployment:

<s7viewers_root>/libs/responsive_image.js
Set up existing images.

The library reads certain configuration attributes from an image instance it is working with. Define attributes before the s7responsiveImage API function is called for such image.

It is also suggested that you put the existing image URL into the data-src attribute. Then, set up the existing src attribute to have a 1x1 GIF image encoded as Data URI. Doing so, reduces the number of HTTP requests that are sent by the web page at load time. Note, however, that if SEO (search engine optimization) is needed, it is better to set up a title attribute on the image instance.

The following is an example of defining data-breakpoints attribute for the image and using a 1x1 GIF encoded as Data URI:
```
<img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" data-src="https://s7d9.scene7.com/is/image/Scene7SharedAssets/Backpack_B" data-breakpoints="360,720,940">
```
Call the s7responsiveImage API function for every image instance that the library manages.

Call the s7responsiveImage API function for every image instance that the library manages. After such a call, the library replaces the original image with the image that is downloaded from Image Serving according to the runtime size of the IMG element in the web page layout and the device screen’s density.

The following code is an example of calling s7responsiveImage API function on an image, assuming that responsiveImage is an ID of that image:
```
<script type="text/javascript"> 
 s7responsiveImage(document.getElementById("responsiveImage")); 
</script>
```

Example

The library supports working with many image instances on the web page simultaneously. Therefore, repeat steps 1 and 2 above for each image that you want the library to manage.

It is the responsibility of the web page to style the image element to make it flexible in size. The Responsive Image library itself does not differentiate between fixed-size and “fluid” images. If applied to a fixed-size image it loads the new image only once.

The following code is a complete example of a trivial web page that has a single fluid image managed by the Responsive Image library. The example contains extra CSS styling to make the image “responsive” to the web browser window size:

<!DOCTYPE html> 
<html> 
 <head> 
  <style type="text/css"> 
  .container { 
   width: 50%; 
  } 
  .fluidimage { 
   max-width: 100%; 
  } 
  </style> 
 </head> 
 <body> 
  <div class="container"> 
   <img id="responsiveImage" src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" data-src="https://s7d9.scene7.com/is/image/Scene7SharedAssets/Backpack_B" data-breakpoints="200,400,600,800" class="fluidimage"> 
  </div> 
  <script type="text/javascript" src="https://s7d9.scene7.com/s7viewers/libs/responsive_image.js"></script> 
  <script type="text/javascript"> 
   s7responsiveImage(document.getElementById("responsiveImage")); 
  </script> 
 </body> 
</html>

Using Smart Crop

There are two Smart Crop modes available in AEM 6.4 and Dynamic Media Viewers 5.9:

Manual - user-defined breakpoints and corresponding Image Service commands are defined within an attribute in the image element.
Smart Crop - computed smart crop renditions are automatically retrieved from the delivery server. The best rendition is selected using the runtime size of the image element.

To use Smart Crop mode you set the data-mode attribute to smart crop. For example:

<img 
src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" 
data-src="https://imageserver.com/is/image/ExampleCo/SmartCropAsset" 
data-mode="smartcrop">

The associated image element dispatches a s7responsiveViewer event during runtime when the breakpoint changes.

         responsiveImage.addEventListener("s7responsiveViewer", function (event) { 
           var s7event = event.s7responsiveViewerEvent; 
           if(s7event.type == "breakpointchanged") { 
              console.log("New width: " + s7event.width); 
              console.log("Old width: " + s7event.oldWidth); 
           } 
        });