I'm using Fontforge to design a typeface, but I have a problem: I cannot draw round circles! :(

I click the circle tool, then draw the circle in the usual fashion (holding down Shift to get a circle, rather than an ellipse) – but as soon as I let go of the left mouse button, the circle changes and wind up looking all irregular, like this:

A non-round circle, drawn in Fontforge.

Background: I'm working by expanding the GNU FreeSans font (a Truetype font) to which I'm adding glyphs for my own writing system. If I open a new project in Fontforge, drawing circles works just fine.

I'm thinking this has something to do with the fact that PostScript fonts use cubic Bézier curves, while Truetype uses quadratic? (Though this is only a guess on my part.)

According to the "Help > About…" menu, I'm using the following version of Fontforge:

git hash: b9149c13e...
Version: 00:15 UTC 31-Jul-2017

FontForge can draw circles, but the circle primitive does not exist for font outlines. So they get automatically converted to a somewhat close shape using Bézier curves.

While it's possible to approximate a perfect circle with Bézier curves, it is proven to be mathematically impossible.

There is no advantage over using either cubic or quadratic curves, as they are equivalent as far as circles are concerned.

(While it may be possible to draw circles in a totally new font, you will see that as soon as you save such a font as either TrueType or Type 1 – the only outline types that can be used in modern OpenType fonts – they get converted to those same curves.)

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  • Hi, I was having trouble drawing perpendicular lines in fontforge. Is there a simple way? – klaus Mar 1 '19 at 14:59

I think this problem is related to both the cubic/quadratic setting and grid snapping. Are you drawing at a very small scale?

A workaround could be to draw a large circle, and then scale it down. This way you maintain a more circle-like shape.

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  • Does FontForge automatically snap all on and off curve points to the closest integer point? It is not required for Type 1 fonts (although highly recommended), and I don't know if floating point coordinates are even possible for TrueType fonts. It may influence the shape at any size (and particularly for relatively small circles on a coarse design grid). – usr2564301 Feb 13 '18 at 14:30

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