UnderstandingFontEmbedding

What it is

Font embedding simply means that when a website is in need for a specific font to display a particular, then this font is downloaded and temporarily installed.

From a designers point of view this is really nice, but there are important issues regarding licensing.

History

Font embedding was introduced by Microsoft with Internet Explorer 4 a long long time ago. This was never adapted by other Browsers, and there was a good reason for that: IE only accepts so-called EOT-fonts. Now this format, although it has clear merits, was owned by Microsoft, and Microsoft never even tried to make it a standard. For that reason others stood away from this format.

In 2009, two things changed: Firstly, Almost all others (with the notable exception of Chrome) browsers started to implement font embedding, although in a very different way. Secondly, Microsoft made the EOT-format public and at the same time started to make it a W3C-accepted standard.

That's good news, although for the time being it means that one has to provide different CSS rules for the IE and all the other browser.

IE and EOT

EOT addresses two important issues:

• It can be reduced to contain not all but only those characters of a particular font which got actually used on a particular web site.

• It can be bound to a particular URL. In other words, only when the font is downloaded from a URL listed in the EOT files will IE use it. These allows to address licensing issues.

The way Microsoft has implemented it is unfortunately different from other browser: You cannot specify "Local" or "Format". If you are interested in details, google for it.

TTF fonts

TTF fonts are used by the rest of the world. Unfortunately there is no way to address licensing issues. Strictly speaking one can use only free fonts with this technique. Good news is that everybody is allowed to distribute "APL385 Unicode" freely.

Converting a TTF font into EOT

To make "APL385 Unicode" available for font embedding in IE, we need an EOT file. Now there is a tool available from Microsoft called WEFT that theoretically allows us to do this, but unfortunately IE won't use the resulting EOT file. The reasons are unknown.

But there is a tools available that can create an EOT file that is used by IE8. Originally it was a UNIX/LINUX project:

http://code.google.com/p/ttf2eot/

but you can

download the Windows version.

This tool has a disadvantage: it does not allow us to bind the EOT-file to a particular URL. In our case, however, it doesn't matter.

The syntax to convert any font is easy; given you are in a directory where the exe as well as the font to be converted is located:

  ttf2eot.exe OLD-FONT.ttf NEW-FONT.eot

Here is CSS code that defines a font "APLFont" from an embedded font. Note that IE must come first, and that the IE part must not contain neither "local" nor "format" - IE doesn't understand them. Note that the link http://misc.aplteam.com/apl385U.eot is real, but of course you should not use it.

/* IE first */
@font-face {
        font-family: 'APLFont';
        src:    url("http://misc.aplteam.com/apl385U.eot");
}

@font-face {
        font-family: 'APLFont';
        src:    url("http://misc.aplteam.com/apl385.ttf");
}

Now "APLFont" can be used in the same way as any other font-family in CSS. An example:

pre{
font-family:"APL385 Unicode","APLX Upright",APLFont,monospace;}

Note that this lets the browser try to use a local "APL385 Unicode" font first. If there is no such font installed on the local machine, it tries to find "APLX Upright". Only when this fails, too, it makes use of the embedded font.

The eot file is available for download.

Author: KaiJaeger

CategoryUnicode