Use FontForge

Demo Walkthrough

In this example, we're going to convert a .TTF (TrueType Format) into a .BDF (Bitmap Distribution Format). I'm using an open licensed font downloaded from Google Font, Source Serif Pro

Open Font

Use the file menu and choose Open Font from the list. Navigate to a directory where your desired font resides. Select the font and open it.

Set Font Size

From the element menu, select Bitmap Strikes Available. In this dialog, you will need to specific how large you want your font to be. The font size is fixed with Bitmap fonts, so if you want to use different sizes, you'll need to make separate files.

Generate Bits

From the element menu, select Generate Bitmap. Similar to the previous dialog, enter the font size of your liking. You can make it smaller here. Be aware, values too small will not generate BDF's. 

Export Converted Font

From the file menu, select Generate Fonts. In the dialog, select No Outline Font and BDF from the dropdown options. Use the navigation UI to save the file in your directory of choice. Click the generate button to save the file. 

BDF Resolution

This dialog menu will pop up after clicking generate. You can choose one of the options from the list. If you'd like a different font size, you can enter that in the Other labeled input box. Click OK to save it!

Optimize File Size

If you take a look at the file size of the .bdf, it's roughly around 900K – That can be a bit larger than needed, especially if you plan to store a lot of image and sound assets. In cases where you need to save on every byte, you can optimize the file size of your fonts by selecting only the characters you want to use. If you scroll through the full list of glyphs, you'll see there's extra special characters – A whole bunch of them! If you don't need them in your project, just select the basic set of upper/lower and alphanumeric characters. You can click + hold and drag to make selections easier. With them selected, use the Regenerate Bitmap option under the element menu to reprocess the glyphs. Then, select generate font from the file menu and save it out.

Font Colors

The color of the fonts can be setup in your code. The CircuitPython library uses HEX color codes. This is similar to web color pickers but formatted slightly different. Most HEX color pickers use a hashtag in the front of the value, like, #000000. In CircuitPython, instead of a hashtag, 0x is used. Here's a few examples.

  • Black =  0x000000
  • White = 0xFFFFFF
  • Purple = 0x8f42f4
This guide was first published on Feb 18, 2019. It was last updated on Feb 18, 2019. This page (Use FontForge) was last updated on Sep 21, 2019.