Lazy-retina is based on fasterize lazyload, it's the same code with retina support and external options.
It's a standalone script that weights ~1KB minified gzipped.
- Add lazy-retina.min.js to your page before any
<script>tag, either src or inline if you do not have any other scripts in the<head>. - Change all
<img>tags to lazyload :
<img
data-src="real/image/src.jpg"
src="data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw=="
onload="lzld(this)" onerror="lzld(this)"
width="200" height="400" >It's possible to use lazy-retina for non-lazyloaded images, it's the same syntax and the same process :
- Add lazy-retina.min.js to your page before any
<script>tag, either src or inline if you do not have any other scripts in the<head>. - Change all
<img>tags to add support :
<img
src="real/image/src.jpg"
onload="lzld(this)" onerror="lzld(this)"
width="200" height="400" >lazy-retina is used on :
- mobile.lemonde.fr, news, 1st mobile website in France. source (pdf)
We can configure lazy-retina for custom use :
<script src="lazy-retina.js"></script>
<script>
lzld.config.retina = true; // force retina
lzld.config.lazy-attr = "data-mysrc-attr"; // change attribute
</script>retina: Set the retina support, defaultauto(the retina is determined bywindow.devicePixelRatio), it accepts a boolean to force support.hdCallback: The callback to transform thesrcin a retinasrc,var hdSrc = hdCallback(src);lazyAttr: The lazy attribute, defaultdata-src.minDevicePixelRatio: The min device pixel ratio to enable retina in "auto" mode.offset: Vertical offset in px. Used for preloading images while scrolling
The default hd callback simply add @2x to the img like on iOS platforms :
function defaultHdCallback(src)
{
var srcSegments = src.split("."),
srcWithoutExtension = srcSegments.slice(0, (srcSegments.length - 1)).join("."),
extension = srcSegments[srcSegments.length - 1];
return srcWithoutExtension + "@2x." + extension;
}Force an update of all loaded images :
// We force retina and we update all loaded images
lzld.config.retina = true;
lzld.update();Check if the device is retina according to lzld.config.minDevicePixelRatio.
IE6+ or modern browser.
IE6/7 originally does not support data uri:s images but using the onerror event on to-be-lazyloaded images, we're able to register the current image in the lazyloader. The only drawback is that you can have red crosses showing that original data uri:s image cannot be loaded. But well, it's old IE so no big deal.
You can have IE6/7 support without the hack, use the b.gif image instead of the data uri:s and remove onerror.
Lazy-retina is based on fasterize lazyload, so it's efficient and speedy. You can see how the lazyload part works on https://github.com/fasterize/lazyload/.
The retina part is no more complicated, it test if retina is active and supported and execute a callback to modify the source in order to load the retina image file.
Fully based on very powerful https://github.com/fasterize/lazyload/
(The MIT Licence)
Copyright (c) 2012 Greg Bergé, http://neoziro.com
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.