This polyfill takes the official CSS Filter Effects syntax, which spec you can find over here and translates it to the different equivalent techniques that the browsers know for those effects:
- Prefixing for WebKit/Blink-based browsers
- Translating into SVG-filters for Firefox
- Translating into DirectX-filters for IE 6-9
For instance, this allows you to assign a property like
filter: blur(10px);
in your stylesheets and the polyfill will take care that it works in as many browsers as possible.
- grayscale*
- sepia*
- blur
- invert*
- brightness
- drop-shadow
Have a look at this overview.
* the IEs only support 0% or 100% values
Currently the polyfill is able to support
- Chrome 20+ (brightness filter 28+),
- Opera 15+
- Safari 6+,
- Yandex 1+,
- Firefox 4+,
- IE 6 - 9 on desktop (IE 6 & 7 slightly degraded),
and
- iOS 6+ Safari/Chrome/Webview
- Chrome 28+ on Android,
- Opera Mobile 14+,
- Blackberry Browser 10+,
- Firefox 4+ on Mobile,
- IE on Windows Phone 7, which just supports grayscale.
Also have a look at http://caniuse.com/css-filters
- IE 10+,
- older Presto-based Operas,
- Opera Mini,
- Android browser
Why is IE 6 - 9 supported, but not IE 10 or higher? Well, since Microsoft decided to switch sides and to now follow standards, they killed their old proprietary filters beginning with IE 10 which I rely on for emulation.
Altough they did introduce SVG filters sadly those are limited to a usage inside SVGs. They cannot be applied to HTML-elements.
Even triggering legacy mode does not help any more. So this is why we are left at the end with no hook/support at all in IE10+ :(
Older Operas with Presto engine are not supported, as they offer none of the hooks I used.
First create a <script> element in which you define the absolute(!) path to the polyfill library (the stuff in the /lib/ subfolder) in a variable named polyfilter_scriptpath, like so:
<script>
var polyfilter_scriptpath = '/css-filters-polyfill/lib/';
</script>This is important both for the old IEs and the web worker script.
Should you not want the document stylesheets to not get automatically parsed, like when your plan is to apply filters only via JavaScript, then you can additionally set a polyfilter_skip_stylesheets switch:
<script>
var polyfilter_scriptpath = '/css-filters-polyfill/lib/';
var polyfilter_skip_stylesheets = true;
</script>Then you link cssParser.js and css-filters-polyfill.js from the polyfill library.
<script src="/css-filters-polyfill/lib/cssParser.js"></script>
<script src="/css-filters-polyfill/lib/css-filters-polyfill.js"></script>In an ideal world you should minify and concatenate both of them together with your other JavaScript. If you don't want your page to get blocked by script-loading you put the scripts way down before the closing </body>. This might lead to some flickering of the filter effects during loading. If you can't live with the short flickering, put the scripts in the <head> of the page. Then it'll be gone, but your page will load slower. You decide.
This polyfill supports filter declarations in embedded (<style>) and external (<link rel="stylesheet">) stylesheets. It does not support inline-styles (i.e. style-attributes).
You define a filter by using the unprefixed W3C syntax, e.g.:
.element{
filter: blur(10px);
}And you can even assign two filters at once, e.g.
.element{
filter: sepia(1) blur(10px);
}In addition the polyfill also extends the JavaScript CSSStyleDeclaration object, so that you can assign filter styles on the fly as you are used to with CSS. But instead of exposing a element.style.filter property as one would think, you instead need to address element.style.polyfilter, e.g.:
element.style.polyfilter = 'blur(10px)';or via jQuery:
$(element).css('polyfilter','blur(10px)');And, again, you can assign two filters at once, e.g.
element.style.polyfilter = 'sepia(1) blur(10px)';Note: This does not work for IE 6 & 7. They just ignore any programmatic assignment.
Likewise, if you want to animate a filter, then you do this:
var value = 0,
increment = 1
elem = document.getElementById('filtered');
window.setInterval(function(){
value += increment;
elem.style.polyfilter = 'blur(' + value + 'px)';
if(value >= 10 || value <= 0) increment *= -1;
},100);Note: This again does not work for IE 6 & 7. They just ignore any programmatic assignment.
If you practice domain sharding and serve your assets from a different domain than the page you have two options to solve the problem of the poylfill not being allowed to refetch the stylesheets:
a) If you use the same domain, just with different subdomains, e.g. www.yourdomain.com + assets.yourdomain.com, then you can set
document.domain = "yourdomain.com";and you are fine.
b) If you use different domains, then you need to activate HTTP CORS headers (Cross-Origin Resource Sharing) on the machine that hosts the stylesheets. If it is an Apache machine you can add the following to its/an .htaccess in its root:
<IfModule mod_headers.c>
<FilesMatch "\.css$">
Header set Access-Control-Allow-Origin "*"
</FilesMatch>
</IfModule>
Or if you want more security, replace the * with the requesting domain:
<IfModule mod_headers.c>
<FilesMatch "\.css$">
Header set Access-Control-Allow-Origin "requestingdomain.com"
</FilesMatch>
</IfModule>
See http://schepp.github.io/CSS-Filters-Polyfill/examples/
Copyright (c) 2012 - 2013 Christian Schepp Schaefer
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