is there a viable way to feature detect support for image:data base64

using something along the lines of:

background:url(data:image/gif;base64,R0lGODlhIwAhALMAAAAAADQ0NENDQ25ubouLi6ioqLa2ttPT0/Dw8P///wAAAAAAAAAAAAAAAAAAAAAAACwAAAAAIwAhAAAIpQABCBxIsCCAAAYTKlw4cECCAQwjMnSY4KHEiwQpVrSIUaLGjRw7Kvy4EYEAkSNBljyJ0iDJiiZbulQJk6XMhjQTxLyJk+ZOngBe6rTJU+jPojmTKqXZc6nTpAKFPp0qsMDUqyoHWsWKleBWrk8LfgV5AKjYnGXNakWrdi3NtG3HbjTQtmrOAnUByK2It+7eBH3j5iSQVy5cv3PzegWsuCDExmYDAgA7) no-repeat center center;}

is fine but I want to be able to provide graceful degradation (the css assertion is through javascript) when base64 is not available.

obviously, IE prior to v8 lacks this functionality so I could go by browser - but i'd prefer to h开发者_JS百科ave it feature detected, if possible.

any ideas on how do go about doing it?

This might be what you are looking for : http://weston.ruter.net/2009/05/07/detecting-support-for-data-uris/

I worked on a script that adds a partial support of the DataURI scheme in IE6+ : http://phenxdesign.net/projects/phenx-web/iedatauri/example.php and the code is here : http://code.google.com/p/phenx-web/source/browse/trunk/iedatauri/

IE5+ supports a sort of data URI too, it is but not always possible to use it : http://www.betalon.com/blog/html_css/data-uri-in-css-crossbrowser.htm

Using the above to extend the mootools Browser.Features object (if anyone finds it useful, modernizr does not support it)

http://www.jsfiddle.net/dimitar/5JT45/13/show/ or https://gist.github.com/821370

(function() {
    Browser.Features.base64 = null;
    var callback = function() {
        Browser.Features.base64 = this.width == 1 && this.height == 1;        
        // alert(Browser.Features.base64); // true || false
    };

    var img = new Image(), img = document.id(img) || new Element("img");
    img.onload = img.onerror = img.onabort = callback;
    // 1x1 px gif to test with
    img.src = "data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///ywAAAAAAQABAAACAUwAOw==";

})();

Found this plugin for Modernizr on their wiki https://github.com/Modernizr/Modernizr/issues/14:

Modernizr.addTest('datauri',function(){
  var data = new Image();
  data.onload = data.onerror = function(){
    return (this.width == 1 && this.height == 1);
  }
  data.src = "data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///ywAAAAAAQABAAACAUwAOw==";
})