Font Validator with rasterization (i.e. hinting) test out now!

Hin-Tak Leung

Hi,

I have re-implemented (part of) the rasterization test - which tests for hinting problems in truetype/opentype fonts. This is the last missing part that Microsoft didn't release last autumn. The 2nd last part was the webkit based XML-viewer bridge a month or two ago. GUI on Linux is functionally complete with this; and with this piece, all the missing/non-portable parts have been more or less re-implemented.

It turns out that FreeType silently works around many hinting problems. A somewhat mundane patch allows it to message out such problems. This forms the basis of the new implementation.   

According to the older 2003 FontVal binary, about 20% of Microsoft's own shipped fonts on win 8 show some degree of problems in this area. Most of them are genuine, although as some might suspect, the older 2003 Font Validator is occasionally buggy... In a nut shell, the new implementation gets FreeType to tell you hinting problems it has been silently working around, and it largely agrees with the (non-buggy part of...) the older Font Validator.

The code is at [1], the windows/dotnet/mono binaries at [2], and technical details in [3]. I'll do the Mac OS X package in a couple of days. Linux users (potential ones? I know of only one - me) needs a patch which was posted to freetype-devel. windows/mac users have patched FreeType bundled in [2].

I uploaded two sets of binaries, one for current-ish computers, (the embedded python interpreter requires dotnet 4+ or mono), the other for the older dotnet v2. The latter without the embedded python interpreter, and what it brought along - the scripts for joining/splitting ttc's etc. Mac OS X package in a couple of days when I get round to it.

And please feel free to click the donate button above the download links.

[1] https://github.com/HinTak/Font-Validator
[2] https://sourceforge.net/projects/hp-pxl-jetready/files/Microsoft%20Font%20Validator/
[3] https://github.com/HinTak/Font-Validator/issues/5

Jason Campbell

So you're using one rasterizer to flag problems in a different rasterizer? I know you think they are very similar, but it doesn't really pass the QA sniff test. 

Hin-Tak Leung

Well, if you own the source code of "the other rasterizer", please feel free to release it under an agreeable license.

Some (many?) hinting errors are independent of rasterizer. One in the new implementation - where hinting instructions refer to control point n, where only m (<n) points have been defined so far, is wrong in whichever rasterizer you care to use. It is a broken font, which ever way you look at it.