font-Roboto/third_party/fontcrunch

Fontcrunch

By Raph Levien, Google

This is a tool for TrueType font spline optimization - a "simplify" command. It tries to create a visual match for the spline using the smallest number of TrueType points. It is notable for counting on-curve points interpolated between two off-curve points as "free," making useful filesize savings.

It depends on fonttools, and has some legacy dependencies on spiro-0.01 This code is available under the Apache v2 license. Spiro code is GNU GPL v2 or later, and Spiro curves are subject to a US patent.

Create 256 directories named 00 .. ff, and populate them with lots of files with .bz extension. Each of these is a nontrivial segment of quad beziers cut from the font, stored as a x0 y0 x1 y1 x2 y2 line per bezier. Lines are represented with (x1, y1) at the midpoint of the two endpoints.

python fontcrunch.py gen yourfont.ttf

Runs the optimizer on each of the .bz files, producing a .bzopt. You can control the level of precision by editing "penalty" in the code (should of course be a parameter). On a fast computer, it should go through about 5 glyphs a second, depending on complexity.

make -j16 # or whatever level of parallelism makes sense on your computer

Regenerate a new TrueType font. You can look at the outlines to check the quality of the result.

python fontcrunch.py pack yourfont.ttf > /tmp/outlines.ps newfont.ttf