Update (Sept. 3, 2010)

• This article originally has the filter and -ms-filter rules reversed, which is against Microsoft’s best practices for IE8. This error has been corrected.
• Thanks to Zoe Mickley Gillenwater for pointing out that IE8 needs to have all the filter functions (i.e. all the stuff in the double quotes) on one line.

The modern web developer wants to be able to use a variety of CSS3 effects together, but sometimes doing this in IE can be challenging, especially if you don’t want to use JavaScript. Let’s take a look a common problem with IE: blocky text in IE when using IE Visual filters on a block of text. For example, if you’ve ever tried to do the cross-browser CSS opacity trick to implement opacity in IE6, this problem manifests itself when the text is styled with no background color. A developer uses this well-known cross browser CSS-foo to make this work:

#badAntiAliasing {
	opacity: 0.5;

        /* IE 8 */
        -ms-filter: "progid:DXImageTransform.Microsoft.Alpha(opacity=50)";

        /* IE 6,7 */
	filter: progid:DXImageTransform.Microsoft.Alpha(opacity=50);

}

And it looks great in every browser, but it looks like crap in Internet Explorer 6 with ClearType turned on. It is especially pronounced when using @font-face embedding with fonts that assume that some sort of anti-aliasing technology is being used. The example below uses Graublau Sans Web with the Alpha filter to illustrate the issue:

Opacity Solution in IE	Opacity Solution in every other browser

This has been a known problem with IE ever since 2006 when ClearType’s product manager, Peter Gurevich, announced on the IEBlog their decision to disable ClearType on elements that use any Visual Filter. If you read the comments on this blog article, you will see many upset developers. I was one of them, since this not only affects the Alpha Filter, but all of IE’s Visual Filters, some of which I use in cssSandpaper to get IE to support CSS3 properties like transform.

Today, however, we can rejoice. There is a usable workaround that will make ClearType rendered fonts look nice when using Visual Filters. In our example above, here is what needs to be done:

body.ie6 #goodAntiAliasing,
body.ie7 #goodAntiAliasing,
body.ie8 #goodAntiAliasing {
	background-color: white;
}

#goodAntiAliasing {
	opacity: 0.5;

        /* IE 8: yes, it is ugly but it has to be on one line. :-( */
        -ms-filter: "progid:DXImageTransform.Microsoft.Chroma(color='white') progid:DXImageTransform.Microsoft.Alpha(opacity=50)";

        /* IE 6,7 is more flexible: it can be on multiple lines. */
	filter: progid:DXImageTransform.Microsoft.Chroma(color='white')
                progid:DXImageTransform.Microsoft.Alpha(opacity=50);

}

What is going on here?

1. The first rule sets the background color of the container to a color that is represents the color of the majority of the background image on the page. Note that this rule uses Paul Irish’s Conditional CSS Pattern to serve it only to IE.
2. The second rule executes two of IE’s Visual Filters:
   • the Chroma Visual Filter, which tells IE “Please make this color transparent”. The color we choose to make transparent is the one we selected in the first rule.
   • the Alpha Visual Filter, which does the opacity trick

Default Opacity in IE	New Opacity Solution in IE

These filters must be in the order given, and not the other way around. Note also that care must be given that the color chosen to be transparent should be the average color of what is behind the text being styled, otherwise you will get less than optimal results. If this background is a complex image, just use the colour that’s used most often.

This fixes not only the IE opacity problem, but also issues with other Visual Filters, such as Matrix. I will be updating cssSandpaper to use this trick so that transformed objects in IE won’t look so blocky.

Take a look at the solution in action (make sure you look at it in IE in order to get the full effect)

SVG fonts for Opera and Chrome

Jonathan Snook wrote a great article regarding Opera 10 and Google Chrome supporting SVG fonts (Chrome can load them without any pesky command line switch!).  He mentions how to convert TrueType fonts to this format using Batik, and that by removing all the <hkren> elements inside the file’s XML can make the font smaller than the original TrueType file.  Too bad the browsers don’t support this format.

Opera’s buggy implementation

I noticed after I launched my first @font-face article that Opera was not loading the fonts on my blog when users visited more than one page. It turns out that Opera 10′s implementation of @font-face is a little buggy. When you feed it a page with an embedded font, you may not see the embedded fonts properly, like in the screenshot below:

Opera sometimes doesn't load the font at all, and removes other styling (click to enlarge).

According to Opera, this happens when “specifying different weights and styles for a single font-family name”. Håkon Wium Lie, the company’s Chief Technology Officer , has described a work-around until the company can fix the problem properly.

I am debating whether to implement the work around on my site, or to wait for Opera to fix the problem and patch all Opera 10 installations via auto-update (I’m leaning towards the latter).

Performance Issues With Font Embedding

One of the comments on the last article came from Steve Souders who had performance concerns with font-embedding. Paul Irish came back with information showing the when browsers load the fonts, and what they do before the font is loaded.  He also shows how to use JavaScript to make the loading behaviour consistent between browsers.

The performance issues with font-embedding is something I am going to be keeping an eye on, especially when it comes to font-services, which the OpenType site believes will be the future of web font distribution for commercial fonts. Although it doesn’t seem like much of an issue currently (my blog seems to load quickly), I don’t want to do anything that would slow down my web applications – especially if I am using them just to make the text look a little prettier.

Windows XP Rendering Issues

Boing-Boing had a bad experience with font-embedding. Turns out they got a lot of complaints when they decided to incorporate it into their website. The reason: some users didn’t have ClearType turned on, and the font Boing-Boing chose looked “like ass” without ClearType.

Below are screenshots of this site without ClearType on:

Internet Explorer without ClearType

Firefox without ClearType

The article stated that there are quite a few XP computers which apparently don’t have ClearType on by default. I wonder if there are any stats to back that up. If so, then developers embed fonts into pages should test that scenario as well. It does look different.