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cssfontstruetypewoff

How to edit/change TTF OS/2 usWeightClass value?

I have the Dosis font which I want to use as a webfont in one of my projects. I can convert the TTF files to WOFF with the Font Squirrel Webfont Generator; nothing new so far. Doing so results in the following error message in the Firefox console:

downloadable font: OS/2: bad weight: 250 (font-family: "dosis" style:normal weight:200 stretch:normal src index:0) source: http://example.com/fonts/dosis-extralight.woff2

The error message is clear and the problem is clear, but I have no clue how I can change the value from 250 to 200 without altering the font in any other way. I tried with FontForge but the newly generated TTF file is completely different than the original. I also tried to use an HEX editor but couldn't make head or tail of the file's content.

Tried it with the “Adobe Font Development Kit for OpenType” and this is the WinMerge DIFF. I can't interpret if this is an issue or not.

enter image description here

Solution

    1. Check if you have got the ttx commandline tool available on your system. If not, follow steps 2-3. If you do, skip to step 4.

    2. Check out this Open Source, multi-platform tool from its Github repository.

    3. Locate the tool ttx in the Tools/osx or Tools/linux or Tools/win folder (whichever is appropriate to your OS platform).

    4. Type ttx -h.

    5. Follow the instructions.

    In short: Run ttx -v -o dosis.xml Dosis-Medium.otf. Edit the generated XML file. Run ttx dosis.xml -o Dosis-Medium-modified.otf. Test your Dosis-Medium-modified.otf.