FreeType patent issue?

Question

Hello all,

http://en.wikipedia.org/wiki/Font_rasterization

Most other systems use the FreeType library, which falls somewhere between Microsoft's and Apple's implementations; it supports hinting and anti-aliasing, and optionally performs subpixel rendering. Due to problems with patent licensing, many binary distributions of it do not support hinting non-Free fonts with the same quality as the Windows and OS X rasterizers, although the functionality is present and easily enabled. The Free fonts included with most Linux distributions look better with FreeType's "auto-hinting" mode, which is high-quality and not encumbered by patents.

What are exactly these "problems with patent licensing"? How can using FreeType affect an ISV?

Regards,

Answer 1

Foreword: This is no legal advice. I am not a lawyer. I'm answering to the best of my knowledge, but I'm just another user.

A strange time to be asking this question, since the patent in question has expired just a few months ago. See the FreeType patents page

TrueType fonts are very complex beasts. Not only do they describe the look of characters using Bézier Curves, they also contain a small virtual machine (much smaller but in concept comparable to Java or .NET) which can execute small byte-code programs helping to turn the curves into pixels.

This byte-code language and virtual machine were patented by apple. FreeType has existed for a very long time in parallel to the patents, shipping with a disabled virtual machine and a work-around algorithm that tried to guess what the byte-code programs might do without looking at them, thereby avoiding the patents. Programmers who had licensed TrueType technology from Apple (or who decided to infringe Apple's patent) could enable FreeType's virtual machine for better text quality.

After Apple's patents expired, FreeType jumped versions from 2.3.x to 2.4.0. All releases from 2.4.0 onwards enable the once patented virtual machine technology by default.

So in summary, FreeType was never in danger of being discarded, but because you were using a library that could be configured to infringe patents, there was a possibility you could have gotten into trouble - up until May 2010.